[mythtv-users] HDPVR audio out of sync in 5.1 AC-3 mode

[Bob Sully]

> Date: Tue, 29 Sep 2009 20:46:05 -0700
> From: Oz <ozdror at adelphia.net>
> Subject: Re: [mythtv-users] HDPVR audio out of sync in 5.1 AC-3 mode

> Hi
>
> I was rushing too soon to say that the problem is solved.
> The problem came back the next day.
>
> I turned the HDPVR off and then on. The problem disappeared for one day
> then came back. I turned it on and off  again the problem disappeared
> and came back
> the next day. Somethings happed during the night to the HDPVR box. This
> problem is only in AC3/Dolby mode. It is OK in AAC/PCM mode.
>
> May be there is a buffer in the HDPVR that is overloaded, and then
> clears when pressing on/off.
>
> I have ubuntu 9.04 that does not support frequency scaling ( does 9.10
> support it?)
>
> Any other ideas how to solve the problem.
>
> My CPU is quad core 2.4Ghz with 4 GB of ram. I have Nvidia 8600 gts.
> When using VPDAU I have very low cpu usage.
>
> Any other ideas how to solve the problem.
>
> -Oz

OK, I recorded another one-hour show last night at a video bitrate of
10Mb/s, 720p video resolution.  Audio is 5.1-channels via the optical.

Watched it this morning.  No audio lag at the beginning, but after about
ten minutes it was 2-3 seconds behind the video and by 20 minutes it was
at least 3-4 seconds behind.  Stopped playback, then restarted and jumped
to the middle of the show.  No lag initially, but it gradually got worse.

*This pretty-well gets the HD-PVR off the hook as the culprit.*

So, now I'm thinking that I might need to tweak my mplayer settings.


As mentioned before: CPU is 2.4GHz quad-core Q6600; video card is an
8600GT - just about the same setup as Oz's machine.  I'm running
0.21-fixes with JYA's mods/VDPAU.


I'm getting even better CPU utilization than before during playback (last
time I checked, it was around 5%):

top - 09:48:03 up 6 days, 11:42,  2 users,  load average: 0.52, 0.48, 0.44
Tasks: 208 total,   1 running, 207 sleeping,   0 stopped,   0 zombie
Cpu(s):  1.2%us,  1.0%sy,  0.0%ni, 97.7%id,  0.0%wa,  0.1%hi,  0.0%si, 
0.0%st
Mem:   8083052k total,  7804568k used,   278484k free,   275184k buffers
Swap:  8393920k total,     3012k used,  8390908k free,  6494828k cached


I'm using mplayer, via mythfrontend, to watch these files.  Here's what's
in ~/.mplayer/config:

#For SPDIF
ao=alsa:device=spdif
ac=hwac3,hwdts,
lavdopts=threads=4

# Default to VDPAU output and codecs
vo=vdpau,xv,
vc=ffh264vdpau,ffmpeg12vdpau,ffwmv3vdpau,ffvc1vdpau,


OK - can anyone suggest optimization of my mplayer defaults that will deal
with this issue and not cause any problems with other videos (.avi,
.mkv/.mpg) which right now play fine without any issues?


Much appreciated - thanks to all for the work on this project so far! 
Looking forward to 0.22.

Bob
-- 
________________________________________
Bob Sully - Simi Valley, California, USA
http://www.malibyte.net
http://www.malibyte.com