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UK DVB-T audio IDs issue [solved]

Symptoms: Some files sourced from freeview DVB re-encoded using mencoder have silent soundtracks.

Analysis: The MPEG-TS stream often contains additional sountracks, for example “audio commentaries” for blind viewers. mencoder incorrectly selects these tracks, even if switch -alang en is given. It seems mencoder will give up trying to find the requested soundtrack and go with the first one it finds.

Solution: Use the -tsprobe <byte position> option to make mencoder search further into the file than it would by default. Also switch -tskeepbroken appears to help deal with broken files.

Example. Set byte offset to half the size of the file

file=1741_20091125102600.mpg
size=$(stat -c %s "$file")
size=$(( $size / 2 ));
mencoder -tskeepbroken -tsprobe $size -alang en <other options....> $file
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