[FFmpeg-devel] [PATCH] AVFoundation: Add -pixel_format option

Carl Eugen Hoyos cehoyos at ag.or.at
Sun May 11 19:34:02 CEST 2014

sfan5 <sfan5 <at> live.de> writes:

> >> +    { AV_PIX_FMT_BGRA, kCVPixelFormatType_32BGRA },
> > This should be AV_PIX_FMT_BGR0: The camera cannot
> > record an alpha channel, the fourth channel is (or at
> > least can be) 0, so it should be ignored.
> > Same for the other 32 bit rgb formats.
> Isn't AVFoundation a generic API for video sources? 
> (not only cameras)
> There might be other devices that can record RGBA.

I can't really answer this but since AVFoundation 
provides transparent images for 32 bit RGB it has 
to be mapped to RGB0 to work at all.
(If a user ever protests that his alpha channel 
disappears, we will have to find a solution.)

> > Right now, if I specify a pixel format that does not
> > work (like gray) FFmpeg prints many error messages
> > but does not quit. Can you reproduce this?
> > The expected behaviour imo is to quit if a pixel
> > format that does not work is requested.
> I can reproduce this, but I am not sure which approach 
> one would to take to fix this.

I cannot really test (I only borrowed a Mac for the quick 
test before) but I would expect that some function call 
returns an error if a pixel format that is not supported 
is requested.

Carl Eugen

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