[FFmpeg-devel] New pixel format uyvy422i12le

[Damien Chabannes]

Hi everyone,

I'm trying to implement a new pixel format in FFmpeg but it appears that my
implementation is not correct. Indeed, when I do a ffplay on a raw video in
this new pixel format, the output is not correct.

The pixel format I want to implement is the uyvy422i12le. Data y, u and v
are stored in the same buffer, in this interlaced way : u0, y0, v0, y1, u1,
y2, v1, y3, u2, y4, v2, y5, ..., each data is encoded on 12 bits and stored
on 16 bits Little Endian.

For adding this new pix_fmt, I have done the following modifications :

   - in libavutil/pixfmt.h, add "AV_PIX_FMT_UYVY422I12LE" in enum
   AVPixelFormat


   - in libavutil/pixdesc.c, add AV_PIX_FMT_UYVY422I12LE in
   av_pix_fmt_descriptors :

    [AV_PIX_FMT_UYVY422I12LE] = {
        .name = "uyvy422i12le",
        .nb_components = 3,
        .log2_chroma_w = 1,
        .log2_chroma_h = 0,
        .comp = {
            { 0, 4, 2, 0, 12, 3, 11, 3 },        /* Y */
            { 0, 8, 0, 0, 12, 7, 11, 1 },        /* U */
            { 0, 8, 4, 0, 12, 7, 11, 5 },        /* V */

   - in libswscale/utils.c, add "[AV_PIX_FMT_UYVY422I12LE]= { 1, 1 }," in
   format_entries

Once FFmpeg compiled with these modifications, if a do a ffplay on a raw
image in uyvy422i12le, I have this output which is uncorrect :
https://ibb.co/g7jG3ss

Here's the command line and the output :

./ffplay -f rawvideo -video_size 3840x2160 -pixel_format uyvy422i12le
test_in
ffplay version 48.1 Copyright (c) 2003-2019 the FFmpeg developers
  built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
  configuration:
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
[rawvideo @ 0x7f47bc000940] Estimating duration from bitrate, this may be
inaccurate
Input #0, rawvideo, from 'test_in':
  Duration: 00:00:00.04, start: 0.000000, bitrate: 6635520 kb/s
    Stream #0:0: Video: rawvideo, uyvy422i12le, 3840x2160, 6635520 kb/s, 25
tbr, 25 tbn, 25 tbc
   1.87 M-V: -0.000 fd=   0 aq=    0KB vq=    0KB sq=    0B f=0/0


you can found the original image here : https://ibb.co/zZrvt5K (colorimetry
is strange but that's normal it's an HDR content).

It looks like I have set bad values in the struct AVComponentDescriptor of
AV_PIX_FMT_UYVY422I12LE, but I do not see which one... Or have I forgotten
to add other modifications necessary to a new pixel format ?

The FFmpeg used is from tag n.42 of the FFmpeg 's official repo.