[mythtv-users] PVR150 audio problems

Rod Smith mythtv at rodsbooks.com
Sun Mar 25 15:40:27 UTC 2007

On Sunday 25 March 2007 07:37, Jason Portwood wrote:
> That was it almost.  It does record in stereo and I had the receiver in
> a multi channel mode.  I switched the receiver to 2ch and the left /
> right speakers played normally.
> Is there any way, like with transcoding, to have convert  the recorded
> video run to all audio channels?

AFAIK, MythTV can't do this. Certain transcoding tools can do it, though. I've 
experimented with this with mencoder, for instance. Here's a script that I 
use (really just as a simplified interface to a single mencoder command):

# Script to convert MythTV .nuv files to MPEG-2 format
nice -n 18 mencoder -vf kerndeint,softskip,scale=720:480,harddup -ofps 
30000/1001 -aspect ${aspect} -ovc lavc -lavcopts 
vcodec=mpeg2video:vrc_buf_size=1835:vrc_maxrate=9600:vbitrate=${vbitrate}:keyint=18:turbo:trell:dc=10 -oac 
lavc -lavcopts acodec=ac3:abitrate=192 -af 
channels=6,surround,center=2,sub -of mpeg -o ${dest} ${src}

Note that everything after "nice" is actually a single line, but I'm sure it's 
gotten split by the e-mail process. You'd call the script with the source 
filename, destination filename, bitrate, and aspect ratio as arguments. I've 
not been very pleased with the results; the audio seems to be slightly 
degraded and I have yet to hear anything come from my rear speakers. At least 
it does mix a reasonable center channel, though. I may try more 
experimentation later; perhaps there's some magic combination of options 
that'll do the trick, but I have yet to discover it. Oh, and this command 
does other things, too, like scale to DVD resolution (720x480) and 
deinterlace. You might or might not want to do these things. Check the 
mencoder man page to see what all the options do.

Rod Smith

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