[mythtv-users] trandcoding messes up 6 channel audio slow audio playback
bryan at clingman.org
Fri Dec 31 00:51:46 UTC 2010
On Thu, 2010-12-30 at 09:43 -0700, Alan Anderson wrote:
> Since upgrading to mythtv 0.24 the transcoding of any show with 6 channel
> audio ends up with slow audio playback. Playback before transcoding is fine,
> after transcoding the sound runs half speed. Some threads here claim it is a
> Alsa issue. But playback before transcoding is fine. If I copy the nuv file
> over to another system and use vlc or mplayer the sound is still slow.
> I have atrpms mythtv rpm 0.24-256.fc13.x86_64 on the backend
> AMD Athlon(tm) 64 X2 Dual Core Processor 4200+ incase its some weird CPU
> related issue floating point.
> I see 0.24-258 is avaialble so I'll update to that.
I have (had) the same issue. It's a bug in mythtranscode. The audio is
actually 1/3 speed because the 6 channels get cut down to 2.
It's the same problem discussed here:
and several times on this list (including myself)
Anyway, the patch is attached. This works by making the audio as
left_transcoded = left/2 + center/2;
right_transcoded = right/2 + center/2;
The patch is an UGLY hack, but it works for the short term. Hopefully
at some point the AC3 stream can just be copied to the transcoded file.
> I see the following error in the log file.
> 2010-12-27 20:31:18.596 Transcoding from
> /video/recordings/3111_20101227200000.mpg to
> 2010-12-27 20:31:18.887 MythCoreContext: Connecting to backend server:
> 192.168.123.20:6543 (try 1 of 1)
> 2010-12-27 20:31:18.932 Using protocol version 63
> 2010-12-27 20:31:18.965 MainServer::ANN Playback
> 2010-12-27 20:31:19.007 adding: pvr.home.lan as a client (events: 0)
> 2010-12-27 20:31:19.042 MainServer::ANN Monitor
> 2010-12-27 20:31:19.073 adding: pvr.home.lan as a client (events: 1)
> 2010-12-27 20:31:21.369 AFD: Opened codec 0x1ecb8f0, id(MPEG2VIDEO)
> 2010-12-27 20:31:21.400 AFD: codec AC3 has 6 channels
> 2010-12-27 20:31:21.435 AFD: Opened codec 0x1ecc8d0, id(AC3) type(Audio)
> 2010-12-27 20:31:21.466 AudioOutput Error: Invalid channel count 6
> 2010-12-27 20:31:21.526 AudioOutput Error: Invalid channel count 6
> 2010-12-27 20:31:21.558 Found video height of 1088. This is unusual and more
> than likely the video is actually 1080 so mythtranscode will treat it as such.
> 2010-12-27 20:31:21.594 New DB connection, total: 2
> Two chanel sound is not a problemn. Only 6 channel.
> I tried to set the transcode option form mp3 to uncompressed it did not help.
> So is therea suggested adjustment for this or do I need to just turn off
> Alan Anderson
> mythtv-users mailing list
> mythtv-users at mythtv.org
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