Can i make stream with flutter camera package?

Question

My purpose is stream to a websocket.

Firstly i need the camera data. I used startImageStream func for that. This func return image as yuv format. I found something about yuv to image widget but i couldnt convert it to base 64.

The question is how can i convert this yuv image data to base64 ? Or this is bad way to make a stream with flutter.

Answer 1

controller.startImageStream((image) {
  // convert image here

  // assuming it's converted
  final imageBytes = <int>[];

  final encodedImage = base64.encode(imageBytes);
});

as for yuv->rgb conversion, you can do something like this (code copied from https://gist.github.com/Alby-o/fe87e35bc21d534c8220aed7df028e03):

// imgLib -> Image package from https://pub.dartlang.org/packages/image
import 'package:image/image.dart' as imglib;
import 'package:camera/camera.dart';

Future<List<int>> convertImagetoPng(CameraImage image) async {
  try {
    imglib.Image img;
    if (image.format.group == ImageFormatGroup.yuv420) {
      img = _convertYUV420(image);
    } else if (image.format.group == ImageFormatGroup.bgra8888) {
      img = _convertBGRA8888(image);
    }

    imglib.PngEncoder pngEncoder = new imglib.PngEncoder();

    // Convert to png
    List<int> png = pngEncoder.encodeImage(img);
    return png;
  } catch (e) {
    print(">>>>>>>>>>>> ERROR:" + e.toString());
  }
  return null;
}

// CameraImage BGRA8888 -> PNG
// Color
imglib.Image _convertBGRA8888(CameraImage image) {
  return imglib.Image.fromBytes(
    image.width,
    image.height,
    image.planes[0].bytes,
    format: imglib.Format.bgra,
  );
}

// CameraImage YUV420_888 -> PNG -> Image (compresion:0, filter: none)
// Black
imglib.Image _convertYUV420(CameraImage image) {
  var img = imglib.Image(image.width, image.height); // Create Image buffer

  Plane plane = image.planes[0];
  const int shift = (0xFF << 24);

  // Fill image buffer with plane[0] from YUV420_888
  for (int x = 0; x < image.width; x++) {
    for (int planeOffset = 0;
        planeOffset < image.height * image.width;
        planeOffset += image.width) {
      final pixelColor = plane.bytes[planeOffset + x];
      // color: 0x FF  FF  FF  FF
      //           A   B   G   R
      // Calculate pixel color
      var newVal = shift | (pixelColor << 16) | (pixelColor << 8) | pixelColor;

      img.data[planeOffset + x] = newVal;
    }
  }

  return img;
}

Some background:

• How to convert Camera Image to Image in Flutter?
• https://github.com/flutter/flutter/issues/26348

In the latter you can find a comment that links to what appears to be more efficient implementation, it's in YUV_2_RGB project: https://github.com/alexcohn/YUV_2_RGB/blob/master/lib/service/image_result_processor_service.dart