On Mon, Dec 3, 2012 at 5:02 AM, Dmitriy Alekseev <alexeev6@xxxxxxxxx> wrote: > Hello. > > I have a pair of capture dongles Avermedia DVD EZMaker 7 (C039) which have cx231xx chip. > Now using vlc and gst-launch-0.10 I can watch/stream video only from one of them simultaneously. > > For example videolan messages I got opening second device: > [0x7f055c001688] v4l2 demux error: > VIDIOC_QBUF failed libv4l2: error mmapping buffer 0: Device or resource busy > [0x7f055c001688] v4l2 demux error: > VIDIOC_QBUF failed libv4l2: warning v4l2 mmap buffers still mapped on close() > [0x7f055c002ec8] v4l2 access error: mmap failed (Device or resource busy) > [0x7f055c002ec8] v4l2 access error: mmap failed (Device or resource busy) > [0xb5c698] main input error: open of `v4l2:///dev/video0' failed: (null) > > I wonder, what the problem is? You're probably using too much USB bandwidth. A single USB host controller does not have enough bandwidth to support two full resolution video captures at the same time. The video is uncompressed, and each will try to use around 60% of the available USB bandwidth. For a scenario like this, you would need to have two separate USB host controllers, reduce the capture resolution significantly, or choose different boards (such as a PCI or PCIe product). Devin -- Devin J. Heitmueller - Kernel Labs http://www.kernellabs.com -- 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
