Mailing List Archive

HDTV on Myth -- is it a "myth?"
I guess my expectations were too high. I've been
watching HD on my combo satellite/terrestrial receiver
a couple of years now, and I expected Myth to be able
to record and play signals equivalent to what I see on
"normal" HDTV (terrestrial) broadcasts. What I
actually get on Myth is slow, jerky, stuttering
playback that often hangs the frontend with something
as simple as skipping forward or backward, or any
activity that pops up the on-screen display.

When I am able to get streams to play, the video is
marred by scaling artifacts and weird interactions
between interlaced and non-interlaced video streams.
For instance, a 1080i source played on a 1080i output
device shows horrible jaggies.
(http://www.pbase.com/jbarnhart/image/34300421.jpg)
The same stream played through the "bob" deinterlacer
looks better (but still not up to the level of the
receiver).

I tried to build a system able to handle this task,
with an Athlon 2800+ processor and a GeForce4 MX video
card, but the system is unable to cope with my
1920x1080i output device. The Xv software player is
unable to keep up with task of decoding MPEG at this
rate, and XvMC simply doesn't work reliably enough to
watch an entire show without hanging mythfrontend.

Were my expectations too high? Is this a matter of
"rough edges" soon to be smoothed out? Or is the
current state of Myth unable to handle HDTV (at
1920x1080i) for anyone? Should I dump my system and
buy new Intel Pentium hardware? Or just go back to
the combo receiver and wait another year for the
software to catch up?

I would love to hear from anyone who is playing
streams at 1920x1080i with no stutters or poor video
quality. What kind of system are you using? Xv or
XvMC? Intel or AMD? Video card?



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Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
I sorta have it running... I have a master be with 2 pvr 250s and one
slave be with 1 pchdtv. The pchdtv is a little flaky (playing 720p)
with a 2.6 ghz p4. It's not bad, it actually looks good, but it does
crash a lot. I don't know yet while it crashes, but I'm working on
it... Should we have a dedicated HDTV with myth support group? :)

I haven't seen any new patches on the pchdtv since the inkling ones,
so I believe I'm running latest and greatest (no XVMC).

Art


On Sat, 9 Oct 2004 12:29:43 -0700 (PDT), Joe Barnhart
<joebarnhart@yahoo.com> wrote:
> I guess my expectations were too high. I've been
> watching HD on my combo satellite/terrestrial receiver
> a couple of years now, and I expected Myth to be able
> to record and play signals equivalent to what I see on
> "normal" HDTV (terrestrial) broadcasts. What I
> actually get on Myth is slow, jerky, stuttering
> playback that often hangs the frontend with something
> as simple as skipping forward or backward, or any
> activity that pops up the on-screen display.
>
> When I am able to get streams to play, the video is
> marred by scaling artifacts and weird interactions
> between interlaced and non-interlaced video streams.
> For instance, a 1080i source played on a 1080i output
> device shows horrible jaggies.
> (http://www.pbase.com/jbarnhart/image/34300421.jpg)
> The same stream played through the "bob" deinterlacer
> looks better (but still not up to the level of the
> receiver).
>
> I tried to build a system able to handle this task,
> with an Athlon 2800+ processor and a GeForce4 MX video
> card, but the system is unable to cope with my
> 1920x1080i output device. The Xv software player is
> unable to keep up with task of decoding MPEG at this
> rate, and XvMC simply doesn't work reliably enough to
> watch an entire show without hanging mythfrontend.
>
> Were my expectations too high? Is this a matter of
> "rough edges" soon to be smoothed out? Or is the
> current state of Myth unable to handle HDTV (at
> 1920x1080i) for anyone? Should I dump my system and
> buy new Intel Pentium hardware? Or just go back to
> the combo receiver and wait another year for the
> software to catch up?
>
> I would love to hear from anyone who is playing
> streams at 1920x1080i with no stutters or poor video
> quality. What kind of system are you using? Xv or
> XvMC? Intel or AMD? Video card?
>
>
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>
>
>
RE: HDTV on Myth -- is it a "myth?" [ In reply to ]
I have a PCHDTV card in my master backend and record quite a bit of
off-air HDTV material. Playback is done on a P4 3.2E, Nvidia FX5500, all
on an Intel D865GLC mobo with 8X AGP, using XV. I'm using FC2, with a
vanilla 2.6.7 kernel, compiled for SMP and SMT (Hyperthreading). I never
see any artifacts or stuttering on this setup. Picture quality is excellent
and as well as sound quality.


-----Original Message-----
From: mythtv-users-bounces@mythtv.org
[mailto:mythtv-users-bounces@mythtv.org] On Behalf Of Joe Barnhart
Sent: Saturday, October 09, 2004 12:30 PM
To: mythtv-users@mythtv.org
Subject: [mythtv-users] HDTV on Myth -- is it a "myth?"

I guess my expectations were too high. I've been
watching HD on my combo satellite/terrestrial receiver
a couple of years now, and I expected Myth to be able
to record and play signals equivalent to what I see on
"normal" HDTV (terrestrial) broadcasts. What I
actually get on Myth is slow, jerky, stuttering
playback that often hangs the frontend with something
as simple as skipping forward or backward, or any
activity that pops up the on-screen display.

When I am able to get streams to play, the video is
marred by scaling artifacts and weird interactions
between interlaced and non-interlaced video streams.
For instance, a 1080i source played on a 1080i output
device shows horrible jaggies.
(http://www.pbase.com/jbarnhart/image/34300421.jpg)
The same stream played through the "bob" deinterlacer
looks better (but still not up to the level of the
receiver).

I tried to build a system able to handle this task,
with an Athlon 2800+ processor and a GeForce4 MX video
card, but the system is unable to cope with my
1920x1080i output device. The Xv software player is
unable to keep up with task of decoding MPEG at this
rate, and XvMC simply doesn't work reliably enough to
watch an entire show without hanging mythfrontend.

Were my expectations too high? Is this a matter of
"rough edges" soon to be smoothed out? Or is the
current state of Myth unable to handle HDTV (at
1920x1080i) for anyone? Should I dump my system and
buy new Intel Pentium hardware? Or just go back to
the combo receiver and wait another year for the
software to catch up?

I would love to hear from anyone who is playing
streams at 1920x1080i with no stutters or poor video
quality. What kind of system are you using? Xv or
XvMC? Intel or AMD? Video card?



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Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
Joe Barnhart wrote:
> I would love to hear from anyone who is playing
> streams at 1920x1080i with no stutters or poor video
> quality. What kind of system are you using? Xv or
> XvMC? Intel or AMD? Video card?

Works quite well for me. P4, 2.8 GHz, OSS emulation on ALSA, no XvMC,
nVidia FX5200.

I submit that the reason this and other similar configurations work well
is that I made it so, since that's what I have. There are in the
neighborhood of 5 of us who have spent the last year or so sequentially
debugging, fixing, and submitting patches for problems we've
encountered. We do not have your hardware. We have not seen your
symptoms. You are the only one capable of debugging and fixing your
problems.

-Doug
Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
--- Doug Larrick <doug@ties.org> wrote:

> Works quite well for me. P4, 2.8 GHz, OSS emulation
> on ALSA, no XvMC,
> nVidia FX5200.

Doug -- Are you outputting to a 1920x1080i device?
The reason I ask is because Xv won't keep up with this
resolution using an Athlon 2800. I also see severe
problems with 720p input streams. They play at half
speed, with unlistenable sound stuttering, with both
Xv and XvMC on my system.

Given the potential advantage of hardware-assisted
MPEG decoding, I'm rather surprised that few people
(and no developers?) are using XvMC.



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Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
Joe Barnhart wrote:
> Doug -- Are you outputting to a 1920x1080i device?

Yes. I can use either a 1920x1080i mode with no deinterlacing, or
1920x540p with bob deinterlacing; they look basically identical until
you activate a zoom mode (at which point bob looks better since the
interlaced mode is no longer line-for-line).

> I also see severe
> problems with 720p input streams. They play at half
> speed, with unlistenable sound stuttering, with both
> Xv and XvMC on my system.

Have you read the recent ALSA discussions on the -dev list?

> Given the potential advantage of hardware-assisted
> MPEG decoding, I'm rather surprised that few people
> (and no developers?) are using XvMC.

XvMC is a PITA because of the way it barely fits into the Myth video
output architecture. You can't apply filters; you have to deal with the
fact that there are fewer in-flight video buffers (frames); seeking is
more difficult because the decoder has to have all the reference frames
for non-I frames, etc. Software decoder is just more flexible.

-Doug
Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
--- Doug Larrick <doug@ties.org> wrote:

> I can use either a 1920x1080i mode with no
> deinterlacing, or
> 1920x540p with bob deinterlacing; they look
> basically identical until
> you activate a zoom mode (at which point bob looks
> better since the
> interlaced mode is no longer line-for-line).

Hmm.. Doesn't something seem fundamentally wrong about
this? Why should 1920x540 look the same as 1920x1080?
I presume you looked at the screen pic I posted of my
setup playing (XvMC) 1920x1080i w/o deinterlacing.
It's horrible.
(http://www.pbase.com/jbarnhart/image/34300421.jpg)

> Have you read the recent ALSA discussions on the
> -dev list?

Yes. I downleveled ALSA to 1.0.5 with no change in
symptoms. I'm outputting AC3 via optical out. Oddly
enough, if I "hide" my sound output device I can get
Xv to play the 720p stream at full speed with no
sound. XvMC still runs at half-speed, however, even
with no sound.

> XvMC is a PITA because of the way it barely fits
> into the Myth video
> output architecture.

I have not found any development docs which hint at
this architecture. I'm not afraid of C++, but it makes
it a little difficult to contribute to the project
when the only documentation I can find is the source
code. I just lack the time to invest to figure out
the architecture on my own.

> You can't apply filters; you
> have to deal with the
> fact that there are fewer in-flight video buffers
> (frames); seeking is
> more difficult because the decoder has to have all
> the reference frames
> for non-I frames, etc. Software decoder is just
> more flexible.

I think my needs are very simple. I have an output
device that is locked to 1080i. I want to play 1080i
streams unmodified to the output device. 720p streams
will have to be rescaled to 1080i on playback, and so
will 480i or 480p. I just want to view recorded TV
programs and DVDs. If the video processing does the
"right thing" there should be no need for filtering,
right?

I have noticed that my "myth" question has not
received a flood of messages like "I'm using it and it
works great." Jarod and I are running Athlon systems
with mucho trouble, and I've had responses from three
Pentium users (yourself included). Of the P4 users,
two are working fine and one is not. I guess just not
many people are using Myth with HDTV monitors yet.
>From the breathless MythTV promotion by EFF
(http://www.eff.org/broadcastflag) I would have
thought HDTV were a lot more debugged.



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Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
>>Have you read the recent ALSA discussions on the
>>-dev list?
>>
>>
>
>Yes. I downleveled ALSA to 1.0.5 with no change in
>symptoms. I'm outputting AC3 via optical out. Oddly
>enough, if I "hide" my sound output device I can get
>Xv to play the 720p stream at full speed with no
>sound. XvMC still runs at half-speed, however, even
>with no sound.
>
>
>
I have sound playback issues with hdtv content also. Audio stutters or
sounds like it is underwater. Mainly with abc. Mplayer plays the same
file with no problems at all so alsa is working, mythtv just has a
problem with keeping up with sending audio out to alsa. I even have a
problem playing some recordings I made using 720x480, 2200 bitrate.
Audio is constantly stuttering.

>>XvMC is a PITA because of the way it barely fits
>>into the Myth video
>>output architecture.
>>
>>
>
>I have not found any development docs which hint at
>this architecture. I'm not afraid of C++, but it makes
>it a little difficult to contribute to the project
>when the only documentation I can find is the source
>code. I just lack the time to invest to figure out
>the architecture on my own.
>
>
>
>> You can't apply filters; you
>>have to deal with the
>>fact that there are fewer in-flight video buffers
>>(frames); seeking is
>>more difficult because the decoder has to have all
>>the reference frames
>>for non-I frames, etc. Software decoder is just
>>more flexible.
>>
>>
>
>I think my needs are very simple. I have an output
>device that is locked to 1080i. I want to play 1080i
>streams unmodified to the output device. 720p streams
>will have to be rescaled to 1080i on playback, and so
>will 480i or 480p. I just want to view recorded TV
>programs and DVDs. If the video processing does the
>"right thing" there should be no need for filtering,
>right?
>
>I have noticed that my "myth" question has not
>received a flood of messages like "I'm using it and it
>works great." Jarod and I are running Athlon systems
>with mucho trouble, and I've had responses from three
>Pentium users (yourself included). Of the P4 users,
>two are working fine and one is not. I guess just not
>many people are using Myth with HDTV monitors yet.
>>From the breathless MythTV promotion by EFF
>(http://www.eff.org/broadcastflag) I would have
>thought HDTV were a lot more debugged.
>
>
>
>
I also have a wierd problem, fast forward works on hdtv content until I
get a blast of noise then I can only ff 1 second at a time but the
timeline jumps 10 seconds. I have not been able to finish watching the
last three recordings of Joan of Arcadia because about 30 minutes into
the playback, it starts playing from the beginning, I can never seem to
get to the end of the show. I am in the process of transcoding one of
the shows to see is I can watch the transcoded file. Besides that, 1080i
looks great.

- James
Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
Joe Barnhart wrote:
> Hmm.. Doesn't something seem fundamentally wrong about
> this? Why should 1920x540 look the same as 1920x1080?

1080i at 30 Hz is identically the same as 540p at 60 Hz. Suggest you do
some reading.

-Doug
Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
On Oct 10, 2004, at 17:21, Joe Barnhart wrote:

> I have noticed that my "myth" question has not
> received a flood of messages like "I'm using it and it
> works great."

I'm using it and it works great. :-)

I flipped down to ALSA 1.0.5a, rebuilt Myth against it, and all my 720p
problems were gone. I get excellent quality playback of both 720p and
1080i content now, all using Xv.

> Jarod and I are running Athlon systems
> with mucho trouble,

Jarod *was* running with mucho trouble, (which I was actually able to
duplicate on a system almost identical to Doug's), but I managed to get
both my P4 and Athlon playing back everything just fine.

> and I've had responses from three
> Pentium users (yourself included). Of the P4 users,
> two are working fine and one is not. I guess just not
> many people are using Myth with HDTV monitors yet.

That, and even fewer folks actually have pcHDTV cards to go with HDTV
displays.

So did you rebuild Myth against the down-graded ALSA libs? I'm not
certain it made a difference here or not, but I made sure to do so on
both systems that had problems and now don't. Enabling extra audio
buffering was the other key for me.

--
Jarod C. Wilson, RHCE
jcw@wilsonet.com

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/
Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
--- Doug Larrick <doug@ties.org> wrote:

> Joe Barnhart wrote:
> > Hmm.. Doesn't something seem fundamentally wrong
> about
> > this? Why should 1920x540 look the same as
> 1920x1080?
>
> 1080i at 30 Hz is identically the same as 540p at 60
> Hz. Suggest you do
> some reading.

What is the same, Doug? The horizontal scanning
frequency of 33.75kHz? I agree. How about the image?
With 1080i you get two different frames of
information, 30 times each second. With 540p you get
two identical frames 30 times each second. Shouldn't
they look different? I think they should.




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Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
--- Jarod Wilson <jcw@wilsonet.com> wrote:

> So did you rebuild Myth against the down-graded ALSA
> libs? I'm not
> certain it made a difference here or not, but I made
> sure to do so on
> both systems that had problems and now don't.
> Enabling extra audio
> buffering was the other key for me.

I first went with 1.0.5rc1 with no change, then 1.0.5,
also no change. I can get 720p playback to work,
sometimes, with Xv and "extra buffering" (and downhill
with a tailwind). XvMC never works at 720p, buffering
or not. The tables turn at 1080i, with Xv not able to
keep up without sound gaps and stutters and XvMC able
to play pretty well, except for the jaggies and
freezing when the OSD comes up.

As I recall you are using a modeline other than
1920x1080i, aren't you? Are you doing the 540p thing
like Doug? I wonder if I'm taxing my system just a
smidgen more, with hardware just a little less capable
(Athlon 2800+, nForce2, 1G dual-channel memory,
GF4MX).

I guess I could pile on more hardware to make Xv work
at 1080i without choking on the audio. Its so darned
wasteful, tho, having all this nice hardware assist
and leaving it turned off! I'd eventually like to
have a system with three or four capture cards, so I
want to use my cpu cycles sparingly.

Do you think it would help to recompile everything
(kernel, myth) for Athlon instead of 586 or 686? (I
doubt it, which is why I haven't done it yet.)

On the other hand, I just want to get a stable working
system, so maybe I'll trash the mobo and get an
Athlon64 and let someone else worry about XvMC. Don't
take this wrong, but in a way I'm sorry you fixed your
problem. ;-) It was nice having a lead blocker who
is so well known in the Myth community. As a
newcomer, I don't expect to be taken as seriously.

Joe Barnhart

P.S. Here's another observation. Setting chmod u+s on
mythfrontend, XvMC uses about 55% cpu playing 1080i
and has sound gaps every two seconds. When I chmod
u-s the cpu goes down to 37% and it plays without
gaps. Weird.

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Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
Joe Barnhart wrote:
> --- Doug Larrick <doug@ties.org> wrote:
>
>
>>Joe Barnhart wrote:
>>
>>>Hmm.. Doesn't something seem fundamentally wrong
>>
>>about
>>
>>>this? Why should 1920x540 look the same as
>>
>>1920x1080?
>>
>>1080i at 30 Hz is identically the same as 540p at 60
>>Hz. Suggest you do
>>some reading.
>
>
> What is the same, Doug? The horizontal scanning
> frequency of 33.75kHz? I agree. How about the image?
> With 1080i you get two different frames of
> information, 30 times each second. With 540p you get
> two identical frames 30 times each second. Shouldn't
> they look different? I think they should.

No.

1080i = 2 fields of 540 lines, at 30 Hz

540p = 1 frame of 540 lines, at 60 Hz.

Six of one, half a dozen of the other. Almost literally.

-Doug
Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
>> What is the same, Doug? The horizontal scanning
>> frequency of 33.75kHz? I agree. How about the image?
>> With 1080i you get two different frames of
>> information, 30 times each second. With 540p you get
>> two identical frames 30 times each second. Shouldn't
>> they look different? I think they should.
>
> No.
>
> 1080i = 2 fields of 540 lines, at 30 Hz
>
> 540p = 1 frame of 540 lines, at 60 Hz.
>
> Six of one, half a dozen of the other. Almost literally.
>
> -Doug
>
Same frequencies for the TV, agreed. It's not exactly the same,
perceptually, however. An 1080i signal will resolve higher vertical
resolution (Kell factor notwithstanding) than a 540p signal, even though
the TV's H/V PLL's will by running at the same rate. The difference would
be most apparent on a still frame with horizontal lines on it.... annoying
30Hz flicker, granted, but higher resolution yes.

-Cory
Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
Cory Papenfuss wrote:
>>> What is the same, Doug? The horizontal scanning
>>> frequency of 33.75kHz? I agree. How about the image?
>>> With 1080i you get two different frames of
>>> information, 30 times each second. With 540p you get
>>> two identical frames 30 times each second. Shouldn't
>>> they look different? I think they should.
>>
>>
>> No.
>>
>> 1080i = 2 fields of 540 lines, at 30 Hz
>>
>> 540p = 1 frame of 540 lines, at 60 Hz.
>>
>> Six of one, half a dozen of the other. Almost literally.
>>
>> -Doug
>>
> Same frequencies for the TV, agreed. It's not exactly the same,
> perceptually, however. An 1080i signal will resolve higher vertical
> resolution (Kell factor notwithstanding) than a 540p signal, even though
> the TV's H/V PLL's will by running at the same rate. The difference
> would be most apparent on a still frame with horizontal lines on it....
> annoying 30Hz flicker, granted, but higher resolution yes.

What I'm saying is that for 1080i, the TV electrically has *no way* of
telling the difference. The signals transmitted are identical, whether
the hardware sends each field, or if you run bob deinterlace in software
and send the exact same fields sequentially.

Note that this is untrue for NTSC and its 525 lines, where one frame has
one more line than the other.

-Doug
Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
>> Same frequencies for the TV, agreed. It's not exactly the same,
>> perceptually, however. An 1080i signal will resolve higher vertical
>> resolution (Kell factor notwithstanding) than a 540p signal, even though
>> the TV's H/V PLL's will by running at the same rate. The difference would
>> be most apparent on a still frame with horizontal lines on it.... annoying
>> 30Hz flicker, granted, but higher resolution yes.
>
> What I'm saying is that for 1080i, the TV electrically has *no way* of
> telling the difference. The signals transmitted are identical, whether the
> hardware sends each field, or if you run bob deinterlace in software and send
> the exact same fields sequentially.
>
> Note that this is untrue for NTSC and its 525 lines, where one frame has one
> more line than the other.
>
> -Doug
>
That's what I thought I said. Frequencies are the same. What
about the 1-line offset though? I believe that even with the same number
of lines/field, the monitor still has to know that it's interlaced so it
can interleave the lines spatially. Otherwise, the two frames will draw
sequentially on top of each other. I think that an interlaced signal
often swaps between positive and negative VSYNC polarity on the redraw to
indicate interlaced.

That would be the ideal situation, but I know that some monitors
don't know the difference and draw one on top of the other (like you
suggest). Either way, it's not going to hurt the monitor since the
freqencies are the same.

-Cory
RE: HDTV on Myth -- is it a "myth?" [ In reply to ]
mythtv-users-bounces@mythtv.org wrote:
> On Oct 10, 2004, at 17:21, Joe Barnhart wrote:
>
>> I have noticed that my "myth" question has not received a flood of
>> messages like "I'm using it and it works great."
>
> I'm using it and it works great. :-)
>
> I flipped down to ALSA 1.0.5a, rebuilt Myth against it, and
> all my 720p problems were gone. I get excellent quality
> playback of both 720p and 1080i content now, all using Xv.
>

When you rebuilt it, did you do any optimization changes specifically
for the Athlon platform? Are you using a stock kernel or customer
build?

Thanks,

Steve
Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
An unrelated if not annoying issue with a mixed HDTV environment, is
that when going to a screen with a live preview, if it has HDTV
content, it takes a very long time to come show up (I've disabled the
previews to see if that fixes it, but I'm not sure if it has...)

IT is much closer to working than before... almost usable now :) (for
the wife that is :)

Art
Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
fuck you remove me from your cocksucker list now.


Steve Frank wrote:

>mythtv-users-bounces@mythtv.org wrote:
>
>
>>On Oct 10, 2004, at 17:21, Joe Barnhart wrote:
>>
>>
>>
>>>I have noticed that my "myth" question has not received a flood of
>>>messages like "I'm using it and it works great."
>>>
>>>
>>I'm using it and it works great. :-)
>>
>>I flipped down to ALSA 1.0.5a, rebuilt Myth against it, and
>>all my 720p problems were gone. I get excellent quality
>>playback of both 720p and 1080i content now, all using Xv.
>>
>>
>>
>
>When you rebuilt it, did you do any optimization changes specifically
>for the Athlon platform? Are you using a stock kernel or customer
>build?
>
>Thanks,
>
>Steve
>
>
>------------------------------------------------------------------------
>
>_______________________________________________
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Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
fuck you remove me from your cocksucker list now.


Art Morales wrote:

>An unrelated if not annoying issue with a mixed HDTV environment, is
>that when going to a screen with a live preview, if it has HDTV
>content, it takes a very long time to come show up (I've disabled the
>previews to see if that fixes it, but I'm not sure if it has...)
>
>IT is much closer to working than before... almost usable now :) (for
>the wife that is :)
>
>Art
>
>
>------------------------------------------------------------------------
>
>_______________________________________________
>mythtv-users mailing list
>mythtv-users@mythtv.org
>http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
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>
Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
On Sat, 9 Oct 2004, Joe Barnhart wrote:

> I guess my expectations were too high. I've been
> watching HD on my combo satellite/terrestrial receiver
> a couple of years now, and I expected Myth to be able
> to record and play signals equivalent to what I see on
> "normal" HDTV (terrestrial) broadcasts. What I
> actually get on Myth is slow, jerky, stuttering
> playback that often hangs the frontend with something
> as simple as skipping forward or backward, or any
> activity that pops up the on-screen display.

<snip>

> Were my expectations too high? Is this a matter of
> "rough edges" soon to be smoothed out? Or is the
> current state of Myth unable to handle HDTV (at
> 1920x1080i) for anyone? Should I dump my system and
> buy new Intel Pentium hardware? Or just go back to
> the combo receiver and wait another year for the
> software to catch up?
>
> I would love to hear from anyone who is playing
> streams at 1920x1080i with no stutters or poor video
> quality. What kind of system are you using? Xv or
> XvMC? Intel or AMD? Video card?


I have been playing with Myth/HDTV since January. It not was until March
that I had something usable. My machine at the time:

2.6GHz HT P4 overclocked to ~2.8GHz
512MB DDR400 RAM
nVidia 440MX video card

Things I learned during this process:

1) NvAGP *must* be set right for your video card/motherboard.
In my case, I needed to comment out/remove
Option "NvAGP" "1"
from my xorg.conf file
2) Hyperthreading is a good thing.
I built a kernel with Hyperthreading/SMP disabled which resulted in
really bad stuttering.
3) Kernel 2.6.7 is a win. Much better than any 2.4 kernel, both for
recording and playback. pcHDTV's 2.6.6 kernel patch works perfectly with
the 2.6.7 kernel.
4) Building Myth/ffmpeg with optimizations for your processor is a win.
For example:
./configure
add/modify "-march=pentium4" in settings.pro and config.mak
qmake
make && make install
5) Recording, Watching and Commercial flagging could not all be done at the
same time. That system was just too slow.
6) Xv is better than XvMC -- if you have enough horsepower.


This all resulted in a machine which would play both 720p and 1080i material
pretty well. It had consistent problems with close-up pans and scrolling
text, but it was watchable.

I decided that to fix the final issues, I must need to upgrade my CPU. So I
relegated my 2.6GHz system to be my Myth backend, and for my front end, I
splurged on:

3.2GHz HT P4
512MB DDR400 RAM
nVidia FX5700LE video card

The result was a setup with almost exactly the same characteristics I had
before. If there was any improvement, it was minor. Obviously, the
extra CPU power was not as necessary as I thought.

Then Doug came along with his latest improvements to Myth. He re-wrote the
audio/video synchronization code. This made a small but noticeable
improvement.

Version 2 of Doug's synchronization code was the final piece. Bruce got
involved and between them they fixed 99.99% of my stuttering problems.
Playback is now silky smooth. I still get rare, very short, "micropauses",
but they are few and far between.

When ALSA 1.0.6a came out, I grabbed it and compiled Myth against it. Major
problems. Quickly went back and recompiled Myth against ALSA 1.0.5.

Hope this helps.


John
Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
Yo braindead,

Have you tried clicking on the links at the bottom of most of the
mails in this list. They will take you to a page that let's you put in
your email address to unsubscribe.

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

Please watch your language


On Mon, 11 Oct 2004 11:34:57 -0400, Robert <lgilmore1@tampabay.rr.com> wrote:
> fuck you remove me from your cocksucker list now.
>
>
>
>
> Art Morales wrote:
>
> >An unrelated if not annoying issue with a mixed HDTV environment, is
> >that when going to a screen with a live preview, if it has HDTV
> >content, it takes a very long time to come show up (I've disabled the
> >previews to see if that fixes it, but I'm not sure if it has...)
> >
> >IT is much closer to working than before... almost usable now :) (for
> >the wife that is :)
> >
> >Art
> >
> >
> >------------------------------------------------------------------------
> >
> >_______________________________________________
> >mythtv-users mailing list
> >mythtv-users@mythtv.org
> >http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
> >
> >
>
>
> _______________________________________________
> mythtv-users mailing list
> mythtv-users@mythtv.org
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>
>
>
Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
Just a couple thoughts/comments. The ratio of HDTV to regular TV myth
users is much smaller, I'd say less than 3%. Most people on these lists
also only stick around while they are having problems. Also, once most
people get their HD setups working they drop off the list and go on with
life. I think there are only 30 or so people who use HDTV that are on
the list here, and many are read only people. Your problem is not
unique, it's just it takes time to track down the problem. HDTV takes a
lot of resources and every CPU, MB, and hard drive will effect things.
I run 3 HDTV tuner cards and record about 20 shows a day. My backend
hasn't crashed in 2 weeks (Before that cvs update it was every 1.5 weeks
or so). There was a several week period where even I had problems
getting playback working well. After a year of completely despising it,
it has since become my friend. I run an athlon 2600 and 333mhz FSB, and
an nvidia fx5200. I have to run XVMC to get 1080i de-interlaced. For
almost a year I went without de-interlacing but several people have
improved this and it works very well.

The only problems I currently have is when watching high-res and
seeking I get audio drop out when the OSD disapears. .. That's it. And
this is on a athlon 2600. I very much do NOT recommend this setup and
if I had to do it over again I would go with a P4 3.2Ghz. The reason is
I have several non-myth related issues that come up from time to time.
Doing backend and frontend on a single 2600 has some bandwidth problems.
When watching HD and recording 3 shows at once, and commercial detecting
is a lot for any system. P4's hyper threading helps quite nicely with
keeping audio sound dropouts down when seeking. My system locks at
times when stopping recording 3 shows and starting recording 3 new
shows, and when I'm watching a movie via mplayer, the movie stops for
2-8 seconds. I also see much more video stuttering with mplayer. The
fact is, HD is not a little thing. I've had problems with data
throughput even with a 5 disk stripped raid system that moves about
100MB a second because recording 3 shows, commercial detecting one, and
watching another is simply too much for my motherboard's FSB to take,
period. I also had more problems until I revamped which PCI/AGP cards
use which IRQ's.

My point I guess is, HD is right on the boarder of what current systems
can take, and in my personal experience it's not JUST cpu that matters,
it's your system bus. They are not all created the same, and every
person doing HD will have things slightly different which can cause odd
problems. My experience tells me that running an 800mhz FSB and a P4
3.2Ghz does a lot better for reducing chances of problems. But then if
you're willing to take the time like I did, you can get something
working as I did.

The ideal setup is a 1-2Ghz backend holding the HD cards doing the
recording and a frontent only carrying about display and streaming
things over the network. This setup would be very hard to have
bandwidth issues on either system.

I do believe HD in myth is ready, and has been. Things are tweaked and
broken. XVMC has more problems now with seeking than it used to, but
this is temporary. Also, if you're running an older version you may
want to grab CVS and if you have a question if it's in a good state or
not e-mail me and I'll let you know. Rarely am I more than a week past
CVS and I'll almost always find a bug if it's there.

Oh, and BTW, here is the compiler settings I use.

-O3 -march=athlon-xp -m3dnow -mmmx -msse -mfpmath=sse
-fomit-frame-pointer

And if you want about a 10% speedup, use gcc 3.4. I did for some time
but I went back to 3.3 because I was trying to find out of 3.4 was
causing seeking issues, it wasn't, and I've been to busy to change
symlinks to 3.4 (mostly forgotten to). 3.4 should be fine and in fact
next build I'll be back to 3.4.

Hope this gives some insight... Oh, I just remebered, last night seeking
did lock the frontend. And a quick tip is even though you don't see the
text, hit the save possition button and it will save it, restart the
frontend and go... I saw this problem once in 5 hours of watching 50
shows (my weekly tv review session). This is a known problem too, it's
just time to fix it, but it's so minor I overlook it. :)

--Brandon


On Sun, Oct 10, 2004 at 11:21:44PM -0700, Joe Barnhart wrote:
>
> --- Jarod Wilson <jcw@wilsonet.com> wrote:
>
> > So did you rebuild Myth against the down-graded ALSA
> > libs? I'm not
> > certain it made a difference here or not, but I made
> > sure to do so on
> > both systems that had problems and now don't.
> > Enabling extra audio
> > buffering was the other key for me.
>
> I first went with 1.0.5rc1 with no change, then 1.0.5,
> also no change. I can get 720p playback to work,
> sometimes, with Xv and "extra buffering" (and downhill
> with a tailwind). XvMC never works at 720p, buffering
> or not. The tables turn at 1080i, with Xv not able to
> keep up without sound gaps and stutters and XvMC able
> to play pretty well, except for the jaggies and
> freezing when the OSD comes up.
>
> As I recall you are using a modeline other than
> 1920x1080i, aren't you? Are you doing the 540p thing
> like Doug? I wonder if I'm taxing my system just a
> smidgen more, with hardware just a little less capable
> (Athlon 2800+, nForce2, 1G dual-channel memory,
> GF4MX).
>
> I guess I could pile on more hardware to make Xv work
> at 1080i without choking on the audio. Its so darned
> wasteful, tho, having all this nice hardware assist
> and leaving it turned off! I'd eventually like to
> have a system with three or four capture cards, so I
> want to use my cpu cycles sparingly.
>
> Do you think it would help to recompile everything
> (kernel, myth) for Athlon instead of 586 or 686? (I
> doubt it, which is why I haven't done it yet.)
>
> On the other hand, I just want to get a stable working
> system, so maybe I'll trash the mobo and get an
> Athlon64 and let someone else worry about XvMC. Don't
> take this wrong, but in a way I'm sorry you fixed your
> problem. ;-) It was nice having a lead blocker who
> is so well known in the Myth community. As a
> newcomer, I don't expect to be taken as seriously.
>
> Joe Barnhart
>
> P.S. Here's another observation. Setting chmod u+s on
> mythfrontend, XvMC uses about 55% cpu playing 1080i
> and has sound gaps every two seconds. When I chmod
> u-s the cpu goes down to 37% and it plays without
> gaps. Weird.
>
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--
Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
On Mon, Oct 11, 2004 at 10:10:30AM -0600, John Patrick Poet wrote:
>
> <snip>
>
> 5) Recording, Watching and Commercial flagging could not all be done at the
> same time. That system was just too slow.
> 6) Xv is better than XvMC -- if you have enough horsepower.
>
> John

My experience has been with XV, I could commercial detect 1-2 shows if I
was not de-interlacing on my 2.6Ghz. When using XVMC, I could commercial
detect from 4-7 shows at once without much stuttering. I believe most
of this stuttering was more data over the bus rather than CPU because I
would see pauses even when the CPU was not maxed. Now that myth lets
you pick the # of shows to detect/transcode at once and I set it to 1,
stuttering has vanished. But again, if you're running backend and
frontend on the same system you are likely not going to be able to run
XV without stuttering, unless it's a P4 3.4 or faster. You do give up
some quality with XvMC but not much, and I recommend it for anyone who
is running a backend on a frontend.

--Brandon
Re: HDTV on Myth -- is it a "myth?" [ In reply to ]
Slightly OT, but does anyone know the status of:

- HD-3000 card status, and
- HD-[23]000 support for QAM?

I looked through the code once and looks like "pseudo"
open-source... i.e. regular data structures and device setup, but then a
*huge* chunk of obscure hex data to blindly dump to the card to make it
go. If QAM could be made to work on this thing, I'd say it's a no-brainer
of a card to go with.

Thanks,
-Cory


*************************************************************************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
*************************************************************************

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