This might help too: http://www.glue.umd.edu/~ankurm/video4linux/introduction.html -----Original Message----- From: video4linux-list-admin@xxxxxxxxxx [mailto:video4linux-list-admin@xxxxxxxxxx]On Behalf Of PUNEET Sent: Wednesday, April 16, 2003 9:56 PM To: video4linux-list@xxxxxxxxxx Subject: Re: reading from BT878 card ... just hangs 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? > > > > >-- >video4linux-list mailing list >Unsubscribe >mailto:video4linux-list-request@xxxxxxxxxx?subject=unsubscribe >https://listman.redhat.com/mailman/listinfo/video4linux-list B+ , BOTH MY BLOOD GROUP AND MY ATTITUDE
