[mythtv] A/V Bug in CVS from 12:00am 3/27 to 12:00am 3/29

[Terry Barnaby]

Greg Grotsky wrote:
> I've been trying to narrow down the issue with audio jitter and
> slow-mo video.  I've determined that it was broken in CVS sometime
> between 3/27/2005 and 3/29/2005.  I checked out CVS MythTV from
> 3/27/2005 and it works for all channels, when I check it out from
> 3/29/2005 (because 3/28 backend segfaults when entering livetv) two
> channels break.  The broken channels give me studdering audio (with
> occasional pops and clicks) and the video is very slow.  When I tune
> to a broken channel on the frontend I get lots of these:
> 
> 2005-04-15 13:01:33.664 Audio buffer overflow, audio data lost!
> 2005-04-15 13:01:33.668 Audio buffer overflow, audio data lost!
> 2005-04-15 13:01:33.668 Audio buffer overflow, audio data lost!
> 
> And on the backend I get lots of these:
> 
> 2005-04-15 13:01:35.624 DVB#0 WARNING - Uncorrectable error in packet, dropped.
> 2005-04-15 13:01:35.624 DVB#0 WARNING - Uncorrectable error in packet, dropped.
> 2005-04-15 13:01:35.624 DVB#0 WARNING - Uncorrectable error in packet, dropped.
> 
> Both channels work fine on CVS from 3/27 and earlier.  I looked
> through the CVS commits from 3/27-3/29 and I'm not sure but these (2)
> are the most relevant commits that I could find.
> 
> ----------------------------------------------------------------------------
> Changes committed by taylor on Sun Mar 27 18:18:56 2005
> 
> Modified Files:
>    in mythtv/libs/libmythtv:
>         dbcheck.cpp siparser.cpp siscan.cpp sitypes.cpp sitypes.h 
> Log Message:
> Addition of Torbjorn Jansson's EitFixUp4 code changes that were missed
> in previous
> DVB patch changes.  One more entry added to dtv_privatetypes so one more
> schema rev.
> ----------------------------------------------------------------------------
> ----------------------------------------------------------------------------
> Changes committed by cpinkham on Mon Mar 28 05:01:39 2005
> 
> Modified Files:
>    in mythtv/libs/libmythtv:
>         NuppelVideoPlayer.cpp NuppelVideoPlayer.h avformatdecoder.cpp 
>         decoderbase.cpp decoderbase.h 
>    in mythtv/programs/mythtranscode:
>         transcode.cpp 
> Log Message:
> 
> Fix transcoding bug related to AC3 passthrough.  Previously if you had AC3
> passthrough turned on and tried to transcode an AC3 recording, the audio
> would not be properly transcoded.  This fixes the audio when AC3 passthrough
> is enabled.
> ----------------------------------------------------------------------------
> 
> I am using DVB with a pcHDTV HD-3000 card, on 32-bit Debian with a
> 2.6.12-rc1 kernel (with built-in DVB), I am also using /dev/dsp for
> audio.  I used the same configure script with all versions of the CVS
> code that I checked out, and I dropped my database to guarantee
> identical settings.  Here is my output from configure that I am using:
> 
> $ ./configure  --disable-audio-arts --disable-audio-jack
> --disable-firewire --disable-ivtv --enable-dvb
> --dvb-path=/usr/src/linux/include --enable-xvmc --enable-opengl-vsync
> Warning: DVB location points into kernel (ok if kernel >= 2.6.11)
> # Basic Settings
> Compile type     release
> Compiler cache   no
> DistCC           no
> Install prefix   /usr/local
> CPU              x86 (model name        : AMD Athlon(tm) 64 Processor 3200+)
> Big Endian       no
> MMX enabled      yes
> Vector Builtins  no
> 
> # Input Support
> Joystick menu    yes
> lirc support     yes
> ivtv support     no
> FireWire support no
> DVB support      yes [/usr/src/linux/include]
> 
> # Sound Output Support
> OSS support      yes
> ALSA support     yes
> aRts support     no
> JACK support     no
> 
> # Video Output Support
> x11 support      yes
> xrandr support   yes
> xv support       yes
> XvMC support     yes
> XvMC VLD support no
> OpenGL vsync     yes
> 
> Creating config.mak and config.h
> 
> P.S. I have XvMC enabled in configure but I don't have it enabled in
> mythfrontend.
> 
> Thanks,
> -Greg
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I may have similar issues with XvMC VLD.
In my case DVB-T channels with more than one audio track cause
problems. Setting the DVB-T card's setting "HW Decoder" works
around the problem.
See my bugzilla bug: 272 at: http://www.mythtv.org/bugs,
or my mail thread:  Problem with Via VLD XVMC display and DVB

There appears to be some AVSync bug in libavcodec or libmythtv that
appears when XvMC is used ...

Terry