[MEncoder-users] Dolby downmix

[Andrew Berg]

On 12/27/2010 9:06 PM, Rolf Ernst wrote:
> The HD PVR actually digitizes off a high quality 
> component analog signal and one of the quirks is that every once in a 
> while it misses a beat (very rarely, but maybe 3 times in an hour 
> unnoticeably so) and only the time stamps keep it in sync. Since 
> mencoder knows how to thread the combined video and audio together none 
> of these glitches matter, which is also why ffmpeg is useless for 
> processing these a/v streams.
That's odd. I never really encountered sync issues with my HD-PVR caps,
even though I process audio and video separately. My commands were
something like this (I may be forgetting something since I use AviSynth
with x264 now instead of MEncoder):

mencoder input.ts -demuxer lavf -oac copy -ovc x264 -x264opts [x264
options] -vf yadif,hqdn3d=0:0:4:4,harddup -o temp.avi
ffmpeg -i temp.avi -f wav - 2>nul | neroaacenc [nero aac options] -of
temp.m4a
mp4box -aviraw temp.avi
tsMuxeR temp.meta (remuxed the raw avc stream - see below)
mp4box -add temp_video.264:fps=29.97 -add temp.m4a -new out.mp4

As long as I used -demuxer lavf and -oac copy (instead of -oac null or
-rawvideo), everything was fine. Then again, I always remuxed the video
(as part of the editing process when cutting out ads) and added
timestamp info to the new raw AVC stream with tsMuxeR. Also, I don't
think I've ever recorded 24p -> 30i telecined material with the HD-PVR.