Benoit PAPILLAULT wrote: > > On Mon, 17 Jun 2002 13:00:38 +0200 > Ronald Bultje <rbultje@xxxxxxxxxxxxxxxxxxx> wrote: > > > There are several quickcam models. Some of them have compression, with > > which you can get more than 5 fps. The problem is mainly that if you capture > > (example) RGB24 frames at a resolution of 384x288, you're doing a total of > > 3x384x288=331.776 byte/frame. given that the total busrate of USB (ideally) > > is 2 MB/s, > > you can get at moest 2*1024*1024 MB/s divided by 331776 byte/frame = 6 > > frames/sec. > > AFAIK, USB bus is 12Mb/s. small update, usb 1.1 is 12 Mb/s, but usb 2.0, now supported on many new platforms, is 480 Mb/s. a real boon to data rich function devices. :) fyi, jackc... If images is 3*384*288 (331776 bytes), I should get > 12000/332 = 36 frames per seconds, which is quite enought. > > I think that in fact, the driver is not always able to decode an image, since > I get some error messages in the logs. > > My model is (from /proc/bus/usb/devices): > D: Ver= 1.10 so, yes, you are running the 12 Mb/s rate. Cls=ff(vend.) Sub=ff Prot=ff MxPS= 8 #Cfgs= 1 > P: Vendor=046d ProdID=0870 Rev= 1.00 > S: Product=Camera > C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr= 90mA > I: If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none) > E: Ad=81(I) Atr=01(Isoc) MxPS= 0 Ivl= 1ms > E: Ad=82(I) Atr=03(Int.) MxPS= 1 Ivl= 16ms > I: If#= 0 Alt= 1 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none) > E: Ad=81(I) Atr=01(Isoc) MxPS=1023 Ivl= 1ms > E: Ad=82(I) Atr=03(Int.) MxPS= 1 Ivl= 16ms > T: Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2 > B: Alloc=700/900 us (78%), #Int= 0, #Iso= 20 > > Whenever I had some time, I'll lock closer to the raw data send by the cam'. > > Benoit > > _______________________________________________ > Video4linux-list mailing list > Video4linux-list@xxxxxxxxxx > https://listman.redhat.com/mailman/listinfo/video4linux-list -- ------------------------------------------------------------------------------- Jack Craig ImageIntegration 831-684-1375 jackc@xxxxxxxxxxxxxxxxxxxx
