Re: [Java-player-users] Missing data in images?

[Fred L. <ff...@ab...>]

Hello,

Finally found some time...

On Thursday 16 Mar 2006 10:24, Radu Bogdan Rusu wrote:
> Hey Fred,
>
> If nobody else figures it out, I will try to do something about it on
> the plane. In general though, it is better to:
> - first, test if the data is ready, using the
> <CameraInterface>.isDataReady () method
> - then try to actually read the data from CameraInterface's buffer.
>
> Example:
> PlayerCameraData camdata = new PlayerCameraData ();
>
> if (camdata.isDataReady ())
> camdata = cam.getData ();

I've done:

                System.out.println("Waiting for image to be ready");
                while (!cam.isDataReady())
                    {
                        // Do nothing, just wait for the data to be ready.
                    }
                System.out.println("Getting image");
                camdata = cam.getData();

and that indeed (almost) solves the problem I was reporting.  Only almost 
because to save the image I have to do:

        for (int h = 0; h < height ; h++)
            for (int w = 0; w < width; w++)
                {
                    file.write(data[(w * 3) + (h * width * 3) + 1]);  // Red
                    file.write(data[(w * 3) + (h * width * 3) + 2]);  // Green
                    file.write(data[(w * 3) + (h * width * 3) + 0]);  // Blue
                }

in order to get the colours right.  The interesting bit is that v4l normally 
creates BGR pixels (i.e. blue and red swapped).  However, I seem to be 
getting BRG pixels from the CameraInterface.  But that's easy enough to fix.

Finally, is the isDataReady()/getData() pair is in a loop, it hangs on the 
second isDataReady() (or am I not supposed to be using it as I do?  Also, at 
the same time I do get loads of

warning : tried to push onto a full message queue
error   : tried to push 2/1 from/onto 4/0

while trying to get the second image.  This is with version 2.0.1 of 
javaclient and a fairly recent cvs version of player.

Cheers,

Fred