Google Glass preview image scrambled with new XE10

问题:

This occurs using a few apks that make use of the camera (e.g., zxing, opencv). It displays a glitched image in the preview but it is still a function of what the camera sees so it appears to be an encoding mismatch. The native camera preview works fine, so the internal apps do not exhibit this problem.

回答1:

For now, please try adding the following workaround after you acquire the Camera but before you setup and start the preview:

Camera.Parameters params = camera.getParameters();
params.setPreviewFpsRange(30000, 30000);
camera.setParameters(params);

(Or just add the setPreviewFpsRange call to your existing parameters if you're setting others as well.)

回答2:

For anyone using ZXing on their Glass, you can build a version from the source code with the above fix.

Add the following method into CameraConfigurationManager.java

  public void googleGlassXE10WorkAround(Camera mCamera) {
        Camera.Parameters params = mCamera.getParameters();
        params.setPreviewFpsRange(30000, 30000);
        params.setPreviewSize(640,360);
        mCamera.setParameters(params);
  }

And call this method immediately after anywhere you see Camera.setParameters() in the ZXing code. I just put it in two places in the CameraConfigurationManager and it worked.

I set the Preview Size to be 640x360 to match the Glass resolution.

回答3:

30 FPS preview is pretty high. If you want to save some battery and CPU, consider the slowest supported FPS to be sufficient:

List<int[]> supportedPreviewFpsRanges = parameters.getSupportedPreviewFpsRange();
int[] minimumPreviewFpsRange = supportedPreviewFpsRanges.get(0);
parameters.setPreviewFpsRange(minimumPreviewFpsRange[0], minimumPreviewFpsRange[1]);

回答4:

The bug still exists as of XE16 and XE16.11 but this code gets past the glitch and shows a normal camera preview, note the three parameter setting lines and their values. I have also tested this at 5000 (5FPS) and it works, and at 60000 (60FPS) and it does not work:

    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        if (mCamera == null) return;

        Camera.Parameters camParameters = mCamera.getParameters();
        camParameters.setPreviewFpsRange(30000, 30000);
        camParameters.setPreviewSize(1920, 1080);
        camParameters.setPictureSize(2592, 1944);
        mCamera.setParameters(camParameters);
        try {
            mCamera.startPreview();
        } catch (Exception e) {
            mCamera.release();
            mCamera = null;
        }
    }

回答5:

This still is an issue as of XE22 (!) Lowering the frames per second to 30 or lower does the trick:

 parameters.setPreviewFpsRange(30000, 30000);

And indeed, don't forget to set the parameters:

camera.setParameters(parameters);

I have found no clear explanation as to why this causes trouble, since 60 fps is included in the supported fps range. The video can record 720p, but I never saw a source add the fps to this.

回答6:

You can set the params.setPreviewSize(1200,800). You can change the values around this range until you can clear color noise.