[FFmpeg-devel] [PATCH 00/10] deprecate av_init_packet() and sizeof(AVPacket) as part of the ABI

[James Almer]

On 2/2/2021 4:33 PM, Andriy Gelman wrote:
> On Mon, 01. Feb 19:44, James Almer wrote:
>> As the subject says, this puts AVPacket in line with AVFrame, allowing
>> easier extensibility of the struct, and preventing potential undefined behavior
>> in some cases when packets are used uninitialized on stack.
>>
>> This set adapts only a few modules, examples, and the tools, as those were the
>> most complex and the ones that better reflect how AVPackets must be used after
>> the deprecation period.
>> I have a branch ready removing every other instance of av_init_packet() in the
>> tree, and all uses of AVPacket on stack i could find. They are pretty trivial,
>> so i wont bother spamming the ML with 40+ patches until the core changes are
>> upstreamed. It's also not exhaustive, as i'm sure i missed a few cases of stack
>> usage, but they can be removed any time between the deprecation of public
>> sizeof(AVPacket) and it's effective removal 2+ years from now.
>> Then there's the few cases where an AVPacket is part of another public struct,
>> as is the case of AVPacketList, or attached_pic in AVSteam. The latter i could
>> adapt right now, but it would mean a lot of preprocessor checks littering the
>> codebase until removed, so i refrained from doing so.
>>
>> James Almer (10):
>>    avformat/mux: use av_packet_alloc() to allocate packets
>>    avformat/movenc: use av_packet_alloc() to allocate packets
>>    avformat/utils: use av_packet_alloc() to allocate packets
>>    doc/examples/demuxing_decoding: use av_packet_alloc() to allocate
>>      packets
>>    doc/examples/transcode_aac: use av_packet_alloc() to allocate packets
>>    doc/examples/transcoding: use av_packet_alloc() to allocate packets
>>    fftools/ffprobe: use av_packet_alloc() to allocate packets
>>    fftools/ffmpeg: use av_packet_alloc() to allocate packets
>>    fftools/ffplay: use av_packet_alloc() to allocate packets
>>    avcodec/packet: deprecate av_init_packet()
>>
>>   doc/examples/demuxing_decoding.c |  25 +--
>>   doc/examples/transcode_aac.c     |  46 +++--
>>   doc/examples/transcoding.c       |  48 +++--
>>   fftools/ffmpeg.c                 | 318 ++++++++++++++++---------------
>>   fftools/ffmpeg.h                 |   4 +
>>   fftools/ffmpeg_opt.c             |   5 +-
>>   fftools/ffplay.c                 | 222 ++++++++++++---------
>>   fftools/ffprobe.c                |  34 ++--
>>   libavcodec/avpacket.c            |  23 ++-
>>   libavcodec/packet.h              |  23 ++-
>>   libavcodec/version.h             |   3 +
>>   libavformat/avformat.h           |   4 +
>>   libavformat/internal.h           |   6 +
>>   libavformat/movenc.c             | 101 ++++++----
>>   libavformat/movenc.h             |   2 +
>>   libavformat/movenchint.c         |  19 +-
>>   libavformat/mux.c                |  44 +++--
>>   libavformat/options.c            |   9 +
>>   libavformat/utils.c              | 106 ++++++-----
>>   19 files changed, 613 insertions(+), 429 deletions(-)
>>
> 
> Hi James,
> 
> In case you didn't see, there is some weirdness with fate over the commits:
> https://patchwork.ffmpeg.org/project/ffmpeg/list/?series=3189

Yeah, i messed up and placed a patch using a FF_API_ define before the 
patch that introduced it :p

With all 10 patches applied it works as intended, but patch 10/10 needs 
to go in first to ensure the above doesn't happen.