添加VideoSink代理类；

添加VideoProcessor针对NV21格式数据进行叠图功能。
v1.0.4

extension-lib/build.gradle

@@ -29,8 +29,9 @@ android {
 }
 
 dependencies {
-    compileOnly 'androidx.annotation:annotation:1.2.0'
+    compileOnly 'androidx.annotation:annotation:1.3.0'
     compileOnly 'org.webrtc:google-webrtc:1.0.32006'
+    api "io.github.crow-misia.libyuv:libyuv-android:0.13.0"
 }
 
 // Because the components are created only during the afterEvaluate phase, you must
@@ -46,7 +47,7 @@ afterEvaluate {
                 // You can then customize attributes of the publication as shown below.
                 groupId = 'com.shencoder'
                 artifactId = 'webrtcextension'
-                version = '1.0.2'
+                version = '1.0.4'
             }
         }
     }

extension-lib/src/main/java/com/shencoder/webrtcextension/BaseNV21VideoProcessor.kt

@@ -0,0 +1,108 @@
+package com.shencoder.webrtcextension
+
+import androidx.annotation.CallSuper
+import org.webrtc.*
+
+/**
+ * 仅处理[NV21Buffer]格式数据基类，会使用反射拿到[NV21Buffer.data]；
+ * 如果想使用此类，则需要[Camera1Enumerator.captureToTexture]是false，
+ * 即[Camera1Capturer.captureToTexture]为false
+ *
+ * you must be call [Camera1Enumerator(false)]
+ *
+ * @author  ShenBen
+ * @date    2021/12/6 08:44
+ * @email   714081644@qq.com
+ */
+abstract class BaseNV21VideoProcessor : VideoProcessor {
+
+    protected var mSink: VideoSink? = null
+
+    @CallSuper
+    override fun setSink(sink: VideoSink?) {
+        mSink = sink
+    }
+
+    @CallSuper
+    override fun onCapturerStarted(success: Boolean) {
+
+    }
+
+    @CallSuper
+    override fun onCapturerStopped() {
+
+    }
+
+    /**
+     * 此方法会间接调用[NV21Buffer.cropAndScale]转为[VideoFrame.I420Buffer]，所以要在super之前处理
+     */
+    final override fun onFrameCaptured(
+        frame: VideoFrame,
+        parameters: VideoProcessor.FrameAdaptationParameters
+    ) {
+        if (parameters.drop) {
+            //直接丢弃
+            return
+        }
+        val buffer = frame.buffer
+        if (buffer is NV21Buffer) {
+            //进处理NV21Buffer
+            //通过反射拿到[NV21Buffer.data]
+            val nv21Class = buffer::class.java
+            val declaredField = nv21Class.getDeclaredField("data")
+            declaredField.isAccessible = true
+            val bytes = declaredField.get(buffer) as ByteArray
+            val nv21Bytes: ByteArray = checkNV21ByteArray(bytes, buffer.width, buffer.height)
+            //处理nv21数据是否成功
+            val success = handleNV21(nv21Bytes, buffer.width, buffer.height, frame.rotation)
+            if (success.not()) {
+                super.onFrameCaptured(frame, parameters)
+                return
+            }
+            //将处理好的nv21数据转换为NV21Buffer，传给VideoFrame
+            val nv21Buffer = NV21Buffer(nv21Bytes, buffer.width, buffer.height, null)
+            val videoFrame = VideoFrame(nv21Buffer, frame.rotation, frame.timestampNs)
+            //调用super方法，传入新生成的VideoFrame
+            super.onFrameCaptured(videoFrame, parameters)
+            videoFrame.release()
+        } else {
+            super.onFrameCaptured(frame, parameters)
+        }
+    }
+
+    @CallSuper
+    override fun onFrameCaptured(frame: VideoFrame) {
+        //将处理好的VideoFrame发送出去
+        mSink?.onFrame(frame)
+    }
+
+    /**
+     * 处理NV21数据
+     *
+     * @param nv21      原始nv21数据，请直接修改此数组的数据，会二次使用
+     * @param width     原始nv21数据的宽
+     * @param height    原始nv21数据的高
+     * @param rotation  原始nv21数据的方向
+     *
+     * @return 是否处理完成；ture:发送[nv21]，false:则按照原有的流程处理
+     */
+    abstract fun handleNV21(
+        nv21: ByteArray,
+        width: Int,
+        height: Int,
+        rotation: Int
+    ): Boolean
+
+    protected fun checkNV21ByteArray(nv21: ByteArray, width: Int, height: Int): ByteArray {
+        //标准大小
+        val size = width * height * 3 / 2
+        return if (size == nv21.size) {
+            nv21
+        } else {
+            //宽或高为奇数时，可能会出现比标准大小大的情况，要进行剪裁
+            val byteArray = ByteArray(size)
+            System.arraycopy(nv21, 0, byteArray, 0, size)
+            byteArray
+        }
+    }
+}