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lists at foxhill

Feb 15, 2010, 12:51 AM

Post #1 of 40 (2740 views)
Permalink
Live TV channel restrictions
I have four DVB-T tuners each configured with four virtual tuners.

With just one tuner recording, it seems that Live TV is restricted to
only getting channels one the same mux as that tuner. Why doesn't it
automatically use a different tuner, either one that's already tuned to
the appropriate mux or one that's totally free? Have I configured
something incorrectly or am I failing to understand how this is
supposed to work.

We're currently transitioning from a Humax PVR9200. This has two
tuners, and handles them fairly sensibly. If it's recording two things
on the same mux, it will record both using one tuner. Live TV then has
no restrictions. If it's recording two things on different muxes, then
Live TV can only get channels on either of those two muxes. Critically,
my wife and daughter don't have to understand the difference between a
channel and a mux (trust me, I tried), they just need to know that
there are times restrictions, and the PVR handles this.

With mythtv, I hoped/assumed that having four (eventually six!) tuners
would pretty much remove all restrictions. The backend would handle
recordings and the four front ends could get any channel with mythtv
handling the selection of tuner.

Regards

Ian



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Jens.Peder.Terjesen at devoteam

Feb 17, 2010, 7:16 AM

Post #2 of 40 (2597 views)
Permalink
Re: Live TV channel restrictions [In reply to]
Ian Oliver wrote:
________________________________________
I have four DVB-T tuners each configured with four virtual tuners.

With just one tuner recording, it seems that Live TV is restricted to
only getting channels one the same mux as that tuner. Why doesn't it
automatically use a different tuner, either one that's already tuned to
the appropriate mux or one that's totally free? Have I configured
something incorrectly or am I failing to understand how this is
supposed to work.

We're currently transitioning from a Humax PVR9200. This has two
tuners, and handles them fairly sensibly. If it's recording two things
on the same mux, it will record both using one tuner. Live TV then has
no restrictions. If it's recording two things on different muxes, then
Live TV can only get channels on either of those two muxes. Critically,
my wife and daughter don't have to understand the difference between a
channel and a mux (trust me, I tried), they just need to know that
there are times restrictions, and the PVR handles this.

With mythtv, I hoped/assumed that having four (eventually six!) tuners
would pretty much remove all restrictions. The backend would handle
recordings and the four front ends could get any channel with mythtv
handling the selection of tuner.

Regards

Ian



_______________________________________________

There is as setting called "Avoid conflicts between live-TV and recordings" or something like that.

I think you find it under "General Settings" but I can't remenber if it is a backend or frontend setting.

Jens
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mtdean at thirdcontact

Feb 17, 2010, 7:08 PM

Post #3 of 40 (2576 views)
Permalink
Re: Live TV channel restrictions [In reply to]
On 02/17/2010 10:16 AM, Terjesen Jens Peder wrote:
> Ian Oliver wrote:
>> I have four DVB-T tuners each configured with four virtual tuners.
>>
>> With just one tuner recording, it seems that Live TV is restricted to
>> only getting channels one the same mux as that tuner. Why doesn't it
>> automatically use a different tuner, either one that's already tuned to
>> the appropriate mux or one that's totally free? Have I configured
>> something incorrectly or am I failing to understand how this is
>> supposed to work.
>>
>> We're currently transitioning from a Humax PVR9200. This has two
>> tuners, and handles them fairly sensibly. If it's recording two things
>> on the same mux, it will record both using one tuner. Live TV then has
>> no restrictions. If it's recording two things on different muxes, then
>> Live TV can only get channels on either of those two muxes. Critically,
>> my wife and daughter don't have to understand the difference between a
>> channel and a mux (trust me, I tried), they just need to know that
>> there are times restrictions, and the PVR handles this.
>>
>> With mythtv, I hoped/assumed that having four (eventually six!) tuners
>> would pretty much remove all restrictions. The backend would handle
>> recordings and the four front ends could get any channel with mythtv
>> handling the selection of tuner.
>
> There is as setting called "Avoid conflicts between live-TV and recordings" or something like that.
>
> I think you find it under "General Settings" but I can't remenber if it is a backend or frontend setting.
>

Also, if you're using multirec, see
http://www.gossamer-threads.com/lists/mythtv/dev/369358#369358 (read the
whole thing, and note that the last solution specified--the one that was
untried at the time--is the best, but if you don't read the whole
message, you won't have all the info you need to make it work).

Also, note that what MythTV is doing is by design. There are valid
reasons for it to behave the way it does rather than using a separate tuner.

Mike
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lists at foxhill

Feb 23, 2010, 6:03 AM

Post #4 of 40 (2443 views)
Permalink
Re: Live TV channel restrictions [In reply to]
In article <4B7CAF18.20004 [at] thirdcontact>, Michael T. Dean wrote:
> Also, if you're using multirec, see
> http://www.gossamer-threads.com/lists/mythtv/dev/369358#369358 (read the
> whole thing, and note that the last solution specified--the one that was
> untried at the time--is the best, but if you don't read the whole
> message, you won't have all the info you need to make it work).

I did read this after posting, but found it discouragingly complex and it also
only looked like a partial solution. However, I guess I need to give it a try.
The bit about "basically tells Myth LiveTV is more important to you than
recordings" concerns me: Live TV isn't more important to us than recordings.
But with four tuners, each with four virtual tuners, the Live TV should nearly
always be able to fine a tuner on the right mux (or free to be tuned to it)
and a spare virtual tuner. If it can't then I'm happy to not get Live TV on
that channel, but in practice, it should never happen.

> Also, note that what MythTV is doing is by design. There are valid
> reasons for it to behave the way it does rather than using a separate tuner.

Even though it means that we can't easily watch what we want on Live TV even
when there are spare tuners and virtual tuners?

Anyway, thanks all for the replies, I'll try the various work-arounds and
explore their limitations.

Regards

Ian



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mtdean at thirdcontact

Feb 23, 2010, 9:07 AM

Post #5 of 40 (2437 views)
Permalink
Re: Live TV channel restrictions [In reply to]
On 02/23/2010 09:03 AM, Ian Oliver wrote:
> In article, Michael T. Dean wrote:
>
>> Also, if you're using multirec, see
>> http://www.gossamer-threads.com/lists/mythtv/dev/369358#369358 (read the
>> whole thing, and note that the last solution specified--the one that was
>> untried at the time--is the best, but if you don't read the whole
>> message, you won't have all the info you need to make it work).
>>
> I did read this after posting, but found it discouragingly complex and it also
> only looked like a partial solution. However, I guess I need to give it a try.
> The bit about "basically tells Myth LiveTV is more important to you than
> recordings" concerns me: Live TV isn't more important to us than recordings.
> But with four tuners, each with four virtual tuners, the Live TV should nearly
> always be able to fine a tuner on the right mux (or free to be tuned to it)
> and a spare virtual tuner. If it can't then I'm happy to not get Live TV on
> that channel, but in practice, it should never happen.
>

The problem the post above "fixes" is that many users complain that once
they start LiveTV, they're locked to the mux from which the capture card
is recording--which is exactly what you were asking about in your
original post. If you always want LiveTV to get a separate physical
tuner, you /are/ saying LiveTV is more important to you than recordings.

MythTV will still tell you that it needs the tuner for a recording if
something starts while you're watching LiveTV, but you've told it to
give a preference to LiveTV by telling it to use a different physical tuner.

>> Also, note that what MythTV is doing is by design. There are valid
>> reasons for it to behave the way it does rather than using a separate tuner.
>>
> Even though it means that we can't easily watch what we want on Live TV even
> when there are spare tuners and virtual tuners?
>
> Anyway, thanks all for the replies, I'll try the various work-arounds and
> explore their limitations.

The post above has a full solution for your situation that does
everything you want. It's not a workaround. It's simply reconfiguring
a DV/Recorder/ so that you can waste your time with LiveTV /and/ so that
doing so is most likely to give you a free physical tuner so you can
change the channel during LiveTV using browse mode (and without having
to go through the pain and suffering involved with hitting a key
(NEXTCARD) or using the EPG to change channels). :)

Note also that NEXTCARD and the EPG are always valid options, too.
They're the solution specified in the first link in the linked post
(i.e. http://www.gossamer-threads.com/lists/mythtv/users/342420#342420 ,
as linked from
http://www.gossamer-threads.com/lists/mythtv/dev/369358#369358 , under
the title, "Best approach: ").

There's also a new setting:

Browse all channels
If enabled, browse mode will shows channels on all available recording
devices, instead of showing channels on just the current recorder.

which, IIRC (I don't use LiveTV), is designed to allow LiveTV users who
are too lazy to go into the EPG the ability to see all channels
available on all tuners and to automatically switch to a different
physical tuner when required. The downside is that--only in LiveTV--it
can make channel changes significantly slower (which is why it's
disabled by default). So, you can decide whether you'd rather every
single channel change is slower in LiveTV, or whether starting LiveTV
gets its own physical tuner to start with (possibly a tuner that will be
required for a recording while LiveTV is running), or whether to just
use NEXTCARD or the EPG (which is pretty much how it's designed to be used).

Mike
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lists at foxhill

Feb 23, 2010, 2:09 PM

Post #6 of 40 (2432 views)
Permalink
Re: Live TV channel restrictions [In reply to]
In article <4B840B51.4000309 [at] thirdcontact>, Michael T. Dean wrote:
> If you always want LiveTV to get a separate physical
> tuner

That isn't what I want. If there is a tuner on the right mux and with a free
virtual tuner, then use it. Failing that, find a free tuner and tune it to the
right mux. Failing that, tell me I can't watch that channel. All PVRs I've met do
pretty much exactly this.

> you /are/ saying LiveTV is more important to you than recordings.

It isn't. Our dual tuner PVR is shoddy in many ways but it hides tuners very
well. It can do 1 or 2 recordings on one mux + live tv on any channel OR 2x
recordings on different muxes and live TV on only available channels.

> MythTV will still tell you that it needs the tuner for a recording if
> something starts while you're watching LiveTV

Telling me is OK, but if I don't respond, I hope it grabs the tuner, but only
when there is no other option.

> but you've told it to
> give a preference to LiveTV by telling it to use a different physical tuner.

How do I do that? Might I be better to buy some HDHRs an reserve these for Live
TV?

> The post above has a full solution for your situation that does
> everything you want. It's not a workaround.

OK, guess I need to try and it see if there are any limitations that are imposed
by the software rather than the hardware.

> so that you can waste your time with LiveTV

Pardon? Just because person A might not like watching news or sport live doesn't
mean that person B is wasting their time by doing so.

> the pain and suffering involved with hitting a key
> (NEXTCARD)

I'm starting to sense a certain attitude. :-(

Wife+daughter want to select a channel. If showing this channel involves the
software having to handle those mux things they don't understand, then said
software should do it to the best of its abilities. If the software cannot do it
because the underlying hardware has no resources to do it, then so be it; they
accept limitations. But having four tuners, each with four virtual tuners, and
having more limitations and hassle than the dual-tuner PVR we are replacing,
caused consternation. Surely as software engineers we can understand that said
consternation is justified?

> Browse all channels
> If enabled, browse mode will shows channels on all available recording
> devices, instead of showing channels on just the current recorder.

I'll try that, but am not sure it will help. We tried typing in channel numbers,
and despite the three free tuners, Live TV would not use anything other than the
first tuner, which was recording on the "wrong" mux.

> is designed to allow LiveTV users who
> are too lazy to go into the EPG

Again, "lazy" is a loaded word. They aren't lazy - they just want the GUI to let
them watch the channel they want to watch. If the underlying hardware can handle
this, why make them jump through hoops?

> So, you can decide whether you'd rather every
> single channel change is slower in LiveTV

That sounds undesirable.

> or whether starting LiveTV
> gets its own physical tuner to start with (possibly a tuner that will be
> required for a recording while LiveTV is running)

That sounds even worse, unless I add a slew of tuners just for Live TV.

> or whether to just
> use NEXTCARD

That sounds hard to explain to people who just want to choose a channel.

> or the EPG (which is pretty much how it's designed to be used).

What do you mean by using the EPG? We use the guide to record programs, but I'm
talking about watching Live TV without recording it.

Currently, we're using our sucky old dual-tuner PVR for watching Live TV as it
does a better job of it than our 4xtuner+4xvirtual mythtv setup. We can continue
to do this, but it does seem a shame that mythtv isn't rather more flexible in
this regard.

I'm happy to add more hardware if it helps, but it sounds like mythtv doesn't
current make best use of available hardware, so I doubt it will help,

Ian



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mtdean at thirdcontact

Feb 23, 2010, 2:27 PM

Post #7 of 40 (2423 views)
Permalink
Re: Live TV channel restrictions [In reply to]
On 02/23/2010 05:09 PM, Ian Oliver wrote:
> In article, Michael T. Dean wrote:
>> so that you can waste your time with LiveTV
>>
> Pardon? Just because person A might not like watching news or sport live doesn't
> mean that person B is wasting their time by doing so.
>

http://www.gossamer-threads.com/lists/mythtv/users/387302#387302 --even
news and sports should be recordings and not LiveTV.

>> or the EPG (which is pretty much how it's designed to be used).
>>
> What do you mean by using the EPG? We use the guide to record programs, but I'm
> talking about watching Live TV without recording it.
>

MENU|Program Guide (or something to that effect)

or, better,

GUIDE (by default, S)

while watching LiveTV.

> Currently, we're using our sucky old dual-tuner PVR for watching Live TV as it
> does a better job of it than our 4xtuner+4xvirtual mythtv setup. We can continue
> to do this, but it does seem a shame that mythtv isn't rather more flexible in
> this regard.
>
> I'm happy to add more hardware if it helps, but it sounds like mythtv doesn't
> current make best use of available hardware, so I doubt it will help,
>

You have to configure it as I described. What you get with MythTV is a
Digital Video /Recorder/. If you want to make LiveTV important, you
have to configure it to be.

If you want to understand my attitude, write a patch to make MythTV work
the way you want and /without/ any of the issues/downsides I've
mentioned. Only then will you understand that you're asking for the
impossible. You /must/ give up something to get what you want. All the
info you need is in the linked posts, plus my previous post with the
mention of the "Browse all channels" setting.

Mike
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totallymaxed at gmail

Feb 23, 2010, 2:47 PM

Post #8 of 40 (2417 views)
Permalink
Re: Live TV channel restrictions [In reply to]
On Tue, Feb 23, 2010 at 10:09 PM, Ian Oliver <lists [at] foxhill> wrote:

> In article <4B840B51.4000309 [at] thirdcontact>, Michael T. Dean wrote:
> > If you always want LiveTV to get a separate physical
> > tuner
>
> That isn't what I want. If there is a tuner on the right mux and with a
> free
> virtual tuner, then use it. Failing that, find a free tuner and tune it to
> the
> right mux. Failing that, tell me I can't watch that channel. All PVRs I've
> met do
> pretty much exactly this.
>
> > you /are/ saying LiveTV is more important to you than recordings.
>
> It isn't. Our dual tuner PVR is shoddy in many ways but it hides tuners
> very
> well. It can do 1 or 2 recordings on one mux + live tv on any channel OR 2x
> recordings on different muxes and live TV on only available channels.
>
> > MythTV will still tell you that it needs the tuner for a recording if
> > something starts while you're watching LiveTV
>
> Telling me is OK, but if I don't respond, I hope it grabs the tuner, but
> only
> when there is no other option.
>
> > but you've told it to
> > give a preference to LiveTV by telling it to use a different physical
> tuner.
>
> How do I do that? Might I be better to buy some HDHRs an reserve these for
> Live
> TV?
>
> > The post above has a full solution for your situation that does
> > everything you want. It's not a workaround.
>
> OK, guess I need to try and it see if there are any limitations that are
> imposed
> by the software rather than the hardware.
>
> > so that you can waste your time with LiveTV
>
> Pardon? Just because person A might not like watching news or sport live
> doesn't
> mean that person B is wasting their time by doing so.
>
> > the pain and suffering involved with hitting a key
> > (NEXTCARD)
>
> I'm starting to sense a certain attitude. :-(
>
> Wife+daughter want to select a channel. If showing this channel involves
> the
> software having to handle those mux things they don't understand, then said
> software should do it to the best of its abilities. If the software cannot
> do it
> because the underlying hardware has no resources to do it, then so be it;
> they
> accept limitations. But having four tuners, each with four virtual tuners,
> and
> having more limitations and hassle than the dual-tuner PVR we are
> replacing,
> caused consternation. Surely as software engineers we can understand that
> said
> consternation is justified?
>
> > Browse all channels
> > If enabled, browse mode will shows channels on all available recording
> > devices, instead of showing channels on just the current recorder.
>
> I'll try that, but am not sure it will help. We tried typing in channel
> numbers,
> and despite the three free tuners, Live TV would not use anything other
> than the
> first tuner, which was recording on the "wrong" mux.
>
> > is designed to allow LiveTV users who
> > are too lazy to go into the EPG
>
> Again, "lazy" is a loaded word. They aren't lazy - they just want the GUI
> to let
> them watch the channel they want to watch. If the underlying hardware can
> handle
> this, why make them jump through hoops?
>
> > So, you can decide whether you'd rather every
> > single channel change is slower in LiveTV
>
> That sounds undesirable.
>
> > or whether starting LiveTV
> > gets its own physical tuner to start with (possibly a tuner that will be
> > required for a recording while LiveTV is running)
>
> That sounds even worse, unless I add a slew of tuners just for Live TV.
>
> > or whether to just
> > use NEXTCARD
>
> That sounds hard to explain to people who just want to choose a channel.
>
> > or the EPG (which is pretty much how it's designed to be used).
>
> What do you mean by using the EPG? We use the guide to record programs,
> but I'm
> talking about watching Live TV without recording it.
>
> Currently, we're using our sucky old dual-tuner PVR for watching Live TV as
> it
> does a better job of it than our 4xtuner+4xvirtual mythtv setup. We can
> continue
> to do this, but it does seem a shame that mythtv isn't rather more flexible
> in
> this regard.
>
> I'm happy to add more hardware if it helps, but it sounds like mythtv
> doesn't
> current make best use of available hardware, so I doubt it will help,
>
> Ian
>
>
Ian,

I totally agree with your perspective on this issue. Below i describe a fix
for this that we have in development;

We are working on a patch to MythTV 0.21 that does exactly what you are
describing for LiveTV & for scheduler recordings too - ie MythTV
automagically manages multirec tuners so that it always makes sure that if a
multirec tuner is already tuned to a channel from a given MUX that
subsequent requests from either LiveTV viewing or the scheduler for other
channels on that MUX are allocated to a Multirec tuner derived from that
same physical tuner...if no physical tuner is delivering channels from the
MUX required then a new Multirec tuner will be allocated on an unused
physical tuner. This means that there is never a situation where you can
have two physical tuners tuned to the same MUX. All of this is automatically
handled for the user and no manual tuner selection is required. Alongside
the above we have removed the limitation of only 5 multirec tuners per
physical tuner.

We have the LiveTV part of the above working well now and are just starting
working on integrating and testing the recordings scheduler so that it uses
the same logic now. As soon as we have the scheduler working we will release
a patch for MythTV 0.21 and then we hope to test and then commit a 0.22
version subsequently.

All the best


Andrew


mtdean at thirdcontact

Feb 23, 2010, 3:42 PM

Post #9 of 40 (2425 views)
Permalink
Re: Live TV channel restrictions [In reply to]
On 02/23/2010 05:47 PM, Andrew Herron wrote:
> I totally agree with your perspective on this issue. Below i describe
> a fix for this that we have in development;
>
> We are working on a patch to MythTV 0.21 that does exactly what you
> are describing for LiveTV & for scheduler recordings too - ie MythTV
> automagically manages multirec tuners so that it always makes sure
> that if a multirec tuner is already tuned to a channel from a given
> MUX that subsequent requests from either LiveTV viewing or the
> scheduler for other channels on that MUX are allocated to a Multirec
> tuner derived from that same physical tuner...if no physical tuner is
> delivering channels from the MUX required then a new Multirec tuner
> will be allocated on an unused physical tuner.

MythTV already does this. That's the crux of the problem that Ian is
describing.

> This means that there is never a situation where you can have two
> physical tuners tuned to the same MUX.

That would be new--i.e. causing MythTV to "jump tuners" from whatever
("later") tuner it's using to (an "earlier") one that's already tuned to
a mux when the LiveTV user requests a channel change.

It would also have effects on future recordings and the schedule (as if
LiveTV locks that tuner to the mux that /was/ in use and the scheduler
had planned to change to a different mux for the next recording...).

> All of this is automatically handled for the user and no manual tuner
> selection is required.

Which is "Browse all channels" (which was added to MythTV for version
0.22 and is disabled by default).

> Alongside the above we have removed the limitation of only 5 multirec
> tuners per physical tuner.

You do realize that limitation was put there because there are
significant scalability problems with multirec that become progressively
worse as the number of virtual tuners increases past 5.

> We have the LiveTV part of the above working well now and are just
> starting working on integrating and testing the recordings scheduler
> so that it uses the same logic now. As soon as we have the scheduler
> working we will release a patch for MythTV 0.21 and then we hope to
> test and then commit a 0.22 version subsequently.

So, other than the one new feature I mentioned, it sounds like you guys
have just implemented, "Browse all channels," in MythTV 0.21.

If, in fact, your implementation is better than the one we have now, the
patch is appreciated, but please ensure you do proper research before
submitting the patch and describe exactly what's different from what we
currently have (other than 0.21-fixes support :).

Mike

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totallymaxed at gmail

Feb 23, 2010, 4:23 PM

Post #10 of 40 (2413 views)
Permalink
Re: Live TV channel restrictions [In reply to]
On Tue, Feb 23, 2010 at 11:42 PM, Michael T. Dean
<mtdean [at] thirdcontact>wrote:

> On 02/23/2010 05:47 PM, Andrew Herron wrote:
>
>> I totally agree with your perspective on this issue. Below i describe a
>> fix for this that we have in development;
>>
>> We are working on a patch to MythTV 0.21 that does exactly what you are
>> describing for LiveTV & for scheduler recordings too - ie MythTV
>> automagically manages multirec tuners so that it always makes sure that if a
>> multirec tuner is already tuned to a channel from a given MUX that
>> subsequent requests from either LiveTV viewing or the scheduler for other
>> channels on that MUX are allocated to a Multirec tuner derived from that
>> same physical tuner...if no physical tuner is delivering channels from the
>> MUX required then a new Multirec tuner will be allocated on an unused
>> physical tuner.
>>
>
> MythTV already does this. That's the crux of the problem that Ian is
> describing.
>
>
> This means that there is never a situation where you can have two physical
>> tuners tuned to the same MUX.
>>
>
> That would be new--i.e. causing MythTV to "jump tuners" from whatever
> ("later") tuner it's using to (an "earlier") one that's already tuned to a
> mux when the LiveTV user requests a channel change.
>

Mike - as I said in my original post we have this working now...and it works
well and it avoids the situation that Ian describes whereby currently MythTV
may double up Tuners and have them delivering channels from the same MUX.


>
> It would also have effects on future recordings and the schedule (as if
> LiveTV locks that tuner to the mux that /was/ in use and the scheduler had
> planned to change to a different mux for the next recording...).


Which is why we are implementing the same Tuner management for the Scheduler
currently.


>
>
> All of this is automatically handled for the user and no manual tuner
>> selection is required.
>>
>
> Which is "Browse all channels" (which was added to MythTV for version 0.22
> and is disabled by default).


But the standard Myth implementation still double allocates tuners and
wastes resources as Ian describes. Our code optimises physical tuner usage
and does that automatically for the user.


>
>
> Alongside the above we have removed the limitation of only 5 multirec
>> tuners per physical tuner.
>>
>
> You do realize that limitation was put there because there are significant
> scalability problems with multirec that become progressively worse as the
> number of virtual tuners increases past 5.


We currently are successfully testing with 10 multirec tuners per physical
tuner and we see no such performance issues to date. As I write this one of
the test backends is utilising 7 multirec tuners on one physical tuner and
4 each on the other two tuners. We are regularly testing with 20+ multirec
tuners in use concurrently across 3 physical tuners.


>
>
> We have the LiveTV part of the above working well now and are just
>> starting working on integrating and testing the recordings scheduler so that
>> it uses the same logic now. As soon as we have the scheduler working we will
>> release a patch for MythTV 0.21 and then we hope to test and then commit a
>> 0.22 version subsequently.
>>
>
> So, other than the one new feature I mentioned, it sounds like you guys
> have just implemented, "Browse all channels," in MythTV 0.21.
>

Well the efficient use of multirec tuners is really at the core of what we
are doing. The current way MythTV handles multirec tuners in this respect is
not optimal and it is this change that really addresses the issues that Ian
raises in his original post. Optimising the allocation of multirec tuners
both when the user is consuming LiveTV and when the Scheduler is managing
recordings is what this is about - and to achieve that we have to have
MythTV do the management automatically for us.


>
> If, in fact, your implementation is better than the one we have now, the
> patch is appreciated, but please ensure you do proper research before
> submitting the patch and describe exactly what's different from what we
> currently have (other than 0.21-fixes support :).
>

We will do the above and i hope that what we have done will prove to be a
valuable enhancement to MythTV that anyone who uses multirec like we all do
will find useful.

Andrew


mtdean at thirdcontact

Feb 23, 2010, 4:35 PM

Post #11 of 40 (2416 views)
Permalink
Re: Live TV channel restrictions [In reply to]
On 02/23/2010 07:23 PM, Andrew Herron wrote:
> On Tue, Feb 23, 2010 at 11:42 PM, Michael T. Dean wrote
>> Alongside the above we have removed the limitation of only 5 multirec
>>
>>> tuners per physical tuner.
>>>
>> You do realize that limitation was put there because there are significant
>> scalability problems with multirec that become progressively worse as the
>> number of virtual tuners increases past 5.
>>
> We currently are successfully testing with 10 multirec tuners per physical
> tuner and we see no such performance issues to date. As I write this one of
> the test backends is utilising 7 multirec tuners on one physical tuner and
> 4 each on the other two tuners. We are regularly testing with 20+ multirec
> tuners in use concurrently across 3 physical tuners.
>

It's the scheduler itself that slows with more virtual recorders. Try
running complete reschedules with varying numbers of virtual tuners.
Also, if your patch doesn't obsolete and remove the "Browse all
channels" setting, try with and without that setting using varying
numbers of virtual tuners.

>> If, in fact, your implementation is better than the one we have now, the
>> patch is appreciated, but please ensure you do proper research before
>> submitting the patch and describe exactly what's different from what we
>> currently have (other than 0.21-fixes support :).
>>
> We will do the above and i hope that what we have done will prove to be a
> valuable enhancement to MythTV that anyone who uses multirec like we all do
> will find useful.
>

Great. With a good description of what you've done and how it differs
from/improves upon all of the many pieces we have involved with
multirec, it will make it a lot easier for someone to review the patch.
I'm looking forward to seeing the patch.

Oh, and if it decreases the number of settings we have (as it sounds
like it may), I'll definitely love that part of it. :)

Thanks,
Mike
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totallymaxed at gmail

Feb 23, 2010, 7:12 PM

Post #12 of 40 (2408 views)
Permalink
Re: Live TV channel restrictions [In reply to]
On Wed, Feb 24, 2010 at 12:35 AM, Michael T. Dean
<mtdean [at] thirdcontact>wrote:

> On 02/23/2010 07:23 PM, Andrew Herron wrote:
>
>> On Tue, Feb 23, 2010 at 11:42 PM, Michael T. Dean wrote
>>
>> Alongside the above we have removed the limitation of only 5 multirec
>>>
>>>
>>>> tuners per physical tuner.
>>>>
>>>>
>>> You do realize that limitation was put there because there are
>>> significant
>>> scalability problems with multirec that become progressively worse as the
>>> number of virtual tuners increases past 5.
>>>
>>>
>> We currently are successfully testing with 10 multirec tuners per physical
>> tuner and we see no such performance issues to date. As I write this one
>> of
>> the test backends is utilising 7 multirec tuners on one physical tuner
>> and
>> 4 each on the other two tuners. We are regularly testing with 20+ multirec
>> tuners in use concurrently across 3 physical tuners.
>>
>>
>
> It's the scheduler itself that slows with more virtual recorders. Try
> running complete reschedules with varying numbers of virtual tuners. Also,
> if your patch doesn't obsolete and remove the "Browse all channels" setting,
> try with and without that setting using varying numbers of virtual tuners.
>
>
> If, in fact, your implementation is better than the one we have now, the
>>> patch is appreciated, but please ensure you do proper research before
>>> submitting the patch and describe exactly what's different from what we
>>> currently have (other than 0.21-fixes support :).
>>>
>>>
>> We will do the above and i hope that what we have done will prove to be a
>> valuable enhancement to MythTV that anyone who uses multirec like we all
>> do
>> will find useful.
>>
>>
>
> Great. With a good description of what you've done and how it differs
> from/improves upon all of the many pieces we have involved with multirec, it
> will make it a lot easier for someone to review the patch. I'm looking
> forward to seeing the patch.
>
> Oh, and if it decreases the number of settings we have (as it sounds like
> it may), I'll definitely love that part of it. :)
>
> Thanks,
>
> Mike
>

Hi Mike,

Just to give you a taster...This is the current patch. It's a bit ugly in my
opinion, but OK for work in progress (things will move some more).

This patch requires unique channel numbers. Identical channel numbers on two
or more sources doesn't work, and any collisions must be fixed, or the other
channels will be rendered inaccessible - first result returned by SQL is
always used. So far, the work centered around DVB-T and DVB-S cards. Capture
card channels (with channel changer script) fail to switch from one channel
to another because right now the ShouldSwitchToAnotherCard function is
short-circuited to always return true and Myth excludes the current tuner
when "it should switch", which results in a popup box saying all tuners are
busy. This will be addressed in the very near future.

This patch only addresses live tv. It doesn't fix browse mode, and
collisions between scheduled recordings and Live TV can result in anything
from an inconvenience - you have to restart Live TV - to a missed recording.

Target is to change the way recorders work: have "infinite" multirec support
built into the TVRec class, and also have the recordings scheduler pick a
tuner on the fly, just in time to record the program, rather than
pre-schedule it, in order to have optimum tuner usage across the board.

What would happen if all the tuners are in use and a recording is about to
start and there's no tuner for it - especially if the tuners are busy due to
different people watching different things on Live TV throughout the house,
is still up to debate, and there may not be a "one size fits all" solution
to it.

The patch is for Myth 0.21+fixes20787 from Avenard's VDPAU-patched sources,
but it should give you a clear insight of what we're doing though, even if
it's not ready for prime time. One more thing this patch does not include
the change to allow for more multirec tuners - that is a separate and simple
patch though and I will post it if it would be useful to anyone on the list.

Any insight would be appreciated Mike, cheers.


Andrew



--
Head of Software & Technology
Convergent Home Technologies Ltd
www.dianemo.co.uk
www.cascade-media.co.uk
Attachments: find_another_tuner_live_tv.patch (12.1 KB)


lists at foxhill

Feb 24, 2010, 1:00 AM

Post #13 of 40 (2382 views)
Permalink
Re: Live TV channel restrictions [In reply to]
In article <4B845636.5060602 [at] thirdcontact>, Michael T. Dean wrote:

> MENU|Program Guide (or something to that effect)
>
> or, better,
>
> GUIDE (by default, S)
>
> while watching LiveTV.

I know how to get the guide up, just not how to use it to watch Live TV.

> write a patch to make MythTV work
> the way you want and /without/ any of the issues/downsides I've
> mentioned.
> Only then will you understand that you're asking for the
> impossible. You /must/ give up something to get what you want.

Have you ever used another PVR such as the Humax dual-tuner models? They manage to
make Live TV far more seamless than mythtv does despite far fewer underlying
hardware resources. They don't prioritise Live TV over recordings (the exact
opposite), they do make smart use of tuners to keep one free for Live TV if
possible, and they do let you select any Live TV channel that it's physically
possible to let you select without any extra hoop jumping.

If it isn't easy/possible to get mythtv to perform as well as or better than
existing PVRs do, then perhaps we're looking at software architecture issues?

> All the
> info you need is in the linked posts, plus my previous post with the
> mention of the "Browse all channels" setting.

I did give Browse All Channels a quick go, but it also seemed to refuse to let me
select a channel that was on a different mux. I'll try again now that I've done a
load of updates.

Ian



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http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users


lists at foxhill

Feb 24, 2010, 1:00 AM

Post #14 of 40 (2377 views)
Permalink
Re: Live TV channel restrictions [In reply to]
In article <71798b431002231447s37173807laa3b8cf7724ed773 [at] mail>,
Andrew Herron wrote:
> I totally agree with your perspective on this issue.

Thanks, that's good to know! But can I repeat that I'm not the one who needs
to be happy: the target audience is my wife and daughter. They want to turn on
the TV, select a channel, and it just to happen. They (grudgingly) accept that
there are at times good reasons why things aren't possible, but I sold mythtv
to them as a "just add tuners until it works" solution.

> We are working on a patch to MythTV 0.21 that does exactly what you are
> describing for LiveTV & for scheduler recordings too - ie MythTV
> automagically manages multirec tuners so that it always makes sure that if a
> multirec tuner is already tuned to a channel from a given MUX that
> subsequent requests from either LiveTV viewing or the scheduler for other
> channels on that MUX are allocated to a Multirec tuner derived from that
> same physical tuner...if no physical tuner is delivering channels from the
> MUX required then a new Multirec tuner will be allocated on an unused
> physical tuner.

That sounds perfect.

> This means that there is never a situation where you can
> have two physical tuners tuned to the same MUX.

I'm guessing that one exception to this is when recordings+live exceed the
number of virtual tuners on that mux?

> All of this is automatically
> handled for the user and no manual tuner selection is required. Alongside
> the above we have removed the limitation of only 5 multirec tuners per
> physical tuner.

It's now sounding even better! I've currently set 4 virtual tuners per DVB-T
USB stick, but this is really because I just don't understand the
software/system limitations yet.

> We have the LiveTV part of the above working well now and are just starting
> working on integrating and testing the recordings scheduler so that it uses
> the same logic now.

I'm hoping that recordings are prioritised over Live TV and will boot it off
the tuner if required?

> As soon as we have the scheduler working we will release
> a patch for MythTV 0.21 and then we hope to test and then commit a 0.22
> version subsequently.

Excellent, many thanks. Mythtv is close to perfect as a PVR and getting Live
TV to the same level will be the icing on the cake. I'm looking forwards to
retiring all the gubbins in our stair cupboard, and my a/v and remote
distribution systems, and having mythtv as the "one true solution"

Regards

Ian



_______________________________________________
mythtv-users mailing list
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http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users


lists at foxhill

Feb 24, 2010, 1:00 AM

Post #15 of 40 (2376 views)
Permalink
Re: Live TV channel restrictions [In reply to]
In article <71798b431002231912q6dbb98a1j6ecce56379437e5e [at] mail>,
Andrew Herron wrote:
> What would happen if all the tuners are in use and a recording is about to
> start and there's no tuner for it - especially if the tuners are busy due to
> different people watching different things on Live TV throughout the house,
> is still up to debate, and there may not be a "one size fits all" solution
> to it.

Personally, I would always prioritise recordings. Our use case is that
important stuff gets recorded and Live TV is stuck on in the morning and
evening to catch the current news, weather and traffic in an ad-hoc and low
priority way.

My problem is that this used to be slick. Our PVR is set to auto-standby over
night and then come on tuned to BBC News 24 first thing on a morning. So the
TV gets turned on, and there is the news. I'm planning on doing the same with
mythtv using the WOL and the telnet socket, but I first need to be more
confident with Live TV so I can slowly wean everyone off the old PVR.

Ian



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lists at foxhill

Feb 24, 2010, 1:00 AM

Post #16 of 40 (2375 views)
Permalink
Re: Live TV channel restrictions [In reply to]
In article <4B8467FC.5080009 [at] thirdcontact>, Michael T. Dean wrote:
> if
> LiveTV locks that tuner to the mux that /was/ in use and the scheduler
> had planned to change to a different mux for the next recording.

My (admittedly naive!) angle on this is that Live TV shouldn't be
"locking" or "grabbing" anything. It gets to use virtual tuners that are
free, it also gets to tune a tuner that's free if there isn't one on the
right mux, but if a recording comes along and needs the resource, then
tough!

Ian



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mtdean at thirdcontact

Feb 24, 2010, 1:11 AM

Post #17 of 40 (2360 views)
Permalink
Re: Live TV channel restrictions [In reply to]
On 02/24/2010 04:00 AM, Ian Oliver wrote:
> Michael T. Dean wrote:
>
>> if
>> LiveTV locks that tuner to the mux that /was/ in use and the scheduler
>> had planned to change to a different mux for the next recording.
>>
> My (admittedly naive!) angle on this is that Live TV shouldn't be
> "locking" or "grabbing" anything. It gets to use virtual tuners that are
> free, it also gets to tune a tuner that's free if there isn't one on the
> right mux, but if a recording comes along and needs the resource, then
> tough!
>

Make sure you tell that to the person who selected, "Record it later, I
want to watch TV," when the popup came up saying that the tuner was
needed for a recording--then maybe it won't happen a 2nd time.

Mike
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totallymaxed at gmail

Feb 24, 2010, 1:33 AM

Post #18 of 40 (2357 views)
Permalink
Re: Live TV channel restrictions [In reply to]
HI Ian,

On Wed, Feb 24, 2010 at 9:00 AM, Ian Oliver <lists [at] foxhill> wrote:

> In article <71798b431002231447s37173807laa3b8cf7724ed773 [at] mail>,
> Andrew Herron wrote:
> > I totally agree with your perspective on this issue.
>
> Thanks, that's good to know! But can I repeat that I'm not the one who
> needs
> to be happy: the target audience is my wife and daughter. They want to turn
> on
> the TV, select a channel, and it just to happen. They (grudgingly) accept
> that
> there are at times good reasons why things aren't possible, but I sold
> mythtv
> to them as a "just add tuners until it works" solution.
>

Our target audience is your wife & daughter too...or to be precise their
equivalents in other families ;-)


>
> > We are working on a patch to MythTV 0.21 that does exactly what you are
> > describing for LiveTV & for scheduler recordings too - ie MythTV
> > automagically manages multirec tuners so that it always makes sure that
> if a
> > multirec tuner is already tuned to a channel from a given MUX that
> > subsequent requests from either LiveTV viewing or the scheduler for other
> > channels on that MUX are allocated to a Multirec tuner derived from that
> > same physical tuner...if no physical tuner is delivering channels from
> the
> > MUX required then a new Multirec tuner will be allocated on an unused
> > physical tuner.
>
> That sounds perfect.
>
> > This means that there is never a situation where you can
> > have two physical tuners tuned to the same MUX.
>
> I'm guessing that one exception to this is when recordings+live exceed the
> number of virtual tuners on that mux?
>

No in fact we see no point in allocating another physical tuner to an
already tuned MUX. We're testing how multirec tuners scale beyond 10
instances (see Mikes earlier comments about possible performance bottlenecks
in multirec) - so far we're getting very positive performance stats on this
though.


>
> > All of this is automatically
> > handled for the user and no manual tuner selection is required. Alongside
> > the above we have removed the limitation of only 5 multirec tuners per
> > physical tuner.
>
> It's now sounding even better! I've currently set 4 virtual tuners per
> DVB-T
> USB stick, but this is really because I just don't understand the
> software/system limitations yet.
>
> > We have the LiveTV part of the above working well now and are just
> starting
> > working on integrating and testing the recordings scheduler so that it
> uses
> > the same logic now.
>
> I'm hoping that recordings are prioritised over Live TV and will boot it
> off
> the tuner if required?
>

The existing setup options will allow you to customise this to your
preference.


>
> > As soon as we have the scheduler working we will release
> > a patch for MythTV 0.21 and then we hope to test and then commit a 0.22
> > version subsequently.
>
> Excellent, many thanks. Mythtv is close to perfect as a PVR and getting
> Live
> TV to the same level will be the icing on the cake. I'm looking forwards to
> retiring all the gubbins in our stair cupboard, and my a/v and remote
> distribution systems, and having mythtv as the "one true solution"
>
> Regards
>
> Ian
>
>

--
Head of Software & Technology
Convergent Home Technologies Ltd
www.dianemo.co.uk
www.cascade-media.co.uk


tortise at paradise

Feb 24, 2010, 1:46 AM

Post #19 of 40 (2356 views)
Permalink
Re: Live TV channel restrictions [In reply to]
----- Original Message -----
From: "Ian Oliver" <lists [at] foxhill>
To: <mythtv-users [at] mythtv>
Sent: Wednesday, February 24, 2010 11:09 AM
Subject: Re: [mythtv-users] Live TV channel restrictions

Interesting thread that I've just come across that also interests me and my familial "clients".

In article <4B840B51.4000309 [at] thirdcontact>, Michael T. Dean wrote:
> If you always want LiveTV to get a separate physical
> tuner

>That isn't what I want. If there is a tuner on the right mux and with a free
virtual tuner, then use it. Failing that, find a free tuner and tune it to the
right mux. Failing that, tell me I can't watch that channel. All PVRs I've met do
pretty much exactly this.

I think this "if" logic is flawed. (I assume LiveTV needs a free dedicated tuner, not a shared Tuner, it should first hunt for a
free tuner. An assumption here is that the code is not setup to directly jump tuners to use a tuner which is already pulling a mux,
when there remain free virtual tuners on the tuner.)

I suggest a useful perspective is that LiveTV is a different beast to a recording mux and they merit recognition of their
differences in their treatment.

A LiveTV Tuner is ideally locked to one tuner - why - because a Live user may want to choose any channel from any mux anytime.

A Rec Tuner is distinguished by not having an enduser who is going to demand the tuner change any time to any mux.

These distinctions seem fundamental to me.

So, from a different perspective, what is an ideal number of tuners? That depends. The most efficient number of tuners one should
ever want should be {[number of mux] + [number of LiveTV viewers]}

[number of LiveTV viewers] deserves further clarification, that is not the number of frontends, rather it is the maximum number
simultaneous Frontend viewers likely or perhaps possible. So in a house with 6 frontends but only 3 people present 3 is likely to
be enough for [number of LiveTV viewers].

To highlight that the current mythtv setup is a problem, consider we have 3 muxs here, I have 4 (multirec) tuners (T0, T1, T2 and
T3) and I have enabled LiveTV selecting a free Tuner. (I forget the exact phrase) Multirec recordings start at T0 and work their
way up, T0, T1, T2 - and that is all that's needed for all combination of recordings, so long as there is no demand for channels > 5
on any mux. A LiveTV session ("LiveTV1") is opened on a frontend and mythtv selects T3. All good.

Now a second frontend LiveTV session ("LiveTV2") is started on a second frontend - and that is when it falls apart because LiveTV2
also gets T3 - and suddenly the problem is back again as one tuner dominates controlling the mux and effectively limiting the
channel options available to those on that mux (therefore for LiveTV1 and LiveTV2). Manually swapping Tuners works for the
technically savvy - mostly I find T2 is free, however mythtv should really have put LiveTV2 user onto T2, assuming it to be free,
which mostly it will be. I've not tested a 5th tuner however I expect the situation would be the same, LiveTV1 gets T4 as would
LiveTV2 also get T4. T3 would remain lonely, would it not? (reservation: I've not managed to get my head around how this might
work if Mike Dean's "Revolving" next Virtual Tuner assignment method might impact on this and experience suggests I'd be best to
configure it and test to comment on it however Mike might be able to comment on its impact in the scenario I portrait)

Regarding the more than 5 virtual tuner limit, the useful limits here seem to be hardware based and therefore quite variable,
depending on the individual servers capabilities, mainly its effective pipe size to the HDD(s). Where there are more than 5
channels in a mux then it is possible to want to record all of them simultaneously, however how many channels are people getting in
a mux? We do have arguably 9 useful channels here (3 are radio/audio - still valid channels with less hardware requirement each) on
one mux, so in that respect the limitation shows a flaw in my above reckoning of the optimal number of tuners, as it assumes one
tuner can simultaneously record all channels, which is clearly not the case here. However I understand a mux has a capacity and the
nine is pretty much approaching the mux's capacity? One possibility might be to assign a mux to a tuner - and therefore specify the
number of channels that tuner is to handle. - and reduce replication however I do not understand the code here and certainly am not
saying it should be done that way and that would only be helpful when there were enough Tuners for all situations, which will often
not be the case.

Knowing (and respecting) the majority dev preference of recording all material in advance (and still considering the issues here
before I form a firm view here, I see valid arguments for each view), and having found LiveTV in the past to be no where as reliable
as the recording performance (which I have difficulty recalling crashing ever - no doubt for good reason - the dev's interest has
been there) I have actually also implemented a HDHomerun Dual Tuner on the LAN (in addition to the two 500T cards giving 4 tuners)
and where the Frontend PC has enuff puff I have used VLC for LiveTV, as it has been faster and more reliable for me. (That means I
can leave VLC running LiveTV and in 48 hours it is still running) Recently LiveTV with limited testing has behaved itself so this
old experience may be remedied now, I'm not sure yet. There are pluses and minuses to each approach, vdpau is certainly one of the
considerations!

I hope these comments are helpful, in the least for providing some useful perspective for the patch coders however you may have
covered all this off.

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tortise at paradise

Feb 24, 2010, 2:10 AM

Post #20 of 40 (2356 views)
Permalink
Re: Live TV channel restrictions [In reply to]
----- Original Message -----
From: "Michael T. Dean" <mtdean [at] thirdcontact>
To: <mythtv-users [at] mythtv>
Sent: Wednesday, February 24, 2010 11:27 AM
Subject: Re: [mythtv-users] Live TV channel restrictions


On 02/23/2010 05:09 PM, Ian Oliver wrote:
> In article, Michael T. Dean wrote:
>> so that you can waste your time with LiveTV
>>
> Pardon? Just because person A might not like watching news or sport live doesn't
> mean that person B is wasting their time by doing so.
>

>http://www.gossamer-threads.com/lists/mythtv/users/387302#387302 --even
news and sports should be recordings and not LiveTV.

OK I get that the dev promoted model is to set a recording to record - and if you are there at start time, then don't watch Live,
watch the recording while it continues to record. I confirm that works well for me - when the viewing is planned and the recording
pre-set. It is a different paradigm that requires significant intellectual "openness" to re-orient ones thinking to.

What I am unclear about is when one more spontaneously watches LiveTV, Pauses, and then Resumes - then LiveTV is arguably no longer
LiveTV. (Its delayed or recorded TV) Can someone clarify for me, is "Paused/Resumed 'LiveTV'" still considered LiveTV in the
context of the liveTV vs watching recorded TV debate? Is this consideration at all relevant?

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tortise at paradise

Feb 24, 2010, 2:19 AM

Post #21 of 40 (2358 views)
Permalink
Re: Live TV channel restrictions [In reply to]
----- Original Message -----
From: "Ian Oliver" <lists [at] foxhill>
To: <mythtv-users [at] mythtv>
Sent: Wednesday, February 24, 2010 10:00 PM
Subject: Re: [mythtv-users] Live TV channel restrictions


In article <4B8467FC.5080009 [at] thirdcontact>, Michael T. Dean wrote:
> if
> LiveTV locks that tuner to the mux that /was/ in use and the scheduler
> had planned to change to a different mux for the next recording.

> My (admittedly naive!) angle on this is that Live TV shouldn't be
"locking" or "grabbing" anything. It gets to use virtual tuners that are
free, it also gets to tune a tuner that's free if there isn't one on the
right mux, but if a recording comes along and needs the resource, then
tough!

Well yes, but tough for which? One possible solution is a setting choice of LiveTV dominance or Recording dominance to define who
it is tough for, assuming no user guiding intervention. Designing the system to avoid the need for this choice is of course
preferable.

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totallymaxed at gmail

Feb 24, 2010, 5:50 AM

Post #22 of 40 (2317 views)
Permalink
Re: Live TV channel restrictions [In reply to]
On Wed, Feb 24, 2010 at 9:46 AM, Tortise <tortise [at] paradise> wrote:

>
> ----- Original Message ----- From: "Ian Oliver" <lists [at] foxhill>
> To: <mythtv-users [at] mythtv>
> Sent: Wednesday, February 24, 2010 11:09 AM
> Subject: Re: [mythtv-users] Live TV channel restrictions
>
> Interesting thread that I've just come across that also interests me and my
> familial "clients".
>
>
> In article <4B840B51.4000309 [at] thirdcontact>, Michael T. Dean wrote:
>
>> If you always want LiveTV to get a separate physical
>> tuner
>>
>
> That isn't what I want. If there is a tuner on the right mux and with a
>> free
>>
> virtual tuner, then use it. Failing that, find a free tuner and tune it to
> the
> right mux. Failing that, tell me I can't watch that channel. All PVRs I've
> met do
> pretty much exactly this.
>
> I think this "if" logic is flawed. (I assume LiveTV needs a free dedicated
> tuner, not a shared Tuner, it should first hunt for a free tuner. An
> assumption here is that the code is not setup to directly jump tuners to use
> a tuner which is already pulling a mux, when there remain free virtual
> tuners on the tuner.)
>
> I suggest a useful perspective is that LiveTV is a different beast to a
> recording mux and they merit recognition of their differences in their
> treatment.
>
> A LiveTV Tuner is ideally locked to one tuner - why - because a Live user
> may want to choose any channel from any mux anytime.
>
> A Rec Tuner is distinguished by not having an enduser who is going to
> demand the tuner change any time to any mux.
>
> These distinctions seem fundamental to me.
>

Well our view is that in the multirec world it makes more sense to only ever
have one physical tuner tuned to a given MUX at any one time. MythTV then
accepts requests from a user who wants to watch LiveTV or from the Scheduler
for tuner resources and manages/arbitrates those requests - automatically.
The user can then decide whether LIveTV usage or scheduler recordings take
preference. This maximises the use of the physical tuner resources by
allowing MythTV automate that tuner allocation/management logic for us...and
at the same time removes the need for the user to make those decisions.

The patch we have posted in this thread is a step along this road...with
some refinement and additional code to extend its reach into the scheduler
we think it offers some real advantages. We have testers already using the
patch and the feedback so far is really very positive from this
predominantly non-technical audience.



>
> So, from a different perspective, what is an ideal number of tuners? That
> depends. The most efficient number of tuners one should ever want should be
> {[number of mux] + [number of LiveTV viewers]}
>
> [number of LiveTV viewers] deserves further clarification, that is not the
> number of frontends, rather it is the maximum number simultaneous Frontend
> viewers likely or perhaps possible. So in a house with 6 frontends but only
> 3 people present 3 is likely to be enough for [number of LiveTV viewers].
>
> To highlight that the current mythtv setup is a problem, consider we have 3
> muxs here, I have 4 (multirec) tuners (T0, T1, T2 and T3) and I have enabled
> LiveTV selecting a free Tuner. (I forget the exact phrase) Multirec
> recordings start at T0 and work their way up, T0, T1, T2 - and that is all
> that's needed for all combination of recordings, so long as there is no
> demand for channels > 5 on any mux. A LiveTV session ("LiveTV1") is opened
> on a frontend and mythtv selects T3. All good.
>
> Now a second frontend LiveTV session ("LiveTV2") is started on a second
> frontend - and that is when it falls apart because LiveTV2 also gets T3 -
> and suddenly the problem is back again as one tuner dominates controlling
> the mux and effectively limiting the channel options available to those on
> that mux (therefore for LiveTV1 and LiveTV2). Manually swapping Tuners
> works for the technically savvy - mostly I find T2 is free, however mythtv
> should really have put LiveTV2 user onto T2, assuming it to be free, which
> mostly it will be. I've not tested a 5th tuner however I expect the
> situation would be the same, LiveTV1 gets T4 as would LiveTV2 also get T4.
> T3 would remain lonely, would it not? (reservation: I've not managed to
> get my head around how this might work if Mike Dean's "Revolving" next
> Virtual Tuner assignment method might impact on this and experience suggests
> I'd be best to configure it and test to comment on it however Mike might be
> able to comment on its impact in the scenario I portrait)
>

The patch we have posted essentially fixes the above problem pretty
effectively - and requires no manual tuner management from the user.


>
> Regarding the more than 5 virtual tuner limit, the useful limits here seem
> to be hardware based and therefore quite variable, depending on the
> individual servers capabilities, mainly its effective pipe size to the
> HDD(s). Where there are more than 5 channels in a mux then it is possible
> to want to record all of them simultaneously, however how many channels are
> people getting in a mux? We do have arguably 9 useful channels here (3 are
> radio/audio - still valid channels with less hardware requirement each) on
> one mux, so in that respect the limitation shows a flaw in my above
> reckoning of the optimal number of tuners, as it assumes one tuner can
> simultaneously record all channels, which is clearly not the case here.
> However I understand a mux has a capacity and the nine is pretty much
> approaching the mux's capacity? One possibility might be to assign a mux to
> a tuner - and therefore specify the number of channels that tuner is to
> handle. - and reduce replication however I do not understand the code here
> and certainly am not saying it should be done that way and that would only
> be helpful when there were enough Tuners for all situations, which will
> often not be the case.
>

Again our patch essentially does allocate a physical tuner to each requested
MUX. If additional requests come in from other frontends for any channels on
a MUX that is already available from a physical tuner then another multirec
tuner is allocated and the request is satisfied. I agree the only limitation
is the physical hardwares ability to handle the multiple multirec streams
and this will vary from system to system.


>
> Knowing (and respecting) the majority dev preference of recording all
> material in advance (and still considering the issues here before I form a
> firm view here, I see valid arguments for each view), and having found
> LiveTV in the past to be no where as reliable as the recording performance
> (which I have difficulty recalling crashing ever - no doubt for good reason
> - the dev's interest has been there) I have actually also implemented a
> HDHomerun Dual Tuner on the LAN (in addition to the two 500T cards giving 4
> tuners) and where the Frontend PC has enuff puff I have used VLC for LiveTV,
> as it has been faster and more reliable for me. (That means I can leave VLC
> running LiveTV and in 48 hours it is still running) Recently LiveTV with
> limited testing has behaved itself so this old experience may be remedied
> now, I'm not sure yet. There are pluses and minuses to each approach, vdpau
> is certainly one of the considerations!
>
> I hope these comments are helpful, in the least for providing some useful
> perspective for the patch coders however you may have covered all this off.


I think all of above is useful perspective. I agree that there are strongly
held views about LiveTV consumption but on the other hand we see actual
users asking for a better experience when consuming LiveTV and I think
therefore both of these needs need to be addressed.

All the best


Andrew



--
Head of Software & Technology
Convergent Home Technologies Ltd
www.dianemo.co.uk
www.cascade-media.co.uk
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mtdean at thirdcontact

Feb 24, 2010, 9:30 AM

Post #23 of 40 (2282 views)
Permalink
Re: Live TV channel restrictions [In reply to]
On 02/24/2010 05:10 AM, Tortise wrote:
> From: "Michael T. Dean"
>> On 02/23/2010 05:09 PM, Ian Oliver wrote:
>>> In article, Michael T. Dean wrote:
>>>> so that you can waste your time with LiveTV
>>>>
>>> Pardon? Just because person A might not like watching news or sport
>>> live doesn't
>>> mean that person B is wasting their time by doing so.
>>>
>> http://www.gossamer-threads.com/lists/mythtv/users/387302#387302
>> --even news and sports should be recordings and not LiveTV.
>
> OK I get that the dev promoted model is to set a recording to record -
> and if you are there at start time, then don't watch Live, watch the
> recording while it continues to record. I confirm that works well for
> me - when the viewing is planned and the recording pre-set. It is a
> different paradigm that requires significant intellectual "openness"
> to re-orient ones thinking to.
>
> What I am unclear about is when one more spontaneously watches LiveTV,
> Pauses, and then Resumes - then LiveTV is arguably no longer LiveTV.
> (Its delayed or recorded TV) Can someone clarify for me, is
> "Paused/Resumed 'LiveTV'" still considered LiveTV in the context of
> the liveTV vs watching recorded TV debate?

Yes.

> Is this consideration at all relevant?

Yes, for all the reasons you mentioned in your other post. As long as a
user has control over the channel being watched--thus overriding the
scheduler's decisions for the efficient use of tuners--and may demand a
channel (and, therefore, potentially a tuner) change at any time, and as
long as a user has opened a "keep recording whatever program I happen to
tune and leave the recording under my control until I exit Live TV"
session (thereby "locking" the tuner as unavailable), we have Live TV in
progress. Since MythTV's scheduler doesn't read users' minds, it can
not plan for efficient recording/usage of tuners as well as it can with
scheduled recordings.

Mike
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mtdean at thirdcontact

Feb 24, 2010, 9:45 AM

Post #24 of 40 (2283 views)
Permalink
Re: Live TV channel restrictions [In reply to]
On 02/24/2010 04:46 AM, Tortise wrote:
> From: "Ian Oliver"
>> Michael T. Dean wrote:
>>> If you always want LiveTV to get a separate physical
>>> tuner
>> That isn't what I want. If there is a tuner on the right mux and with
>> a free virtual tuner, then use it. Failing that, find a free tuner
>> and tune it to the right mux.

That's the default configuration of MythTV. The part you're complaining
about is that you're then "stuck" on the mux. To fix that, enable
"Browse all channels."

>> Failing that, tell me I can't watch that channel. All PVRs I've met
>> do pretty much exactly this

/me wonders just how many PVR's you've seen that support recording from
X virtual tuners on each of Y physical capture cards

I can turn your MythTV system into something just as "simple to use and
always works like I expect" as a dual-tuner TiVo. That's an easy
problem. :)

> I think this "if" logic is flawed. (I assume LiveTV needs a free
> dedicated tuner, not a shared Tuner, it should first hunt for a free
> tuner. An assumption here is that the code is not setup to directly
> jump tuners to use a tuner which is already pulling a mux, when there
> remain free virtual tuners on the tuner.)
>
> I suggest a useful perspective is that LiveTV is a different beast to
> a recording mux and they merit recognition of their differences in
> their treatment.
>
> A LiveTV Tuner is ideally locked to one tuner - why - because a Live
> user may want to choose any channel from any mux anytime.
>
> A Rec Tuner is distinguished by not having an enduser who is going to
> demand the tuner change any time to any mux.
>
> These distinctions seem fundamental to me.
>
> So, from a different perspective, what is an ideal number of tuners?
> That depends. The most efficient number of tuners one should ever
> want should be {[number of mux] + [number of LiveTV viewers]}
>
> [number of LiveTV viewers] deserves further clarification, that is not
> the number of frontends, rather it is the maximum number simultaneous
> Frontend viewers likely or perhaps possible. So in a house with 6
> frontends but only 3 people present 3 is likely to be enough for
> [number of LiveTV viewers].
>
> To highlight that the current mythtv setup is a problem, consider we
> have 3 muxs here, I have 4 (multirec) tuners (T0, T1, T2 and T3) and I
> have enabled LiveTV selecting a free Tuner. (I forget the exact
> phrase) Multirec recordings start at T0 and work their way up, T0,
> T1, T2 - and that is all that's needed for all combination of
> recordings, so long as there is no demand for channels > 5 on any
> mux. A LiveTV session ("LiveTV1") is opened on a frontend and mythtv
> selects T3. All good.
>
> Now a second frontend LiveTV session ("LiveTV2") is started on a
> second frontend - and that is when it falls apart because LiveTV2 also
> gets T3 - and suddenly the problem is back again as one tuner
> dominates controlling the mux and effectively limiting the channel
> options available to those on that mux (therefore for LiveTV1 and
> LiveTV2). Manually swapping Tuners works for the technically savvy -
> mostly I find T2 is free, however mythtv should really have put
> LiveTV2 user onto T2, assuming it to be free, which mostly it will
> be. I've not tested a 5th tuner however I expect the situation would
> be the same, LiveTV1 gets T4 as would LiveTV2 also get T4. T3 would
> remain lonely, would it not? (reservation: I've not managed to get
> my head around how this might work if Mike Dean's "Revolving" next
> Virtual Tuner assignment method might impact on this and experience
> suggests I'd be best to configure it and test to comment on it however
> Mike might be able to comment on its impact in the scenario I portrait)

This is exactly what the post I linked allows the user to configure.
You can configure MythTV so that it either always re-uses a physical
card (meaning you're stuck on the mux unless you a) hit NEXTCARD, b) use
the EPG, or c) enable "Browse all channels")--this being the default
configuration--or can configure it so that MythTV always grabs a
different physical tuner for each Live TV session (assuming one is
available, or if not, grabs a virtual tuner already "stuck" on a mux due
to some other recording or Live TV session)--this being the
configuration where you tell MythTV that Live TV is important to you.
Note that in the second case, you get exactly what you seem to want--a
separate physical capture card for each LiveTV session.

> Regarding the more than 5 virtual tuner limit, the useful limits here
> seem to be hardware based and therefore quite variable, depending on
> the individual servers capabilities, mainly its effective pipe size to
> the HDD(s).

Really, it's a scalability issue. On any given hardware, scheduling
becomes a much harder (and, therefore, much slower) process as the
number of virtual tuners grows. It's not the absolute time required for
scheduling that caused the devs who implemented multirec to choose a
limit of 5 virtual tuners (as the absolute time /would/ be hardware
specific), it's the difference in scheduling time required between 5 and
6 (and 7 and 8 and ...) virtual tuners. Graph it and you'll see a
non-linear growth.

Mike
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totallymaxed at gmail

Feb 24, 2010, 4:42 PM

Post #25 of 40 (2194 views)
Permalink
Re: Live TV channel restrictions [In reply to]
On Wed, Feb 24, 2010 at 5:45 PM, Michael T. Dean <mtdean [at] thirdcontact>wrote:

> On 02/24/2010 04:46 AM, Tortise wrote:
>
>> From: "Ian Oliver"
>>
>> Michael T. Dean wrote:
>>>
>>>> If you always want LiveTV to get a separate physical
>>>> tuner
>>>>
>>> That isn't what I want. If there is a tuner on the right mux and with a
>>> free virtual tuner, then use it. Failing that, find a free tuner and tune it
>>> to the right mux.
>>>
>>
> That's the default configuration of MythTV. The part you're complaining
> about is that you're then "stuck" on the mux. To fix that, enable "Browse
> all channels."
>
>
Well our experience is that to achieve what your describing above you need a
very specific tuner setup otherwise MythTV's 'standard' behaviour is exactly
as Ian and his family experience... even if you enable "Browse all
channels". Yes "Browse all channels" allows you to browse but it will not
allow you to select and tune to any channels that are not on your currently
tuned MUX.



> Failing that, tell me I can't watch that channel. All PVRs I've met do
>>> pretty much exactly this
>>>
>>
> /me wonders just how many PVR's you've seen that support recording from X
> virtual tuners on each of Y physical capture cards
>
> I can turn your MythTV system into something just as "simple to use and
> always works like I expect" as a dual-tuner TiVo. That's an easy problem.
> :)


I think the point being made above is that he wants MythTV to 'manage' this
situation for him and currently it doesn't.


>
>
> I think this "if" logic is flawed. (I assume LiveTV needs a free
>> dedicated tuner, not a shared Tuner, it should first hunt for a free tuner.
>> An assumption here is that the code is not setup to directly jump tuners to
>> use a tuner which is already pulling a mux, when there remain free virtual
>> tuners on the tuner.)
>>
>> I suggest a useful perspective is that LiveTV is a different beast to a
>> recording mux and they merit recognition of their differences in their
>> treatment.
>>
>> A LiveTV Tuner is ideally locked to one tuner - why - because a Live user
>> may want to choose any channel from any mux anytime.
>>
>> A Rec Tuner is distinguished by not having an enduser who is going to
>> demand the tuner change any time to any mux.
>>
>> These distinctions seem fundamental to me.
>>
>> So, from a different perspective, what is an ideal number of tuners? That
>> depends. The most efficient number of tuners one should ever want should be
>> {[number of mux] + [number of LiveTV viewers]}
>>
>> [number of LiveTV viewers] deserves further clarification, that is not the
>> number of frontends, rather it is the maximum number simultaneous Frontend
>> viewers likely or perhaps possible. So in a house with 6 frontends but only
>> 3 people present 3 is likely to be enough for [number of LiveTV viewers].
>>
>> To highlight that the current mythtv setup is a problem, consider we have
>> 3 muxs here, I have 4 (multirec) tuners (T0, T1, T2 and T3) and I have
>> enabled LiveTV selecting a free Tuner. (I forget the exact phrase)
>> Multirec recordings start at T0 and work their way up, T0, T1, T2 - and that
>> is all that's needed for all combination of recordings, so long as there is
>> no demand for channels > 5 on any mux. A LiveTV session ("LiveTV1") is
>> opened on a frontend and mythtv selects T3. All good.
>>
>> Now a second frontend LiveTV session ("LiveTV2") is started on a second
>> frontend - and that is when it falls apart because LiveTV2 also gets T3 -
>> and suddenly the problem is back again as one tuner dominates controlling
>> the mux and effectively limiting the channel options available to those on
>> that mux (therefore for LiveTV1 and LiveTV2). Manually swapping Tuners
>> works for the technically savvy - mostly I find T2 is free, however mythtv
>> should really have put LiveTV2 user onto T2, assuming it to be free, which
>> mostly it will be. I've not tested a 5th tuner however I expect the
>> situation would be the same, LiveTV1 gets T4 as would LiveTV2 also get T4.
>> T3 would remain lonely, would it not? (reservation: I've not managed to
>> get my head around how this might work if Mike Dean's "Revolving" next
>> Virtual Tuner assignment method might impact on this and experience suggests
>> I'd be best to configure it and test to comment on it however Mike might be
>> able to comment on its impact in the scenario I portrait)
>>
>
> This is exactly what the post I linked allows the user to configure. You
> can configure MythTV so that it either always re-uses a physical card
> (meaning you're stuck on the mux unless you a) hit NEXTCARD, b) use the EPG,
> or c) enable "Browse all channels")--this being the default
> configuration--or can configure it so that MythTV always grabs a different
> physical tuner for each Live TV session (assuming one is available, or if
> not, grabs a virtual tuner already "stuck" on a mux due to some other
> recording or Live TV session)--this being the configuration where you tell
> MythTV that Live TV is important to you. Note that in the second case, you
> get exactly what you seem to want--a separate physical capture card for each
> LiveTV session.


However in the 2nd case mentioned above...where a separate physical tuner is
allocated to each LiveTV session...you will currently get sub-optimal use of
tuners with multiple tuners tuner to the same MUX. This limits the choice of
TV channels that can be viewed concurrently to the ones that are available
on the MUX's already being tuned.


>
>
> Regarding the more than 5 virtual tuner limit, the useful limits here seem
>> to be hardware based and therefore quite variable, depending on the
>> individual servers capabilities, mainly its effective pipe size to the
>> HDD(s).
>>
>
> Really, it's a scalability issue. On any given hardware, scheduling
> becomes a much harder (and, therefore, much slower) process as the number of
> virtual tuners grows. It's not the absolute time required for scheduling
> that caused the devs who implemented multirec to choose a limit of 5 virtual
> tuners (as the absolute time /would/ be hardware specific), it's the
> difference in scheduling time required between 5 and 6 (and 7 and 8 and ...)
> virtual tuners. Graph it and you'll see a non-linear growth.
>

Well I have to say that we dont see this performance issue in our testing
using the current scheduler but with the upper limit on multirec tuners
lifted to say 10. What your describing is not apparent to us. However what
is apparent is that the way multirec tuners are implemented currently seems
less efficient than it might be. This is an area we're looking at
currently...but performance is not driving this so much as reducing code
complexity. We'll post some patches in this area as soon as we have a
reasonably clean implementation.

Andrew



--
Head of Software & Technology
Convergent Home Technologies Ltd
www.dianemo.co.uk
www.cascade-media.co.uk

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