[Libav-user] "No accelerated colorspace conversion found from yuv420p to rgb24" FFmpeg 2.5.3

coordz at megaroms.co.uk coordz at megaroms.co.uk
Tue Feb 17 13:58:10 CET 2015

> Hi, I was looking around to find the reason for the warning while running
> with the compiled FFmpeg:
> "No accelerated colorspace conversion found from yuv420p to rgb24"
> and found it's related to the reason of not usging the GPU.

It's not at all related to the GPU. It's related to their being no
architecture specific version of the colorspace conversion for the CPU you
are targeting.

> did the following with no difference:
> 1) compiled the FFmpeg with x264

Wouldn't expected it to.

> 2) added to the configure flags: --enable-neon

This will help the performance of the non -CPU specific version of the
colour conversion and a good flag to have anyway.

> 3) added --enable-static

Maybe a slight performance difference if using link time code generation
but otherwise useless.

> this warning become when calling:
> sws_getContext with PIX_FMT_RGB24 where the source is YUV420P
> compiled for iOS all architecture but when trying only one still same
> result
> any idea?

The warning is simply that no one has written an optimized version of the
colorspace conversion in libswscale for ARM. I can only see PPC and x86
asm versions, i.e. it's nothing to worry about.

> Thanks,
> Yaron
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