[FFmpeg-devel] [PATCH] Exposing forced flag for DVD and PGS subtitles

[Reimar Döffinger]

On 16 Apr 2012, at 12:45, Joakim Plate <elupus at ecce.se> wrote:
> Erik Miranda <erikmiranda <at> gmail.com> writes:
>> This patch adds a "forced" member to the AVSubtitleRect structure and 
>> implements setting this flag in the DVD and PGS subtitle decoders, since 
>> these are the formats I'm aware of that include such a function. Since 
>> this patch changes AVSubtitleRect, it leads to a public API change. As 
>> far as I can tell, this is the best method to allow access to this 
>> information. Please advise me if otherwise, or if further changes are 
>> required as part of changing AVSubtitleRect. I think the libavcodec 
>> version would need a bump, correct?
> 
> There is already a content dispostion type for forced. That is stream
> global thou. So one option would be to duplicate forced subs into a
> secondary subtitle stream.

What would be the point? What would someone do with that information except drop all non-forced ones?
I guess it might be relevant if you want to preserve the info when reencoding.
It should be possible to avoid the API/ABI breakage by adding an extra array to AVSubtitle instead of putting it into the AVSubtitleRect.
Though we might consider changing the whole API so extending the rect is possible without changing the API in the future.