[mythtv-users] New "Playback Profiles" Screen (was HD 720p Audio/Video sync problem - some times)

Thu Dec 13 04:16:33 UTC 2007

Anyone know where I might find instructions on using the new Playback 
Profiles screen in 0.21?  I'm hoping I can solve the problem described 
in previous post with playback settings.

BTW, I might mention that I have lots of old recordings from PBS that 
play back fine.  I never saw this problem before some time around early 
October.  I think PBS started using a new variation on the codec that 
confuses Myth.  Just a theory.

DaveD

DaveD wrote:
> I am having trouble with A/V sync on some HD shows recorded from our PBS 
> channel.  It is the only channel I get that broadcasts 720p.  Some shows 
> have the problem, some do not.  What happens is the video continuously 
> races ahead of the sound and Myth constantly adjusts, some times slowing 
> the video, some times speeding up (and dropping parts of) the sound.  
> It's very unwatchable.
>
> Good news is I can watch the recordings with Xine or Mplayer.  Both work 
> fine.  Myth works fine on all other HD recordings (all other HD channels 
> are 1080i).  All SD works fine.
>
> I am running a FE/BE combo myth system on a dual core athlon with 2Gb 
> RAM, Nvidia 7600, dual SATA.  I am running Axel's 0.21-171_trunk_r14785 
> RPM on an up-to-date x86_64 FC7 (2.6.23.1-21 kernel) with 
> ALSA:passthrough sound.  I tried switching sound to /dev/dsp, no 
> change.  I tried a complete install of Ubuntu, which comes with Myth 
> 0.20.2.  Same problem, exactly.  I also have two 64-bit athlon single 
> core systems, both with older Nvidia cards, both running the same 
> version of FC7 and Myth (frontend only), both have the same problem.
>
> I have seen similar posts but no solutions yet.  I've included 
> Myth-frontend and Mplayer's output, below.  Mplayer had the exact same 
> output on both a "good" and "bad" file while playing them both 
> successfully.  Myth-frontend used different codecs (see below).   I have 
> not found any documentation on Myth's new Playback Profiles (codec 
> selection?) screen.  I find the best results using their default CPU++ 
> setting, but I've tried the three they provide, with no change in this 
> problem and decreased performance (or functionality) in other areas with 
> the other choices.
>
> Anyone have any suggestions?
>
> DaveD
>
> Myth-frontend's output during playback of problem recording:
> 2007-12-10 19:14:48.202 TV: Attempting to change from None to 
> WatchingPreRecorded
> 2007-12-10 19:14:48.284 AFD: Opened codec 0xccf9d0, id(MPEG2VIDEO) 
> type(Video)
> 2007-12-10 19:14:48.285 AFD: Opened codec 0xcca770, id(AC3) type(Audio)
> 2007-12-10 19:14:48.287 Opening ALSA audio device 'spdif'.
> 2007-12-10 19:14:48.305 DPMS Deactivated
> 2007-12-10 19:14:48.325 AudioOutput Warning: Mixer attach error -2: No 
> such file or directory
>                        Check Mixer Name in Setup: '/dev/mixer'
> 2007-12-10 19:14:48.653 VideoOutputXv: XVideo Adaptor Name: 'NV17 Video 
> Texture'
> 2007-12-10 19:14:50.160 Realtime priority would require SUID as root.
> 2007-12-10 19:14:50.161 TV: Changing from None to WatchingPreRecorded
> 2007-12-10 19:14:50.268 Video sync method can't support double framerate 
> (refresh rate too low for bob deint)
> 2007-12-10 19:14:50.274 Video timing method: USleep with busy wait
> 2007-12-10 19:14:50.778 AO: dropping back audio_buffer_unused
> ... more of these, but they stop after a few seconds...
> 2007-12-10 19:14:53.734 AO: dropping back audio_buffer_unused
> 2007-12-10 19:14:54.827 DPMS Reactivated.
>
> Myth-frontend's output during playback of recording that works well:
> 2007-12-10 19:18:03.201 TV: Attempting to change from None to 
> WatchingPreRecorded
> 2007-12-10 19:18:03.284 AFD: Opened codec 0x56b1c10, id(MPEG2VIDEO) 
> type(Video)
> 2007-12-10 19:18:03.285 AFD: Opened codec 0x56f1980, id(AC3) type(Audio)
> 2007-12-10 19:18:03.286 Opening ALSA audio device 'spdif'.
> 2007-12-10 19:18:03.290 AudioOutput Warning: Mixer attach error -2: No 
> such file or directory
>                        Check Mixer Name in Setup: '/dev/mixer'
> 2007-12-10 19:18:03.304 DPMS Deactivated
> 2007-12-10 19:18:03.409 VideoOutputXv: XVideo Adaptor Name: 'NV17 Video 
> Texture'
> 2007-12-10 19:18:04.489 Realtime priority would require SUID as root.
> 2007-12-10 19:18:04.489 TV: Changing from None to WatchingPreRecorded
> 2007-12-10 19:18:04.591 Video sync method can't support double framerate 
> (refresh rate too low for bob deint)
> 2007-12-10 19:18:04.593 Video timing method: USleep with busy wait
> 2007-12-10 19:18:04.729 AO: dropping back audio_buffer_unused
> ... more of these, but they stop after a few seconds...
> 2007-12-10 19:18:05.021 AO: dropping back audio_buffer_unused
> 2007-12-10 19:18:30.479 DPMS Reactivated.
>
>
> Mplayer's console output (most of, same on both recordings):
> Playing 2095_20071129060000.mpg.
> TS file format detected.
> VIDEO MPEG2(pid=1984) AUDIO A52(pid=1985) NO SUBS (yet)!  PROGRAM N. 1
> VIDEO:  MPEG2  1280x720  (aspect 3)  59.940 fps  38810.4 kbps (4851.3 
> kbyte/s)
> ==========================================================================
> Opening video decoder: [mpegpes] MPEG 1/2 Video passthrough
> VDec: vo config request - 1280 x 720 (preferred colorspace: Mpeg PES)
> Could not find matching colorspace - retrying with -vf scale...
> Opening video filter: [scale]
> The selected video_out device is incompatible with this codec.
> Try appending the scale filter to your filter list,
> e.g. -vf spp,scale instead of -vf spp.
> VDecoder init failed :(
> Opening video decoder: [libmpeg2] MPEG 1/2 Video decoder libmpeg2-v0.4.0b
> Selected video codec: [mpeg12] vfm: libmpeg2 (MPEG-1 or 2 (libmpeg2))
> ==========================================================================
> ==========================================================================
> Forced audio codec: hwac3
> Opening audio decoder: [hwac3] AC3/DTS pass-through S/PDIF
> No accelerated IMDCT transform found
> hwac3: switched to AC3, 384000 bps, 48000 Hz
> AUDIO: 48000 Hz, 2 ch, ac3, 384.0 kbit/25.00% (ratio: 48000->192000)
> Selected audio codec: [hwac3] afm: hwac3 (AC3 through S/PDIF)
> ==========================================================================
> AO: [alsa] 48000Hz 2ch ac3 (1 bytes per sample)
> Starting playback...
>
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