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RE: Saving YUVY image from V4L2 buffer to file




Devin,

Many thanks for the quick reply.

Yes I'm getting some sort of an image. When I was experimenting I managed to get an image but in grayscale & showing multiple copies of the same image covering the top half of the image. I imagine it was distorted because I was not converting to RGB correctly.

All the best,

 

Owen




> Date: Wed, 3 Feb 2010 12:54:02 -0500
> Subject: Re: Saving YUVY image from V4L2 buffer to file
> From: dheitmueller@xxxxxxxxxxxxxx
> To: oo_hehir@xxxxxxxxxxx
> CC: video4linux-list@xxxxxxxxxx
> 
> On Wed, Feb 3, 2010 at 12:40 PM, Owen O' Hehir <oo_hehir@xxxxxxxxxxx> wrote:
> >
> > Hello All,
> >
> > I'm trying to save a captured image from a USB camera to a file. The capture is based on V4L2 video capture example from the V4L2 API spec. http://v4l2spec.bytesex.org/spec/a16706.htm
> >
> > The V4L2 set pointers (via mmap) to to the USB image (in YUV 4:2:2 (YUYV)) and as far as I can see the simplest way to save the image in a recognised format is in RGB format, specifically in PPM (Netpbm color image format).
> >
> > As such I've expanded the process_image function:
> 
> Independent of the conversion function, are you sure you are getting a
> valid YUV frame at all?  A completely green frame is what you will get
> back if you had a buffer which was memset(0).  Hence it's possible
> that the data you are passing *into* your conversion function is
> completely blank.
> 
> Devin
> 
> -- 
> Devin J. Heitmueller - Kernel Labs
> http://www.kernellabs.com
 		 	   		  
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