Em 23-09-2010 23:19, Daniel Moraes escreveu: > Hi Mauro, > > thanks a lot for your help. I would only take a few more questions. > > 1. A computer can have more than one USB Bus? As far as I know the USB Bus is unique. Yes, it can have as many bus as designed by the manufacturer. You can also add other buses by buying USB adapter cards. > 2. Whereas HP webcam uses the same USB Bus but has a more compressed stream, is there a way to compress or reduce the stream of a webcam that uses a generic driver like the HP Webcam does with your drive? It will depend on the chipset used by the cameras, the screen resolution, and the number of frames per sec. > 3. Is there a way to check the amount of bandwich in an USB Bus? Yes. you can watch /proc/bus/usb/devices. It will provide not only the information about each connected device on your usb bus, but also the speed used. For example, a quick test here: $ lsusb Bus 008 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 007 Device 003: ID 2040:4200 Hauppauge Bus 007 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub This machine has 2 USB 2.0 buses (bus 7 and bus 8), with an WinTV USB2 device connected at bus 7, reading a stream at 640x480x30fps: cat /proc/bus/usb/devices showed (I removed the info for the USB 1.1 buses): T: Bus=08 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=480 MxCh= 6 B: Alloc= 0/800 us ( 0%), #Int= 0, #Iso= 0 D: Ver= 2.00 Cls=09(hub ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1 P: Vendor=1d6b ProdID=0002 Rev= 2.06 S: Manufacturer=Linux 2.6.35+ ehci_hcd S: Product=EHCI Host Controller S: SerialNumber=0000:00:1d.7 C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr= 0mA I:* If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub E: Ad=81(I) Atr=03(Int.) MxPS= 4 Ivl=256ms T: Bus=07 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=480 MxCh= 6 B: Alloc=408/800 us (51%), #Int= 0, #Iso= 5 D: Ver= 2.00 Cls=09(hub ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1 P: Vendor=1d6b ProdID=0002 Rev= 2.06 S: Manufacturer=Linux 2.6.35+ ehci_hcd S: Product=EHCI Host Controller S: SerialNumber=0000:00:1a.7 C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr= 0mA I:* If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub E: Ad=81(I) Atr=03(Int.) MxPS= 4 Ivl=256ms T: Bus=07 Lev=01 Prnt=01 Port=05 Cnt=01 Dev#= 3 Spd=480 MxCh= 0 D: Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1 P: Vendor=2040 ProdID=4200 Rev= 1.00 S: Product=WinTV USB2 S: SerialNumber=0002819348 C:* #Ifs= 3 Cfg#= 1 Atr=80 MxPwr=500mA I: If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=ff Driver=em28xx E: Ad=81(I) Atr=03(Int.) MxPS= 1 Ivl=128ms E: Ad=82(I) Atr=01(Isoc) MxPS= 0 Ivl=125us E: Ad=84(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 0 Alt= 1 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=ff Driver=em28xx E: Ad=81(I) Atr=03(Int.) MxPS= 1 Ivl=128ms E: Ad=82(I) Atr=01(Isoc) MxPS=1024 Ivl=125us E: Ad=84(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 0 Alt= 2 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=ff Driver=em28xx E: Ad=81(I) Atr=03(Int.) MxPS= 1 Ivl=128ms E: Ad=82(I) Atr=01(Isoc) MxPS=1448 Ivl=125us E: Ad=84(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 0 Alt= 3 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=ff Driver=em28xx E: Ad=81(I) Atr=03(Int.) MxPS= 1 Ivl=128ms E: Ad=82(I) Atr=01(Isoc) MxPS=2048 Ivl=125us E: Ad=84(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 0 Alt= 4 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=ff Driver=em28xx E: Ad=81(I) Atr=03(Int.) MxPS= 1 Ivl=128ms E: Ad=82(I) Atr=01(Isoc) MxPS=2304 Ivl=125us E: Ad=84(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I:* If#= 0 Alt= 5 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=ff Driver=em28xx E: Ad=81(I) Atr=03(Int.) MxPS= 1 Ivl=128ms E: Ad=82(I) Atr=01(Isoc) MxPS=2580 Ivl=125us E: Ad=84(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 0 Alt= 6 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=ff Driver=em28xx E: Ad=81(I) Atr=03(Int.) MxPS= 1 Ivl=128ms E: Ad=82(I) Atr=01(Isoc) MxPS=2892 Ivl=125us E: Ad=84(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 0 Alt= 7 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=ff Driver=em28xx E: Ad=81(I) Atr=03(Int.) MxPS= 1 Ivl=128ms E: Ad=82(I) Atr=01(Isoc) MxPS=3072 Ivl=125us E: Ad=84(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I:* If#= 1 Alt= 0 #EPs= 0 Cls=01(audio) Sub=01 Prot=00 Driver=snd-usb-audio I:* If#= 2 Alt= 0 #EPs= 0 Cls=01(audio) Sub=02 Prot=00 Driver=snd-usb-audio I: If#= 2 Alt= 1 #EPs= 1 Cls=01(audio) Sub=02 Prot=00 Driver=snd-usb-audio E: Ad=83(I) Atr=01(Isoc) MxPS= 20 Ivl=125us The bandwidth is per bus. In this case, bus 7 shows: B: Alloc=408/800 us (51%), #Int= 0, #Iso= 5 Eg: the stream is using 51% of the USB for just one single stream. If I want to plug another device, I'll need to use bus 8, as it is free: B: Alloc= 0/800 us ( 0%), #Int= 0, #Iso= 0 If I try to use bus 7 for another HVR-950 using the same resolution, it will return the error you got (-ENOSPC), as otherwise, it would be using more than 800 slots, of an USB bus that can provide only 800 ISOC slots, according with USB 2.0 specs. Cheers, Mauro > > Att, > Daniel Bastos Moraes > > > > On Tue, Sep 21, 2010 at 4:48 PM, Mauro Carvalho Chehab <mchehab@xxxxxxxxxx <mailto:mchehab@xxxxxxxxxx>> wrote: > > Hi Daniel, > > Em 21-09-2010 16:05, Daniel Moraes escreveu: > > I'm using Ubuntu 10.04 and I need to get images from two Multilaser > > Cameras simultaneously. First I tried to do that using OpenCV, but I > > got an error. So, I entered the OpenCV Mailing List to report that and > > I discovered that's a driver problem. To ensure that, I used mplayer > > to get imagens from the both cameras and I got the following error > > (again): > > > >> v4l2: ioctl streamon failed: No space left on device > > This is not a driver issue, but a limit imposed by USB specs. This > error code is returned by USB core when you try to use more than 100% of > the available bandwidth for an USB isoc stream. > > The amount of bandwidth basically depends on what type of compression > is provided by your webcams. > > You'll need to plug the other webcam on a separate USB bus. > > > > The cameras model is Multilaser WC0440. > > > > This problem only happens when I try to capture images from two > > IDENTICAL cameras simultaneously. I have three cameras here, two > > Multilaser Cameras and one HP Camera, from my laptop. I have no > > problem to capture images from my HP Camera and one of the Multilaser > > Cameras simultaneously, but when I try to capture from the both > > Multilaser Cameras simultaneously, i got that error. > > > > I think that the problem may be something related to the generic > > driver. When I use the Multilaser Cameras, they use the same driver. > > That's not happen with the HP Camera, which uses another driver. > > Probably, the HP Camera is connected internally into a different USB bus, > or provide a more compressed stream. > > > Someone knows a solution for that? > > > > Att, > > Daniel Bastos Moraes > > Graduando em Ciência da Computação - Universidade Tiradentes > > +55 79 88455531 > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-media" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx <mailto:majordomo@xxxxxxxxxxxxxxx> > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
