On 25 Jun 2003 15:53:48 -0400 "Brian J. Murrell" <[EMAIL PROTECTED]> wrote:
> I occasionally get ring buffer overflows when recording from my > Matrox Marvel. Me too, except mine suddenly started happening at the start of every recording and I have not been able to record for a couple of months now. > I wonder if somebody who knows more could at least explain what the > error means and give a brief technical summary of the process of > capturing and how the audio ring buffer is involved in it all. I guess Andrew Stevens should answer that but I'll have a go since I have rummaged throught the source trying to understand it (I didn't succeed, mind you). The ring buffer is in shared memory. The application sets it up and tells the sound driver where it is. The driver puts the sound data in it and signals the app that there is data ready. If the app doesn't take the sound data out quick enough it overflows. > For the record, I believe the audio ring buffer overflows I get are > due to latencies in the marvel linux driver. I suspect the > latencies get really bad when the picture is noisy, like when it > goes out of sync(i.e. from the source). I think the jpeg compressor > gets tied up trying to compress that and does not give enough > resources to the other parts of the capture process, overflowing the > buffer of audio samples. I tend to agree that the problem is in the Marvel driver. Lavrec seems to go in a loop: get a picture, get some sound, get a picture, etc. If for some reason it gets stuck waiting for a picture the ring buffer eventually overflows because the sound driver just carries on filling it up regardless. > As I write this I wonder if simply increasing the size of the audio > ring buffer would solve some of these problems or would it just > create other problems? It might help in your case but in mine it seems the first picture never comes so it probably wouldn't help me. It's treating the symptom rather than the cause though. Martin ------------------------------------------------------- This SF.Net email is sponsored by: INetU Attention Web Developers & Consultants: Become An INetU Hosting Partner. Refer Dedicated Servers. We Manage Them. You Get 10% Monthly Commission! INetU Dedicated Managed Hosting http://www.inetu.net/partner/index.php _______________________________________________ Mjpeg-users mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/mjpeg-users
