Re: [Java-player-users] More JavaClient camera woes

[Radu B. R. <ru...@cs...>]

Hey Reymond,
(good to have you onboard!)

I just checked the Camera interface, and you are right, it wasn't 
processing the images correctly. The fix was trivial though (I might 
have missed it since my tests were done with cameras with very low 
resolution).

Basically you need to modify CameraInterface.java and replace the 
following two lines (in readData()):
-            for (int i = 0; i < PLAYER_CAMERA_IMAGE_SIZE; i++)
-                image[i] = (byte)is.readUnsignedByte ();    /* 
compressed image data */
with:
+               int totalBytes = 13;
+               int bytes;
+               while (totalBytes < this.size)
+               {
+                       // read the compressed image data
+                       bytes = is.read (image, totalBytes - 13, 
this.size - totalBytes);
+                       totalBytes += bytes;
+               }

I have also attached a patch (use patch -p1 < javaclient.camera.patch) 
to this e-mail, and have also commited these changes to the CVS SF 
repository. Please, if possible, use the Javaclient HEAD (from CVS) - 
see instructions at http://sourceforge.net/cvs/?group_id=135304 - and 
Player 1.6.5.

Ah, I also added an example on how to use the Camera to our examples web 
page (http://java-player.sourceforge.net/examples.php).

P.S. No need to use cam.readData() if you run the client in threaded 
mode (runThreaded...).

PPS. I just discovered a bug in the non-threaded version of the client, 
so please, if possible, use in threaded mode at all times until I get a 
chance to fix it.

Cheers,
Radu.

-- 
| Radu Bogdan Rusu | http://rbrusu.com/
| http://www9.cs.tum.edu/people/rusu/
| Intelligent Autonomous Systems
| Technische Universitaet Muenchen


Raymond Sheh wrote:

> Hi all!
>
> I'm trying to get CameraInterface working, much like Sunny was (list 
> email 2005-09-15, can't figure out how to reply to the same thread 
> since I just joined). I'm getting really weird things coming in and it 
> looks like things are getting somewhat mixed up. This is before I even 
> try to decode the image - the headers look a little messed up.
>
> Here's my code, basically a gutted version of SpaceWandererExample:
>
> ===============
> public class Blah
> {
>         public static void main (String[] args)
>         {
>                 PlayerClient interlink = new 
> PlayerClient("192.168.1.10", 6665);
>                 CameraInterface cam = 
> interlink.requestInterfaceCamera(1, 'r');
>                 interlink.runThreaded (-1, -1);
>                 try { Thread.sleep (1000); } catch (Exception e) { }
>                 while (true)
>                 {
>                         cam.readData();
>                         System.out.println("Got data\n");
>                         System.out.println("Camera size is " + 
> cam.getWidth() + "/" + cam.getHeight());
>         }
>         }
> }
> ===============
>
> Here's the output I get:
> ===============
> $ java Blah
> Player v.1.6.4
> [PlayerClient] : Got response for device 40(cameracompress) with 
> access: r
> [PlayerClient] : Unknown message type received in read()
> [PlayerClient] : Unknown message type received in read()
> [PlayerClient] : Unknown message type received in read()
> [PlayerClient] : Unknown message type received in read()
> [PlayerClient] : Unknown message type received in read()
> [PlayerClient] : Unknown message type received in read()
> [PlayerClient] : Unknown message type received in read()
> [PlayerClient] : Unknown message type received in read()
> Got data
>
> Camera size is 5121/6898
> [PlayerClient] : Unknown message type received in read()
> [PlayerClient] : Unknown message type received in read()
> Got data
>
> Camera size is -2647/-9978
> [PlayerClient] : Unknown message type received in read()
> <...>
> ===============
> Funnily enough, the program seems to block for a long time at the line 
> "cam.readData();" (generally the "Got data" line appears after a long 
> pause).
>
> I'm sure the Player server side of things works - we have another 
> Player client that connects via the standard C++ interface libraries 
> and it seems to behave nicely. The camera itself is the standard V4L 
> driver hooked through CameraCompress (but the same thing happens when 
> I direct Player to any of the other cameras on our robots).
>
>
> Anyone have any ideas as to what might be happening? I notice the 
> documentation says something about this interface not being intended 
> for server-client, what does that actually mean in terms of 
> useability? Radu, what did you have to do when you dived into the 
> player driver as you mentioned in your reply to Sunny's email?
>
>
> Cheers!
>
> - Raymond
>