Re: [FFmpeg-devel] [RFC]x264 avcc and related issue

[Zhao Zhili <quinkblack@foxmail.com>]

> 在 2024年3月6日，上午1:58，Andreas Rheinhardt <andreas.rheinhardt@outlook.com> 写道：
> 
> Zhao Zhili:
>> There are multiple encoders which can output bitstream in avcc/hvcc format,
>> e.g, x264, x265 and videotoolbox. This can improve performance depends on
>> container format (no more ff_avc_parse_nal_units_buf).
>> 
>> The problem is these encoders output parameter sets directly, not contained
>> in a complete AVC/HEVC configuration box. But muxers only expect
>> extradata in
>> annexb format, or a complete AVC/HEVC configuration box, not support such
>> length+sps+length+pps format. The following command will output a broken
>> file:
>> 
>> ./ffmpeg -i input.mp4 -an -c:v libx264 -x264-params annexb=0 broken.mp4
>> 
>> I want to fix this issue and improve the performance at the same time.
>> 
>> There are multiple options that I don't know how to make a choice.
>> 
>> 1. At the muxer level? It's easy and ugly. And there are corner case
>> like 00 00 01 xx can be start code of annexb and size of avcc at the
>> same time.
>> 
>> 2. A new bsf? It looks less useful outside of libavcodec. And encoder
>> can't enable a bsf automatically.
>> 
>> 3. A specific helper like h26x_vcc.h? Can it be more general?
>> 
>> Any more suggestions?
>> 
> 
> If we support a new packetization (even if it only affects extradata),
> we would need to support it everywhere -- decoders and muxers, too. I
> don't see an advantage or a need for a new packetization, as AFAIK all
> containers with ISOBMFF packetization also use the ISOMBFF configuration
> box. So I am against 1. and 2.
> Implementing this inside lavc seems like the best approach; I don't know
> whether a common helper for this will be useful: While these lists
> certainly have a common pattern, there are subtle changes between them
> which will probably make a common helper unsuitable.

You mean separated implementations just inside libx264/libx265?

> 
> - Andreas
> 
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