> >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. > > Would you share what you're using to do this with? > Read the Progamming-FAQ from XawTV or the v4l api for details of mmaped capture. Here's the general idea, I haven't tested this under linux yet: loop: select input #1 // or select different TV channel :) VIDIOCMCAPTURE // tell the drive to grab A frame, this function is non-blocking VIDIOCSYNC // wait till we got a frame in our buffer select input #2 // do this here so the card has time to sync with the next input during memcpy (1-2ms) memcpy to input#1_buffer //save the image for later processing grab frame sync select input #3 memcpy to input#2_buffer grab frame sync select input #4 memcpy to input#3_buffer grab frame sync memcpy to input#4_buffer You'll probably want to put this in a thread and use a second thread for reading buffers. If you can't get hold of a 4 input bt878/9 card, you can easily convert a normal 1 input card to support all 4 inputs. Read the bt878 docs, they have all the diagrams.
