Frame capture feature

Author: rostopira

android/src/main/java/com/cloudwebrtc/webrtc/FlutterWebRTCPlugin.java

@@ -7,11 +7,13 @@
 import android.util.Log;
 import android.util.LongSparseArray;
 
+import com.cloudwebrtc.webrtc.record.FrameCapturer;
 import com.cloudwebrtc.webrtc.utils.ConstraintsArray;
 import com.cloudwebrtc.webrtc.utils.ConstraintsMap;
 import com.cloudwebrtc.webrtc.utils.EglUtils;
 import com.cloudwebrtc.webrtc.utils.ObjectType;
 
+import java.io.File;
 import java.util.*;
 
 import org.webrtc.AudioTrack;
@@ -108,6 +110,7 @@ private FlutterWebRTCPlugin(Registrar registrar, MethodChannel channel) {
                 .setSamplesReadyCallback(getUserMediaImpl.audioSamplesInterceptor)
                 .createAudioDeviceModule();
 
+
         mFactory = PeerConnectionFactory.builder()
                 .setOptions(new PeerConnectionFactory.Options())
                 .setVideoEncoderFactory(new DefaultVideoEncoderFactory(eglContext, true, true))
@@ -312,6 +315,18 @@ public void onMethodCall(MethodCall call, Result result) {
             Integer recorderId = call.argument("recorderId");
             getUserMediaImpl.stopRecording(recorderId);
             result.success(null);
+        } else if (call.method.equals("captureFrame")) {
+            String path = call.argument("path");
+            String videoTrackId = call.argument("trackId");
+            if (videoTrackId != null) {
+                MediaStreamTrack track = localTracks.get(videoTrackId);
+                if (track instanceof VideoTrack)
+                    new FrameCapturer((VideoTrack) track, new File(path), result);
+                else
+                    result.error("It's not video track", null, null);
+            } else {
+                result.error("Track is null", null, null);
+            }
         } else {
             result.notImplemented();
         }

android/src/main/java/com/cloudwebrtc/webrtc/record/FrameCapturer.java

@@ -0,0 +1,92 @@
+package com.cloudwebrtc.webrtc.record;
+
+import android.graphics.ImageFormat;
+import android.graphics.Rect;
+import android.graphics.YuvImage;
+import android.os.Handler;
+import android.os.Looper;
+
+import org.webrtc.VideoFrame;
+import org.webrtc.VideoSink;
+import org.webrtc.VideoTrack;
+import org.webrtc.YuvHelper;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+
+import io.flutter.plugin.common.MethodChannel;
+
+public class FrameCapturer implements VideoSink {
+    private VideoTrack videoTrack;
+    private File file;
+    private final MethodChannel.Result callback;
+    private boolean gotFrame = false;
+
+    public FrameCapturer(VideoTrack track, File file, MethodChannel.Result callback) {
+        videoTrack = track;
+        this.file = file;
+        this.callback = callback;
+        track.addSink(this);
+    }
+
+    @Override
+    public void onFrame(VideoFrame videoFrame) {
+        if (gotFrame)
+            return;
+        gotFrame = true;
+        videoFrame.retain();
+        VideoFrame.Buffer buffer = videoFrame.getBuffer();
+        VideoFrame.I420Buffer i420Buffer = buffer.toI420();
+        ByteBuffer y = i420Buffer.getDataY();
+        ByteBuffer u = i420Buffer.getDataU();
+        ByteBuffer v = i420Buffer.getDataV();
+        int width = i420Buffer.getWidth();
+        int height = i420Buffer.getHeight();
+        int[] strides = new int[] {
+            i420Buffer.getStrideY(),
+            i420Buffer.getStrideU(),
+            i420Buffer.getStrideV()
+        };
+        final int chromaWidth = (width + 1) / 2;
+        final int chromaHeight = (height + 1) / 2;
+        final int minSize = width * height + chromaWidth * chromaHeight * 2;
+        ByteBuffer yuvBuffer = ByteBuffer.allocateDirect(minSize);
+        YuvHelper.I420ToNV12(y, strides[0], v, strides[2], u, strides[1], yuvBuffer, width, height);
+        YuvImage yuvImage = new YuvImage(
+            yuvBuffer.array(),
+            ImageFormat.NV21,
+            width,
+            height,
+            strides
+        );
+        videoFrame.release();
+        new Handler(Looper.getMainLooper()).post(() -> {
+            videoTrack.removeSink(this);
+        });
+        try {
+            if (!file.exists())
+                //noinspection ResultOfMethodCallIgnored
+                file.createNewFile();
+        } catch (IOException io) {
+            callback.error("IOException", io.getLocalizedMessage(), io);
+            return;
+        }
+        try (FileOutputStream outputStream = new FileOutputStream(file)) {
+            yuvImage.compressToJpeg(
+                new Rect(0, 0, width, height),
+                100,
+                outputStream
+            );
+            callback.success(null);
+        } catch (IOException io) {
+            callback.error("IOException", io.getLocalizedMessage(), io);
+        } catch (IllegalArgumentException iae) {
+            callback.error("IllegalArgumentException", iae.getLocalizedMessage(), iae);
+        } finally {
+            file = null;
+        }
+    }
+
+}

lib/media_stream_track.dart

@@ -35,6 +35,12 @@ class MediaStreamTrack {
     );
   }
 
+  captureFrame(String filePath) =>
+    _channel.invokeMethod(
+      'captureFrame',
+      <String, dynamic>{'trackId':_trackId, 'path': filePath},
+    );
+
   Future<void> dispose() async {
     await _channel.invokeMethod(
       'trackDispose',