[FFmpeg-devel] [PATCH] avcodec/tiff: Try to fix subsampling default

[Michael Niedermayer]

On Sat, Sep 28, 2019 at 07:13:59PM +0300, Skakov Pavel wrote:
> >This ensures the default ycbcr_subsampling is 2 while also
> >ensuring the subsampling values are correct for all pixel formats.
> >This solution while it takes a few lines more code should be more
> >robust
> 
> In TIFF specification only CbCr subsampling is allowed. The field is explicitly named "YCbCrSubsampling", so introducing another subsampling variable serves no purpose other than introducing confusion.

Well, you are technically correct
But having subsampling of 2 "accessible" when subsampling is not 2 is asking
for out of array accesses.

I mean if you set subsampling so it is always correct for the used pixel
format then any code can use it and its fine

But if subsampling is only valid for one colorspace and 2 otherwise
now you have to proof and maintain that condition that no code ever uses the
subsampling value unless the colorspace is ycbcr

I have no strong oppinon on this but at the least the subsampling field
would need to be renamed to ycbcr_subsampling if its invalid in the
more general case

thx

[...]
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