Hello, I am trying to capture from a webcam with a fixed frame rate. I am using ffmpeg (svn revision 21498) with the following options:
./ffmpeg -y -t 00:01:00 -f video4linux2 -r 30 -s 352x288 -i /dev/video0 -vcodec msmpeg4v2 -f avi -r 30 video.avi I used two webcams where uvcvideo shows being capable of 352x288 at 30fps. For some reason, ffmpeg cannot keep the input frame rate, and it starts to go down. There are processing resources available in the system (Ubuntu Karmic 9.10, and also Voyage Linux 0.62 (Debian-based). I have tried specifying the qscale option, but it did not make any difference. Also, both cameras can output raw and mjpeg, but it also did not make a difference. I have updated uvc on Karmic to the version available as a gzip file on the official website. dmesg shows tons of uvcvideo: Dropping payload (out of sync). and every now and then: [28339.492016] uvcvideo: uvc_v4l2_ioctl(VIDIOC_QBUF) [28339.492022] uvcvideo: Queuing buffer 30. [28339.492030] uvcvideo: uvc_v4l2_ioctl(VIDIOC_DQBUF) for both cameras. On Voyage Linux (kernel 2.6.30), it shows several msgs like the following ones [26440.191029] uvcvideo: Queuing buffer 3. [26440.191405] uvcvideo: uvc_v4l2_ioctl(VIDIOC_DQBUF) [26440.201496] uvcvideo: uvc_v4l2_ioctl(VIDIOC_DQBUF) [26440.211579] uvcvideo: uvc_v4l2_ioctl(VIDIOC_DQBUF) [26440.221661] uvcvideo: uvc_v4l2_ioctl(VIDIOC_DQBUF) [26440.230034] uvcvideo: Frame complete (EOF found). [26440.231743] uvcvideo: uvc_v4l2_ioctl(VIDIOC_DQBUF) [26440.231753] uvcvideo: Dequeuing buffer 4 (3, 14800 bytes). [26440.249905] uvcvideo: uvc_v4l2_ioctl(VIDIOC_QBUF) [26440.249921] uvcvideo: Queuing buffer 4. [26440.249950] uvcvideo: uvc_v4l2_ioctl(VIDIOC_DQBUF) Cameras are Microsoft NX-3000 and Genius eFace 1325R Does anyone have an idea, or need more info? Thanks Cesar _______________________________________________ Linux-uvc-devel mailing list Linux-uvc-devel@lists.berlios.de https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
