On Wed, Jun 17, 2020 at 04:22:06PM +0530, Gautam Ramakrishnan wrote: > Hi all, > > I am working on the JPEG2000 decoder. However I am having trouble > understanding pixel formats correctly. > For example, from my understanding, the reference file p1_01.j2k pixel > format does not get recognized by the native decoder. When I force a > gray8 format on it, I am able to get output similar to opj_decompress > (I have made other modifications to the decoder as well). > It would be great if I could be referred to some documentation which > would help me understand how exactly the pixel format selection works.
for libavcodec in general the decoder sets the format in AVCodecContext.pix_fmt, for interpreting what each format is you can see libavutil/pixdesc.* libavutil/pixfmt.h There are also a few other colospace related fields color_primaries, color_trc, colorspace, color_range, chroma_sample_location to choose the pix_fmt for a jpeg2000 image, the code is IIRC basically trying to guess it from various fields from the jpeg2000 thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB There will always be a question for which you do not know the correct answer.
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