> > ATSC uses 1080i rather than 1080p because they couldn't quite squeeze > > 1080p into the 19.something Mbps available. I wonder if 1080p/24 would > > have fit, that would have been a better match for most 1080 material. > > Hmm, interesting. Anybody know how much bandwidth we can reasonably > expect from 100 Mbit ethernet?
I think it should be 100 Mbps or very close to it. With twisted pair, I suppose collisions happen inside the switch/hub boxes, in theory they ought to be able to buffer packets and not lose bandwidth on the wire like you do with coax. Of course lamely designed hardware could spoil things, as always. 100 Mbps should be enough for any consumer video. (compressed, obviously) > > It is not obvious to me why OGD needs a large FPGA but we can get by > > with a small one. Other than having two heads, what is OGD doing that > > we don't need to? > > They are implementing a full blown graphics card with OpenGL. This takes > up a lot of space. So an alternate FPGA "firmware" could leave out some OpenGL stuff and include a video decoder instead. > The more I read, the more it seems that H.264 is > really not > that computationally expensive (compared, at least, to OpenGL), it is > just that > the industry is used to the low compression, easy-to-deal-with MPEG > standards > that came earlier. H.264 is computationally expensive if you are using a CPU. Even mpeg2 takes a fair amount of CPU to decode. > We can > probably > just either reconfigure the FPGA (not good) Why not good? Is this very slow? Does it "wear out" the FPGA? (Some of don't know that much about FPGAs, as is probably obvious by now.) > Back to being allowed to implement things, we should probably find a > legal > way to implement an H.264 decoder without running into patent trouble > -- there > is a section of the wikipedia article about this that I suggest > everyone read. Though > nobody has decided to legally track down x264 or similar projects, > wikipedia made > it sound like they could at the drop of a pin. Do we know how much the patent royalties cost? How long until they expire? > >> The 6446 is designed for transcoding, so it has a resizer, etc, but I > >> think > >> you are right -- the 6443 should be fine. > > > > The 6443 doesn't have a scaler? Ouch. > > We should be able to implement one in the FPGA without too much > trouble. If it > can fit, shaving $10 off the BOM is worth it. I keep hoping that TI (or whoever) will come out with a faster DSP and we can do the whole thing in the DSP without an FPGA. >From May: >>> Blackfin (it seems powerful) >>> >>> http://www.analog.com/processors/blackfin/ >> >> The "large" roadmap at >> http://www.analog.com/processors/blackfin/images/bf_roadmap_022607_large.jpg >> has prices. $17.50-$21.95 for the Dual Core 600 Mhz ADSP-BF561, >> which appears to be the fastest. >> >> They claim to do some jobs faster than TI, e.g. FFT in 51% fewer cycles. >> I haven't found any video decoding benchmarks. > > This should mean that a DST or DCT (or the inverse) would be faster as > well since these produce only half as much output. > > But the more I read, the more confused I get. After a while the brain > will sort it out. So James, has your brain sorted it out yet? Is Blackfin any good to us? _______________________________________________ Open-hardware-ethervideo mailing list [email protected] http://lists.duskglow.com/mailman/listinfo/open-hardware-ethervideo
