Re: Multi-channel receive
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From: Stefan R. <st...@s5...> - 2012-03-31 11:37:03
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On Mar 30 Chris Wj wrote: > On Thu, Mar 29, 2012 at 7:50 PM, Stefan Richter > <st...@s5...>wrote: > > This should indeed work. IIRC there are libdc1394 users who do actually > > capture video streams with packets larger than 4 kiB. > > > > So our software supports that, but be warned that Texas Instruments > > controllers will not work for you. They have a too small isochronous > > reception FIFO and will inevitably give you corruption due to dropped (or > > maybe incomplete?) packets. > > > Oh man... I just went back and checked and my host controller has the Texas > Instruments TSB82AA2 chip! It is the Data Optic 1394b PCI Express > Controller. Do you foresee me having to get a new controller? How big of an > issue do you think this will be for me? From what I have heard, TSB82AA2 is useless for high-bandwidth video. Of course, isochronous transmissions are about guaranteed data rate and limited latency but without delivery guarantee in the first place (in contrast to asynchronous transactions with guaranteed delivery but no bandwidth guarantee and (almost) unlimited latency). Though video folks appreciate it if delivery failures occur rarely or not at all. But with TSB82AA2, large 1394b isochronous packets reportedly result in corruptions of practically every video frame, IIRC. Extrapolating from those reports to the application that you described, I suspect that you would get corruptions to an intolerable extent too. Hence be prepared to have to look for an Agere FW643E(2) based card. IOI, Point Grey Research, Unibrain and maybe others offer such cards. -- Stefan Richter -=====-===-- --== ===== http://arcgraph.de/sr/ |