java - BitmapFactory.decodeByteArray() is returning NULL

Question

I am using the previewCallback from the camera to try and grab images. Here is the code I am using

private Camera.PreviewCallback mPrevCallback = new Camera.PreviewCallback() 
{
        public void onPreviewFrame( byte[] data, Camera Cam ) {
                Log.d("CombineTestActivity", "Preview started");
                Log.d("CombineTestActivity", "Data length = " 
                        + data.length );
                currentprev = BitmapFactory.decodeByteArray( data, 0, 
                        data.length );

               if( currentprev == null )
                   Log.d("CombineTestActivity", "currentprev is null" );

                Log.d("CombineTestActivity", "Preview Finished" );

        }
};

the length of the data always comes otu the same as 576000.

Also I have tried changing the parameters of the camera so the image comes back as different formats. Here is what it looks like when I do that.

mCamera = Camera.open();
camParam = mCamera.getParameters();
camParam.setPreviewFormat( ImageFormat.RGB_565 );
mCamera.setParameters( camParam );
    mCamera.setPreviewCallback( mPrevCallback );

However both when I change the preview format and when I leave it as its default of NV21, BitmapFactory.decodeByteArray comes back as null. I have also tried changing the preview format to JPEG type. I even get a debug statement in the ddms, this is what I get

"D/skia (14391): --- SkImageDecoder::Factory returned null"

Answer 1

Alright, hopefully this will help.

Scoured the internet looking for a fast solution, and found the perfect thing.

This works as of Android 2.1

Thanks to off3nsiv3 from this page.

// Convert to JPG
Size previewSize = camera.getParameters().getPreviewSize(); 
YuvImage yuvimage=new YuvImage(data, ImageFormat.NV21, previewSize.width, previewSize.height, null);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
yuvimage.compressToJpeg(new Rect(0, 0, previewSize.width, previewSize.height), 80, baos);
byte[] jdata = baos.toByteArray();

// Convert to Bitmap
Bitmap bmp = BitmapFactory.decodeByteArray(jdata, 0, jdata.length);

Just a little modification to off3nsiv3's code and you're set. The FPS is still incredibly high compared to manual decoding.

For the above code, the 80 is the jpeg quality (0 from 100, 100 being best).