Beaglebone Black Video Capture: Error "select timeout"

Question

Hey I'm following Derek Molloy's tutorial:

http://derekmolloy.ie/beaglebone/beaglebone-video-capture-and-image-processing-on-embedded-linux-using-opencv/#comment-30209

Using a Logitech c310 webcam, that is supported by the Linux UVC drivers.

root@beaglebone:/boneCV# v4l2-ctl --all
Driver Info (not using libv4l2):
        Driver name   : uvcvideo
        Card type     : UVC Camera (046d:081b)
        Bus info      : usb-musb-hdrc.1.auto-1
        Driver version: 3.8.13
        Capabilities  : 0x84000001
                Video Capture
                Streaming
Format Video Capture:
        Width/Height  : 640/480
        Pixel Format  : 'YUYV'
        Field         : None
        Bytes per Line: 1280
        Size Image    : 614400
        Colorspace    : SRGB
Crop Capability Video Capture:
        Bounds      : Left 0, Top 0, Width 640, Height 480
        Default     : Left 0, Top 0, Width 640, Height 480
        Pixel Aspect: 1/1
Video input : 0 (Camera 1: ok)
Streaming Parameters Video Capture:
        Capabilities     : timeperframe
        Frames per second: 30.000 (30/1)
        Read buffers     : 0
Priority: 2

So we can see it is read by the Beagleboard no problem. When I try to capture the video, I simply get this error:

root@beaglebone:/boneCV# ./capture -f -c 600 -o > output.raw
Force Format 1
select timeout

Looking at other threads, people don't seem to know how to answer this question, can anyone with experience on this project help me out?

Answer 1

Well I can say the issue is resolved. After rebooting and trying the camera again after several hours, it magically seems to work.

The only thing I changed is the capture call to be simpler it is now:

./capture -o > output.raw

I haven't converted the raw file to mpeg4 yet, since I'm installing ffmpeg as I type this, however I can confirm that grabbing still images is working. The filesize of the output.raw is confirmation that it is indeed capturing video as well. If anyone finds this and is stuck, I will be glad to give assistance as much as I can.

Strangely, it only seems to capture video after using the picture grabber program first. So there must be something the grabber is initializing that isn't happening in the capture.

UPDATE: Ok it turns out that the YUYV video mode is not working but the mjpeg does, putting it into grabber mode initialized mjpeg mode and that's why it worked. Not sure why YUYV doesn't work yet.

Answer 2

If you compare the image size of YUYV and that of MJPEG you will notice that the former is much larger than the latter. BBB has limited bandwidth on its USB port so thats why you cannot operate your camera in YUYV format. MJPEG outputs compressed video stream. Different opencv versions tend to change the resolution that you set with v4l2-ctl command so you have to change the resolution in the boneCV code. I'm not sure how its done in c++ but in python, check Changing camera resolution in opencv code. According to Matthew, Bandwidth limitations he tested and found out the bandwidth to be 13.2MB/s.