* Varying frame rate
@ 2009-08-15 21:48 Haavard Holm
2009-08-16 0:43 ` Maxim Levitsky
0 siblings, 1 reply; 7+ messages in thread
From: Haavard Holm @ 2009-08-15 21:48 UTC (permalink / raw)
To: video4linux-list
Hello,
I am writing an application that capture video/pictures from a webcam.
My program is built on moinejf.free.fr/*svv*.*c*
which again is built on v4l2spec.bytesex.org/v4l2spec/*capture*.*c*
OS is linux 2.6.29.6-217.2.3.fc11.x86_64
Webcam is "Logitech Quickcam Pro for Notebooks" (046d:0991)
My obeservation is : Depending on what my camera focus on, the framerate
varies from 5 to 15 fps. I have tried several times, same result.
Why is that. How can I avoid this ?
Best regards
Håvard Holm
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* Re: Varying frame rate
2009-08-15 21:48 Varying frame rate Haavard Holm
@ 2009-08-16 0:43 ` Maxim Levitsky
2009-08-16 6:03 ` Jean-Francois Moine
0 siblings, 1 reply; 7+ messages in thread
From: Maxim Levitsky @ 2009-08-16 0:43 UTC (permalink / raw)
To: Haavard Holm; +Cc: video4linux-list
On Sat, 2009-08-15 at 23:48 +0200, Haavard Holm wrote:
> Hello,
>
> I am writing an application that capture video/pictures from a webcam.
> My program is built on moinejf.free.fr/*svv*.*c*
> which again is built on v4l2spec.bytesex.org/v4l2spec/*capture*.*c*
>
> OS is linux 2.6.29.6-217.2.3.fc11.x86_64
> Webcam is "Logitech Quickcam Pro for Notebooks" (046d:0991)
>
> My obeservation is : Depending on what my camera focus on, the framerate
> varies from 5 to 15 fps. I have tried several times, same result.
>
> Why is that. How can I avoid this ?
I have observed similar issues with uvc camera on my aspire one (low
frame rate while the illumination is low)
Probably this is a hardware issue, and maybe there is a control to turn
this off.
Best regards,
Maxim Levitsky
>
> Best regards
>
> Håvard Holm
>
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* Re: Varying frame rate
2009-08-16 0:43 ` Maxim Levitsky
@ 2009-08-16 6:03 ` Jean-Francois Moine
2009-08-16 6:09 ` Maxim Levitsky
2009-08-16 8:35 ` Haavard Holm
0 siblings, 2 replies; 7+ messages in thread
From: Jean-Francois Moine @ 2009-08-16 6:03 UTC (permalink / raw)
To: video4linux-list
On Sun, 16 Aug 2009 03:43:52 +0300
Maxim Levitsky <maximlevitsky@gmail.com> wrote:
> On Sat, 2009-08-15 at 23:48 +0200, Haavard Holm wrote:
[snip]
> > My obeservation is : Depending on what my camera focus on, the
> > framerate varies from 5 to 15 fps. I have tried several times, same
> > result.
[snip]
> I have observed similar issues with uvc camera on my aspire one (low
> frame rate while the illumination is low)
>
> Probably this is a hardware issue, and maybe there is a control to
> turn this off.
Hello,
The frame rate depends on the exposure time. If auto exposure is set,
you may have such a behaviour.
Best regards.
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Jef | http://moinejf.free.fr/
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* Re: Varying frame rate
2009-08-16 6:03 ` Jean-Francois Moine
@ 2009-08-16 6:09 ` Maxim Levitsky
2009-08-16 8:35 ` Haavard Holm
1 sibling, 0 replies; 7+ messages in thread
From: Maxim Levitsky @ 2009-08-16 6:09 UTC (permalink / raw)
To: Jean-Francois Moine; +Cc: video4linux-list
On Sun, 2009-08-16 at 08:03 +0200, Jean-Francois Moine wrote:
> On Sun, 16 Aug 2009 03:43:52 +0300
> Maxim Levitsky <maximlevitsky@gmail.com> wrote:
>
> > On Sat, 2009-08-15 at 23:48 +0200, Haavard Holm wrote:
> [snip]
> > > My obeservation is : Depending on what my camera focus on, the
> > > framerate varies from 5 to 15 fps. I have tried several times, same
> > > result.
> [snip]
> > I have observed similar issues with uvc camera on my aspire one (low
> > frame rate while the illumination is low)
> >
> > Probably this is a hardware issue, and maybe there is a control to
> > turn this off.
>
> Hello,
>
> The frame rate depends on the exposure time. If auto exposure is set,
> you may have such a behaviour.
Exactly, that is what I was trying to say, but didn't...
Best regards,
Maxim Levitsky
>
> Best regards.
>
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* Re: Varying frame rate
2009-08-16 6:03 ` Jean-Francois Moine
2009-08-16 6:09 ` Maxim Levitsky
@ 2009-08-16 8:35 ` Haavard Holm
2009-08-16 9:09 ` Jean-Francois Moine
1 sibling, 1 reply; 7+ messages in thread
From: Haavard Holm @ 2009-08-16 8:35 UTC (permalink / raw)
To: video4linux-list
On 08/16/2009 08:03 AM, Jean-Francois Moine wrote:
> On Sun, 16 Aug 2009 03:43:52 +0300
> Maxim Levitsky<maximlevitsky@gmail.com> wrote:
>
>
>> On Sat, 2009-08-15 at 23:48 +0200, Haavard Holm wrote:
>>
> [snip]
>
>>> My obeservation is : Depending on what my camera focus on, the
>>> framerate varies from 5 to 15 fps. I have tried several times, same
>>> result.
>>>
> [snip]
>
>> I have observed similar issues with uvc camera on my aspire one (low
>> frame rate while the illumination is low)
>>
>> Probably this is a hardware issue, and maybe there is a control to
>> turn this off.
>>
> Hello,
>
> The frame rate depends on the exposure time. If auto exposure is set,
> you may have such a behaviour.
>
From a c-program - how do I turn off auto exposure ?
Best
Håvard Holm
> Best regards.
>
>
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* Re: Varying frame rate
2009-08-16 8:35 ` Haavard Holm
@ 2009-08-16 9:09 ` Jean-Francois Moine
2009-08-17 13:52 ` RE : " Jonathan Lafontaine
0 siblings, 1 reply; 7+ messages in thread
From: Jean-Francois Moine @ 2009-08-16 9:09 UTC (permalink / raw)
To: video4linux-list
On Sun, 16 Aug 2009 10:35:56 +0200
Haavard Holm <haavard.holm@ntnu.no> wrote:
[snip]
> > The frame rate depends on the exposure time. If auto exposure is
> > set, you may have such a behaviour.
> >
>
> From a c-program - how do I turn off auto exposure ?
You may do it by the VIDIOC_S_CTRL ioctl (look at
v4l2-apps/util/v4l2-ctl.cpp in the LinuxTv mercurial main repository)
Otherwise, by program, I know about v4l2ucp or vlc (1.0.x).
Best regards.
--
Ken ar c'hentañ | ** Breizh ha Linux atav! **
Jef | http://moinejf.free.fr/
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* RE : Varying frame rate
2009-08-16 9:09 ` Jean-Francois Moine
@ 2009-08-17 13:52 ` Jonathan Lafontaine
0 siblings, 0 replies; 7+ messages in thread
From: Jonathan Lafontaine @ 2009-08-17 13:52 UTC (permalink / raw)
To: video4linux-list
Hi, I want to know what is the new procedure or
email adress for the new V4L newsletter?
________________________________________
De : video4linux-list-bounces@redhat.com [video4linux-list-bounces@redhat.com] de la part de Jean-Francois Moine [moinejf@free.fr]
Date d'envoi : 16 août 2009 05:09
À : video4linux-list@redhat.com
Objet : Re: Varying frame rate
On Sun, 16 Aug 2009 10:35:56 +0200
Haavard Holm <haavard.holm@ntnu.no> wrote:
[snip]
> > The frame rate depends on the exposure time. If auto exposure is
> > set, you may have such a behaviour.
> >
>
> From a c-program - how do I turn off auto exposure ?
You may do it by the VIDIOC_S_CTRL ioctl (look at
v4l2-apps/util/v4l2-ctl.cpp in the LinuxTv mercurial main repository)
Otherwise, by program, I know about v4l2ucp or vlc (1.0.x).
Best regards.
--
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Jef | http://moinejf.free.fr/
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end of thread, other threads:[~2009-08-17 13:54 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2009-08-15 21:48 Varying frame rate Haavard Holm
2009-08-16 0:43 ` Maxim Levitsky
2009-08-16 6:03 ` Jean-Francois Moine
2009-08-16 6:09 ` Maxim Levitsky
2009-08-16 8:35 ` Haavard Holm
2009-08-16 9:09 ` Jean-Francois Moine
2009-08-17 13:52 ` RE : " Jonathan Lafontaine
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