If your question was
Where are these pixel formats defined?
Go to http://ffmpeg.org/download.html and download the source of ffmpeg. Then unpack it
tar -xavf FILENAME.tar.*
and descend to the folder in the source code that is called libavutil
cd ffmpeg-*/libavutil/
and open the file pixfmt.h
where you will find a description of all pixel formats. A few sample lines
AV_PIX_FMT_YUV420P, ///< planar YUV 4:2:0, 12bpp, (1 Cr & Cb sample per 2x2 Y samples)
AV_PIX_FMT_YUYV422, ///< packed YUV 4:2:2, 16bpp, Y0 Cb Y1 Cr
AV_PIX_FMT_RGB24, ///< packed RGB 8:8:8, 24bpp, RGBRGB...
AV_PIX_FMT_BGR24, ///< packed RGB 8:8:8, 24bpp, BGRBGR...
AV_PIX_FMT_YUV422P, ///< planar YUV 4:2:2, 16bpp, (1 Cr & Cb sample per 2x1 Y samples)
Additionally you can read https://en.wikipedia.org/wiki/YUV and it’s cited sources and external links.
libavutil/pixfmt.h
:AV_PIX_FMT_YUVJ420P, ///< planar YUV 4:2:0, 12bpp, full scale (JPEG), deprecated in favor of AV_PIX_FMT_YUV420P and setting color_range
.