[FFmpeg-devel] [RFC] QuickTime CC mux support

Reimar Döffinger Reimar.Doeffinger at gmx.de
Sat Oct 20 10:52:34 CEST 2012

On Fri, Oct 19, 2012 at 05:45:12PM +0000, Jason Livingston wrote:
> (Sorry for top replying, I will get my email fixed ASAP.)
> Carl, the raw CC data is compatible with many different containers, but the wrapping/embedding process is different in each, and some conversions are quite complicated.  I can only work on the QuickTime track for now.
> This will fix ticket 846, because it will write the correct headers for this type of track.
> Given the above, is it better to copy the packets as-is or to demux/remux the data within the packets?  I have tried both approaches and they both work.  The latter is more complicated code and more potential to break things though.

For mov-to-mov I think copying 1:1 is best in principle I think.
But the problem is that at some point we want to support copying
wtv-to-mov for example.
The good thing is that so far all CC formattings can be distinguished
from the data without knowing the demuxer (MPlayer does this for
But there is still the question of how to do the conversion that
will be necessary.
If for example we should standardize on one format and make all
demuxer convert to it and all muxer from it (with the issue that
it can mean quite some processing, and particularly for WTV with the
split 608/708 format that seems difficult - though a solution to
that might be to standardize on the WTV format, with the disadvantage
that processing the data becomes impossible if you safe the CC data
as a raw stream because the packet sizes are necessary to know how
to process the data).
I so far was too lazy to decide on that, which is why it is rather
messy currently, sorry :-(

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