Author Topic: WebCam and Libusb  (Read 180 times)

Paul Smedley

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WebCam and Libusb
« on: January 20, 2021, 04:58:37 am »
Hi Wim,

When I started developing webcam support I produced USB Webcam Tests that required usbecd.sys in order to function. It only supported a few webcams owned by those persons that helped me out by testing. It is not recommended to be used anymore. At that time only usbecd.sys supported the required isochronous transfers. Since then I worked on usbcalls.dll and usbresmg.sys to implement a.o. isochronous transfers and that capability is nowadays present in both ArcaOS and Lars Erdmann drivers.

What would be really cool would be to add support to our libusb port for ISO transfers - that would simplify porting linux apps that support webcams using (iirc) libuvc....

Cheers,

Paul

Wim Brul

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Re: WebCam and Libusb
« Reply #1 on: January 20, 2021, 05:36:12 pm »
Hi Paul,

Hi Wim,

When I started developing webcam support I produced USB Webcam Tests that required usbecd.sys in order to function. It only supported a few webcams owned by those persons that helped me out by testing. It is not recommended to be used anymore. At that time only usbecd.sys supported the required isochronous transfers. Since then I worked on usbcalls.dll and usbresmg.sys to implement a.o. isochronous transfers and that capability is nowadays present in both ArcaOS and Lars Erdmann drivers.

What would be really cool would be to add support to our libusb port for ISO transfers - that would simplify porting linux apps that support webcams using (iirc) libuvc....

Cheers,

Paul

Yes Paul, that would be very cool. The question remains how to accomplish that...

With my libusb notes and usbcalls api documentation at hand it must be possible to implement that support. Perhaps a phased implementation is necessary. First convert libusb to support asynchronous bulk and interupt transfers and then, when that works, implement asynchronous isochronous transfers. There must be a way to test this. Normally I would write a simple application to test e.g. synchronous bulk transfers and then, when that works,  modify that application to use asynchronous bulk transfers. Or I would use an existing application for that purpose. The problem is that I am not really an application programmer and I will have to resort to assembler or simple borland c programming.

I think this calls for a separate thread.

Regards,
Wim

Martin Iturbide

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Re: WebCam and Libusb
« Reply #2 on: January 20, 2021, 07:06:53 pm »
Hi

I slip this thread so you can keep discussing this interesting topic.

Regards
Martin Iturbide
OS2World NewsMaster
... just share the dream.