[FFmpeg-devel] [PATCH] avformat/ac3dec: detect fairplay encryption

[James Almer]

On 3/4/2020 1:56 PM, Carl Eugen Hoyos wrote:
> Am Mi., 4. März 2020 um 17:53 Uhr schrieb Sebastian Hubbard
> <sebh-at-google.com at ffmpeg.org>:
>>
>> I knew this was an ABI change and probably wasn't going to be
>> acceptable, but I decided to share it for consideration anyway.
>> There's special code in av_probe_input_format3 to skip over id3 tags
>> for the purposes of format detection, but Apple uses id3 tags to
>> signal information for HLS audio only tracks. Maybe this change
>> shouldn't be made, but if it could ever be helpful for another format
>> prober to know about leading id3 tags this is the only way I could
>> imagine it.
> 
> If the additional fields are necessary (I don't know), they could be
> added to the end of the struct where they do not break abi.
> 
> Carl Eugen

sizeof(AVProbeData) is part of the ABI because its doxy doesn't strictly
state otherwise. This means we can't add new fields to it, even at the
end, until a major bump. Else we'll be breaking ABI.