2.4.19-pre8 != bk -rv2.4.19-pre8

<TR><TD><b>clips</b><TD>A list of clipping rectangles. <em>(Set only)</em></TD>

(i.e. PCI-PCI transfer to the frame buffer of the video card)

Each call to the <b>read</b> syscall returns the next available image from the device. It is up to the caller to set format and size (using the VIDIOCSPICT and VIDIOCSWIN ioctls) and then to pass a suitable size buffer and length to the function. Not all devices will support

Once the mmap has been made the VIDIOCMCAPTURE ioctl starts the capture to a frame using the format and image size specified in the video_mmap (which should match or be below the initial query size). When the VIDIOCMCAPTURE ioctl returns the frame is <em>not</em> captured yet, the driver just instructed the hardware to start the capture. The application has to use the VIDIOCSYNC ioctl to wait until the capture of a frame is finished. VIDIOCSYNC takes the frame number you want to wait for as argument.
<p>
It is allowed to call VIDIOCMCAPTURE multiple times (with different frame numbers in video_mmap->frame of course) and thus have multiple outstanding capture requests. A simple way do to double-buffering using this feature looks like this:
<pre>
/* setup everything */
VIDIOCMCAPTURE(0)

while (whatever) {
   VIDIOCMCAPTURE(1)
   VIDIOCSYNC(0)
   /* process frame 0 while the hardware captures frame 1 */
   VIDIOCMCAPTURE(0)
   VIDIOCSYNC(1)
   /* process frame 1 while the hardware captures frame 0 */
}

</pre>
Note that you are <em>not</em> limited to only two frames. The API allows up to 32 frames, the VIDIOCGMBUF ioctl returns the number of frames the driver granted. Thus it is possible to build deeper queues to avoid loosing frames on load peaks.
<p>
While capturing to memory the driver will make a "best effort" attempt to capture to screen as well if requested. This normally means all frames that "miss" memory mapped capture will go to the display.

'diff -r' between 2.4.19-pre8 downloaded from ftp.kernel.org and the same version extracted from bitkeeper (parent is bk://linux.bkbits.net/linux-2.4), produce the follow diff. it's not a big issue, but it's a little annoying to apply -ac patches.