Video4Linux API: Trying to access User and Extended Controls on MeeGo

[Klen]

PROBLEM SOLVED!!!

Hello all,

While reading through the MeeGo documentation , I noticed that the v4l2 API is supported on MeeGo.

I am working on porting Maemo application to MeeGo, but got stuck at the v4l2 implementation. I am trying to read a camera control variable V4L2_CID_FOCUS_ABSOLUTE, but end up with an error argument not supported. When I try to enumerate through all of the supported control arguments I do not retrieve any, while the same code return 24 user controls on a maemo device.

Question:
1.) Is it possible to use http://v4l2spec.bytesex.org/spec/x542.htm and Extended Controls of v4l2 API on MeeGo.

2.) If so, do you have any idea why the code bellow returns 24 controls of Maemo device and 0 on Meego.

void InitV4l2Driver(){
	const char *device = "/dev/video0"; //tried video 1, 2, 3 and 4
	fd = open(device, O_RDWR, 0);
	
	if(fd < 0) {
		fprintf(stderr, "Unable to open %s: %s\n", device, strerror(errno));
		printf("Unable to open %s: %s\n", device, strerror(errno));
	}

        int count=0;
        struct v4l2_queryctrl qctrl;
        qctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL;
   
        while (0 == ioctl (fd, VIDIOC_QUERYCTRL, &qctrl)) {
	       count++;
               qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
        }
        printf("Number of controls: %d\n",count);
}

Thx for your help.

Klen

[gnuton]

Hi,
I guess you could get 0 if the security policy doesn't allow you that operation.
Have you defined an aegis file for your app?

I suppose you need a manifest file like this:
<aegis>
<request>
<credential name="GRP::video " />
<for path="/opt/MY_APP_NAME/bin/MY_APP_NAME" />
</request>
</aegis>

Even if "user" unix user belongs to "video" unix group sometime it's necessary to request for that capability explicitly.

[Klen]

Thanks Gnuton for your addvice.

I managed to solve the problem. The solution can be found on this MeeGoo forum thread. I am running applications logged in as developer and get video privilidges. I know this becaus I can create a gstreamer pipleine and I can do that only when logged in as developer.

Will need to add the manifest when I get to release stage of the application dev.

Thanks again,
Klen