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Re: [Linphone-developers] videodisplay fails(Segmentation fault)

From: petr . pisar
Subject: Re: [Linphone-developers] videodisplay fails(Segmentation fault)
Date: Mon, 28 Dec 2009 14:54:03 +0100
User-agent: Mutt/1.5.20 (2009-06-14)

On Mon, Dec 28, 2009 at 04:09:18PM +0800, Atom Chan wrote:
> My camera is Logitech QuickCam Express, I didn't install sepicial driver for
> it, I launched Cheese and it works, but not very fine.
> I launched mediastreamer-2.3.0/tests/videodisplay, however the program
> crashed.

I have tested linphone with Logitec QuickCam Express Plus (gspca_spca561
module) and I hit two problems:

Kernel sends video stream in BGRA format and application is to convert it to
something more portable. There is libv4l library which can be LD_PRELOADED and
that can do the conversion. Actually, it would make more sense if
mediastreamer used this library to access V4L devices instead of direct access.
This aproach is recommend by libv4l authors (surprisingly). Kernel developers
stated strongly conversion is not kernel job.

With this library, I'm able to get picture via V4L1. The only problem is
picture is rotated about 180 °. I guess axis orientation is reversed.

Second problem is I'm not able to get picture via V4L2 interface with or
without the libv4l library. Linphone does not crash, it shows only black
frame. But other V4L2 appliactions crash randomly. Some interface
details seem not to be covered completely (from point of view of kernel or
user space).

-- Petr

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