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pcHDTV with PVR-350 for output

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ddl5 at danlan

Oct 22, 2004, 9:56 PM

Post #1 of 35 (4898 views)
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pcHDTV with PVR-350 for output

I've been trying to send ATSC programming from a pcHDTV card through the MPEG
decoder in a PVR-350 using MythTV 0.16. It seemed that the configuration
setting to use the PVR-350's output was just being ignored. (I could run
an X server on the 350 and then of course everything displayed on the TV,
but through the dumb framebuffer interface.) There were no error messages
or anything else to indicate that the PVR-350 was being accessed at all.

Finally I had the thought to try using the PVR-350's own analog tuner as a
source rather than the pcHDTV. The PVR-350's output then came to life, turned
on and off by the configuration option in Playback Settings just as it should
be. Is something in MythTV deciding that the PVR-350's MPEG decoder can't
handle the ATSC stream? Or is there some interdependence between PVR-350
capture and output (which would seem to defeat the purpose of MythTV's
distributed architecture)?

Something else funny I've noticed when using the pcHDTV card. If I don't
run dtvsignal to set the card to a channel with a valid signal before I
try to "Watch TV" the front end hangs. On killing it I see there was a
tuner error. This is with a 2.6.6 kernel and associated patches from
the pcHDTV site.

Dan Lanciani
ddl [at] danlan*com

jcw at wilsonet

Oct 22, 2004, 10:10 PM

Post #2 of 35 (4810 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

On Friday 22 October 2004 21:56, Dan Lanciani wrote:
> I've been trying to send ATSC programming from a pcHDTV card through the
> MPEG decoder in a PVR-350 using MythTV 0.16. It seemed that the
> configuration setting to use the PVR-350's output was just being ignored.
> (I could run an X server on the 350 and then of course everything displayed
> on the TV, but through the dumb framebuffer interface.) There were no
> error messages or anything else to indicate that the PVR-350 was being
> accessed at all.
>
> Finally I had the thought to try using the PVR-350's own analog tuner as a
> source rather than the pcHDTV. The PVR-350's output then came to life,
> turned on and off by the configuration option in Playback Settings just as
> it should be. Is something in MythTV deciding that the PVR-350's MPEG
> decoder can't handle the ATSC stream? Or is there some interdependence
> between PVR-350 capture and output (which would seem to defeat the purpose
> of MythTV's distributed architecture)?

First off, the 350's decoder is set up for NTSC or PAL sized mpeg2 frames, not
ATSC sized frames. I don't think the hardware is physically capable of
handling something that big. Second, why on earth would you want to output
HDTV content through an SVideo connection that is 720x480, interlaced? You'd
effectively be down-sampling the ATSC signal back down to NTSC, so why even
bother? For HDTV, you really need to be outputting to your TV via VGA, DVI or
component for it to be worthwhile. This has all been discussed before, please
search the archives if you want more insight.

> Something else funny I've noticed when using the pcHDTV card. If I don't
> run dtvsignal to set the card to a channel with a valid signal before I
> try to "Watch TV" the front end hangs. On killing it I see there was a
> tuner error. This is with a 2.6.6 kernel and associated patches from
> the pcHDTV site.

Works for me without doing that, no clue what's up there.

--
Jarod C. Wilson, RHCE
jcw [at] wilsonet

Got a question? Read this first...
http://catb.org/~esr/faqs/smart-questions.html
MythTV, Fedora Core & ATrpms documentation:
http://wilsonet.com/mythtv/
MythTV Searchable Mailing List Archive
http://www.gossamer-threads.com/lists/mythtv/

ddl5 at danlan

Oct 22, 2004, 10:31 PM

Post #3 of 35 (4804 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

Jarod Wilson <jcw [at] wilsonet> wrote:

|On Friday 22 October 2004 21:56, Dan Lanciani wrote:
|> I've been trying to send ATSC programming from a pcHDTV card through the
|> MPEG decoder in a PVR-350 using MythTV 0.16. It seemed that the
|> configuration setting to use the PVR-350's output was just being ignored.=
|=20
|> (I could run an X server on the 350 and then of course everything display=
|ed
|> on the TV, but through the dumb framebuffer interface.) There were no
|> error messages or anything else to indicate that the PVR-350 was being
|> accessed at all.
|>
|> Finally I had the thought to try using the PVR-350's own analog tuner as a
|> source rather than the pcHDTV. The PVR-350's output then came to life,
|> turned on and off by the configuration option in Playback Settings just as
|> it should be. Is something in MythTV deciding that the PVR-350's MPEG
|> decoder can't handle the ATSC stream? Or is there some interdependence
|> between PVR-350 capture and output (which would seem to defeat the purpose
|> of MythTV's distributed architecture)?

|=46irst off, the 350's decoder is set up for NTSC or PAL sized mpeg2 frames=
|, not=20
|ATSC sized frames. I don't think the hardware is physically capable of=20
|handling something that big.

So does something in the MythTV code know this and simply refuse to try? Is
this documented anywhere?

|Second, why on earth would you want to output=
|=20
|HDTV content through an SVideo connection that is 720x480, interlaced?

Because I don't care about "H"DTV. I just want ATSC reception converted
to NTSC.

|You'=
|d=20
|effectively be down-sampling the ATSC signal back down to NTSC,

Yes, that's exactly what I want.

|so why even=
|=20
|bother?

Because analog will eventually go away and even now ATSC offers me a picture
with less ghosting and interference.

|For HDTV, you really need to be outputting to your TV via VGA, DVI =
|or=20
|component for it to be worthwhile.

Well, clearly this is a matter of opinion (as suggested by the existence of
set top boxes that receive ATSC and downconvert to NTSC as necessary). My TVs
do not have VGA, DVI, or component inputs.

It's possible that I misunderstood the generality of the MythTV model. I
thought that the pcHDTV card was just another source of input and the PVR-350
just another output device.

|This has all been discussed before, plea=
|se=20
|search the archives if you want more insight.

I've searched extensively and I found nothing to answer my question. Could
you point me to the specific discussion of PVR-350 output used with the
pcHDTV as source?

Dan Lanciani
ddl [at] danlan*com

jr at jrh

Oct 22, 2004, 10:48 PM

Post #4 of 35 (4808 views)
Permalink

RE: pcHDTV with PVR-350 for output [In reply to]

While mythtv is fairly general it does actually store encoder specific cards
like the pvrXXX series and the pchdtv cards in their native format. Ie, the
*.nuv files are actually just mpg or ts files respectively with a nuv
suffix. There is no way the PVR350 is going to play a pchdtv atsc stream.

On the other hand there is EVERY reason to want to do what you are asking, I
really can't understand Jarod (who otherwise is an absolute font of good
information) saying there isn't. An atsc stream of even standard definition
programming is going to usually blow away the ntsc equivalent, no matter the
source, including cable, over the air, and satellite. So while you are not
going to be able to use the pvr350 for your output, getting it working is
not a bad idea by any means. You will need a fairly beefy machine to either
resize in real time or transcode ahead of time.

> -----Original Message-----
> From: mythtv-users-bounces [at] mythtv [mailto:mythtv-users-
> bounces [at] mythtv] On Behalf Of Dan Lanciani
> Sent: Friday, October 22, 2004 10:32 PM
> To: mythtv-users [at] mythtv
> Subject: Re: [mythtv-users] pcHDTV with PVR-350 for output
>
> Jarod Wilson <jcw [at] wilsonet> wrote:
>
> |On Friday 22 October 2004 21:56, Dan Lanciani wrote:
> |> I've been trying to send ATSC programming from a pcHDTV card through
> the
> |> MPEG decoder in a PVR-350 using MythTV 0.16. It seemed that the
> |> configuration setting to use the PVR-350's output was just being
> ignored.=
> |=20
> |> (I could run an X server on the 350 and then of course everything
> display=
> |ed
> |> on the TV, but through the dumb framebuffer interface.) There were no
> |> error messages or anything else to indicate that the PVR-350 was being
> |> accessed at all.
> |>
> |> Finally I had the thought to try using the PVR-350's own analog tuner
> as a
> |> source rather than the pcHDTV. The PVR-350's output then came to life,
> |> turned on and off by the configuration option in Playback Settings just
> as
> |> it should be. Is something in MythTV deciding that the PVR-350's MPEG
> |> decoder can't handle the ATSC stream? Or is there some interdependence
> |> between PVR-350 capture and output (which would seem to defeat the
> purpose
> |> of MythTV's distributed architecture)?
>
> |=46irst off, the 350's decoder is set up for NTSC or PAL sized mpeg2
> frames=
> |, not=20
> |ATSC sized frames. I don't think the hardware is physically capable of=20
> |handling something that big.
>
> So does something in the MythTV code know this and simply refuse to try?
> Is
> this documented anywhere?
>
> |Second, why on earth would you want to output=
> |=20
> |HDTV content through an SVideo connection that is 720x480, interlaced?
>
> Because I don't care about "H"DTV. I just want ATSC reception converted
> to NTSC.
>
> |You'=
> |d=20
> |effectively be down-sampling the ATSC signal back down to NTSC,
>
> Yes, that's exactly what I want.
>
> |so why even=
> |=20
> |bother?
>
> Because analog will eventually go away and even now ATSC offers me a
> picture
> with less ghosting and interference.
>
> |For HDTV, you really need to be outputting to your TV via VGA, DVI =
> |or=20
> |component for it to be worthwhile.
>
> Well, clearly this is a matter of opinion (as suggested by the existence
> of
> set top boxes that receive ATSC and downconvert to NTSC as necessary). My
> TVs
> do not have VGA, DVI, or component inputs.
>
> It's possible that I misunderstood the generality of the MythTV model. I
> thought that the pcHDTV card was just another source of input and the PVR-
> 350
> just another output device.
>
> |This has all been discussed before, plea=
> |se=20
> |search the archives if you want more insight.
>
> I've searched extensively and I found nothing to answer my question.
> Could
> you point me to the specific discussion of PVR-350 output used with the
> pcHDTV as source?
>
> Dan Lanciani
> ddl [at] danlan*com

ddl5 at danlan

Oct 22, 2004, 11:11 PM

Post #5 of 35 (4802 views)
Permalink

RE: pcHDTV with PVR-350 for output [In reply to]

"jack" <jr [at] jrh> wrote:

|While mythtv is fairly general it does actually store encoder specific cards
|like the pvrXXX series and the pchdtv cards in their native format. Ie, the
|*.nuv files are actually just mpg or ts files respectively with a nuv
|suffix.

Right, I got that. And I think it is the correct approach since it preserves
maximum information. However, I somehow had the idea that it would transcode
and scale as necessary near the output. (In my defense, there is a lot of code
in MythTV proper and a rather large number of libraries. It isn't immediately
obvious that it doesn't do this. :)

|There is no way the PVR350 is going to play a pchdtv atsc stream.

Sure, if it could I could just copy from /dev/dtv to /dev/video17. A few
little scripts to make recordings and I wouldn't need MythTV at all... :)

|So while you are not
|going to be able to use the pvr350 for your output, getting it working is
|not a bad idea by any means. You will need a fairly beefy machine to either
|resize in real time or transcode ahead of time.

I set this up on a 3.2GHz P4 machine with that in mind. But it sounds like
what I want doesn't really fit the current MythTV infrastructure. (By the
way, the *other* thing I want is FireWire/DV in/out which might present
similar problems.) Since MythTV is already rather large and complicated
(and given the problems I'm having with the front end hanging) I'm not sure
whether starting from scratch might be more efficient than hacking the existing
code.

Dan Lanciani
ddl [at] danlan*com

ijr at po

Oct 22, 2004, 11:38 PM

Post #6 of 35 (4797 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

On Saturday 23 October 2004 02:11 am, Dan Lanciani wrote:
> "jack" <jr [at] jrh> wrote:
> |While mythtv is fairly general it does actually store encoder specific
> | cards like the pvrXXX series and the pchdtv cards in their native format.
> | Ie, the *.nuv files are actually just mpg or ts files respectively with a
> | nuv suffix.
>
> Right, I got that. And I think it is the correct approach since it
> preserves maximum information. However, I somehow had the idea that it
> would transcode and scale as necessary near the output. (In my defense,
> there is a lot of code in MythTV proper and a rather large number of
> libraries. It isn't immediately obvious that it doesn't do this. :)

If you tell it to transcode, it will. It won't be realtime, though.

> |There is no way the PVR350 is going to play a pchdtv atsc stream.
>
> Sure, if it could I could just copy from /dev/dtv to /dev/video17. A few
> little scripts to make recordings and I wouldn't need MythTV at all... :)

No, there isn't. The decoder on the -350 isn't capable of decoding hdtv - it
can't handle anything more than 480i (or standard pal), and it can't decode
ac-3 audio - and will ignore anything but the first audio stream, so if
that's the ac3 stream (which is standard), you won't get any audio at all.

Isaac
_______________________________________________
mythtv-users mailing list
mythtv-users [at] mythtv
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

ddl5 at danlan

Oct 22, 2004, 11:57 PM

Post #7 of 35 (4795 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

Isaac Richards <ijr [at] po> wrote:

|On Saturday 23 October 2004 02:11 am, Dan Lanciani wrote:
|> "jack" <jr [at] jrh> wrote:
|> |While mythtv is fairly general it does actually store encoder specific
|> | cards like the pvrXXX series and the pchdtv cards in their native format.
|> | Ie, the *.nuv files are actually just mpg or ts files respectively with a
|> | nuv suffix.
|>
|> Right, I got that. And I think it is the correct approach since it
|> preserves maximum information. However, I somehow had the idea that it
|> would transcode and scale as necessary near the output. (In my defense,
|> there is a lot of code in MythTV proper and a rather large number of
|> libraries. It isn't immediately obvious that it doesn't do this. :)
|
|If you tell it to transcode, it will.

How would I tell it to transcode in this situation?

|It won't be realtime, though.

What prevents it from being real time?

|> |There is no way the PVR350 is going to play a pchdtv atsc stream.
|>
|> Sure, if it could I could just copy from /dev/dtv to /dev/video17. A few
|> little scripts to make recordings and I wouldn't need MythTV at all... :)
|
|No, there isn't.

No, there isn't what?

Dan Lanciani
ddl [at] danlan*com

doug at ties

Oct 23, 2004, 6:39 AM

Post #8 of 35 (4807 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

Dan Lanciani wrote:
> |> Right, I got that. And I think it is the correct approach since it
> |> preserves maximum information. However, I somehow had the idea that it
> |> would transcode and scale as necessary near the output. (In my defense,
> |> there is a lot of code in MythTV proper and a rather large number of
> |> libraries. It isn't immediately obvious that it doesn't do this. :)
> |
> |If you tell it to transcode, it will.
>
> How would I tell it to transcode in this situation?
>
> |It won't be realtime, though.
>
> What prevents it from being real time?

It's way too compute intensive. Probably by a factor of at least 2. It
would have to decode, resample, and re-encode. Doing this in software
is beyond the capabilities of current general-purpose computing hardware.

There's also the small matter that what Myth stores for HDTV is an
MPEG-TS (transport stream) file, not an MPEG-PS (program stream) as
expected by the PVR-350. This is aside from the frame-size limitations
mentioned by others. Nothing in MythTV is set up to account for any of
this at all.

To do what you want to do, you're better off using an nVidia MX-440 or
FX5200 and using its svideo output, since you *do* have the horsepower
to decode ATSC-sized frames in realtime. Then the video card would do
the scaling (in hardware), and you're good to go. An MX-440 is less than
$50.

-Doug

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ddl5 at danlan

Oct 23, 2004, 1:58 PM

Post #9 of 35 (4796 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

Doug Larrick <doug [at] ties> wrote:

|Dan Lanciani wrote:
|> |> Right, I got that. And I think it is the correct approach since it
|> |> preserves maximum information. However, I somehow had the idea that it
|> |> would transcode and scale as necessary near the output. (In my defense,
|> |> there is a lot of code in MythTV proper and a rather large number of
|> |> libraries. It isn't immediately obvious that it doesn't do this. :)
|> |
|> |If you tell it to transcode, it will.
|>
|> How would I tell it to transcode in this situation?
|>
|> |It won't be realtime, though.
|>
|> What prevents it from being real time?
|
|It's way too compute intensive. Probably by a factor of at least 2. It
|would have to decode, resample, and re-encode. Doing this in software
|is beyond the capabilities of current general-purpose computing hardware.

Hmm. From reading the hardware requirements documentation I had gotten the
(mis?)impression that even machines slower than "state of the art" could
handle a dumb capture card and software display decoding at the same time.
That's the same number of MPEG encode/decode steps. I don't have a good feel
for the cost of resampling, but I would think that going from 480p to 480i
(which should take care of any SD stream?) would not require much computation
since it's only re-arranging scan lines. Am I missing something?

|There's also the small matter that what Myth stores for HDTV is an
|MPEG-TS (transport stream) file, not an MPEG-PS (program stream) as
|expected by the PVR-350.

I'm not clear on how the on-disk format enters into it. Is there some
architectural reason that there can't be any post-processing after reading
the data? In any case, storing the whole transport stream might be something
to rethink eventually, especially if multicasting pay services take off. No
sense saving stuff you can't even watch...

|This is aside from the frame-size limitations
|mentioned by others.

The frame size capabilities happen to line up nicely with the capabilities of
the display devices that can be connected, so I guess the conversion has to
happen somewhere. :)

|Nothing in MythTV is set up to account for any of
|this at all.

Yes, I completely misunderstood this before. I thought that the intent was
to support arbitrary capture and display devices in any combination. I didn't
realize that playback was constrained by the source. As I mentioned, this
will probably be a problem for the other thing I was hoping to have (FireWire
in and out).

|To do what you want to do, you're better off using an nVidia MX-440 or
|FX5200 and using its svideo output, since you *do* have the horsepower
|to decode ATSC-sized frames in realtime. Then the video card would do
|the scaling (in hardware), and you're good to go. An MX-440 is less than
|$50.

I have an FX5200 in the machine now. Historically I haven't been pleased
with the results from TV-out-supporting video cards. It always seemed like
the NTSC mode was an afterthought and the timing was never quite right,
leading to the need for tweaks specific to each television. (My ultimate
goal is to feed the output of the PVR box into my house's distribution
system in place of--or in addition to--the current off-the-shelf Panasonic
PVR which is analog-only.) However, I played mainly with ATI and Matrox cards
before.

If I have to I can just decode to the PVR-350's frame buffer device. This
keeps up fine, but something is confused about the aspect ratios.

Dan Lanciani
ddl [at] danlan*com

danielk at mrl

Oct 23, 2004, 3:12 PM

Post #10 of 35 (4799 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

]Hmm. From reading the hardware requirements documentation I had gotten the
](mis?)impression that even machines slower than "state of the art" could
]handle a dumb capture card and software display decoding at the same time.
]That's the same number of MPEG encode/decode steps. I don't have a good feel
]for the cost of resampling, but I would think that going from 480p to 480i
](which should take care of any SD stream?) would not require much computation
]since it's only re-arranging scan lines. Am I missing something?

Resampling is not very expensive. But decoding HDTV in software requires
about a P4 3Ghz and encoding a 640x480 MPEG2 stream requires about the
same amount of hardware. So you are looking at a P4 6Ghz just to avoid
using a $35 video card with TV-out. MPEG decoding is relatively simple
and quick (although we do struggle with it at 1080i), but encoding in
real-time is still generally done with specialized hardware.

]|There's also the small matter that what Myth stores for HDTV is an
]|MPEG-TS (transport stream) file, not an MPEG-PS (program stream) as
]|expected by the PVR-350.
]I'm not clear on how the on-disk format enters into it. Is there some
]architectural reason that there can't be any post-processing after reading
]the data? In any case, storing the whole transport stream might be something
]to rethink eventually, especially if multicasting pay services take off. No
]sense saving stuff you can't even watch...

It wouldn't be very difficult to save a PES stream instead of a TS
stream. But then we couldn't implement some of the nice features coming
to ATSC soon. And because the PVR-350 hardware isn't capable of decoding
HDTV sized frames there is little incentive to save PES streams. We
already save only the pid's we need so the space savings would only be
about 2%.

-- Daniel

ddl5 at danlan

Oct 23, 2004, 3:57 PM

Post #11 of 35 (4782 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

|]Hmm. From reading the hardware requirements documentation I had gotten the
|](mis?)impression that even machines slower than "state of the art" could
|]handle a dumb capture card and software display decoding at the same time.
|]That's the same number of MPEG encode/decode steps. I don't have a good feel
|]for the cost of resampling, but I would think that going from 480p to 480i
|](which should take care of any SD stream?) would not require much computation
|]since it's only re-arranging scan lines. Am I missing something?
|
|Resampling is not very expensive. But decoding HDTV in software requires
|about a P4 3Ghz and encoding a 640x480 MPEG2 stream requires about the
|same amount of hardware.

Then if I were watching an ATSC program and tried to start a recording from
Svideo in (or a tuner) on a dumb capture card one or both would likely fail
on a single P4/3.2GHz?

|So you are looking at a P4 6Ghz just to avoid
|using a $35 video card with TV-out.

I'm looking at what it would take to have a general solution that will
support the same kinds of features as commercial DVRs, but of course without
annoying copy protection mechanisms. Independence of input and output encoding
is also important to support FireWire/DV. If the required CPU power if just
out of reach today on a single processor machine it will probably be well
within reach in a year on a dual processor machine.

As far as cheap (or even expensive) video cards with TV-out, my experience
hasn't been good, but I'll certainly give it another try. I already have the
FX5200, though I've noticed that fast-play doesn't actually work (it shows
little spurts of fast motion, but generally gets behind). I don't know if
that is a video card issue. I'd really love to just feed DV to a Sony DVMC
or Miglia decoder since they produce nice NTSC timing.

Dan Lanciani
ddl [at] danlan*com

ender at speakeasy

Oct 23, 2004, 4:41 PM

Post #12 of 35 (4789 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

On Oct 23, 2004, at 6:12 PM, Daniel Thor Kristjansson wrote:
> Resampling is not very expensive. But decoding HDTV in software
> requires
> about a P4 3Ghz and encoding a 640x480 MPEG2 stream requires about the
> same amount of hardware. So you are looking at a P4 6Ghz just to avoid

This is a stat i keep seeing... Is there a consensus on a minumum for
decoding HDTV on an Athlon XP, Sempron, or A64?

--chris

nate.strickland at gmail

Oct 24, 2004, 12:45 PM

Post #13 of 35 (4770 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

Yeah, I too am curious about that. Would 2 3Ghz xenons be able to do
it? Or a dual 64 bit amd system?

On Sat, 23 Oct 2004 19:41:26 -0400, Chris Curtis <ender [at] speakeasy> wrote:
>
> On Oct 23, 2004, at 6:12 PM, Daniel Thor Kristjansson wrote:
> > Resampling is not very expensive. But decoding HDTV in software
> > requires
> > about a P4 3Ghz and encoding a 640x480 MPEG2 stream requires about the
> > same amount of hardware. So you are looking at a P4 6Ghz just to avoid
>
> This is a stat i keep seeing... Is there a consensus on a minumum for
> decoding HDTV on an Athlon XP, Sempron, or A64?
>
> --chris
>
>
> _______________________________________________
> mythtv-users mailing list
> mythtv-users [at] mythtv
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>
>
>

danielk at mrl

Oct 24, 2004, 7:36 PM

Post #14 of 35 (4769 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

]Then if I were watching an ATSC program and tried to start a recording from
]Svideo in (or a tuner) on a dumb capture card one or both would likely fail
]on a single P4/3.2GHz?

You could use nuppelvideo for the frame capture card and it should work.
But using mpeg-4 would probably be a bad idea. Most commercial PVR
software doesn't support using frame grabbers. (Hardware MPEG-4 capture
cards still cost lots-o-money.)

]I'm looking at what it would take to have a general solution that will
]support the same kinds of features as commercial DVRs, but of course without
]annoying copy protection mechanisms. Independence of input and output encoding
]is also important to support FireWire/DV. If the required CPU power if just
]out of reach today on a single processor machine it will probably be well
]within reach in a year on a dual processor machine.

You can't have complete independence of input and output encoding
without very high CPU requirements. Which is why commercial DVRs insist
on computers with matched hardware encoders and hardware decoders.

But don't fret too much about FireWire/DV, a P4/1.8Mhz can cope with DV,
and FireWire HDTV won't require any more decoding power than
over-the-air HDTV. The biggest obstacle will be encryption, as the FCC
is allowing cable operators to encrypt FireWire video. MythTV will not
work with these as inputs.

]As far as cheap (or even expensive) video cards with TV-out, my experience
]hasn't been good, but I'll certainly give it another try. I already have the
]FX5200, though I've noticed that fast-play doesn't actually work (it shows
]little spurts of fast motion, but generally gets behind). I don't know if
]that is a video card issue. I'd really love to just feed DV to a Sony DVMC
]or Miglia decoder since they produce nice NTSC timing.

We can get fast-play working with HDTV, but it's not yet high priority.
It's mostly a ffmpeg w/MythTV issue. I don't think anyone is working on
DV out, DV looks pretty crappy compared to what you can do with a good
TV-out setting (For instance, I can get my plain old TV to sync to a
800x600 signal from the FX5200.) The problem with the nvidia output
stage is the analog filter, it has too few taps and produces some
ringing around edges in the image. You can reduce or eliminate this by
using a higher output resolution than your capture resolution.

For reference, in terms of CPU requirements (low to high):
nuppelvideo enc, nuppelvideo dec, DV enc, mpeg2 dec, DV dec, mpeg4 dec,
mpeg2 enc (480i on a P4 [at] 3Gh, 1080i on $10,000 hardware encoder.)
mpeg4 enc (480i on a P4 [at] 3Gh, 1080i on $100,000 hardware encoder.)

You can make mpeg encoding faster by doing a worse job of it, like
"Quicktime Pro" does, but even so it demands a serious processor.

-- Daniel

ddl5 at danlan

Oct 24, 2004, 8:47 PM

Post #15 of 35 (4764 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

Daniel Thor Kristjansson <danielk [at] mrl> wrote:

|You can't have complete independence of input and output encoding
|without very high CPU requirements.

If "very high" equates to about twice what we have now, it shouldn't be
long before this is not a problem. In any case, it would be nice to have
at least *some* independence...

|Which is why commercial DVRs insist
|on computers with matched hardware encoders and hardware decoders.

The commercial DVR I bought doesn't insist on a computer at all. :)

|But don't fret too much about FireWire/DV, a P4/1.8Mhz can cope with DV,

Meaning that it can transcode to it from any of the on-disk formats you may
use in real time or meaning that it can only render it to a display?

|and FireWire HDTV won't require any more decoding power than
|over-the-air HDTV. The biggest obstacle will be encryption, as the FCC
|is allowing cable operators to encrypt FireWire video. MythTV will not
|work with these as inputs.

I didn't realize it worked with any FireWire input; is this documented
somewhere? (I don't care about encrypted streams; I just want to move
video among my internal devices.)

|]As far as cheap (or even expensive) video cards with TV-out, my experience
|]hasn't been good, but I'll certainly give it another try. I already have the
|]FX5200, though I've noticed that fast-play doesn't actually work (it shows
|]little spurts of fast motion, but generally gets behind). I don't know if
|]that is a video card issue. I'd really love to just feed DV to a Sony DVMC
|]or Miglia decoder since they produce nice NTSC timing.
|
|We can get fast-play working with HDTV, but it's not yet high priority.
|It's mostly a ffmpeg w/MythTV issue.

Ah, I didn't realize that this was not supposed to work. Does any kind
of fast forward functionality work? Rewind?

|I don't think anyone is working on
|DV out, DV looks pretty crappy compared to what you can do with a good
|TV-out setting

Sorry, but I really find this a bit hard to believe. :( And even if it
doesn't look good it is the accepted way to interconnect with other non-
display devices.

|(For instance, I can get my plain old TV to sync to a
|800x600 signal from the FX5200.)

I'm not sure what this means. Are you actually generating 600 (300 interlaced)
scan lines? If so that's not real NTSC anymore. Maybe you can get a specific
TV so sync to it, but it won't work as a general video source. And this is
my main gripe with the TV-out support on every video card I've ever tried. You
can tweak this and that to get it to almost look right on a particular TV, but
the signal is so far out of spec that it's useless for anything else.

|The problem with the nvidia output
|stage is the analog filter, it has too few taps and produces some
|ringing around edges in the image. You can reduce or eliminate this by
|using a higher output resolution than your capture resolution.

I haven't even noticed the ringing yet. It is completely overshadowed by
the horrible motion artifacts. Even as someone moves their hand across the
screen you can see lots of black scan line "checks" around the motion. I
know it isn't a problem with the source stream because my ancient DTC-100
renders a perfect NTSC representation of the same program. I don't know if
it is an MPEG decoding issue or an NTSC encoding problem, but it (IMHO) makes
the output useless. (See my previous message about the FX5200.)

I'm going to keep playing for a while, but I get the feeling that what I
want (ATSC source; real NTSC out) is not possible with the current selection
of hardware and software. :(

Dan Lanciani
ddl [at] danlan*com

danielk at mrl

Oct 25, 2004, 6:18 AM

Post #16 of 35 (4762 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

On Sun, 24 Oct 2004, Dan Lanciani wrote:
]Daniel Thor Kristjansson <danielk [at] mrl> wrote:
]If "very high" equates to about twice what we have now, it shouldn't be
]long before this is not a problem. In any case, it would be nice to have
]at least *some* independence...

Very high would be 10 to 20 times the CPUs of today if you wanted to
encode 1080i. Outputting 640x480 MPEG2 while decoding 1080i should be
doable in a few years.

]|But don't fret too much about FireWire/DV, a P4/1.8Mhz can cope with DV,
]Meaning that it can transcode to it from any of the on-disk formats you may
]use in real time or meaning that it can only render it to a display?

It is probably possible to do both now on a fast computer, but it is
not implemented in MythTV.

]I didn't realize it worked with any FireWire input; is this documented
]somewhere? (I don't care about encrypted streams; I just want to move
]video among my internal devices.)

Not yet, but it is possible, and there is some interest in doing it.
Macintosh software for doing it already exists.

]|We can get fast-play working with HDTV, but it's not yet high priority.
]|It's mostly a ffmpeg w/MythTV issue.
]Ah, I didn't realize that this was not supposed to work. Does any kind
]of fast forward functionality work? Rewind?

Skip works. And fast forward works on very powerful processors. But we
can make it easier on the processor, it just requires some tweaking. But
first we need to get regular play working better.

]|I don't think anyone is working on
]|DV out, DV looks pretty crappy compared to what you can do with a good
]|TV-out setting
]Sorry, but I really find this a bit hard to believe. :( And even if it
]doesn't look good it is the accepted way to interconnect with other non-
]display devices.

Yes, it is an accepted interconnect so it belongs in MythTV. But I
don't think antone is working on it.

]|(For instance, I can get my plain old TV to sync to a
]|800x600 signal from the FX5200.)
]I'm not sure what this means. Are you actually generating 600 (300
]interlaced) scan lines? If so that's not real NTSC anymore. Maybe you

Yes, it works with my specific TV. It should actually work with most TVs
with composite input, but I've never published my modeline because it
can destroy some older TV's.

]can get a specific TV so sync to it, but it won't work as a general
]video source. And this is my main gripe with the TV-out support on
]every video card I've ever tried. You can tweak this and that to get
]it to almost look right on a particular TV, but the signal is so far
]out of spec that it's useless for anything else.

Hmmm, well safe modeline adjustment could be added to MythTV. Right now
MythTV setup is admitedly a pain. There are some standalone programs out
there to generate modelines. One used to actually come with both RedHat
and Mandrake, but has been dumped because most computer monitors these
days tell X11 how to drive the monitor. But TV's don't and setting them
up is very much like setting up XFree86 was like 10 years ago.

]I haven't even noticed the ringing yet. It is completely overshadowed by
]the horrible motion artifacts. Even as someone moves their hand across the
]screen you can see lots of black scan line "checks" around the motion. I
]know it isn't a problem with the source stream because my ancient DTC-100
]renders a perfect NTSC representation of the same program. I don't know if
]it is an MPEG decoding issue or an NTSC encoding problem, but it (IMHO) makes
]the output useless. (See my previous message about the FX5200.)

Are you using XvMC? Try XV if you are. This sounds like a bug. Does
it look good in mplayer? Does it look good on your monitor?
If it looks good on your monitor, and not on TV out, you may have a
broken nvidia video card.

]I'm going to keep playing for a while, but I get the feeling that what I
]want (ATSC source; real NTSC out) is not possible with the current selection
]of hardware and software. :(

It is not one of the setups we test, but it should work if the output is
an XV surface.

-- Daniel

bolek-mythtv at curl

Oct 25, 2004, 7:53 AM

Post #17 of 35 (4760 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

Daniel Thor Kristjansson wrote:
> ]|(For instance, I can get my plain old TV to sync to a
> ]|800x600 signal from the FX5200.)
> ]I'm not sure what this means. Are you actually generating 600 (300
> ]interlaced) scan lines? If so that's not real NTSC anymore. Maybe you
>
> Yes, it works with my specific TV. It should actually work with most TVs
> with composite input, but I've never published my modeline because it
> can destroy some older TV's.

It is very unlikely that your (plain NTSC) TV is actually syncing to a
800x600 signal. Even though you may have specified 800x600 modeline, the
graphics card is doing the scan conversion to standard NTSC before
outputting anything via TV-out. This is actually a major source of
quality problems with the graphics card TV-out.

Bolek
_______________________________________________
mythtv-users mailing list
mythtv-users [at] mythtv
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

rtjacob at earthlink

Oct 25, 2004, 8:30 AM

Post #18 of 35 (4764 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

<snip>
> First off, the 350's decoder is set up for NTSC or PAL sized mpeg2 frames,
> not
> ATSC sized frames. I don't think the hardware is physically capable of
> handling something that big. Second, why on earth would you want to output
> HDTV content through an SVideo connection that is 720x480, interlaced? You'd
> effectively be down-sampling the ATSC signal back down to NTSC, so why even
> bother? For HDTV, you really need to be outputting to your TV via VGA, DVI or
> component for it to be worthwhile. This has all been discussed before, please
> search the archives if you want more insight.

This is partially true.. I can take recordings from my PCHDTV card that are 480i
convert them to PS and they play fine.. It seems that the PVR350 will not handle
the stripped TS that hdtvrecorer currently makes. You of course still have the
seperate issue if the hd program uses ac3, but the video plays just fine.. You
are correct on the 720p and 1080i standards with the PVR350.. I can play back
dvb recordings no problem with the pvr350 which are no different in PS format
than ATSC is in PS format..

I actually wanted to setup my PCHdtv to only recorde the 480i content (Most HD
programming I can get is 480i) just because I could get the programming I
wanted over a digital medium and not have to pay the cable company or use an
antenna and get a grainy picture..

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

jcw at wilsonet

Oct 25, 2004, 11:59 AM

Post #19 of 35 (4754 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

On Friday 22 October 2004 22:31, Dan Lanciani wrote:
> Jarod Wilson <jcw [at] wilsonet> wrote:

> |Second, why on earth would you want to output=
> |=20
> |HDTV content through an SVideo connection that is 720x480, interlaced?
>
> Because I don't care about "H"DTV. I just want ATSC reception converted
> to NTSC.
>
> |You'=
> |d=20
> |effectively be down-sampling the ATSC signal back down to NTSC,
>
> Yes, that's exactly what I want.
>
> |so why even=
> |=20
> |bother?
>
> Because analog will eventually go away and even now ATSC offers me a
> picture with less ghosting and interference.
>
> |For HDTV, you really need to be outputting to your TV via VGA, DVI =
> |or=20
> |component for it to be worthwhile.
>
> Well, clearly this is a matter of opinion (as suggested by the existence of
> set top boxes that receive ATSC and downconvert to NTSC as necessary). My
> TVs do not have VGA, DVI, or component inputs.

Ah, sorry. Bad assumption on my part, assumed you were outputting to an HDTV.

> It's possible that I misunderstood the generality of the MythTV model. I
> thought that the pcHDTV card was just another source of input and the
> PVR-350 just another output device.

As Taylor pointed out, I wasn't entirely correct in my general statement that
the 350's output can't handle ATSC-sized frames. It definitely can't handle
1080i and 720p content though.

> |This has all been discussed before, plea=
> |se=20
> |search the archives if you want more insight.
>
> I've searched extensively and I found nothing to answer my question. Could
> you point me to the specific discussion of PVR-350 output used with the
> pcHDTV as source?

http://www.gossamer-threads.com/lists/engine?list=mythtv&do=search_results&search_forum=all&search_string=hdtv+350&search_type=AND

--
Jarod C. Wilson, RHCE
jcw [at] wilsonet

Got a question? Read this first...
http://catb.org/~esr/faqs/smart-questions.html
MythTV, Fedora Core & ATrpms documentation:
http://wilsonet.com/mythtv/
MythTV Searchable Mailing List Archive
http://www.gossamer-threads.com/lists/mythtv/

jcw at wilsonet

Oct 25, 2004, 12:04 PM

Post #20 of 35 (4769 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

On Friday 22 October 2004 22:48, jack wrote:
> On the other hand there is EVERY reason to want to do what you are asking,

Bad assumption on my part, figured he was outputting to an HDTV.

> I really can't understand Jarod (who otherwise is an absolute font of good
> information) saying there isn't.

I can't see that there's EVERY reason to do this, but I better understand what
the OP is trying to do now.

> An atsc stream of even standard
> definition programming is going to usually blow away the ntsc equivalent,
> no matter the source, including cable, over the air, and satellite.

Apparently, I have a very clean cable signal, because my NTSC stuff on NTSC
televisions looks great... Haven't yet tried down-sampling anything ATSC to
watch on an analog set (no reason to, I'd rather just watch it on my HDTV
w/DD5.1 ;-).

--
Jarod C. Wilson, RHCE
jcw [at] wilsonet

Got a question? Read this first...
http://catb.org/~esr/faqs/smart-questions.html
MythTV, Fedora Core & ATrpms documentation:
http://wilsonet.com/mythtv/
MythTV Searchable Mailing List Archive
http://www.gossamer-threads.com/lists/mythtv/

jcw at wilsonet

Oct 25, 2004, 12:11 PM

Post #21 of 35 (4746 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

On Saturday 23 October 2004 16:41, Chris Curtis wrote:
> On Oct 23, 2004, at 6:12 PM, Daniel Thor Kristjansson wrote:
> > Resampling is not very expensive. But decoding HDTV in software
> > requires
> > about a P4 3Ghz and encoding a 640x480 MPEG2 stream requires about the
> > same amount of hardware. So you are looking at a P4 6Ghz just to avoid
>
> This is a stat i keep seeing... Is there a consensus on a minumum for
> decoding HDTV on an Athlon XP, Sempron, or A64?

I have no problems at all with an Athlon XP 3200+ and a GeForce FX 5200. CPU
usage ranges anywhere from 60% to 85%, depending on the filters applied and
the source. I haven't had a chance to do much benchmarking yet, but usage
does seem a little lower since moving to a 2.6.9 kernel compiled with gcc 3.4
(versus my prior 2.6.7 kernel compiled w/gcc 3.3). Still need to figure out
what is going on when I try to compile Myth w/gcc 3.4, the frontend likes to
bomb out for some reason. Probably going to shift from 0.16 to CVS next
weekend, since a whole bunch of stuff relevant to my setup has been added
recently...

--
Jarod C. Wilson, RHCE
jcw [at] wilsonet

Got a question? Read this first...
http://catb.org/~esr/faqs/smart-questions.html
MythTV, Fedora Core & ATrpms documentation:
http://wilsonet.com/mythtv/
MythTV Searchable Mailing List Archive
http://www.gossamer-threads.com/lists/mythtv/

pc-mythtv04 at crowcastle

Oct 25, 2004, 12:49 PM

Post #22 of 35 (4768 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

On Mon, 2004-10-25 at 15:11, Jarod Wilson wrote:
> I have no problems at all with an Athlon XP 3200+ and a GeForce FX 5200.

I haven't checked the CPU load, but on my Athlon XP 2500+ (barton core)
and GeForce FX 5200, I'm having some trouble with my current settings on
Myth, but it works great using "mplayer -vo xv /dev/video32" to watch
TV. I'm using Jarod's XF86Config file, so instead of true 1080i, it's
540p (and the horizontal resolution is cut in half).

I have a Gentoo system with all the latest everything. I believe that
mplayer has xvmc support.

My to-do list includes:

* Try to get a real 1080i mode working (is it even possible with the
latest nVidia drivers?)
* Get Myth to play as well as mplayer.
* Benchmark the CPU load
* Experiment with transcoding of HDTV

Issues with HDTV and Myth that I think are still outstanding:

* Auto-switching of video modes to match source (1080i vs. 720p
primarily)
* Graphics assume a 4:3 display, so they look weird on a 16:9 (at least
with the blue theme)

--PC

jcw at wilsonet

Oct 25, 2004, 1:19 PM

Post #23 of 35 (4753 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

On Monday 25 October 2004 12:49, Preston Crow wrote:
> On Mon, 2004-10-25 at 15:11, Jarod Wilson wrote:
> > I have no problems at all with an Athlon XP 3200+ and a GeForce FX 5200.
>
> I haven't checked the CPU load, but on my Athlon XP 2500+ (barton core)
> and GeForce FX 5200, I'm having some trouble with my current settings on
> Myth

I'm guessing you're frequently pegging your CPU.

> but it works great using "mplayer -vo xv /dev/video32" to watch
> TV.

I actually get better results viewing with Myth. My signal isn't great, which
may be the cause of mplayer's issues (bad audio sync, occasional loss of
audio, occasional pixelization).

> I'm using Jarod's XF86Config file, so instead of true 1080i, it's
> 540p (and the horizontal resolution is cut in half).

You're using my *old* config file. (See below :-)

> My to-do list includes:
>
> * Try to get a real 1080i mode working (is it even possible with the
> latest nVidia drivers?)

My currently posted X config file includes 1080i modes that work quite nicely
w/the nvidia 6111 driver. I'm actually running 880x480p for the UI and
standard-def TV, 1760x960i for high-def TV, both of which fit just about
perfectly on my TV, no overscan.

> * Get Myth to play as well as mplayer.
> * Benchmark the CPU load
> * Experiment with transcoding of HDTV
>
> Issues with HDTV and Myth that I think are still outstanding:
>
> * Auto-switching of video modes to match source (1080i vs. 720p
> primarily)

I wish my TV supported 720p... This is just an xrandr thing. Enable "separate
modes for playback and UI", set your UI mode (540p mode highly recommended
over 1080i mode for readability) and your default mode, then set overrides
for other content. I have 880x480 as my UI mode, 1760x960 as my default
playback mode, then an override for 720x480 content to display in 880x480. If
I could actually do 720p, I'd have an override for that matching 1280x720
content. Of course, you must also have all these modes defined in your X
config file and validated when the X server starts up.

> * Graphics assume a 4:3 display, so they look weird on a 16:9 (at least
> with the blue theme)

I think part of it is that I'm just used to it now, but both GANT and
Titivillus look good to me in 16:9.

--
Jarod C. Wilson, RHCE
jcw [at] wilsonet

Got a question? Read this first...
http://catb.org/~esr/faqs/smart-questions.html
MythTV, Fedora Core & ATrpms documentation:
http://wilsonet.com/mythtv/
MythTV Searchable Mailing List Archive
http://www.gossamer-threads.com/lists/mythtv/

ddl5 at danlan

Oct 25, 2004, 2:07 PM

Post #24 of 35 (4763 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

Daniel Thor Kristjansson <danielk [at] mrl> wrote:

|On Sun, 24 Oct 2004, Dan Lanciani wrote:
|]Daniel Thor Kristjansson <danielk [at] mrl> wrote:
|]If "very high" equates to about twice what we have now, it shouldn't be
|]long before this is not a problem. In any case, it would be nice to have
|]at least *some* independence...
|
|Very high would be 10 to 20 times the CPUs of today if you wanted to
|encode 1080i. Outputting 640x480 MPEG2 while decoding 1080i should be
|doable in a few years.

I'll settle for decoding 480i/p and outputting 640x480 MPEG2. :)

|]|We can get fast-play working with HDTV, but it's not yet high priority.
|]|It's mostly a ffmpeg w/MythTV issue.
|]Ah, I didn't realize that this was not supposed to work. Does any kind
|]of fast forward functionality work? Rewind?
|
|Skip works. And fast forward works on very powerful processors.

In this context is my 3.2GHz P4 very powerful or are we still talking
about the future?

|]|(For instance, I can get my plain old TV to sync to a
|]|800x600 signal from the FX5200.)
|]I'm not sure what this means. Are you actually generating 600 (300
|]interlaced) scan lines? If so that's not real NTSC anymore. Maybe you
|
|Yes, it works with my specific TV. It should actually work with most TVs
|with composite input, but I've never published my modeline because it
|can destroy some older TV's.

I think you will find that the ability to sync to a signal that far from
the standard is not common, unless maybe your TV happens to be some sort
of combined multi-sync monitor. Are you certain that the card is putting
out a 600/300 line signal rather than down converting?

|]can get a specific TV so sync to it, but it won't work as a general
|]video source. And this is my main gripe with the TV-out support on
|]every video card I've ever tried. You can tweak this and that to get
|]it to almost look right on a particular TV, but the signal is so far
|]out of spec that it's useless for anything else.
|
|Hmmm, well safe modeline adjustment could be added to MythTV. Right now
|MythTV setup is admitedly a pain. There are some standalone programs out
|there to generate modelines. One used to actually come with both RedHat
|and Mandrake, but has been dumped because most computer monitors these
|days tell X11 how to drive the monitor. But TV's don't and setting them
|up is very much like setting up XFree86 was like 10 years ago.

But again, I really don't want to set the output up for a particular TV.
I want to generate NTSC standard video that I can feed into my distribution
system and watch on any TV (or even tape). We have many existence proofs
that it is possible to generate an NTSC signal that is generally correct
without being TV-specific (e.g., my DTC-100 HDTV box, many DSS receivers,
DVD players, etc.) Just the fact that we are talking about setting up for
a TV suggests that something is seriously lacking in TV-out support...

|]I haven't even noticed the ringing yet. It is completely overshadowed by
|]the horrible motion artifacts. Even as someone moves their hand across the
|]screen you can see lots of black scan line "checks" around the motion. I
|]know it isn't a problem with the source stream because my ancient DTC-100
|]renders a perfect NTSC representation of the same program. I don't know if
|]it is an MPEG decoding issue or an NTSC encoding problem, but it (IMHO) makes
|]the output useless. (See my previous message about the FX5200.)
|
|Are you using XvMC?

Beats me. I'm just using the defaults.

|Try XV if you are. This sounds like a bug. Does
|it look good in mplayer?

Haven't tried it.

|Does it look good on your monitor?

I've been staring at this for a while now and I think I can see similar
artifacts on the monitor. However, they are much less noticeable and I
may just be fooling myself that they are there at all. I would not have
noticed them were I not comparing to the TV version. On the other hand,
the monitor is a lot smaller than the TV.

The last time I saw artifacts similar to this I discovered that the signal
had its chroma and luma components offset by a frame or a field (it wasn't
clear which). This seemed to upset the color decoder, especially when a
bright object moved "through" the chroma information of another part of
the scene. In the current case the effect shows up well with dark moving
objects, so while it may also be a matter of an NTSC error confusing the
color decoder, it probably isn't the same error.

Dan Lanciani
ddl [at] danlan*com

john at BlueSkyTours

Oct 25, 2004, 2:07 PM

Post #25 of 35 (4753 views)
Permalink

Re: pcHDTV with PVR-350 for output [In reply to]

On Mon, 25 Oct 2004, Jarod Wilson wrote:

> On Monday 25 October 2004 12:49, Preston Crow wrote:
>
> > * Auto-switching of video modes to match source (1080i vs. 720p
> > primarily)
>
> I wish my TV supported 720p... This is just an xrandr thing. Enable "separate
> modes for playback and UI", set your UI mode (540p mode highly recommended
> over 1080i mode for readability) and your default mode, then set overrides
> for other content. I have 880x480 as my UI mode, 1760x960 as my default
> playback mode, then an override for 720x480 content to display in 880x480. If
> I could actually do 720p, I'd have an override for that matching 1280x720
> content. Of course, you must also have all these modes defined in your X
> config file and validated when the X server starts up.

If you are *not* compiling Myth up yourself, then the "separate modes for
playback and UI" mode is not available. You need to enable xrandr in
settings.pro, when you compile myth. Xrandr defaults to disabled, since it
is unclear which distributions include it.

Xrandr does not work well with all window managers. For example, forget
about using it with ratpoison. It works pretty well with KDE, WindowMaker
and Window Manger Improved. I personally use Window Manager Improved:

http://wmi.modprobe.de/

It is a *very* lean window manager which can be used complete without a
mouse. It is a little funky to learn how to use, however.

When using xrandr, make sure the *first* show you watch after starting up
X/Myth invokes the highest resolution desired. After that everything works
quite well. If the first show you watch invokes a lower resolution, when
you do need a higher resolution, it will sometimes mask off part of the
screen. I occationally think I have found a solution to this problem, but
then it happens again...oh well.

John

--
"I'm an internationalist", John Kerry told The Crimson. "I'd like to see our
troops dispersed through the world only at the directive of the United
Nations."

"President Bush will never cede the best interests of the national security
of the American people to anybody but the president of the United States,
along with the Congress" -- Kevin A. Madden, Bush spokesperson

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