[mythtvnz] Cutting H.264 DVB-T files with ffmpeg without transcoding

[David Moore]

Anybody worked out a reliable way to cut recordings from Freeview 
terrestrial using ffmpeg? I get different problems with different 
recordings, e.g., sometimes ffmpeg seems to hang and other times it 
produces files myth won't play. I don't want to transcode the video 
because it takes forever on my system so I'm trying to use the "-vcodec 
copy" option.

So far this is the best I have come up with after a lot of trial and error:

ffmpeg -async 1 -ss [start time] -t [duration] -i recording.mpg -vcodec 
copy -acodec ac3 -ab 384k -f dvd cut_recording.mpg

The "-async 1" seems to be needed to keep audio in sync with video. The 
"-f dvd" might (not sure yet) be a fix for av mux errors. Audio is 
transcoded to AC3 since most channels only have LATM AAC audio.

I have ffmpeg SVN-r23148 patched with Paul Kendall's LATM patch to 
handle the audio on TV1, TV2, etc.