isochronous transfer for UVC camera

[SAITOU Toshihide]

In message: <201210301341.00350.hselasky at c2i.net>
            Hans Petter Selasky <hselasky at c2i.net> writes:
> On Tuesday 30 October 2012 12:22:47 SAITOU Toshihide wrote:
>> In message: <20121030.000648.193690728.toshi at ruby.ocn.ne.jp>
>> 
>>             SAITOU Toshihide <toshi at ruby.ocn.ne.jp> writes:
>> > In message: <201210291436.08940.hselasky at c2i.net>
>> > 
>> >             Hans Petter Selasky <hselasky at c2i.net> writes:
>> >> On Monday 29 October 2012 13:54:34 SAITOU Toshihide wrote:
>> >>> #define PKT_LEN        0x1400
>> >> 
>> >> The packet length is not this value I think.
>> >> 
>> >> The 0x1000 is part of the packet multiplier for High-Speed USB's
>> >> wMaxPacketSize.
>> >> 
>> >> It is (1+2) * 0x400. Try that and see what happens.
>> > 
>> > Thank you for your quick response.
>> > 
>> > I can't use the FreeBSD now so I will try this tomorrow.  But Mac OS X
>> > 10.6.8 with libus 1.0.9, callback is not invoked too with some
>> > combination of the value below:
>> > 
> 
> Hi,
> 
>> > #define PKT_LEN        0x400
>> > #define PKTS_PER_XFER  8
>> 
> 
> You can compare with output when running webcamd. Make sure webcamd is not 
> running when you start your application!
> 
>> It dose not affect on the FreeBSD.
> 
> PKT_LEN should be 0xC00

Yes, I tried this too because usbdump of the pwcview use this value.
The webcamd is not running when I was logging my code.


>> >> Also there is usbdump -i usbusX -f Y -s 65536 -vvv, which will show the
>> >> actual traffic.
>> 
>> ! This is very useful.
>> 
>>    $ usbdump -i usbus2 -f 4.0 -s 65536 -vvv       (unit 4)
> 
> To get both READ and WRITE control requests, you should do:
> 
> usbdump -i usbus2 -f 4.0 -f 4.128 -s 65536 -vvv
> 
>>    $ usbdump -i usbus2 -f 4.130 -s 65536 -vvv     (unit 4, endpoint 0x82)
>> 
>> I have compared with other application (pwcview).
>> 
>> There are a lot of VS_PROBE_CONTROL transfer than expected. But it may
>> not be a problem because I have tried these transfer reproduced from
>> dump data. The problem I noticed is that the libusb_claim_interface of
>> my code is not logged. Is this function really implemented?
> 
> The claim interface is almost like a NOP under FreeBSD.

Is this true about these functions below?  I compare with pwcview +
webcamd using ``usbdump -i usbus2 -f 4 -s 65536 -vvv'' the noticeable
difference is existence of the SET INTERFACE request.

>>    libusb_set_interface_alt_setting(handle, 1, 1);
>>    libusb_control_transfer(handle, 0x01, 0x0b, 0x0100, 0x0100, NULL, 0,
>> TIMEOUT);

Thank you.

---
SAITOU Toshihide