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POImage preview is very slow on Nexus4
 

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  1. POImage preview is very slow on Nexus4
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    <p>I need to increase fps rate in my app. Now i have between 6 - 10 FPS which is very low imo because i have Nexus4. So i decided to switch from setPreviewCallback to setPreviewCallbackWithBuffer but i do not see ANY difference in framerate. In log i can see that addressess of buffers are changing circular but still i have only 6 - 10 fps (sometimes 12 but rarely)... Could you try to give me some advices? BTW. I have Android 4.4 and i tried OpenCV but there result is almost the same... My code is: </p> <pre><code>public class XPreview extends SurfaceView implements SurfaceHolder.Callback, Camera.PreviewCallback { private SurfaceHolder mHolder; private Camera mCamera; long mTimer = 0; public XPreview(Context context, Camera camera) { super(context); mCamera = camera; mHolder = getHolder(); mHolder.addCallback(this); } public void surfaceCreated(SurfaceHolder holder) { } public void surfaceDestroyed(SurfaceHolder holder) { } public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) { if (mHolder.getSurface() == null){ // preview surface does not exist return; } // stop preview before making changes try { mCamera.stopPreview(); } catch (Exception e){ // ignore: tried to stop a non-existent preview } try { int formatt = mCamera.getParameters().getPreviewFormat(); int bytesPerPx = ImageFormat.getBitsPerPixel( formatt ); int width = mCamera.getParameters().getPreviewSize().width; int height = mCamera.getParameters().getPreviewSize().height; int size = (int)( ( width * height * bytesPerPx ) / 8.0); Parameters params = mCamera.getParameters(); mCamera.setParameters(params); Log.d(TAG, "Data: " + formatt + " " + bytesPerPx + " " + width + "x" + height + " " + size ); mCamera.setPreviewDisplay(mHolder); mCamera.setPreviewCallbackWithBuffer(this); mCamera.addCallbackBuffer( new byte[size] ); mCamera.addCallbackBuffer( new byte[size] ); mCamera.addCallbackBuffer( new byte[size] ); mCamera.addCallbackBuffer( new byte[size] ); mCamera.addCallbackBuffer( new byte[size] ); mCamera.startPreview(); } catch (Exception e){ Log.d(TAG, "Error starting camera preview: " + e.getMessage()); } } @Override public void onPreviewFrame(byte[] data, Camera camera) { long time = System.currentTimeMillis(); Log.d( TAG, "Time between frames: " + ( time - mTimer ) + "ms, FPS: " + ( 1000.0 / (time - mTimer )) + ", data " + data ); mTimer = time; camera.addCallbackBuffer(data); } } </code></pre> <p>Activity:</p> <pre><code>public class RTP extends Activity { private Camera mCamera; private XPreview mPreview; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mCamera = Camera.open(); mPreview = new XPreview(this, mCamera); FrameLayout preview = (FrameLayout) findViewById( R.id.frameLayout1 ); preview.addView(mPreview); } @Override public void onPause(){ super.onPause(); if( mCamera != null ){ mCamera.stopPreview(); mCamera.release(); mCamera = null; } } } </code></pre> <p>Edit:</p> <pre><code>Parameters params = mCamera.getParameters(); params.setRecordingHint(true); mCamera.setParameters(params); </code></pre> <p>This decreased delay between frames to about ~30ms with version with buffers and decresed delay to about 60 with version without buffer. Anyway i'd be glad if someone could give me some more advices. <br><br>A bit deeper tests shows that now i have between 24 and 31 fps using version with buffering and two buffers and between 15 and 22 using default version.</p>
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    1. USMichal W
    1. USMichal W
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    1. COSo, you are OK at 24+ fps now?
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      1. USAlex Cohn
    2. COYou know, the more the better ;) Moreover trick with with redording hint has disadvantage in image quality. I think it does but maybe i am wrong? Even with this trick GC is called very often and he shouldn't i belive because i use preview with buffer. I'm not sure if this is it works or maybe i'm doing something wrong.
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      1. POImage preview is very slow on Nexus4
      1. USMichal W
    3. COOne easy improvement could be to decouple `onPreveiwFrame()` from the main thread, see http://stackoverflow.com/questions/18149964/best-use-of-handlerthread-over-other-similar-classes/19154438#19154438
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      1. USAlex Cohn
 

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