thanks for the quick replies,
I appreciate it
Andrew
p.s.
Here's a code snippet
VIDIOSYNC is the command that takes 100ms
t.Start();
ioctl(fd,VIDIOCMCAPTURE,&gb1);
t.Stop();
cout <<"vidocapture call "; t.Print();
t.Start();
ioctl(fd,VIDIOCSYNC, &gb1.frame);
t.Stop();
cout << "vidosync time ";t.Print();
t.Start();
memcpy(buffers, map_ + gb_buffers.offsets[0], width*height);
t.Stop();
cout <<" memcopy from buffer ";t.Print();
Billy Biggs wrote:
Andrew Wilson (a_wilson@xxxxxxx):I'm trying to grab a 640x480 BW frame as fast as possible, it currently takes roughly 100milliseconds per grab. The live video feed straight to the monitor runs smoothly at 60fps though, shouldn't a frame grab be 17 milliseconds?Video is interlaced, so for NTSC you'll only get 240 scanlines per field. If you're capturing at 640x480, you're probably capturing frames, so you'll only get one frame every 33ms. If you want <33ms delays, you'll need one of the new bttv drivers with V4L2 support that allows you to ask for field-rate capture, then you can get a new frame every 16.6ms. It shouldn't take 100ms per grab though, something sounds wrong. Post your code somewhere and maybe someone can take a look at it. -Billy -- video4linux-list mailing list Unsubscribe mailto:video4linux-list-request@xxxxxxxxxx?subject=unsubscribe https://listman.redhat.com/mailman/listinfo/video4linux-list
