On Tue, Nov 09, 2010 at 09:43:29AM +0100, Michael PARKER wrote: > I'm attempting to capture a single frame from the /dev/video0 output of > my HVR-4000 card's analogue tuner as a JPEG. > > Whilst several resources exist for capturing the output of a card with > h/w MPEG compression, I'm unable to determine the format of the > /dev/video0 data for a frame grabber such as the HVR-4000. According to the sourcecode the cx88 chip can do 8 bit grayscale, 15/16/24/32 bit RGB/BGR, and two variants of 4:2:2 YCbCr. > Can anyone suggest a means by which I can capture a single frame from a > frame grabber card? Can I just use "dd if=/dev/video0 of=image.jpg bs=64K" > or similar or do I have to access the card via the V4L2 drivers? Yes, dd should work but you need to use a blocksize that can hold a complete frame and count=1 if you want a single frame. JPEG, as mentioned above, is not possible with this board. The resolution and data format can be selected with V4L2 ioctls. Daniel -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
