[TriEmbed] BBB USB webcam issues?

[Carl Nobile]

Alex,

Both the BBB and RPi have version 2 USB which specifies 500mA as the
maximum allowed current through a USB connector. The max speed of a USB 2
is 480 megabits per second. Here is an interesting addressing some of the
issue you mentioned.
http://electronics.stackexchange.com/questions/24700/why-are-usb-devices-slower-than-480-mbit-s

Carl


On Mon, Jul 6, 2015 at 2:51 PM, Alex Davis via TriEmbed <
triembed at triembed.org> wrote:

> Anyone have experience with the BeagleBone Black and USB webcams? In my
> experience with v4l2 and UVC USB webcams on the BBB, getting an image
> above 320x240 is unreliable and 320x240 or below is occasionally
> unreliable. I've seen this on two separate BBBs under 3.8 and 3.14
> kernels. It is more reliable if you set the webcam to send a compressed
> image stream (JPEG) vs uncompressed (YUV), so it makes me think the
> issue is data-rate dependent on the USB bus.
>
> I am using a Microsoft Lifecam Cinema camera. It is rock-solid on my
> Debian laptop running a 3.8 kernel at up to the native 12800x720
> resolution.
>
> I know with the early Raspberry Pi there is an issue with limited USB
> current, but I don't think that's the case with the BBB. I use at
> minimum a 2A 5V supply, which should be plenty for the BBB and the USB
> webcam. Could it be some hardware issue limited to the original 2 GB
> eMMC models that I have?
>
> There isn't much on the web with regards to BBB-specific webcam issues.
> I've seen BBB projects using high-end logitech cameras for live
> streaming, so it must work for some.
>
> --
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-- 
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Carl J. Nobile (Software Engineer)
carl.nobile at gmail.com
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