Android Camera为一些用户提供了多行的错误图片

Question

1) Some users of my app are taking some bugged pictures that look like that:

http://lh3.ggpht.com/i_VKS_Z1Ike5V8gEySiscQRRNkLwZMvv1a6u9diJrkWWGgYXUS-kqqxvAylhLIEJ1gs3MMZSEYIJJ4hX

The only thing I do is standard bitmap API in jpegCallback:

BitmapFactory.Options opts = new BitmapFactory.Options();
opts.inSampleSize = 4;
bm = BitmapFactory.decodeByteArray(data, 0, data.length, opts);
bm = Bitmap.createScaledBitmap(bm , 640, 480,  true);

and then write it on the disk

 imageFile = new File("/sdcard/app_dir/upload.jpg");
 FileOutputStream outStream = new FileOutputStream(imageFile);
 bm.compress(CompressFormat.JPEG, 75, outStream);
 outStream.flush();
 outStream.close();

2) edit: I've removed a call to setPreviewSize like explain there: Android: Jpeg saved from camera looks corrupted

I think it did help for some users (Desire HD), but I can tell others still got the issue (Desire S).

I really wish someone could explain the reason why pics looks distorded in the first place.

Answer 1

Well, it looks like you made some mistake with image size while decoding bitmap from byte array. Can you post code you are using for: - setting up camera - setting up decode parameters - retrieval of image data

Answer 2

I can't tell you why you're getting garbled data from some devices and not others, but I can suggest a workaround that seems to be working successfully for my app.

Your example code scales the camera's JPEG down to 640x480 before saving it off to the SD card. So I'm guessing you don't require the full-sized camera image.

If this assumption is true, you can skip Camera's takePicture() API entirely, and just save a preview frame to SD card. The easiest way to do this is with setOneShotPreviewCallback() :

mCamera.setOneShotPreviewCallback( new StillPictureCallback() );

This will invoke once, and hand you back a buffer of data from the camera:

private class StillPictureCallback implements Camera.PreviewCallback {
    @Override
    public void onPreviewFrame(byte[] data, Camera camera) {
        mPictureTask = new SaveStillPictureTask();
        byte[] myData = null;
        if ( data != null ) {
            myData = data.clone();
        }
        mPictureTask.execute(myData);
    }
}

The callback invokes a background task to compress the data and save it to the file. The only bit of code I'm leaving out is the part that queries the camera for the preview frame format, width and height via getCameraInfo() . Note also that the Android YUVImage class was introduced with Froyo, so if you need to support earlier versions of Android, you will need to roll your own conversion code (there are examples here on StackOverflow).

/**
 * Background task to compress captured image data and save to JPEG file.
 * 
 */
private class SaveStillPictureTask extends AsyncTask<byte[], Void, Void> {

    private static final String TAG="VideoRecorder.SaveStillPictureTask";

    @Override
    protected Void doInBackground(byte[]... params) {
        byte[] data = params[0];
        FileOutputStream out = null;
        Bitmap bitmap = null;
        if ( data == null ) {
            Log.e(TAG, "doInBackground: data is null");
            return null;
        }

        try {
            out = new FileOutputStream(mSnapshotFilePath);

            // Use the preview image format, as documented in Android SDK javadoc
            if ( (mPreviewImageFormat == ImageFormat.NV21) || (mPreviewImageFormat == ImageFormat.YUY2) ) {
                saveYUVToJPEG( mCamera, out, data );
            } else if (mPreviewImageFormat == ImageFormat.JPEG) {
                Log.d(TAG, "directly write JPEG to storage");
                out.write(data);
            } else {
                Log.d(TAG, "try decoding to byte array");
                bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);
                if ( bitmap != null ) {
                    bitmap.compress(Bitmap.CompressFormat.JPEG, 90, out);
                } else {
                    Log.e(TAG, "decodeByteArray failed, no decoded data");
                }
            }
        } 
        catch (FileNotFoundException ignore) {;} 
        catch (IOException ignore) {;}
        finally {
            if ( out != null ) {
                try {
                    out.close();
                } catch (IOException ignore) {;}
                out = null;
            }
            if ( bitmap != null ) {
                bitmap.recycle();
                bitmap = null;
            }
            data = null;
        }

        return null;
    }
}

/**
 * Save YUV image data (aka NV21 or YUV420sp) data to JPEG file.
 * 
 * @param camera
 * @param out
 * @param data
 */
protected void saveYUVToJPEG( Camera camera, FileOutputStream out, byte[] data ) {
    YuvImage yuvimg = null;
    try {
        int width = mPreviewWidth;
        int height = mPreviewHeight;

        Rect rect = new Rect();
        rect.left   = 0;
        rect.top    = 0;
        rect.right  = width  - 1;       
        rect.bottom = height - 1;       // The -1 is required, otherwise a buffer overrun occurs
        yuvimg = new YuvImage(data, mPreviewImageFormat, width, height, null);
        yuvimg.compressToJpeg(rect, 90, out);
    } finally {
        yuvimg = null;
    }
}

Answer 3

I had the exact same problem on an HTC Desire S.

I updated the mobile system per Settings -> About phone -> software updates

I also implemented the following code:

       Camera.Parameters parameters = mCamera.getParameters();
       parameters.setPictureFormat(PixelFormat.JPEG);
       mCamera.setParameters(parameters);

Worked for me.