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

bram kortleven bram at bramkortleven.be
Sat Oct 2 21:46:56 UTC 2010


I'm no expert in the details of the software, encryption and modulation etc,...

But I found out that when viewing a recording in the MythWeb Flashbased player, everything is 'normal'...
So it _must_ be a LiveTV/recordings -player issue in the MythTV frontend of some kind, not handling the changed method of the recorded streams...? Or is this a pack of BS?

Still,
I haven't found the answer to my LMSC / LAMC question in the mailing list archives :s

Bram

----- Original Message -----
From: "Philippe Van Der Gucht" <philippe at vandergucht.org>
To: mythtv-users at mythtv.org
Sent: Saturday, October 2, 2010 11:22:04 PM
Subject: Re: [mythtv-users] Suddenly started getting 'WriteAudio: buffer underrun'

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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