[FFmpeg-devel] Slice direction in swscale.

Ramiro Polla ramiro.polla
Mon Sep 7 08:31:24 CEST 2009


In sws_scale() there is some code to adjust src and srcStride if it
seems the slices go from bottom to top. This is traced back to r15249,
and the discussion leading to the patch is here:

I have also stumbled upon this:

I have not been able to test this code, not even with the sample
pointed at the first link above. The sample plays something very
distorted in ffplay, something with a badly scaled chroma in mplayer,
and plays properly in vlc.

Does anyone know of a sample that triggers code? Certainly it's not
with ffmpeg/ffplay, since we run sws_scale on the whole picture
instead of slice-based, but I suppose this could be tested with

Anyways the sliceDir check is very hackish and undocumented. Would it
be acceptable for this to be removed and always require top-to-bottom
strides or expect the user to flip things himself?

Ramiro Polla

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