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Multicast your noisy frontend or backend to a quiet box?

 

 

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tortise at paradise

Feb 3, 2012, 3:01 PM

Post #1 of 11 (1293 views)
Permalink
Multicast your noisy frontend or backend to a quiet box?

Seems VLC may be able to transcode and multi/unicast a desktop screen.

I've not got it working but the flurry of debug messages suggest it
might work, and it seems its flooding my LAN as traffic is challenged.

VLC runs and may be casting the screen, however memory climbs until it,
and the swap are exhausted where it then kills itself.

Predictably VLC 1.1.4 looks more promising than 1.0.6.

I am now using Frontend VLC server:
DISPLAY=:0 cvlc -vv screen:// --sout
"#transcode{vcodec=h264,acodec=mpga,vb=800,ab=128}:standard{access=udp,mux=ts,url=239.255.12.42:5004}"

VLC client also not sure, possibilities might include rtp or udp
versions of:
rtp://@:5004
rtp://239.255.12.42@:5004

Anyone interested in this concept or advancing it?

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nick.rout at gmail

Feb 3, 2012, 5:01 PM

Post #2 of 11 (1240 views)
Permalink
Re: Multicast your noisy frontend or backend to a quiet box? [In reply to]

On Sat, Feb 4, 2012 at 12:01 PM, tortise <tortise [at] paradise> wrote:
> Seems VLC may be able to transcode and multi/unicast a desktop screen.
>
> I've not got it working but the flurry of debug messages suggest it might
> work, and it seems its flooding my LAN as traffic is challenged.
>
> VLC runs and may be casting the screen, however memory climbs until it, and
> the swap are exhausted where it then kills itself.
>
> Predictably VLC 1.1.4 looks more promising than 1.0.6.
>
> I am now using Frontend VLC server:
> DISPLAY=:0 cvlc -vv screen:// --sout
> "#transcode{vcodec=h264,acodec=mpga,vb=800,ab=128}:standard{access=udp,mux=ts,url=239.255.12.42:5004}"
>
> VLC client also not sure, possibilities might include rtp or udp versions
> of:
> rtp://@:5004
> rtp://239.255.12.42@:5004
>
> Anyone interested in this concept or advancing it?

I fail to see what this has to do with mythtv.

But if you are trying to send a facsimile of a mythfrontend screen
around the house why not simply install mythfrontend on the target
machine?

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nick.rout at gmail

Feb 3, 2012, 5:04 PM

Post #3 of 11 (1243 views)
Permalink
Re: Multicast your noisy frontend or backend to a quiet box? [In reply to]

On Sat, Feb 4, 2012 at 2:01 PM, Nick Rout <nick.rout [at] gmail> wrote:
> On Sat, Feb 4, 2012 at 12:01 PM, tortise <tortise [at] paradise> wrote:
>> Seems VLC may be able to transcode and multi/unicast a desktop screen.
>>
>> I've not got it working but the flurry of debug messages suggest it might
>> work, and it seems its flooding my LAN as traffic is challenged.
>>
>> VLC runs and may be casting the screen, however memory climbs until it, and
>> the swap are exhausted where it then kills itself.
>>
>> Predictably VLC 1.1.4 looks more promising than 1.0.6.
>>
>> I am now using Frontend VLC server:
>> DISPLAY=:0 cvlc -vv screen:// --sout
>> "#transcode{vcodec=h264,acodec=mpga,vb=800,ab=128}:standard{access=udp,mux=ts,url=239.255.12.42:5004}"
>>
>> VLC client also not sure, possibilities might include rtp or udp versions
>> of:
>> rtp://@:5004
>> rtp://239.255.12.42@:5004
>>
>> Anyone interested in this concept or advancing it?
>
> I fail to see what this has to do with mythtv.
>
> But if you are trying to send a facsimile of a mythfrontend screen
> around the house why not simply install mythfrontend on the  target
> machine?

in particular, you are taking a compressed video, sending it over the
network from backend to frontend, uncompressing it to your video card,
compressing it again with vlc, transmitting it over a network,
uncompressing it again to the target machine's video card. Seems a
colossal waste of effort., not to mention downgrade in quality as a
result of the multiple decoding and encoding.

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tortise at paradise

Feb 3, 2012, 6:18 PM

Post #4 of 11 (1243 views)
Permalink
Re: Multicast your noisy frontend or backend to a quiet box? [In reply to]

On 4/02/2012 2:04 p.m., Nick Rout wrote:

>> I fail to see what this has to do with mythtv.

End user desirement.

not to mention downgrade in quality as a result of the multiple decoding
and encoding.

I think this comment would have been particularly applicable to analogue
signals, however given these are digital one would hope it was lossless.
Accept it might not be though.



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james6.0 at gmail

Feb 3, 2012, 6:57 PM

Post #5 of 11 (1240 views)
Permalink
Re: Multicast your noisy frontend or backend to a quiet box? [In reply to]

>
>
> not to mention downgrade in quality as a result of the multiple decoding
> and encoding.
>
> I think this comment would have been particularly applicable to analogue
> signals, however given these are digital one would hope it was lossless.
> Accept it might not be though.


Not the case with lossy compression. Imagine lossy compression as a cookie
cutter, a different shape is a different codec. Use two different codecs,
and you get the losses of both


dmoo1790 at ihug

Feb 3, 2012, 7:26 PM

Post #6 of 11 (1242 views)
Permalink
Re: Multicast your noisy frontend or backend to a quiet box? [In reply to]

On 4/02/2012, at 3:57 PM, James Gray <james6.0 [at] gmail> wrote:

>
> not to mention downgrade in quality as a result of the multiple decoding and encoding.
>
> I think this comment would have been particularly applicable to analogue signals, however given these are digital one would hope it was lossless. Accept it might not be though.
>
> Not the case with lossy compression. Imagine lossy compression as a cookie cutter, a different shape is a different codec. Use two different codecs, and you get the losses of both
> _______________________________________________
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Even worse. Even with the same codec you still get losses because the 2nd (3rd, etc) coding stage compresses an image with less info than the original.


nick.rout at gmail

Feb 3, 2012, 8:02 PM

Post #7 of 11 (1233 views)
Permalink
Re: Multicast your noisy frontend or backend to a quiet box? [In reply to]

On Sat, Feb 4, 2012 at 3:18 PM, tortise <tortise [at] paradise> wrote:
> On 4/02/2012 2:04 p.m., Nick Rout wrote:
>
>>> I fail to see what this has to do with mythtv.
>
>
> End user desirement.

I am surprised everyone in your house wants to watch the same thing at
the same time, with pauses governed by one user. The very antithesis
of what mythtv is all about.

Perhaps if you told us the *point* of the exercise it might make some sense.

>
>
>> not to mention downgrade in quality as a result of the multiple decoding and
>> encoding.
>
> I think this comment would have been particularly applicable to analogue
> signals, however given these are digital one would hope it was lossless.
>  Accept it might not be though.
>

Nonsense, what has digital got to do with it?

lossy=lossy=lossy.

>
>
>
> _______________________________________________
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> mythtvnz [at] lists
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tortise at paradise

Feb 5, 2012, 4:31 PM

Post #8 of 11 (1229 views)
Permalink
Re: Multicast your noisy frontend or backend to a quiet box? [In reply to]

On 4/02/2012 5:02 p.m., Nick Rout wrote:
>> End user desirement.
>
> I am surprised everyone in your house wants to watch the same thing at
> the same time, with pauses governed by one user.

Seems a bit of a jump from the subject, which was intended to be more
about multi-casting and less about noisy frontends. With the benefit of
hindsight it might have been better to not refer to noisy frontends, my
apologies for the noise.

>The very antithesis
> of what mythtv is all about.

For me mythtv is an open source effort that evolves with user / dev
input. I'd need persuasion that using mythtv in a way it does not
currently do, yet is capable of doing, is not what its all about, seems
quite the contrary reality for me. To add to my case I also observe the
paradigm shift "requirement" that mythtv is, that mythtv is designed
that one does not watch live tv exemplifies that paradigm shift is what
mythtv is about, and for me it is not necessarily limited to that single
mind change. There are some things best viewed live. World cup finals
come to mind. Of course its best to record the final, watch it largely
live (with minimal delay) yet with the ability to pause/rewind
etc....While this is a significant aspect of mythtv its, for me anyway,
not the holy grail or conclusion of mythtv's path forward, which is (for
me) not closed to other paradigm shifts.

The concept is not new and has been considered, even to the extent of
enjoying initial dev coding for this some years ago. Its just, like
many desirements, not publicly implemented successfully yet.

When using the older SD mythtv I did broadcast a mythtv frontend around
the house using a modulator that was relatively affordable. This worked
very well, requiring a tuner device with each display to access. (that
generally meant a SD TV! However in the DVB-T HD world a HD modulator
and HDHomerun would enable any LAN connected PC to view the stream,
should one shell out the dosh for such a beast... some modulators also
include IPTV LAN outputs.) I don't plan to detail use scenarios, except
to note they proved to be more than I initially expected as it was more
flexible than I'd expected, and having lost something I had remains an
itch that demands a cure.

> Perhaps if you told us the *point* of the exercise it might make some sense.

As per the title I've been trying to play the same thing on a few
frontends all synced up, (+/- a couple of seconds lag acceptable, -
without necessarily pushing this on everyone in the house) given the
costs, e.g. the price of DVB-T modulators and HDMI splitter
implementation problems, not to mention an existing LAN, multicasting a
frontend seemed a viable, if not the best path forward. If it were a
cheaper noisy frontend in the garage that might have also been fine.

VLC can be easily run to multicast a file and shows / tests whether the
LAN is multicast capable (or not), however getting it to do the display
was not so out of the box, and as has been pointed out there may well be
significant clone quality display issues with HD video.

I've since considered the frontend control socket, so it may be I can
use that to instruct a few frontends, while minimising LAN traffic.

http://www.mythtv.org/wiki/Frontend_control_socket gives an overview
including apps already accessing the socket. Any of those apps might be
adapted to do the above. http://nowsci.com/mythmobile/ is notably
absent from the list of apps.

So far the best way I can see to do this for me would be writing a
webpage to link in with mythweb to do this. One could then access this
from wherever, particularly an android for roaming control. Pausing etc
would have to be done from that page to keep the sync up. If there was
too much time drift a resync with the chosen frontend could be easily
included.

An intial play with the socket (LAN IP's subs with x.x.x.x) shows it
does things like:

# query location
Playback Recorded 00:37:16 of 01:04:09 1x 1001 2012-02-05T21:29:00 55904
myth://x.x.x.x:6543/1001_20120205212900.mpg 25

# play file myth://x.x.x.x:6543/1001_20120205212900.mpg
OK





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nick.rout at gmail

Feb 5, 2012, 10:40 PM

Post #9 of 11 (1229 views)
Permalink
Re: Multicast your noisy frontend or backend to a quiet box? [In reply to]

On Mon, Feb 6, 2012 at 1:31 PM, tortise <tortise [at] paradise> wrote:
> On 4/02/2012 5:02 p.m., Nick Rout wrote:
>>>
>>> End user desirement.
>>
>>
>> I am surprised everyone in your house wants to watch the same thing at
>> the same time, with pauses governed by one user.
>
>
> Seems a bit of a jump from the subject, which was intended to be more about
> multi-casting and less about noisy frontends.  With the benefit of hindsight
> it might have been better to not refer to noisy frontends, my apologies for
> the noise.
>
>
>>The very antithesis
>> of what mythtv is all about.
>
> For me mythtv is an open source effort that evolves with user / dev input.
>  I'd need persuasion that using mythtv in a way it does not currently do,
> yet is capable of doing, is not what its all about, seems quite the contrary
> reality for me.  To add to my case I also observe the paradigm shift
> "requirement" that mythtv is, that mythtv is designed that one does not
> watch live tv exemplifies that paradigm shift is what mythtv is about, and
> for me it is not necessarily limited to that single mind change.  There are
> some things best viewed live.  World cup finals come to mind. Of course its
> best to record the final, watch it largely live (with minimal delay) yet
> with the ability to pause/rewind etc....While this is a significant aspect
> of mythtv its, for me anyway, not the holy grail or conclusion of mythtv's
> path forward, which is (for me) not closed to other paradigm shifts.
>
> The concept is not new and has been considered, even to the extent of
> enjoying initial dev coding for this some years ago.  Its just, like many
> desirements, not publicly implemented successfully yet.
>
> When using the older SD mythtv I did broadcast a mythtv frontend around the
> house using a modulator that was relatively affordable.  This worked very
> well, requiring a tuner device with each display to access. (that generally
> meant a SD TV! However in the DVB-T HD world a HD modulator and HDHomerun
> would enable any LAN connected PC to view the stream, should one shell out
> the dosh for such a beast... some modulators also include IPTV LAN outputs.)
> I don't plan to detail use scenarios, except to note they proved to be more
> than I initially expected as it was more flexible than I'd expected, and
> having lost something I had remains an itch that demands a cure.

But if you want to multicast a video file, why not simply do that,
rather than trying to multicats a desktop?

>
>
>> Perhaps if you told us the *point* of the exercise it might make some
>> sense.
>
>
> As per the title I've been trying to play the same thing on a few frontends
> all synced up, (+/- a couple of seconds lag acceptable, - without
> necessarily pushing this on everyone in the house) given the costs, e.g. the
> price of DVB-T modulators and HDMI splitter implementation problems, not to
> mention an existing LAN, multicasting a frontend seemed a viable, if not the
> best path forward.   If it were a cheaper noisy frontend in the garage that
> might have also been fine.
>

Seems to me if you really want to do this you run the hdmi output of
your "master" frontend to your various screens around the home. I
believe this can be done with cat5 and reasonably priced baluns, eg
http://www.amazon.com/Sabrent-Extension-Extender-adapter-200-Feet/dp/B001PT1A7C%3FSubscriptionId%3DAKIAI6J7BJOOUGGBRIBA%26tag%3Dhdoc5-20%26linkCode%3Dxm2%26camp%3D2025%26creative%3D165953%26creativeASIN%3DB001PT1A7C

> VLC can be easily run to multicast a file and shows / tests whether the LAN
> is multicast capable (or not), however getting it to do the display was not
> so out of the box, and as has been pointed out there may well be significant
> clone quality display issues with HD video.
>
> I've since considered the frontend control socket, so it may be I can use
> that to instruct a few frontends, while minimising LAN traffic.
>
> http://www.mythtv.org/wiki/Frontend_control_socket gives an overview
> including apps already accessing the socket.  Any of those apps might be
> adapted to do the above.  http://nowsci.com/mythmobile/ is notably absent
> from the list of apps.
>

I think we are all familiar with the frontend control socket. Are you
suggesting writing a program to tell X number of frontends to all
start playing the same file at the same time? And then querying the
frontends to make sure they are all approximately in sync, and making
adjustments to keep them in sync?

> So far the best way I can see to do this for me would be writing a webpage
> to link in with mythweb to do this.  One could then access this from
> wherever, particularly an android for roaming control.  Pausing etc would
> have to be done from that page to keep the sync up.  If there was too much
> time drift a resync with the chosen frontend could be easily included.
>
> An intial play with the socket (LAN IP's subs with x.x.x.x) shows it does
> things like:
>
> # query location
> Playback Recorded 00:37:16 of 01:04:09 1x 1001 2012-02-05T21:29:00 55904
> myth://x.x.x.x:6543/1001_20120205212900.mpg 25
>
> # play file myth://x.x.x.x:6543/1001_20120205212900.mpg
> OK
>

Still not sure of the endgame here. Do you want to be able to wander
from room to room and keep watching the same programme? I can't see
any other use for this in a home setting.

If that is what you want I would suggest looking at how bar video
systems are set up. The TVs all appear to be in sync, and the music
videos at least seem to be played form a computer (Sky Sport etc is
different. I suspect (given the absolute crap quality you seem in some
bars) that they indeed modulate the signal and tune into it on an
otherwise unused tv channel. Same with Sky setups in motels etc

Someone must be doing it better though.

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criggie at criggie

Feb 5, 2012, 11:56 PM

Post #10 of 11 (1238 views)
Permalink
Re: Multicast your noisy frontend or backend to a quiet box? [In reply to]

On 06/02/12 19:40, Nick Rout wrote:
> Someone must be doing it better though.

Plenty of options, but each has some kind of flaw.
I like option 4 for its versatility.


Option 1

http://www.rextron.com/product_detail.php?class3_id=103&class1_type_id=2
http://www.cdlnz.com/productimages/pdfs/av116.pdf


One of these per "display screen", up to four in total.
HDMI $428+GST Audio
http://www.cdlnz.com/index.html?do=viewproduct&p=VMC500&code=VCNM-G90

DVI-D $224+GST No audio
http://www.cdlnz.com/index.html?do=viewproduct&p=VMC500&code=VCND-90

VGA is also available, no price atm, and it doesn't carry sound either.

Only seems to support windows according to the docs, you need a sender
app running on the master box.

--------------------------------------------
Option 2

http://www.cdlnz.com/productimages/pdfs/ev214.pdf

One of these per "display screen", up to 4/8 in total.
VGA $110+GST
http://www.cdlnz.com/index.html?do=viewproduct&p=VMC500&code=EVA02R

Sender, one only required
http://www.cdlnz.com/index.html?do=viewproduct&p=VMC500&code=EVA128L
8 port version $374+GST
http://www.cdlnz.com/index.html?do=viewproduct&p=VMC500&code=EVA124L
4 port version $252+GST

This is VGA only, stereo audio only, and tops out at 1280x1024 at 100m
of cat5. Its not IP based.

--------------------------------------------
Option 3

8 way HDMI splitter $270+GST
http://www.cdlnz.com/index.html?do=viewproduct&p=HDMI300&code=HDMI18MDY


One pair of these per receiver screen
Transmitter $150 +GST
http://www.cdlnz.com/productimages/pdfs/hdmic6tir.pdf
Receiver $150 +GST
http://www.cdlnz.com/productimages/pdfs/hdmic6rir.pdf

Note you need two runs of cat6 to each, and they're quite limited in
length at 1080P. Its also not IP based.

-------------------------------------------
Option 4

A couple of cheap ex-lease laptops or desktops with mythfrontend running
on each. And they can be used to do other stuff.
Can even run windows on them if you want.
Apple Macs make fine frontends too.


--
Criggie

http://criggie.org.nz/

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tortise at paradise

Feb 6, 2012, 1:10 AM

Post #11 of 11 (1237 views)
Permalink
Re: Multicast your noisy frontend or backend to a quiet box? [In reply to]

On 6/02/2012 8:56 p.m., criggie wrote:
> On 06/02/12 19:40, Nick Rout wrote:
>> Someone must be doing it better though.
>
> Plenty of options, but each has some kind of flaw.
> I like option 4 for its versatility.
>
>
> Option 1
>
> http://www.rextron.com/product_detail.php?class3_id=103&class1_type_id=2
> http://www.cdlnz.com/productimages/pdfs/av116.pdf
>
>
> One of these per "display screen", up to four in total.
> HDMI $428+GST Audio
> http://www.cdlnz.com/index.html?do=viewproduct&p=VMC500&code=VCNM-G90
>
> DVI-D $224+GST No audio
> http://www.cdlnz.com/index.html?do=viewproduct&p=VMC500&code=VCND-90
>
> VGA is also available, no price atm, and it doesn't carry sound either.
>
> Only seems to support windows according to the docs, you need a sender
> app running on the master box.
>
> --------------------------------------------
> Option 2
>
> http://www.cdlnz.com/productimages/pdfs/ev214.pdf
>
> One of these per "display screen", up to 4/8 in total.
> VGA $110+GST
> http://www.cdlnz.com/index.html?do=viewproduct&p=VMC500&code=EVA02R
>
> Sender, one only required
> http://www.cdlnz.com/index.html?do=viewproduct&p=VMC500&code=EVA128L
> 8 port version $374+GST
> http://www.cdlnz.com/index.html?do=viewproduct&p=VMC500&code=EVA124L
> 4 port version $252+GST
>
> This is VGA only, stereo audio only, and tops out at 1280x1024 at 100m
> of cat5. Its not IP based.
>
> --------------------------------------------
> Option 3
>
> 8 way HDMI splitter $270+GST
> http://www.cdlnz.com/index.html?do=viewproduct&p=HDMI300&code=HDMI18MDY
>
>
> One pair of these per receiver screen
> Transmitter $150 +GST
> http://www.cdlnz.com/productimages/pdfs/hdmic6tir.pdf
> Receiver $150 +GST
> http://www.cdlnz.com/productimages/pdfs/hdmic6rir.pdf
>
> Note you need two runs of cat6 to each, and they're quite limited in
> length at 1080P. Its also not IP based.
>
> -------------------------------------------
> Option 4
>
> A couple of cheap ex-lease laptops or desktops with mythfrontend running
> on each. And they can be used to do other stuff.
> Can even run windows on them if you want.
> Apple Macs make fine frontends too.

Thanks for your time on this criggie, I also prefer option 4, as I have
the frontends and wired LAN connections to them now. Its easily syncing
the material on multiple places that's the problem I'm looking to solve.
Option 3 would also achieve that, however running many lengths of CAT5
is the major roadblock to that idea.

Option 1 is curious, as you said seems to require software drivers on
the master, does not say supports linux. Why is it limited to 4 clients?
Seems that it works on an existing LAN, which asks the question how
exactly? Couldn't find a manual to explain further. Probably does
something similar to what I asked in the OP, with "drives" running like
VLC, pulling the desktop and sending it out in some IP fashion, at a
guess I'd say it sends 4 unicasts.

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