Date: Tue, 13 Nov 2012 17:44:11 +0100 From: Hans Petter Selasky <hselasky@c2i.net> To: SAITOU Toshihide <toshi@ruby.ocn.ne.jp> Cc: freebsd-usb@freebsd.org Subject: Re: isochronous transfer packet is out of sequence Message-ID: <201211131744.11220.hselasky@c2i.net> In-Reply-To: <20121114.002306.36926536.toshi@ruby.ocn.ne.jp> References: <201211121342.47141.hselasky@c2i.net> <201211131452.16508.hselasky@c2i.net> <20121114.002306.36926536.toshi@ruby.ocn.ne.jp>
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On Tuesday 13 November 2012 16:23:06 SAITOU Toshihide wrote: > In message: <201211131452.16508.hselasky@c2i.net> > > Hans Petter Selasky <hselasky@c2i.net> writes: > > On Tuesday 13 November 2012 14:26:52 SAITOU Toshihide wrote: > >> In message: <201211121342.47141.hselasky@c2i.net> > >> > >> Hans Petter Selasky <hselasky@c2i.net> writes: > >> > On Monday 12 November 2012 12:52:08 SAITOU Toshihide wrote: > >> >> I have tryed the USB isochronous transfer for UVC cam using libusb > >> >> interface and I find the packet fragment is out of sequence on the > >> >> FreeBSD(1). But I don't find it on the MacBook(2). > >> >> > >> >> (1) FreeBSD 9.1-RC2, Intel Core i7 3770T > >> >> (2) Mac OS X 10.6.8, Intel Core 2 Duo, libusb 1.0.9 (single core) > >> >> > >> >> Can I prevent this behaviour using libusb interface or is > >> >> this an expected behaviour? > >> >> > >> >> The bellow I issued two libusb_submit_transfer at the beginning. > >> >> > >> >> Hi, There are some internal limits, maybe not visible directly at libusb level. The host hardware usually does not handle more than 128 milliseconds of transfers at a time. You should not sumbit more frames than will be processed in (128 - 16) / 2 ms at any time. For HighSpeed with fastest interval you will need around 8*2*56 ms worth of frames, which is the maximum supported. grep -r USB_MAX_FS_ISOC_FRAMES_PER_XFER /usr/include grep -r USB_MAX_HS_ISOC_FRAMES_PER_XFER /usr/include Webcamd has patches for the Linux code, to fix this issue. --HPS
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