[mythtv-users] Suddenly started getting 'WriteAudio: buffer underrun'

Philippe Van Der Gucht philippe at vandergucht.org
Sat Oct 2 21:22:04 UTC 2010


Some more info, this time from an ffmpeg -i on a recording:

FFmpeg version SVN-r0.5.1-4:0.5.1-1ubuntu1, Copyright (c) 2000-2009 
Fabrice Bellard, et al.
   configuration: --extra-version=4:0.5.1-1ubuntu1 --prefix=/usr 
--enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib 
--enable-libgsm --enable-libschroedinger --enable-libspeex 
--enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib 
--disable-stripping --disable-vhook --enable-runtime-cpudetect 
--enable-gpl --enable-postproc --enable-swscale --enable-x11grab 
--enable-libdc1394 --enable-shared --disable-static
   libavutil     49.15. 0 / 49.15. 0
   libavcodec    52.20. 1 / 52.20. 1
   libavformat   52.31. 0 / 52.31. 0
   libavdevice   52. 1. 0 / 52. 1. 0
   libavfilter    0. 4. 0 /  0. 4. 0
   libswscale     0. 7. 1 /  0. 7. 1
   libpostproc   51. 2. 0 / 51. 2. 0
   built on Mar  4 2010 12:35:30, gcc: 4.4.3
[mpegts @ 0x9a512c0]invalid dts/pts combination

Seems stream 0 codec frame rate differs from container frame rate: 50.00 
(50/1) -> 25.00 (25/1)
     Last message repeated 76 times
Input #0, mpegts, from '18771_20101002165500.mpg':
   Duration: 00:54:34.88, start: 22920.906556, bitrate: 3151 kb/s
   Program 1
     Stream #0.0[0x3ad]: Video: mpeg2video, yuv420p, 704x576 [PAR 16:11 
DAR 16:9], 15000 kb/s, 25 tbr, 90k tbn, 50 tbc
     Stream #0.1[0x399](dut): Audio: mp2, 48000 Hz, stereo, s16, 160 kb/s

The frame rate mismatch is also mentioned on previous recordings that 
show smooth playback so I'd ignore it.

However 'invalid dts/pts combination' looks new to me...

Philippe Van Der Gucht wrote:
> More info, this is an extract of my frontend log:
> 2010-10-02 21:44:54.168 The realtime priority setting is not enabled.
> 2010-10-02 21:44:54.168 TV: Changing from None to WatchingLiveTV
> 2010-10-02 21:44:54.168 TV: State is LiveTV & mctx == ctx
> 2010-10-02 21:44:54.169 TV: UpdateOSDInput done
> 2010-10-02 21:44:54.169 TV: UpdateLCD done
> 2010-10-02 21:44:54.169 TV: ITVRestart done
> 2010-10-02 21:44:54.172 Video timing method: USleep with busy wait
> 2010-10-02 21:44:54.236 VDPAU: Added 2 output surfaces (total 4, max 4)
> 2010-10-02 21:44:56.783 ProgramInfo(): Updated pathname '':'' -> 
> '18773_20101002214456.mpg'
> 2010-10-02 21:44:56.785 FilterManager: Failed to load filter 
> 'colorspace', no such filter exists
> 2010-10-02 21:45:02.672 VDPAU: Created 2 output surfaces.
> 2010-10-02 21:45:02.672 VDPAU: Created VDPAU render device 1920x1080
> 2010-10-02 21:45:02.709 NVP(5): Forcing decode extra audio option on 
> (Video method requires it).
> 2010-10-02 21:45:02.711 FilterManager: Failed to load filter 
> 'colorspace', no such filter exists
> 2010-10-02 21:45:02.711 AFD: Opened codec 0xb03bc7d0, id(MPEG2VIDEO) 
> type(Video)
> 2010-10-02 21:45:02.711 AFD: codec MP2 has 2 channels
> 2010-10-02 21:45:02.712 AFD: Opened codec 0xb141a400, id(MP2) type(Audio)
> 2010-10-02 21:45:02.712 AFD Error: Could not find decoder for codec 
> (DVB_TELETEXT), ignoring.
> 2010-10-02 21:45:02.826 Opening audio device 'default'. ch 2(2) sr 48000 
> (reenc 0)
> 2010-10-02 21:45:02.826 Opening ALSA audio device 'default'.
> 2010-10-02 21:45:02.875 mixer unable to find control Master 1
> 2010-10-02 21:45:02.876 NVP(5): Enabling Audio
> 2010-10-02 21:45:02.913 VDPAU: Added 2 output surfaces (total 4, max 4)
> 2010-10-02 21:45:06.210 NVP(5): prebuffering pause
> 2010-10-02 21:45:06.387 NVP(5): prebuffering pause
> 
>  From here on it's nothing but these 'prebuffering pause' in the log...
> 
> Philippe Van Der Gucht wrote:
>> Greetings!
>>
>> I had a smooth running mythtv 0.22+fixes system with a HVR-4000 and 2 
>> days ago recordings started to stutter.
>>
>> This only happens with certain channels of my satellite provider 
>> 'tv-vlaanderen'.
>> I am almost certain they changed the encoding of their channels.
>>
>> However when playing the recordings via the console with mplayer 
>> everything runs smoothly!
>> This is how I know mythtv's internal player does not know how to 
>> handle them.
>>
>> I have upgraded to 0.23.0+fixes but to no avail.
>>
>> Can I at least use an external player for recordings as a workaround? 
>> I have not found how.
>>
>> Thanks for any help.
>>
>>
> 
> 



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