[FFmpeg-devel] [PATCH 2/2] libavcodec/mjpeg: remove YUVJ mentions

[Paul B Mahol]

On 12/11/17, Michael Niedermayer <michael at niedermayer.cc> wrote:
> On Mon, Dec 11, 2017 at 12:09:33PM -0500, Vittorio Giovara wrote:
>> >* On 12/8/17, Paul B Mahol <onemda at gmail.com <http://gmail.com>>*
>> >> On 12/8/17, Vittorio Giovara <vittorio.giovara at gmail.com
>> >> <http://ffmpeg.org/mailman/listinfo/ffmpeg-devel>> wrote:
>> >*> If we were to break this feature, I'd suggest going the full route of
>> *>*> adding a PixelFormaton and work on a sws alternative (one is allowed
>> to
>> *>*> dream no?).
>> *>
>> > This is step to right direction, why would adding yet another API be
>> > better
>> > solution?
>> >
>> > J formats are hack - misfeature - most obvious reason why nobody added
>> > 10bit J formats, or one of alpha. Calling it otherwise, points to
>> > severe
>> > lack of understanding of problem.
>>
>> I am perfectly aware that the J formats are a hack, that's why it would
>> be
>> nice to avoid introducing more hacks to get rid of them.
>> As it has been pointed out in the other thread, simply adding
>> .color_range
>> does not properly solve this problem, it is a breaking change without
>> proper deprecation period, and in general it seems like not a good idea
>> API-wise to add an endless number of fields to AVCodec.
>> Like I said, having dealt with the problem in the past, the only way I
>> suggest to go forward is decoupling codec/filter negotiation from pixel
>> formats and use a different scaling/color conversion library.
>
> The problem is completely unrelated to the scaling/color conversion
> library. Its difficult to remove them from libavcodec and libavfilter.
> And i belive paul is doing good and hard work here.
>
> If there is a issue in swscale from spliting range out, iam happy to
> look into fixing that if someone gives me a reproduceable test case
>
> thx

Just create separate pixel format for every color range, bitdepth,
colorspace, etc combination.

Or you want pixel formats as objects?

struct AVPixelFormatHax {
    enum ColorMissingSpace color_space;
    enum ColorFillRange color_range;
    enum ColorPrimus  color_primaries;
    int  nb_components;
    int *bitdepths;
    int  nb_planes;

    Copy big pixdesc struct and add more stuff here... (Can this be
done in pure C?)
}

Now you feed this pile of items to each function in lib*