Hello Laurent,
I'm a little less interested in looking at this patch
given your comments (that the highest quality is already
being set), but I will take a look at it.
RE the 2006 cameras, according to luvcview, I don't
have YUYV support for high resolutions - are you sure
about this? I'd love to get a higher quality high res
image. Output is;
luvcview version 0.2.0
video /dev/video0
/dev/video0 does not support read i/o
{ pixelformat = 'MJPG', description = 'MJPEG' }
{ discrete: width = 160, height = 120 }
Time interval between frame: 1/30, 1/25, 1/20, 1/15,
1/10, 1/5,
{ discrete: width = 176, height = 144 }
Time interval between frame: 1/30, 1/25, 1/20, 1/15,
1/10, 1/5,
{ discrete: width = 320, height = 240 }
Time interval between frame: 1/30, 1/25, 1/20, 1/15,
1/10, 1/5,
{ discrete: width = 352, height = 288 }
Time interval between frame: 1/30, 1/25, 1/20, 1/15,
1/10, 1/5,
{ discrete: width = 640, height = 480 }
Time interval between frame: 1/30, 1/25, 1/20, 1/15,
1/10, 1/5,
{ pixelformat = 'YUYV', description = 'Uncompressed' }
{ discrete: width = 160, height = 120 }
Time interval between frame: 1/15, 1/10, 1/5,
{ discrete: width = 176, height = 144 }
Time interval between frame: 1/15, 1/10, 1/5,
----- Original Message -----
>From: "Laurent Pinchart" <[EMAIL PROTECTED]>
>To: <linux-uvc-devel@lists.berlios.de>
>Subject: Re: [Linux-uvc-devel] LQC Pro 5000 picture
quality settings
>Date: Sat, 24 Mar 2007 18:23:06 +0100
>
> Hi Martijn,
>
> > > I have a Logitch Quickcam Pro 5000 which runs fine
with linux-uvc
> > > drivers, but I was wondering on how to set the JPEG
quality it gives.
> > > What I'd like is to have uncompressed output, and
compress it myself,
> > > but according to luvcview, the YUYV output has size
limitations. Is
> > > there any other way to grab a good quality, full-size
image? The
> > > bandwidth must be a bottleneck, but the framerate can
be low, as I am
> > > only interested in still images.
> >
> > Hate to reply to my own post, but after some googling I
found that
> > v4l2 has an ioctl called VIDIOC_[GS]_JPEGCOMP to get/set
the JPEG
> > compression level. However, this is not implemented in
the linux-uvc
> > driver. I tried reading the UVC documentation, but this
information
> > is a bit too complicated for me. I am willing to test
and implement
> > this ioctl, but I need help/directions on how to
implement this.
> > Anyone knows?
>
> You're right, the driver doesn't implement
VIDIOC_[GS]_JPEGCOMP yet. Luckily
> for you, it shouldn't be difficult to support those ioctls :-)
>
> The relevant part of the spec is section 4.3.1.1 (UVC
1.1). The compression
> quality is stored in the wCompQuality field, ranging from
0 to 10000. The
> resolution (step) is reported by the device but is
currently not retrieved by
> the driver.
>
> The driver negotiates video streaming parameters in
uvc_probe_video()
> (uvc_video.c). Have a look at uvc_v4l2_set_streamparm()
(uvc_v4l2.c) to see
> how the function is used to set the frame rate. It should
be quite easy to
> copy the function and modify it to set the compression
quality. You should of
> course add some sanity checks: setting the JPEG
compression quality doesn't
> make sense for YUYV.
>
> On a side note, the driver currently sets the quality to
the highest value
> supported by the device. If your quality issues come from
the JPEG
> compression, you will have to use YUYV. The first
generation Logitech webcams
> only supported YUYV streaming at high resolutions. The new
ones (2006 and
> later) suport YUYV at all resolutions.
>
> Feel free to ask for more information if you run into any
problem. Looking
> forward for your patch :-)
>
> Cheers,
>
> Laurent Pinchart
> _______________________________________________
> Linux-uvc-devel mailing list
> Linux-uvc-devel@lists.berlios.de
> https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
>
--
Ian Latter
Late night coder ..
http://midnightcode.org/
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