Re: qv4l2 (was [PATCH] LED control)

Re: qv4l2 (was [PATCH] LED control)

[Hans Verkuil]

> On Sun, 15 Mar 2009 08:14:56 -0700 (PDT)
> Trent Piepho <xyzzy@speakeasy.org> wrote:
>
>> > - this asks to have a kernel generated with CONFIG_NEW_LEDS,
>>
>> So?
>>
>> > - the user must use some new program to
>> > access /sys/class/leds/<device>,
>>
>> echo, cat?
>>
>> > - he must know how the LEDs of his webcam are named in the /sys
>> > tree.
>>
>> Just give them a name like video0:power and it will be easy enough to
>> associate them with the device.  I think links in sysfs would do it
>> to, /sys/class/video4linux/video0/device/<ledname> or something like
>> that.
>>
>> The advantage of using the led class is that you get support for
>> triggers and automatic blink functions, etc.
>
> Sorry for I don't see the usage of blinking the LEDs for a webcam.
>
> Again, using the led class makes me wonder about:
>
> 1) The end users.
>
> Many Linux users don't know the kernel internal, nor which of the too
> many applications they should use to make their devices work. If no
> developper creates a tool to handle the webcams, the users have to
> search again and again. Even if there is a full documentation, they
> will try anything and eventually ask the kernel developpers why they
> cannot have their LEDs switched on.
>
> Actually, there are a few programs that can handle the webcam
> parameters. In fact I know only 'v4l2-ctl': I did not succeeded to
> compile qv4l2

What compile errors do you get?

If you do not have qt3 installed, then it will be interesting to see if
you can compile the qv4l2 in my ~hverkuil/v4l-dvb-qv4l2 tree which is qt4.
It still needs more cleanup and tweaking before I can merge that in the
v4l-dvb tree, though.

Regards,

        Hans

-- 
Hans Verkuil - video4linux developer - sponsored by TANDBERG

Re: qv4l2 (was [PATCH] LED control)

[Jean-Francois Moine]

On Tue, 17 Mar 2009 09:45:40 +0100 (CET)
"Hans Verkuil" <hverkuil@xs4all.nl> wrote:
	[snip]
> > Actually, there are a few programs that can handle the webcam
> > parameters. In fact I know only 'v4l2-ctl': I did not succeeded to
> > compile qv4l2
> 
> What compile errors do you get?
> 
> If you do not have qt3 installed, then it will be interesting to see
> if you can compile the qv4l2 in my ~hverkuil/v4l-dvb-qv4l2 tree which
> is qt4. It still needs more cleanup and tweaking before I can merge
> that in the v4l-dvb tree, though.

Hello Hans,

Yes, I have qt4. I got your tree and the qv4l2 generation is OK.

I could change the controls of my webcam (but, indeed, the JPEG
parameters).

Little problem: if I directly do 'start capture', the program loops
displaying the single word: 'dqbuf'.

Otherwise, streaming works fine, but the CPU load is heavy: 85%
(vm: 40Mb) versus 60% with gtk+ (vm: 15Mb) and 8% with vlc (vm: 137Mb).

Regards.

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