[FFmpeg-devel] Internal handling of subtitles in ffmpeg

Reimar Döffinger Reimar.Doeffinger
Fri Jan 2 20:45:37 CET 2009

On Fri, Jan 02, 2009 at 07:57:06PM +0100, Michael Niedermayer wrote:
> > Of course that is assuming you want it to be a requirement, and not just
> > a promise from FFmpeg side to set them.
> the idea was to let the lavc core fill these in from the authorative
> variant both for decoding and encoding.
> Anyway this promise can be added later without breaking ABI

I wouldn't object to it then, but waiting till we have some actual
implementations to me sounds nicer still ;-).

> Suggested patch below, if you are ok with this ill try to change the
> existing code to that and commit.

No objections, it definitely is a step forward.

> Btw, URLs from mphq for testing are welcome, i think our regression tests
> dont cover the subtitles and i suspect neither does fate?

Without verification:
http://samples.mplayerhq.hu/ogg/bgc.sub.dub.ogm (text in ogg)
http://samples.mplayerhq.hu/mov/subtitles-embedded/ (I think text in
mov, I used some for testing, but not sure if all are proper files)
http://samples.mplayerhq.hu/sub/ (don't ask me, I only used those in
NeroMP4 which is vobsub in mov)
http://samples.mplayerhq.hu/Matroska/mewmew/ ass in mkv

> Also strictly below breaks ABI and would need a major bump, does anyone mind
> if i ignore this as i belive noone is using AVSubtitle yet and so it would
> do more harm than good ...

I do not mind, but I am none of those who are impacted by ABI at all :-)

> and id like to change the uint16_t fields to int if there are no objections
> and we alraedy break ABI ...

I think that is a good idea in principle, but that might be considered a
bit of an API break.
I am not sure in how far these values need to be checked, probably it's
not a problem, but worth thinking about.

Reimar D?ffinger

More information about the ffmpeg-devel mailing list