[ros-users] Webcam Use
Christian Verbeek
verbeek at servicerobotics.eu
Fri Jan 14 17:06:27 UTC 2011
Hi,
Did anyone use the MJPG format? I mean grabbing the MJPG data, writing
it to a file and than try to decompress and view it?
The thing is that it would be very cheap to copy the mjpg data to a
sensor_msgs/CompressedImage message and the transmit the image to a
remote computer. What I found is that mjpg is not jpg. I had to patch
libjpg in order to insert the missing DHT segment manually. Are there
any other means of making use of the mjpg data?
Regards
Christian
Am 06.01.2011 02:22, schrieb Homer Manalo:
> Thanks for the info Patrick, that would be a likely candidate beside
> the webcam pro 9000. Eric, that was a very informative post. Now we
> have a better understanding on the hardware we will get.
>
> Thanks,
> Homer
>
> On Thu, Jan 6, 2011 at 6:06 AM, Eric Perko <wisesage5001 at gmail.com
> <mailto:wisesage5001 at gmail.com>> wrote:
>
> Homer,
>
> Some numbers on using a webcam with my uvc_cam driver (they are a
> little fuzzy since it's been a while since I did the tests, but it
> should be about right). No changes to the driver were made between
> these tests, and all were running the same version of Ubuntu
> (64-bit unless it wasn't supported, like on the Core Duo). We were
> doing 640x480 @ 30fps and I believe had to do a YUYV to RGB
> conversion in the driver because the cameras did not support
> outputting RGB (though I can't recall if that is the Logitech
> Webcam Pro 9000 or these other crappy, no brand cameras we were
> using before the Webcam Pro 9000s).
>
> Anyways, the numbers:
>
> 1. Intel Core Duo, somewhere between 2.0 and 2.4 GHz (Mac Mini,
> circa 2006-2007): somewhere around 40% CPU per camera. Basically,
> what I remember was that we were gonna lose a whole CPU core to
> just a pair of cameras and that was unacceptable.
> 2. Intel Core 2 Duo, 2.0 GHz (IBM Thinkpad T61, circa 2007): about
> 10-15% CPU per camera.
> 3. Intel Core i7 920, 2.66GHz (Custom build, Summer 2009): very
> low usage, sometimes even showing up at 0% in the System Monitor.
> 5-8% tops when it does show up.
>
> As you can see, for whatever reason, the Core 2 kicks the crap out
> of the Core Duo. 64-bits vs 32-bits, extra SSE voodoo, better USB
> drivers on the T61 than the Mac Mini, who knows why? Anyways,
> definitely something to think about. Also, any webcam that you can
> use in an RGB mode as opposed to YUYV where the driver is going to
> have to spend time converting from YUYV to RGB will be good.
>
> That said, we've been quite happy with the Webcam Pro 9000s. Let
> me know if you have any other questions about it. I'm including
> the console output of guvcview, which lists the different image
> sizes and 1/FPS pairs that the camera clams to support in
> different modes (MJPG or YUYV in this case), in case anyone
> wonders about that and doesn't have a Webcam Pro 9000 on hand to
> find out :)
>
> Hope that helps.
>
> - Eric
>
> guvcview console output:
>
> video device: /dev/video0
> /dev/video0 - device 1
> Init. UVC Camera (046d:0809) (location: usb-0000:00:1d.7-5)
> { pixelformat = 'YUYV', description = 'YUV 4:2:2 (YUYV)' }
> { discrete: width = 640, height = 480 }
> Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5,
> { 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 = 360 }
> Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5,
> { discrete: width = 640, height = 400 }
> Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5,
> { discrete: width = 768, height = 480 }
> Time interval between frame: 1/25, 1/20, 1/15, 1/10, 1/5,
> { discrete: width = 800, height = 456 }
> Time interval between frame: 1/25, 1/20, 1/15, 1/10, 1/5,
> { discrete: width = 800, height = 504 }
> Time interval between frame: 1/25, 1/20, 1/15, 1/10, 1/5,
> { discrete: width = 800, height = 600 }
> Time interval between frame: 1/25, 1/20, 1/15, 1/10, 1/5,
> { discrete: width = 864, height = 480 }
> Time interval between frame: 1/25, 1/20, 1/15, 1/10, 1/5,
> { discrete: width = 960, height = 720 }
> Time interval between frame: 1/15, 1/10, 1/5,
> { discrete: width = 1280, height = 720 }
> Time interval between frame: 2/15, 1/5,
> { discrete: width = 1280, height = 800 }
> Time interval between frame: 2/15, 1/5,
> { discrete: width = 1600, height = 904 }
> Time interval between frame: 1/5,
> { discrete: width = 1600, height = 1000 }
> Time interval between frame: 1/5,
> { discrete: width = 1600, height = 1200 }
> Time interval between frame: 1/5,
> { pixelformat = 'MJPG', description = 'MJPEG' }
> { discrete: width = 640, height = 480 }
> Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5,
> { 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 = 360 }
> Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5,
> { discrete: width = 640, height = 400 }
> Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5,
> { discrete: width = 768, height = 480 }
> Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5,
> { discrete: width = 800, height = 456 }
> Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5,
> { discrete: width = 800, height = 504 }
> Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5,
> { discrete: width = 800, height = 600 }
> Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5,
> { discrete: width = 864, height = 480 }
> Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5,
> { discrete: width = 960, height = 720 }
> Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5,
> { discrete: width = 1280, height = 720 }
> Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5,
> { discrete: width = 1280, height = 800 }
> Time interval between frame: 1/25, 1/20, 1/15, 1/10, 1/5,
> { discrete: width = 1600, height = 904 }
> Time interval between frame: 1/10, 1/5,
> { discrete: width = 1600, height = 1000 }
> Time interval between frame: 1/10, 1/5,
> { discrete: width = 1600, height = 1200 }
> Time interval between frame: 1/10, 1/5,
> checking format: 1196444237
> VIDIOC_G_COMP:: Invalid argument
> compression control not supported
> vid:046d
> pid:0809
> driver:uvcvideo
> Adding control for Pan (relative)
> Adding control for Tilt (relative)
> Adding control for Pan Reset
> Adding control for Tilt Reset
> Adding control for Pan/tilt Reset
> Adding control for Focus (absolute)
> mapping control for Pan (relative)
> mapping control for Tilt (relative)
> mapping control for Pan Reset
> mapping control for Tilt Reset
> mapping control for Pan/tilt Reset
> mapping control for Focus (absolute)
> mapping control for LED1 Mode
> mapping control for LED1 Frequency
> mapping control for Disable video processing
> mapping control for Raw bits per pixel
>
>
>
> On Wed, Jan 5, 2011 at 12:00 PM, Patrick Goebel
> <patrick at casbs.stanford.edu <mailto:patrick at casbs.stanford.edu>>
> wrote:
>
> Hi Homer,
>
> I have had several years of good experience with the Philips
> SPC1300NC
> both under Windows using RoboRealm and now more recently under
> Ubuntu+ROS using Eric Perko's uvc_cam package (git clone
> https://github.com/ericperko/uvc_cam.git) and OpenCV. I
> haven't done
> any benchmarking under Linux but under Windows I was getting
> as high as
> 80 fps at 160x120 resolution and manual exposure.
>
> --patrick
>
> On 1/5/2011 6:53 AM, Homer Manalo wrote:
> > Thanks! Anyone had used Philips SPC1300NC or a creative webcam?
> >
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