The Logitech cameras I've used only support YUV streaming at the highest possible resolution. Thus, ffmpeg is always streaming at 1024x576 from the driver, no matter what resolution you request.
In order to capture lower resolutions, you would have to use the MJPEG mode instead of YUV. However, I have no idea if ffmpeg would support such a method. I am not sure why the bitrate is still high despite the lower framerate. Perhaps ffmpeg doesn't know about the new framerate controls that have been added to the V4L2 API. In other words, ffmpeg might always be capturing at the max framerate. It might be possible to fix that with a patch to ffmpeg. -David On Mon, 2006-11-13 at 23:04 +0100, Vidar Normann wrote: > Thanks for your replies Luca and Martin, I really appreciate it. > Although lowering frames-per-second > and resolution does not help at all. See paste at end of post. > > On 11/13/06, Martin Rubli <[EMAIL PROTECTED]> wrote: > On Mon, 13 Nov 2006 19:46:25 +0100, Vidar Normann > <[EMAIL PROTECTED]> > wrote: > > > after a discussion on ffmpeg's mailing-list it seems the > reason I'm > > unable to record > > from two webcams at the same time lies in the uvc-driver.. > > I am able to record from either of the webcams, but if I try > to record at > > the same time > > I get the following error when invoking the ffmpeg-command > to record from > > /dev/video1 > > while another ffmpeg is recording from /dev/video0: > > -- > > ioctl(VIDIOC_STREAMON): No space left on device > > Could not find video grab device > > -- > > I notice that the last entry in dmesg is this: > > -- > > uvcvideo: Failed to submit isoc URB 0 (-28). > > -- > > > > Is there a bug in uvc or is there another explanation? > > FYI I'm using the Logitech QuickCam for Notebooks for Pro > and > > using the newest CVS of the Split-branch of UVC. > > What resolutions and frame rates are you using? Have you tried > QVGA? I > know I had two cameras work at the same time but I may never > have tried > resolutions above QVGA. > > Cheers, > Martin > > I reran both commands: > ffmpeg -vd "/dev/video1" -an -vcodec mpeg4 -s 320x240 -r 5 -y > "test2.avi" > FFmpeg version SVN-r7012, Copyright (c) 2000-2006 Fabrice Bellard, et > al. > configuration: --enable-xvid --enable-gpl > libavutil version: 49.0.2 > libavcodec version: 51.25.0 > libavformat version: 51.6.0 > built on Nov 13 2006 15:34:26, gcc: 3.3.5 (Debian 1:3.3.5-13) > [video4linux2 @ 0x83a81f0][4]Capabilities: 4000001 > The V4L2 driver changed the video from 320x240 to 1024x576 > Input #0, video4linux2, from '': > Duration: N/A, bitrate: N/A > Stream #0.0: Video: rawvideo, yuv422, 1024x576, 47185 kb/s, 5.00 > fps(r) > PIX_FMT_YUV420P will be used as an intermediate format for rescaling > Output #0, avi, to 'test2.avi': > Stream #0.0: Video: mpeg4, yuv420p, 320x240, q=2-31, 200 kb/s, 5.00 > fps(c) > Stream mapping: > Stream #0.0 -> #0.0 > Press [q] to stop encoding > frame= 80 q=2.0 Lsize= 221kB time= 16.0 bitrate= 113.0kbits/s > video:213kB audio:0kB global headers:0kB muxing overhead 3.500250% > > -- > So far so good, it records until I press 'q', the problem arises when > I try to record from the other > webcam as well: > -- > ffmpeg -vd "/dev/video0" -an -vcodec mpeg4 -s 320x240 -r 5 -y > "test1.avi" > FFmpeg version SVN-r7012, Copyright (c) 2000-2006 Fabrice Bellard, et > al. > configuration: --enable-xvid --enable-gpl > libavutil version: 49.0.2 > libavcodec version: 51.25.0 > libavformat version: 51.6.0 > built on Nov 13 2006 15:34:26, gcc: 3.3.5 (Debian 1:3.3.5-13) > [video4linux2 @ 0x83a81f0][4]Capabilities: 4000001 > The V4L2 driver changed the video from 320x240 to 1024x576 > ioctl(VIDIOC_STREAMON): No space left on device > Could not find video grab device > -- > > The thing that I notice is the third last line, seems the v4l2-driver > forces transfer in a 1024x576 > resolution? Other than that, I have no idea and I don't know what to > do. > > Regards, > Vidar > > _______________________________________________ > Linux-uvc-devel mailing list > Linux-uvc-devel@lists.berlios.de > https://lists.berlios.de/mailman/listinfo/linux-uvc-devel _______________________________________________ Linux-uvc-devel mailing list Linux-uvc-devel@lists.berlios.de https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
