[libav-api] questions about sws_scale's slice direction

steve at chinavfx.net steve at chinavfx.net
Tue Apr 30 04:42:11 CEST 2013


 

I've checked swscale_unscaled.c and sws_scale function in it, and I
found that sliceDir seems determined by srcSliceY. but it seems there is
no way to specify a upsize-down image for sws_scale.

Under Windows, any
image captured from a webcam by using Media Foundation are all upside
down, means stride are negative, but if I use this negative stride
directly in sws_scale, the function return 0, means no image are
converted.

So, for this kind of images, how can I use sws_scale to
convert pixel format and output a correct converted upside-down
image?

Thanks for any help.

Steve Yin 
 


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