[FFmpeg-devel] [PATCH 1/2] avcodec, avformat: deprecate anything related to side data merging

wm4 nfxjfg at googlemail.com
Thu Mar 16 18:24:30 EET 2017


On Thu, 16 Mar 2017 13:38:03 +0000
Rostislav Pehlivanov <atomnuker at gmail.com> wrote:

> On 16 March 2017 at 04:20, wm4 <nfxjfg at googlemail.com> wrote:
> 
> > This patch deprecates anything that has to do with merging/splitting
> > side data. Automatic side data merging (and splitting), as well as all
> > API symbols involved in it, are removed completely.
> >
> > Two FF_API_ defines are dedicated to deprecating API symbols related to
> > this: FF_API_MERGE_SD_API removes av_packet_split/merge_side_data in
> > libavcodec, and FF_API_LAVF_KEEPSIDE_FLAG deprecates
> > AVFMT_FLAG_KEEP_SIDE_DATA in libavformat.
> >
> > Since it was claimed that changing the default from merging side data to
> > not doing it is an ABI change, there are two additional FF_API_ defines,
> > which stop using the side data merging/splitting by default (and remove
> > any code in avformat/avcodec doing this): FF_API_MERGE_SD in libavcodec,
> > and FF_API_LAVF_MERGE_SD in libavformat.
> >
> > It is very much intended that FF_API_MERGE_SD and FF_API_LAVF_MERGE_SD
> > are quickly defined to 0 in the next ABI bump, while the API symbols are
> > retained for a longer time for the sake of compatibility.
> > AVFMT_FLAG_KEEP_SIDE_DATA will (very much intentionally) do nothing for
> > most of the time it will still be defined. Keep in mind that no code
> > exists that actually tries to unset this flag for any reason, nor does
> > such code need to exist. Code setting this flag explicitly will work as
> > before. Thus it's ok for AVFMT_FLAG_KEEP_SIDE_DATA to do nothing once
> > side data merging has been removed from libavformat.
> >
> > In order to avoid that anyone in the future does this incorrectly, here
> > is a small guide how to update the internal code on bumps:
> >
> > - next ABI bump (probably soon):
> >   - define FF_API_LAVF_MERGE_SD to 0, and remove all code covered by it
> >   - define FF_API_MERGE_SD to 0, and remove all code covered by it
> > - next API bump (typically two years in the future or so):
> >   - define FF_API_LAVF_MERGE_SD to 0, and remove all code covered by it
> >   - define FF_API_MERGE_SD_API to 0, and remove all code covered by it
> >
> >  
> Isn't a major bump and API bump? So why wait until major 59 when all things
> getting deprecated get removed at major 58? There's no reason to keep it
> around for longer when it isn't even used.

Apparently we're supposed to keep deprecated APIs around for 2 years.
So to get this crap dead sooner, I've made separate deprecations for
the actual mechanisms, which according to some (michaelni) is an ABI
change.


More information about the ffmpeg-devel mailing list