The following pipeline

gst-launch-1.0 -v multifilesrc location=~/a1_mono.j2c  num-buffers=1 caps="image/x-jpc" ! jpeg2000parse  ! openjpegdec ! imagefreeze ! videoconvert ! ximagesink

fails negotiation

Created attachment 330740 [details] [review]
Force sampling and colorspace to grayscale for single component image

I think this should be a fairly uncontroversial change :)

Note: test file is a monochrome j2c file

So, now that the dust has settled on the latest release, can we please merge this fix into master ? It is quite straightforward: for monochrome images, we can force sampling and colorspace to grayscale.  Thanks :)

Comment on attachment 330740 [details] [review]
Force sampling and colorspace to grayscale for single component image

Does this make sense? I could imagine a use case where someone passes around separate images for e.g. R, G and B.

Maybe only do this if there's no useful info in the caps?

(In reply to Sebastian Dröge (slomo) from comment #6)
> Comment on attachment 330740 [details] [review] [review]
> Force sampling and colorspace to grayscale for single component image
> 
> Does this make sense? I could imagine a use case where someone passes around
> separate images for e.g. R, G and B.
> 
> Maybe only do this if there's no useful info in the caps?

Thanks, that is a good point. This is really edge case, I guess, but I will
add a few lines to handle this.

(In reply to Sebastian Dröge (slomo) from comment #6)
> Comment on attachment 330740 [details] [review] [review]
> Force sampling and colorspace to grayscale for single component image
> 
> Does this make sense? I could imagine a use case where someone passes around
> separate images for e.g. R, G and B.
> 
> Maybe only do this if there's no useful info in the caps?

I believe the parser already does this if caps have no useful info.

So, I am going to close this, not really a bug IMHO. User can always
explicitly set sampling to GRAYSCALE.