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[Spca50x-devs] gspca questions




Hello,

I have a few questions about reading frames from a camera, and thought
I'd put them in one job lot.  Some of them may be v4l questions, so
feel free to point me somewhere else if that's the case.

The camera is a Logitech Quickcam IM, and it's running on a GP2X,
which is an ARM based games console.  It runs kernel 2.4.25 and I've
installed spca5xx-LE.

- Mostly after I call ioctl(fd,VIDIOCMCAPTURE,&vmmap) followed by
  ioctl(fd,VIDIOCSYNC,&n), the VIDIOCSYNC returns after 100
  milliseconds or so, with a valid picture in the buffer.  But quite
  often (about 40% of the time) it returns after a couple of
  milliseconds, and either the buffer is empty (since I've memset() it
  to zeroes beforehand) or it has a stream in it that doesn't appear
  to be a valid JPEG stream.

  I don't know why VIDIOCSYNC should be returning so quickly.  Any
  ideas?

- When VIDIOCSYNC does return and there is a valid picture in the
  buffer, is there anyway to determine exactly how many bytes were
  written?  spcaview searches the buffer for 0xff 0xd9 and I've tried
  that.  Is that the only way?

- Sometimes I get half a JPEG picture.  The stream seems to stop at a
  bright spot in the picture, or at a spot where there is lots of
  detail.  This may be related to VIDIOCSYNC returning early, but I'm
  not sure about that.

Some of this may be related to the ARM CPU not having enough power to
encode a JPEG for each frame.  However, it seems that spca5xx-LE does
not to RGB24 encoding.  The CPU is a 200MHz ARM, with 32MB memory.
Should this be able to run the full spca5xx driver?


Thanks for you patience,
Russell




-- 
Russell Steicke

-- Fortune says:
It is often the case that the man who can't tell a lie thinks he is the best
judge of one.
		-- Mark Twain, "Pudd'nhead Wilson's Calendar"

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