Date: Fri, 20 Apr 2012 16:04:58 +0200 From: Hans Petter Selasky <hselasky@c2i.net> To: freebsd-usb@freebsd.org Subject: Re: usbdump(8) question Message-ID: <201204201604.58751.hselasky@c2i.net> In-Reply-To: <4F9068DE.9090807@rawbw.com> References: <4F9068DE.9090807@rawbw.com>
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On Thursday 19 April 2012 21:34:54 Yuri wrote: > I am trying to use usbdump(8) on one webcam, but the produced, log > causes some questions. > Hi, > 1. Why -s 1024 option doesn't show actual data even though SLEN for > packets is non-zero? The -s option must be set bigger than the maximum total data in a USB transfer, else you will only get parts of the data. Typical value: 65536 > 2. When I run webcamd, first 4 lines of log (with the error) quickly > appear. Webcamd exits quickly, in 0.035s, but usbdump after 1-2 secs > shows the rest of the log. Why is this significant delay? Why the first > 4 lines aren't delayed? Because usbdump uses a big buffer, which is only returned when it is filled up or when a 1 second timeout triggers. --HPS
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