Re: [Spca50x-devs] gspca questions
- Date: Thu, 3 Jan 2008 11:54:42 +0100
- From: Michel Xhaard <mxhaard@xxxxxxxx>
- Subject: Re: [Spca50x-devs] gspca questions
Le jeudi 3 janvier 2008 04:17, Russell Steicke a écrit :
> 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
> - 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,
As i write in my doc the ARM have some trouble with mmap() specially memory
corrupion. I used read() instead
spca5x_LE only forward the mjpeg stream to userspace so that should work with
your 200Mhz ARM
The full driver is not done for embedded,specially a 200Mhz CPU ;-)
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2005.
Spca50x-devs mailing list