Hi,

I refered to the Dev guide and FAQ to get Camera frame.
I can get correct camera frames correctly.
However the frame rate drops even after I disable it.

Here are my test results

1. Never enable image format: FPS is stable and over 60.
2. Enable image format: FPS is 60 during the first few seconds, then becomes 28 ~ 45
3. Enable image format then disable: FPS is about  45 ~ 57

Please see if we can make case 3 have the same good performance as Case 1.
 

Thanks
Jack

Below are my code to dynamic enable/disable image format

using UnityEngine;
using System.Collections;
using System.Runtime.InteropServices;

public class ImageFormat : MonoBehaviour, ITrackerEventHandler {
	
	//private Image.PIXEL_FORMAT mFormat = Image.PIXEL_FORMAT.GRAYSCALE;
	private Image.PIXEL_FORMAT mFormat = Image.PIXEL_FORMAT.RGB565;
	
	private int mRequestFrameNum = 0;
	private bool mRegisteredFormat = false;
	private bool mQCARInitialized = false;

	private bool mToggleEnable = true;
	
	// Use this for initialization
	void Start () {
		QCARBehaviour qcar = (QCARBehaviour)FindObjectOfType(typeof(QCARBehaviour));
		if (qcar) {
			qcar.RegisterTrackerEventHandler(this);
		}
		else {
			Debug.LogError("Could not find QCARBehaviour (i.e. ARCamera) in the scene");
		}
	}
	
	// Implementing OnInitialized() 
	// of ITrackerEventHandler interface
	public void OnInitialized() {
		mQCARInitialized = true;
		mRegisteredFormat = false;
		RegisterFormat ();
	}
	
	// Implementing OnTrackablesUpdated() 
	// of ITrackerEventHandler interface
	public void OnTrackablesUpdated() {
	}
	
	// This is called whenever the app gets paused
	void OnApplicationPause (bool paused) {
		if (paused) {
			// invalidate registered format if app has been paused
			mRegisteredFormat = false;
		} else {
			RegisterFormat();
		}
	}
	
	private void RegisterFormat() {

		if (!mRegisteredFormat) { 
			//first time update or first resume after pause
			//see OnApplicationPaused() above
			CameraDevice.Instance.SetFrameFormat(mFormat, false);
			if (CameraDevice.Instance.SetFrameFormat(mFormat, true)) {
				mRegisteredFormat = true;
				mToggleEnable = true;
			}
			else {
				mFormat = Image.PIXEL_FORMAT.UNKNOWN_FORMAT;
				Debug.LogError("Failed to enale");
			}
		}
	}
	
	// Update is called once per frame
	void Update () {
		// Skip if QCAR has not been initialized yet
		if (mQCARInitialized) {
			if (mRegisteredFormat && mToggleEnable) {
				Image img = CameraDevice.Instance.GetCameraImage(mFormat);
				if (img != null) {
					Debug.Log("Got camera frame. width=" + img.Width);
				}
				else {
					Debug.LogWarning("Failed to get camera frame");
				}
			}
		}
	}
	
	void OnGUI() {
		int bottonw = Screen.width / 2;
		int bottonh = Screen.height / 8;
		GUIStyle style = new GUIStyle();
		style.fontSize = 45;
		if (GUI.Button(new Rect(Screen.width / 2 - bottonh / 2, Screen.height - bottonh, bottonh, bottonh), mToggleEnable.ToString(),
		               style)) {
			mToggleEnable = !mToggleEnable;
			Debug.Log("Toggle. Now is " + mToggleEnable);
			SetFrameFormat(mToggleEnable);
		}
	}
	
	private bool SetFrameFormat(bool enable) {
		if (CameraDevice.Instance.SetFrameFormat(mFormat, enable)) {
			Debug.Log("SetFrameFormat " + enable + " succeed.");
			return true;
		} else {
			Debug.LogWarning("SetFrameFormat " + enable + " fail.");
			return false;
		}
	}
}

Code to measure FPS

// Attach this to a GUIText to make a frames/second indicator.
//
// It calculates frames/second over each updateInterval,
// so the display does not keep changing wildly.
//
// It is also fairly accurate at very low FPS counts (<10).
// We do this not by simply counting frames per interval, but
// by accumulating FPS for each frame. This way we end up with
// correct overall FPS even if the interval renders something like
// 5.5 frames.
 
var updateInterval = 0.5;
 
private var accum = 0.0; // FPS accumulated over the interval
private var frames = 0; // Frames drawn over the interval
private var timeleft : float; // Left time for current interval
 
function Start()
{
    if( !guiText )
    {
        print ("FramesPerSecond needs a GUIText component!");
        enabled = false;
        return;
    }
    timeleft = updateInterval;  
}
 
function Update()
{
    timeleft -= Time.deltaTime;
    accum += Time.timeScale/Time.deltaTime;
    ++frames;
 
    // Interval ended - update GUI text and start new interval
    if( timeleft <= 0.0 )
    {
        // display two fractional digits (f2 format)
        guiText.text = "FPS - " + (accum/frames).ToString("f2");
        timeleft = updateInterval;
        accum = 0.0;
        frames = 0;
    }
}