Re: [Spca50x-devs] gspca v4l2

[Jean-Francois Moine <moinejf@xxxxxxx>]

On Tue, 25 Mar 2008 00:50:21 +0100, Aurélien_Minet <amlabs@xxxxxxx> 
wrote:
>Hi Jean-Francois,

Hi Aurélien,

	[snip]
>> 	echo 0x1f > /sys/module/gspca_main/parameters/debug
>ok,
>(nice to have sysfs interface, what is comp_fac for ?)
	[snip]

It is an estimated compression factor of JPEG frames. For example,
640x480 images are composed of 307200 pixels, which gives a buffer
of the same size (307200 bytes). As it is JPEG compressed, the size
of the frames is about 25000 bytes. With a comp_fac value 30, the
frame buffers allocated by gspca and the application have a size
92160 bytes only (note: comp_fac could be 20 for 640x320, but MUST
be 30 for 320x240 - the frame size is about 15 kB).

>> 3) extract the trace from /var/log/kern.log
>
>trace is in attachment (done with 0.0.19)

Thank you. I looked at it and I found a bug in frame generation.
It is fixed in the version 0.0.20.

BTW, as you are looking at win traces for an other webcam, I join
a little tcl script which simplifies usbsnoop analyse...

Best regards.

-- 
Ken ar c'hentañ	|	      ** Breizh ha Linux atav! **
Jef		|		http://moinejf.free.fr/

Attachment: parsnoop.tcl
Description: Tcl script

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