hi
maybe this pdf by alan cox might help
http://ftp.linux.org.uk/pub/linux/alan/Kernel/Documents/video4linux.pdf
Regards
Puneet
On Thu, 17 Apr 2003 Martin H wrote :
Hi,
I'm trying to write a program to display images from my
tv card
(a Hauppauge (bt878)).
When I try reading from it my program just hangs.
I've set up the card...
----
/* prepare new settings */
tv_vwin.width = 320;
tv_vwin.height = 240;
vid_pic.palette = VIDEO_PALETTE_RGB24;
vid_chan.channel = 1; /*composite 1*/
/* set them */
ioctl(tv_fd, VIDIOCSWIN, &tv_vwin);
if (ioctl(tv_fd, VIDIOCSPICT, &vid_pic) < 0) {
perror("Error setting palette\n");
return 0;
}
if (ioctl(tv_fd, VIDIOCSCHAN, &vid_chan) < 0) {
perror("Error setting channel\n");
return 0;
}
---
...ok as far as I can tell but when I try to read...
---
printf("Trying to read 230400 bytes\n");
bytes_read = read (tv_fd, tv_buff,230400);
printf("Read %d bytes \n",bytes_read);
---
it just hangs on the read. My program still hangs even if I only
try to
read 3 bytes.
However if I replace tv_fd with cam_fd , and thus try to read
from my
webcam the code works fine.
Are my problems because my tv card doesn't support read
operations (is
there any way of telling?) or is there something else odd going
on?
Thanks for any ideas
Martin
PS is there a more up-to-date version of the API documentation
anywhere - perhaps one that doesn't mention the seemingly
non-existent
VIDEO_VC_NORM , mentions that VIDIOCSCHAN might want a structure
rather
than an int and tells me what palette 17 is?
Should I be asking this question elsewhere or looking at some
other
documentation?
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