Le 21/12/2023 à 12:11, Tomas Härdin a écrit :
ons 2023-12-20 klockan 18:04 +0100 skrev Cédric Le Barz:
Le 19/12/2023 à 14:36, Tomas Härdin a écrit :
+ for ( comp = 0; comp < component_count; comp++ ) {
+ avio_write(pb, &sc->j2k_info.j2k_comp_desc[3*comp] , 3);
+ }
Looks like this could be simplified to just
avio_write(pb, sc->j2k_info.j2k_comp_desc, 3*component_count);
+ if (j2k_ncomponents != component_count) {
+ av_log(s, AV_LOG_ERROR, "Incoherence about components
image
number.\n");
+ }
I again feel this should be a hard error
+ for (comp = 0; comp < j2k_ncomponents; comp++) {
+ sc->j2k_info.j2k_comp_desc[comp*j2k_ncomponents] =
bytestream2_get_byteu(&g); // Bitdepth for each component
+ sc->j2k_info.j2k_comp_desc[comp*j2k_ncomponents+1] =
bytestream2_get_byteu(&g); // Horizontal sampling for each
component
+ sc->j2k_info.j2k_comp_desc[comp*j2k_ncomponents+2] =
bytestream2_get_byteu(&g); // Vertical sampling for each
component
+ }
Could be simplified to a single avio_read()
/Tomas
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Here is the new version of the patch taken into account your remarks.
Looks OK. Does this also work with RGB(A)? Seems to not be hardcoded
for YUV at least. Higher bitdepths would also be nice, I've been
working with lossless RGB48 J2K. Doesn't necessarily need to hold up
this patch, just curious.
/Tomas
Any J2K bitdepth can be handled with this patch (up to 31 bits per
component).
Concerning RGBA, The JPEG 2000 sub-descriptor can be referenced either
by the CDCI picture essence descriptor or the RGBA picture essence
descriptor both of which are defined by SMPTE ST 377-1. In this patch it
is only referenced by the CDCI as the RGBA essence descriptor is not yet
implemented in FFmpeg. Nevertheless, I think it should work too with
CDCI essence descriptor : if you have such data, you can try.
Cédric
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