Re: drawing onto CVPixelBuffer
Re: drawing onto CVPixelBuffer
- Subject: Re: drawing onto CVPixelBuffer
- From: douglas welton <email@hidden>
- Date: Sat, 07 May 2011 22:20:09 -0400
Have you taken a look at the CaptureAndCompressIPBMovie sample code? That code does something very similar to what you appear to be in need of.
On May 6, 2011, at 5:30 PM, Jean-Daniel Dupas wrote:
>
>
> Le 6 mai 2011 à 22:22, eveningnick eveningnick a écrit :
>
>> Hi
>> I have a CVPixelBuffer with some background picture.
>> I need to draw on this background some foreground image. I don't need
>> to preserve the initial CVPixelBuffer's content - i just need to add a
>> small foreground watermark onto that buffer.
>>
>> CIImage does allow to create an image from CVPixelBuffer and paint
>> something on top of it (using Core Image filters), but CIImage is
>> "read only" - it takes a source image and generates a brand new image
>> in a new buffer.
>> I can't afford one more copying, that greatly slows things down,
>> because the CVPixelBuffer itself is kind of big. And there are a lot
>> of them per second (they are generated as frames from a movie).
>>
>> Is there any way i could draw without such a copy? Maybe there is any
>> other imaging framework that allows me to work with CVPixelBufferRef?
>> Or should i just 'CVPixelBufferLock' the buffer, and copy raw bytes
>> onto the buffer from my source NSImage (that contains the foreground
>> image) directly using a loop? This doesn't seem the right way though.
>> Could you please help me, what is better to do here?
>
>
> If your pixel buffer has a format supported by the CGBitmapContext API, you can use the later to draw into it.
>
> Create a CGBitmapContext using the memory from you CVPixelBuffer, and draw using the CGContext API.
>
> -- Jean-Daniel
>
>
>
>
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