[mythtv-users] HD upgrade: new problems with playback

Chad masterclc at gmail.com
Sun Feb 18 05:21:37 UTC 2007

On 2/13/07, Willy Boyd <willyboyd at gmail.com> wrote:
> I recently upgraded my combo backend/frontend to better support HD
> playback.  This is what I'm running now:
> ASUS M2NPV-VM w/ 6150, VGA out (1360x768 res)
> Athlon X2 3800+ (AM2, 65w)
> 1gb DDR-800 ram
> NVIDIA driver 9746
> I also upgraded from FC4 -> FC5 -> FC6, and switched to myth SVN.  And
> I switched from using SVIDEO from my spare cablebox, to the tuner
> input of my PVR-250 (long story, don't have the right serial port
> bracket for the ASUS board).  I'm afraid I changed too much at once
> because now I'm having some playback problems.  On the SD recording
> side, I think I can attribute most of it to the weak cable signal,
> which I previously got around using the cable box.  Basically I get a
> lot of "NVP: prebuffering pause" and "WriteAudio: buffer underrun"
> messages in mythfrontend.  I've tried turning off all the playback
> options I could find, i.e. deinterlace, with and w/o realtime prio,
> extra audio buffering, and OpenGL sync.  That helped, but still after
> a while the frontend can hang while watching LiveTV (with said error
> messages in the log).
> However the real kicker came when I tried to test HD playback.  I
> don't have an HD tuner yet so for a test I downloaded "Elephant's
> Dream" from orange.blender.org, both the 1080p version and the "1024"
> version.  Both play pretty well with VLC and mplayer (1024 perfectly,
> 1080p with a few drops).  However, neither play at at with the
> Internal player.  I get a black screen and a whole slew of "NVP: Timed
> out waiting for free video buffers" and "NVP::AddAudioData():p1: Audio
> buffer overflow, audio data lost!".  After a few seconds on the "1024"
> video I get what looks like the video playing really fast, but only a
> few frames per second, and really blocky like satellite on a stormy
> day.  Both clips are MPEG4 with AC3 audio.
> I've tried searching on the only results I've come up with relating to
> these error message pertain to either weak signal (explains, maybe, my
> recording/LiveTV issue), and something about NVIDIA overlay, but I
> also turned off "Use XV picture controls" and other than that I don't
> know what I'm supposed to do to help with that.  I also haven't
> downloaded an HD MPEG2 clip yet but that's next on my list.  Has
> anyone else seen these kinds of issues?  I know this is a semi-popular
> hardware combination so there's got to be something I'm doing wrong.
> Thanks!
> - Willy
> _______________________________________________

That's pretty much what I am running, and I have also built several
identical boxes.  The variable here is that the onboard SPDIF is used
and not an addon card.  I have no problem playing back HDTV recordings
(mpeg2) in both 720p and 1080i, and mpeg4 recordings up to 720p.  I
haven't tried 1080p yet on mpeg4 for 2 reasons:
1.  I wasn't aware of the source video for it (thanks!); and 2.  I
don't have a 1080p set to utilize 1080p on.  I'll test it (on a
non-1080p set) and get back to you.

But in general, this setup should be working just fine for HD, and
definitely for SD, with no prebuffering pauses or buffer overflow
messages.  My guess is that once you get the bracket and remove the
USB audio, those messages might be reduced.

Good luck!


Prebuilt HDTV capable systems at reasonable prices:

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