On Tue, 12 Feb 2013 15:34:13 -0800 (PST), Chris Share <[email protected]> 
wrote:
> Hi,
> 
> I posted the following to this forum a week ago but received no response. Can 
> anyone help with this?
> 
> I'm new to libav. I'd like to write a simple test application that converts a 
> .png image to a movie. I'm basing my code on the "output-example.c" example. 
> The .png image data is stored in an array of chars as RGBA values.
> 
> Am I right in thinking that I need to substitute the code in "fill_yuv_image" 
> with code that writes the array of chars to the AVFrame?
> 
> Is there an example of how to do this anywhere?
> 
> I'm not clear about a few things here:
> 
> Firstly, do I need to rearrange the RGBA data in the input vector so that 
> it's suitable for encoding as YUV420p? I imagine I need to remove the A data 
> (?)
> 
> Secondly, I understand that there's a Y value for every pixel and that the Cb 
> and Cr values are used for four (2x2) pixels. What I don't understand is how 
> the RGB data gets "reduced" to the Cb and Cr values - is there an example of 
> how to do this anywhere? 
> 

You certainly don't want to do manual conversion between RGB and YUV. That's
what libswscale is for.

-- 
Anton Khirnov
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