Fixes for video processing and examples (#495)

* Add utility class NoDropVideoProcessor to force video processing while not connected

* Fix local video tracks not rendering processed frames

+---
+"client-sdk-android": patch
+---
+
+Fix local video tracks not rendering processed frames

+---
+"client-sdk-android": patch
+---
+
+Add utility class NoDropVideoProcessor to force video processing while not connected

@@ -31,6 +31,7 @@ import com.google.mlkit.vision.common.InputImage
 import com.google.mlkit.vision.segmentation.Segmentation
 import com.google.mlkit.vision.segmentation.Segmenter
 import com.google.mlkit.vision.segmentation.selfie.SelfieSegmenterOptions
+import io.livekit.android.room.track.video.NoDropVideoProcessor
 import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.cancel
@@ -41,13 +42,12 @@ import kotlinx.coroutines.sync.Mutex
 import livekit.org.webrtc.EglBase
 import livekit.org.webrtc.SurfaceTextureHelper
 import livekit.org.webrtc.VideoFrame
-import livekit.org.webrtc.VideoProcessor
 import livekit.org.webrtc.VideoSink
 import livekit.org.webrtc.YuvHelper
 import java.io.ByteArrayOutputStream
 import java.nio.ByteBuffer
 
-class SelfieBitmapVideoProcessor(eglBase: EglBase, dispatcher: CoroutineDispatcher) : VideoProcessor {
+class SelfieBitmapVideoProcessor(eglBase: EglBase, dispatcher: CoroutineDispatcher) : NoDropVideoProcessor() {
 
     private var targetSink: VideoSink? = null
     private val segmenter: Segmenter
@@ -138,6 +138,7 @@ class SelfieBitmapVideoProcessor(eglBase: EglBase, dispatcher: CoroutineDispatch
         frameBuffer.release()
         frame.release()
 
+        // Ready for segementation processing.
         val inputImage = InputImage.fromBitmap(bitmap, 0)
         val task = segmenter.process(inputImage)
 
@@ -156,6 +157,7 @@ class SelfieBitmapVideoProcessor(eglBase: EglBase, dispatcher: CoroutineDispatch
                 }
             }
 
+            // Prepare for creating the processed video frame.
             if (lastRotation != rotationDegrees) {
                 surfaceTextureHelper?.setFrameRotation(rotationDegrees)
                 lastRotation = rotationDegrees
@@ -175,6 +177,7 @@ class SelfieBitmapVideoProcessor(eglBase: EglBase, dispatcher: CoroutineDispatch
                 }
 
                 if (canvas != null) {
+                    // Create the video frame.
                     canvas.drawBitmap(bitmap, Matrix(), Paint())
                     surface.unlockCanvasAndPost(canvas)
                 }

@@ -21,17 +21,17 @@ import com.google.mlkit.vision.common.InputImage
 import com.google.mlkit.vision.segmentation.Segmentation
 import com.google.mlkit.vision.segmentation.Segmenter
 import com.google.mlkit.vision.segmentation.selfie.SelfieSegmenterOptions
+import io.livekit.android.room.track.video.NoDropVideoProcessor
 import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.channels.BufferOverflow
 import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.launch
 import livekit.org.webrtc.VideoFrame
-import livekit.org.webrtc.VideoProcessor
 import livekit.org.webrtc.VideoSink
 import java.nio.ByteBuffer
 
-class SelfieVideoProcessor(dispatcher: CoroutineDispatcher) : VideoProcessor {
+class SelfieVideoProcessor(dispatcher: CoroutineDispatcher) : NoDropVideoProcessor() {
 
     private var targetSink: VideoSink? = null
     private val segmenter: Segmenter

+/*
+ * Copyright 2024 LiveKit, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.livekit.android.annotations
+
+/**
+ * The target marked with this annotation is sensitive to the internal
+ * code of WebRTC, and should be directly retested whenever WebRTC version
+ * is upgraded.
+ */
+@Retention(AnnotationRetention.SOURCE)
+annotation class WebRTCSensitive

@@ -476,13 +476,20 @@ constructor(
             source.setVideoProcessor(videoProcessor)
 
             val surfaceTextureHelper = SurfaceTextureHelper.create("VideoCaptureThread", rootEglBase.eglBaseContext)
-            val dispatchObserver = CaptureDispatchObserver()
-            dispatchObserver.registerObserver(source.capturerObserver)
+
+            // Dispatch raw frames to local renderer only if not using a VideoProcessor.
+            val dispatchObserver = if (videoProcessor == null) {
+                CaptureDispatchObserver().apply {
+                    registerObserver(source.capturerObserver)
+                }
+            } else {
+                null
+            }
 
             capturer.initialize(
                 surfaceTextureHelper,
                 context,
-                dispatchObserver,
+                dispatchObserver ?: source.capturerObserver,
             )
             val rtcTrack = peerConnectionFactory.createVideoTrack(UUID.randomUUID().toString(), source)
 

+/*
+ * Copyright 2024 LiveKit, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.livekit.android.room.track.video
+
+import io.livekit.android.annotations.WebRTCSensitive
+import livekit.org.webrtc.VideoFrame
+import livekit.org.webrtc.VideoProcessor
+
+/**
+ * When not connected to a room, the base [VideoProcessor] implementation will refuse
+ * to process frames as they will all be dropped (i.e. not sent).
+ *
+ * This implementation by default forces all frames to be processed regardless of publish status.
+ *
+ * Change [allowDropping] to true if you want to allow dropping of frames.
+ */
+abstract class NoDropVideoProcessor : VideoProcessor {
+    /**
+     * If set to false, forces all frames to be processed regardless of publish status.
+     * If set to true, frames will only be processed when the associated video track is published.
+     *
+     * By default, set to false.
+     */
+    @Suppress("MemberVisibilityCanBePrivate")
+    var allowDropping = false
+
+    @WebRTCSensitive
+    override fun onFrameCaptured(frame: VideoFrame, parameters: VideoProcessor.FrameAdaptationParameters) {
+        if (allowDropping) {
+            super.onFrameCaptured(frame, parameters)
+        } else {
+            // Altered from VideoProcessor
+            val adaptedFrame = VideoProcessor.applyFrameAdaptationParameters(frame, parameters)
+            if (adaptedFrame != null) {
+                this.onFrameCaptured(adaptedFrame)
+                adaptedFrame.release()
+            } else {
+                this.onFrameCaptured(frame)
+            }
+        }
+    }
+}