Sorry for the long delay in responding. I will try these changes.
However, the scoop on the other various patches is as follows:
in 2592x1944 mode, at 10fps, 4bpp for mjpg, the fix_jpeg_bandwidth makes
things worse with 3476 B/frame rather than the device specified 3060
B/frame.
At 2592x1944 mode at 5fps, 2bpp for mjpg, the fix_jpeg_bandwidth ends up
at 1024 B/frame, which allows me to run the three cameras that I want.
At 2592x1944 mode at 5fps, 4bpp for mjpg, the fix_jpeg_bandwidth ends up
at 1984 B/frame, which allows me to run two cameras, but not the third.
However, these numbers are funny. The frame size for 2592x1944x4bpp is
2.5 Megabytes or 20 Mbits. At 5fps, this is 100 Mbits/sec. There should
be ample bandwidth to support three of these streams.
To be honest, I don't understand the units of the B/frame. Can someone
explain it to me?
Philip
On 07-Mar-11 5:53 AM, Alexey Fisher wrote:
Hi Philip,
i probably will not solve your problem but i wont to take a look on it.
Can you please apply attached debug patch and send me the log.
this patch was made on top of fd2b6dd22743f7c96f7c6e97d49ff5f4b422e741
Make sure you have CONFIG_DYNAMIC_DEBUG=y enabled. To start dynamic
debug you need do as root:
echo "module uvcvideo +p"> /sys/kernel/debug/dynamic_debug/control
echo "func uvc_video_decode_end -p"
/sys/kernel/debug/dynamic_debug/control
echo "func uvc_video_decode_start -p"
/sys/kernel/debug/dynamic_debug/control
echo "func uvc_video_decode_data -p"
/sys/kernel/debug/dynamic_debug/control
echo "func uvc_video_decode_isoc -p"
/sys/kernel/debug/dynamic_debug/control
echo "func uvc_video_complete -p"
/sys/kernel/debug/dynamic_debug/control
echo "func uvc_v4l2_do_ioctl -p"
/sys/kernel/debug/dynamic_debug/control
and start video with this, it will make onlöy one shot:
gst-launch-0.10 -v v4l2src num-buffers=1 ! jpegdec ! ffmpegcolorspace !
autovideosink
Am Sonntag, den 06.03.2011, 17:30 -0500 schrieb Philip Gladstone:
It turned out that my kernel had an old uvcvideo module which didn't
have the right debug log messages, and so I'm in the process of
upgrading to a current kernel version. So far, I've managed to render my
machine unbootable [it is a little embedded linux box].
Philip
On 3/6/2011 6:14 AM, Laurent Pinchart wrote:
Hi Philip,
On Sunday 20 February 2011 21:57:24 Philip Gladstone wrote:
I attached two C910s to a small linux box, and ran into the 'Failed to
submit URB' problem.
When I look at the descriptors for this camera, I think I understand the
problem. I'm capturing at 5 Mpixels and I'm trying two cameras.
VideoStreaming Interface Descriptor:
bLength 38
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 28
bmCapabilities 0x01
Still image supported
wWidth 2592
wHeight 1944
dwMinBitRate 403107840
dwMaxBitRate 806215680
dwMaxVideoFrameBufferSize 10077696
dwDefaultFrameInterval 1000000
bFrameIntervalType 3
dwFrameInterval( 0) 1000000
dwFrameInterval( 1) 1333333
dwFrameInterval( 2) 2000000
The video frame size is set to 10Mb. This is surprisingly large as
actual frames captured with MJPEG on this camera are typically 500kb or
less. When I checked the descriptor for the uncompressed version of the
same frame, it came back with the same value of dwMaxVideoFrameBufferSize
(effectively 16 bits per pixel). The values for min/max bit rate are
(correctly) calculated from the frame intervals and the buffer size.
The uvcvideo driver doesn't use the dwMaxVideoFrameBufferSize field to compute
the required bandwidth but queries the device at runtime instead.
You can enable the UVC_TRACE_VIDEO trace flag to get the driver to print the
bandwidth requested by the device to the kernel log.
Typical JPEG compression gets down to 1 bit per pixel, and 2 bits is
very unusual.
What I want to know is what the impact would be of defining a new QUIRK
that overrode the frame buffer size for compressed frames and calculated
them at (say) 2 bits per pixel?
Do other webcams get this right?
You would be surprised by how many webcams get things wrong.
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