xkill wrote: > > > > I'm trying to get video capture from all 4 inputs of a bttv > > > card simultanously ( multiplexed). I've been doing this under > > > FreeBSD/OpenBSD following way: > > > > > > switch_input(0) > > > capture_frame(0) > > > ... > > > ... > > > ... > > > switch_input(3) > > > capture_frame(3) > > > > > > This works ok, although the 25fps dives to 2-3fps with all 4 inputs > > > capturing. I've got pthreaded mmaped capture going under Linux and I'm > > > wondering how I should go about this input switching problem? > > > Is there a better way to archive this under Linux? I'm gonna test this > > > method tonight: > > > > > > > This is a hardware problem. not a software one the bttv chip have one reader > > for pictures and thats it. The bttv does have 4 inputs for reading but these > > input are multiplexed in front of the reader. Sory, but if you wont to > > capture all 4 chanels you need 4 cards. > > > > Anders Gnistrup > > I'm already demultiplexing the 4 channels to achive 4 video streams per > single bttv device. The problems is archieving higher framerates than > 2-3fps per stream by improving the sync speed when switching between > inputs. I'm not asking for 4 channel 25fps capture. Unless the video sources are synchronised, and have exactly the same output levels, the Bt848 will always waste at least one frame to resonchronise the video streams. In theory, if you did synchronise the video streams, you could probably move the input switching code to the irq handler, and have it switch just before the vsync... But without synchronous sources, there is not much you can do. -justin
