Re: [FFmpeg-devel] avformat/mxfenc: SMPTE RDD 48:2018 Amd 1:2022 (FFV1 in MXF) support

[Jerome Martinez <jerome@mediaarea.net>]

On 16/01/2023 15:00, Tomas Härdin wrote:
> JPEG2000 will also need an RGBA descriptor filled out, might be good to
> prepare for that.

this was the idea behind the way it is coded, so there is only a new 
mxf_write_jpeg2000_desc function to write, like the one for FFV1 i.e.
static void mxf_write_jpeg2000_desc(AVFormatContext *s, AVStream *st)
     is_rgb = desc->flags & AV_PIX_FMT_FLAG_RGB;
     pos = mxf_write_cdci_common(s, st, is_rgb ? mxf_rgba_descriptor_key 
: mxf_cdci_descriptor_key);
}

to add.


>
> The ffv1 parsing code in this patch makes me nervous. Isn't the version
> available in metadata?

I implemented a way similar to e.g. mxf_parse_mpeg2_frame by parsing a 
bit the frame.
version and micro_version are available in FFV1Context so could be used 
but I don't know how to get FFV1Context from AVStream or other, need 
help there.


>
>> +        ff_build_rac_states(&c, 0.05 * (1LL << 32), 256 - 8);
> (1LL << 32) / 20 ?

Could be, I don't really care, but this line is copied from ffv1dec.c, I 
think it may be relevant to keep the exact same code for the exact same 
purpose.
Would be no more relevant if version and micro_version can be taken from 
FFV1Context.

Jérôme
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