On Tue, 2010-11-09 at 10:34 +0100, Michael PARKER wrote: > Daniel, > > Many thanks for your mail. Please excuse the naivety of my questions - > I'm a h/w guy and a nube to the s/w world. > Do you know which of these is the default format or how to determine > the format I'm seeing coming out of /dev/video0? $ v4l2-ctl -d /dev/video0 --list-formats $ v4l2-ctl -d /dev/video0 --get-fmt-video $ v4l2-ctl --help > Do you have a suggestion for how data captured from /dev/video0 can be > converted into a recognisable image format (JPEG, GIF, PNG etc.)? > > I'm keen, if possible, to grab the single frame image using just > command line tools and without recourse to ioctls, compiled code etc. v4l2-ctl can set up the device. As you and Daniel mentioned, dd can read off a frame given the proper parameters. > Also, how do I synchronise dd to the beginning of a new frame (and > thus avoid capturing sections of two frames)? When dd open()s the device and does a read() it should start a capture. When dd close()s the device and exits, it should stop the capture. I'm fairly certain stopping and restarting a capture should resynchronize things, but I'm not sure. The overhead of stopping and starting a capture may cause you some noticeable delays, but again, I'm not sure. I think the answer is to write some code and use the Streaming I/O ioctl()s interface to get frame based data. I know you were hoping to avoid that. Regards, Andy > Thanks again, > > Mike -- 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
