> > 1394a is limited to only 5 meters, not even close to long enough. > > This is the reason I decided on Ethernet rather than 1394 in the > > first place. 1394b's 75 meters would be acceptable. We will need > > to confirm this, but it sounds promising. A 1394b solution might > > be less expensive than an Ethernet solution. > > How does that follow? It uses the same cabling, so that would not > cost less, and I doubt that the interface IC would be less given the > prevalence of 10/100.
I was thinking Ethernet probably takes more CPU to decode the IP and TCP layers. Probably not significant compared to decoding the video, especially if we're doing H.264, and Firewire probably needs some CPU support as well. "Never mind." > > TCP with some buffer memory works fine. > > Yes, it does. Of course, FireWire is more reliable and works better. Does Firewire retransmit if data gets corrupted on the wire? > I think that we should not worry too much about FireWire just yet. Yes, our big worry is decoding the video. > so we are probably going to pay around $50- to get the > processing from an FPGA to implement 720p without a DSP. I was under the impression that FPGAs were hundreds if not thousands of dollars? And yet $50 worth of FPGA can decode 720p video? Is this H.264? I presume we also need to decode 1080i which would bump the requirements up a bit. Could the OGD board be used to test the decoder? > eek! turns out that is quiescent current, so the actual (using as much > information as I could from that Ocean Logic article) estimate is more > like 600 mA, not including I/O! (700 mW) IIRC some of the dedicated decoder chips are in the 0.75-2 Watt range. I was under the impression that FPGAs were power hogs? If the total power consumption is less than 10 Watts or so I'll be happy. I want to avoid the 100 Watt sort of power consumption that a CPU or GPU solution burns, along with the noisy unreliable fan. > >> TMS640C6412 DSP since it is 4000-4800 MACs for $40), > > > > Is this faster or slower than TMS320DM6446 ? > > It is in about the same ballpark (the 6446 is 4700 MACs), but the > 6446 also has a Coprocessor for the DSP called the VICP (something > Image Coprocessor), which I could not find _any_ (objective) information > on except references to its memory space on the memory map. I imagine, > however, that it would improve the situation (it is said to help > improve color > space transform, etc -- IDCT is NOT listed) and increase speed at least > a > little, if we could get docs. > > The 6446 also has a ARM920 on it, which is nice (a more familiar > interface, > at least for me, than the DSP) and would be put to use. > > Finally, the 6446 has an "FPGA Interface", which appears to be a > full-duplex > 100Mhz 4 bit read, 4 bit write memory mapped interface from the docs - > not > too useful, but it might be all we need. > > Oh, and the 6446 costs in the mid-$30s. I say we use that instead :-) >From a year ago on the ogp list (the price may have dropped since then?): } The DM6443 looks like a better fit than the DM6446. } The 6443 doesn't have the camera controller, but is (I think) } otherwise the same as the 6446. } } The DM6443 is less expensive than the DM6446, and there is a significant } price drop going from 1000 to 10,000. The DM6443 is $29.95 in quantity } 10,000. I wonder what the price is for 100,000? } } TI has a development system for $2000. } } http://linuxdevices.com/news/NS9968931411.html IIRC there was a mention of a newer model a bit faster than the DM6443/DM6446? (720 MHz vs 600?) Do we have any idea how many of these we could sell? _______________________________________________ Open-hardware-ethervideo mailing list [email protected] http://lists.duskglow.com/mailman/listinfo/open-hardware-ethervideo
