Logitech C920 support

[ofTheo]

The C920 is the replacement for the Logitech C910.
Currently it doesn't work with the UVCCameraControl.m

To make it work change in UVCCameraControl.h
#define UVC_PROCESSING_UNIT_ID 0x03

and in setData and getDataFor in UVCCameraControl.m ( two instances )
controlRequest.wIndex = (unitId << 8) | 0x00;

Note I get quite a bit of latency with this camera when the exposure is on a low value ( ie a dark image ) - I think this is due to the camera sending frames faster than ofQtKitVideoGrabber can handle them. Setting the exposure to a higher value reduces the lag to usable amounts. Might need to look into a way to drop frames in ofQtKitVideoGrabber.

[cpietsch]

i needed to change the camera_settings.yml too:

- name: Logitech c920
  vendorId : 0x046d
  productId: 0x82d
  interfaceNum: 0x03
  # 1280x720 (this is 1/2 res)
  width: 1280
  height: 720

[cpietsch]

any news on dropping frames in ofQtKitVideoGrabber ?

[ofTheo]

I have a fix for this which I should be pushing in a couple of days to OF.
I posted a gist with code which reduces latency down to usable amounts here: openframeworks/openFrameworks#1841 (comment)

its messy but it works. will clean it up and push it to OF soon.

[kylemcdonald]

i tried the following

1. making the changes @ofTheo mentioned above (changing 3 lines of code total)
2. switching out the values in camera_settings.yml like @cpietsch mentioned
3. switching from ofxQTKitVideoGrabber to ofQTKitGrabber
4. reimplementing draw() by copying the ofPixels from the ofQTKitGrabber

but i just get a connection to the isight, and can't connect to the c920. any ideas?

[ofTheo]

you might have to set device id before initGrabber

ie:
vidGrabber.setDeviceID(3);

what does:

vidGrabber.setVerbose(true);
vidGrabber.listDevices();

spit out?

---

Theo Watson
http://theowatson.com

http://openframeworks.cc

On May 6, 2013, at 1:03 PM, Kyle McDonald wrote:

i tried the following

making the changes @ofTheo mentioned above (changing 3 lines of code total)
switching out the values in camera_settings.yml like @cpietsch mentioned
switching from ofxQTKitVideoGrabber to ofQTKitGrabber
reimplementing draw() by copying the ofPixels from the ofQTKitGrabber
but i just get a connection to the isight, and can't connect to the c920. any ideas?

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Reply to this email directly or view it on GitHub.

[kylemcdonald]

ended up taking a different approach, but if i come back to this camera i'll try that -- thanks theo!

[ofTheo]

yeah - you are not really missing out.
the camera can't focus past 3m - I also took a different approach :)

useful code though!

[cpietsch]

would be interesting what approach you guys took!

[orgicus]

I'm interested too. I've just tried using the example in the this repo, but ran into some errors with ofxQTKitVideoGrabber. Have removed it and tried ofQTKitGrabber after reading the above, but I still
get some linking errors:

Undefined symbols for architecture i386:
  "_vImageConvert_BGRA8888toRGB888", referenced from:
      -[QTKitVideoGrabber update] in openFrameworksDebug.a(ofQTKitGrabber.o)
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)

The comments are half an year old. I'm wondering: what is the latest fix/easiest way to get up and running with a c920 cam ? (Currently I'm using oF0.8.0 on osx 10.9)

Thanks!

[bakercp]

hey @orgicus I think I ran into you over on SO. Check out fixes here: https://github.com/bakercp/ofxUVC. The _vImageConvert_BGRA8888toRGB888 means that you need to add the accelerate.framework to your project. I added that in my branch.

[orgicus]

@bakercp Thank you again! I've finally got autofocus/autoexposure control with the c920 camera ! Woo hoo!

Here's what I did:

1. Used your fork of ofxUVC (https://github.com/bakercp/ofxUVC)
2. Add Theo's fixes in (#define UVC_PROCESSING_UNIT_ID 0x03 in UVCCameraControl.h and controlRequest.wIndex = (unitId << 8) | 0x00; in - (BOOL)setData:(long)value withLength:(int)length forSelector:(int)selector at:(int)unitId and - (long)getDataFor:(int)type withLength:(int)length fromSelector:(int)selector at:(int)unitId
3. Use @cpietsch 's definition, but change the name. I've noticed on some macs the grabber lists as "Logitech Camera" but on others as "HD Pro Webcam C920". Too keep every side happy, used the name the grabber sees as the name parameter int the yaml definition. The other params are the same(vendorId : 0x046d
   productId: 0x82d
   interfaceNum: 0x03)

[elliotwoods]

i'm planning to use this for an upcoming workshop at eyeo. so great to see all the info here

@ofTheo - from my experience, it can't really focus past 70cm, and relies too heavily on its software sharpness filter. here's a table of my results for the C910:

Focus table [control value 0-255 / distance (cm)]

255 / 3.5
238 / 3.8
221 / 4
204 / 4.3
187 / 5.3
170 / 6.4
153 / 8
136 / 10.5
119 / 15
102 / 25
85 / 40
68 / 51

more at:
http://www.kimchiandchips.com/blog/?p=564

[elliotwoods]

confirm it works here
i took out ofxYAML (building yaml requires boost or serious hacking)

set the code mentioned by theo at the top
used product id and vendor id from System Report... (same as above)

i think the problem @kylemcdonald was probably getting is that the camera name was wrong
and the code:

    for(int i = 0; i < availableCams.size(); i++){
    if(availableCams.at(i) == cameraName){
            deviceId = i;
        }
    }

needs the right camera name, else it'll use device 0 (i.e. iSight)
mine is "HD Pro Webcam C920"

[orgicus]

I haven't used C910, but as mentioned above successfully used the C920 model.
Regarding camera names, I have to mention that on newer versions of osx (10.8/10.9) I also see "HD Pro Webcam C920" which is what I set in the .yml file. On osx 10.7 I noticed the device name is listed as "Logitech Camera" so probably best to first check out the string output from of when listing video devices and using that same name in the .yml file.

For example, I had an entry like so:

# Note! some computer see the C920 as Logitech Camera, others as HD Pro Webcam C920
- name: Logitech Camera
  vendorId : 0x046d
  productId: 0x82d
  interfaceNum: 0x03
  # 1280x720 (this is 1/2 res)
  width: 1280
  height: 720

Also, if it helps for the workshop to remove some tedium, here the UI I used:
in . file:

    ofxPanel            gui;
    bool                showGUI;
    ofParameter<bool>   autoExposure;
    ofParameter<float>  exposure;
    ofParameter<bool>   autoFocus;
    ofParameter<float>  focus;
    ofParameter<bool>   autoWhiteBalance;
    ofParameter<float>  whiteBalance;
    ofParameter<float>  gain;
    ofParameter<float>  brightness;
    ofParameter<float>  contrast;
    ofParameter<float>  saturation;
    ofParameter<float>  sharpness;
    void                setupGUI();
    void                autoExposureChanged(bool &isAuto);
    void                exposureChanged(float &value);
    void                autoFocusChanged(bool &isAuto);
    void                focusChanged(float &value);
    void                autoWhiteBalanceChanged(bool &isAuto);
    void                whiteBalanceChanged(float &value);
    void                gainChanged(float &value);
    void                brightnessChanged(float &value);
    void                contrastChanged(float &value);
    void                saturationChanged(float &value);
    void                sharpnessChanged(float &value);

and from the .cpp file:

void PT::setupGUI(){
    gui.setup("Camera Settings");
    gui.add(autoExposure.set("auto_exposure", true));
    gui.add(exposure.set("exposure", uvcControl.getExposure(),0,1));
    gui.add(autoFocus.set("auto_focus",true));
    gui.add(focus.set("focus",uvcControl.getAbsoluteFocus(),0,1));
    gui.add(autoWhiteBalance.set("auto_white_balance",true));
    gui.add(whiteBalance.set("white_balance",uvcControl.getWhiteBalance(),0,1));
    gui.add(gain.set("gain",uvcControl.getGain(),0,1));
    gui.add(brightness.set("brightness",/*uvcControl.getBrightness()*/0.5,0,1));//getBrightness returns 1 which is too bright
    gui.add(contrast.set("contrast",uvcControl.getContrast(),0,1));
    gui.add(saturation.set("saturation",uvcControl.getSaturation(),0,1));
    gui.add(sharpness.set("sharpness",uvcControl.getSharpness(),0,1));

    autoExposure.addListener(this,&PT::autoExposureChanged);
    exposure.addListener(this, &PT::exposureChanged);
    autoFocus.addListener(this,&PT::autoFocusChanged);
    focus.addListener(this, &PT::focusChanged);
    autoWhiteBalance.addListener(this,&PT::autoWhiteBalanceChanged);
    whiteBalance.addListener(this, &PT::whiteBalanceChanged);
    gain.addListener(this,&PT::gainChanged);
    brightness.addListener(this,&PT::brightnessChanged);
    contrast.addListener(this,&PT::contrastChanged);
    saturation.addListener(this,&PT::saturationChanged);
    sharpness.addListener(this,&PT::sharpnessChanged);

    gui.loadFromFile("camera_settings.xml");
 }
//...
//Camera controls
void PT::autoExposureChanged(bool &isAuto){
    if(webcam.isInitialized()) uvcControl.setAutoExposure(isAuto);
}
void PT::exposureChanged(float &value){
    if(webcam.isInitialized()) uvcControl.setExposure(value);
}
void PT::autoFocusChanged(bool &isAuto){
    if(webcam.isInitialized()) uvcControl.setAutoFocus(isAuto);
}
void PT::focusChanged(float &value){
    if(webcam.isInitialized()) uvcControl.setAbsoluteFocus(value);
}
void PT::autoWhiteBalanceChanged(bool &isAuto){
    if(webcam.isInitialized()) uvcControl.setAutoWhiteBalance(isAuto);
}
void PT::whiteBalanceChanged(float &value){
    if(webcam.isInitialized()) uvcControl.setWhiteBalance(value);
}
void PT::gainChanged(float &value){
    if(webcam.isInitialized()) uvcControl.setGain(value);
}
void PT::brightnessChanged(float &value){
    if(webcam.isInitialized()) uvcControl.setBrightness(value);
}
void PT::contrastChanged(float &value){
    if(webcam.isInitialized()) uvcControl.setContrast(value);
}
void PT::saturationChanged(float &value){
    if(webcam.isInitialized()) uvcControl.setSaturation(value);
}
void PT::sharpnessChanged(float &value){
    if(webcam.isInitialized()) uvcControl.setSharpness(value);
}
//--------------------------------------------------------------
void PT::exit(){
    gui.saveToFile("camera_settings.xml");
}

My main app class was named PT, but hopefully a find and replace will sort this out for your setup.

Also, regarding ofxYAML I used the pre-build .a file from either Greg's or Satoru's repo.

HTH,
George

[elliotwoods]

ah sorry didn't mention. i'm using c++11 so can't use 'old' pre-built libs
thanks for the info