From: Makorihi <mak...@gm...> - 2012-12-23 22:49:36
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Hi everyone, I want to learn how to pull frame data from a webcam (UVC Spec) via pyusb so that I can later do it on a standalone system with a host controller and microcontroller, but I am having issues with this first step. I've been looking online and trying to figure out how to get useful data from the webcam, but have only gotten as far as being able to view descriptors via control messages. I've used a usb sniffer tool while the webcam was running and saw that after fetching/setting descriptor data, it reset the isochronous transfer and continued to pull frames. Since libusb does not support isochronous, is my method of approach unreasonable? It seems like a bad idea to jump into hardware when I can't even get the webcam to work with python. Thanks -- Jama Mohamed |
From: Wander L. C. <wan...@gm...> - 2012-12-24 12:12:27
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2012/12/23 Makorihi <mak...@gm...>: > Hi everyone, > > I want to learn how to pull frame data from a webcam (UVC Spec) via > pyusb so that I can later do it on a standalone system with a host > controller and microcontroller, but I am having issues with this first > step. I've been looking online and trying to figure out how to get > useful data from the webcam, but have only gotten as far as being able > to view descriptors via control messages. I've used a usb sniffer tool > while the webcam was running and saw that after fetching/setting > descriptor data, it reset the isochronous transfer and continued to > pull frames. Since libusb does not support isochronous, is my method > of approach unreasonable? It seems like a bad idea to jump into > hardware when I can't even get the webcam to work with python. > What OS? AFAIK, libusb 1.0 has full isochronous support on *nix platforms and libusbx has recently added such support through libusbK/libusb-win32. Unfortunately, PyUSB has no support for isochronous transfer yet. Right now I am working on this, there is a 'iso' branch on git which adds support for isochronous transfers. I can write successfully, but I am in trouble to read (not sure if the problem is my Python code or in the test firmware). -- Best Regards, Wander Lairson Costa |
From: Xiaofan C. <xia...@gm...> - 2012-12-24 12:54:49
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On Mon, Dec 24, 2012 at 8:11 PM, Wander Lairson Costa <wan...@gm...> wrote: > What OS? AFAIK, libusb 1.0 has full isochronous support on *nix > platforms Correct. > and libusbx has recently added such support through > libusbK/libusb-win32. Even though libusb-win32 and libusbK supports isochronous transfer, libusbx does not yet support isochronous transfer. > Unfortunately, PyUSB has no support for > isochronous transfer yet. Right now I am working on this, there is a > 'iso' branch on git which adds support for isochronous transfers. I > can write successfully, but I am in trouble to read (not sure if the > problem is my Python code or in the test firmware). -- Xiaofan |
From: Makorihi <mak...@gm...> - 2012-12-24 22:19:13
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Ok, thank's for the info. I've been working on Windows because it was convenient, but I may switch to another OS. On Mon, Dec 24, 2012 at 7:54 AM, Xiaofan Chen <xia...@gm...> wrote: > On Mon, Dec 24, 2012 at 8:11 PM, Wander Lairson Costa > <wan...@gm...> wrote: >> What OS? AFAIK, libusb 1.0 has full isochronous support on *nix >> platforms > > Correct. > >> and libusbx has recently added such support through >> libusbK/libusb-win32. > > Even though libusb-win32 and libusbK supports isochronous > transfer, libusbx does not yet support isochronous transfer. > >> Unfortunately, PyUSB has no support for >> isochronous transfer yet. Right now I am working on this, there is a >> 'iso' branch on git which adds support for isochronous transfers. I >> can write successfully, but I am in trouble to read (not sure if the >> problem is my Python code or in the test firmware). > > > -- > Xiaofan > > ------------------------------------------------------------------------------ > LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial > Remotely access PCs and mobile devices and provide instant support > Improve your efficiency, and focus on delivering more value-add services > Discover what IT Professionals Know. Rescue delivers > http://p.sf.net/sfu/logmein_12329d2d > _______________________________________________ > pyusb-users mailing list > pyu...@li... > https://lists.sourceforge.net/lists/listinfo/pyusb-users -- Jama Mohamed |