How to get Android camera preview data?

Question

My camera app displays a camera preview on the screen and also processes it in the background. Here is the relevant code, condensed as much as possible (e.g. no error handling

Answer 1

From working on Barcode Scanner, which relies heavily on preview data, I feel like I've seen every bug under the sun. My suggestion is simply to not call setPreviewFormat() and let it use the default. The default is what you want here fortunately. There seem to be fewer devices that fail to get the default right, than device that balls up the call to setPreviewFormat(). Try that at least, may or may not be it.

Answer 2

You can also try this

public void takeSnapPhoto() {
camera.setOneShotPreviewCallback(new Camera.PreviewCallback() {
    @Override
    public void onPreviewFrame(byte[] data, Camera camera) {
        Camera.Parameters parameters = camera.getParameters();
        int format = parameters.getPreviewFormat();
        //YUV formats require more conversion
        if (format == ImageFormat.NV21 || format == ImageFormat.YUY2 || format == ImageFormat.NV16) {
            int w = parameters.getPreviewSize().width;
            int h = parameters.getPreviewSize().height;
            // Get the YuV image
            YuvImage yuv_image = new YuvImage(data, format, w, h, null);
            // Convert YuV to Jpeg
            Rect rect = new Rect(0, 0, w, h);
            ByteArrayOutputStream output_stream = new ByteArrayOutputStream();
            yuv_image.compressToJpeg(rect, 100, output_stream);
            byte[] byt = output_stream.toByteArray();
            FileOutputStream outStream = null;
            try {
                // Write to SD Card
                File file = createFileInSDCard(FOLDER_PATH, "Image_"+System.currentTimeMillis()+".jpg");
                //Uri uriSavedImage = Uri.fromFile(file);
                outStream = new FileOutputStream(file);
                outStream.write(byt);
                outStream.close();
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
            }
        }
    }
});}

Answer 3

The only problem was that I didn't set the preview width and height:

params.setPreviewSize(previewWidth, previewHeight);
mCamera.setParameters(params);

This meant that the height and width I allocated for the array (proportional to previewWidth * previewHeight) tended to be a lot larger than the size of the actual data being returned (proportional to the default preview width and preview height). On some phones, the default was the same size as previewWidth and previewHeight, so there was no issue.