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

Rostislav Pehlivanov atomnuker at gmail.com
Thu Mar 16 15:38:03 EET 2017


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.


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