[mythtv-users] Transcoders and closed captions

Jim Stichnoth stichnot at gmail.com
Mon Oct 6 21:44:50 UTC 2008


It turns out that closed captions are a key part of the WAF.  Normally,
MythTV's cc support seems great, but there are some problems with
transcoding.  When I do a lossless mpeg-2 transcode (for permanently
removing commercials), the captions are lost completely.  When I transcode
from mpeg-2 to mpeg-4 with a cutlist, the captions are preserved but delayed
during playback, presumably because the cutlist is not being applied to the
captions.  The one workflow I've found that does the right thing is to
transcode from mpeg-2 to mpeg-4 without a cutlist, then create the cutlist,
and finally do a lossless mpeg-4 transcode with the cutlist.

I'm running MythDora 5 (0.21).  Is this a well-known issue?  Would there
happen to be some patches I can pick up to fix this, or do I need to dig
into the code myself?

On a related topic (and please stop me if this is a verboten topic), I've
noticed that the handful of bittorrent TV programs I've downloaded always
seem to lack captions.  Is this because of problems with the mpeg-4/cc
specification, or with support in the encoding tools, or a deliberate
decision by the people doing the encoding?

Jim
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