Fix VP9 extension surface attach/detach + make it seamless

Issue: #2582

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=152494408

extensions/vp9/src/main/java/com/google/android/exoplayer2/ext/vp9/LibvpxVideoRenderer.java

@@ -186,7 +186,6 @@ public final class LibvpxVideoRenderer extends BaseRenderer {
     }
 
     // We have a format.
-    if (isRendererAvailable()) {
     drmSession = pendingDrmSession;
     ExoMediaCrypto mediaCrypto = null;
     if (drmSession != null) {
@@ -206,8 +205,7 @@ public final class LibvpxVideoRenderer extends BaseRenderer {
         // If we don't have a decoder yet, we need to instantiate one.
         long codecInitializingTimestamp = SystemClock.elapsedRealtime();
         TraceUtil.beginSection("createVpxDecoder");
-          decoder = new VpxDecoder(NUM_BUFFERS, NUM_BUFFERS, INITIAL_INPUT_BUFFER_SIZE,
+        decoder = new VpxDecoder(NUM_BUFFERS, NUM_BUFFERS, INITIAL_INPUT_BUFFER_SIZE, mediaCrypto);
-              mediaCrypto);
         decoder.setOutputMode(outputMode);
         TraceUtil.endSection();
         long codecInitializedTimestamp = SystemClock.elapsedRealtime();
@@ -222,22 +220,6 @@ public final class LibvpxVideoRenderer extends BaseRenderer {
     } catch (VpxDecoderException e) {
       throw ExoPlaybackException.createForRenderer(e, getIndex());
     }
-    } else {
-      skipSource(positionUs);
-      // We need to read any format changes despite not having a codec so that drmSession can be
-      // updated, and so that we have the most recent format should the codec be initialized. We may
-      // also reach the end of the stream. Note that readSource will not read a sample into a
-      // flags-only buffer.
-      flagsOnlyBuffer.clear();
-      int result = readSource(formatHolder, flagsOnlyBuffer, false);
-      if (result == C.RESULT_FORMAT_READ) {
-        onInputFormatChanged(formatHolder.format);
-      } else if (result == C.RESULT_BUFFER_READ) {
-        Assertions.checkState(flagsOnlyBuffer.isEndOfStream());
-        inputStreamEnded = true;
-        outputStreamEnded = true;
-      }
-    }
     decoderCounters.ensureUpdated();
   }
 
@@ -271,27 +253,26 @@ public final class LibvpxVideoRenderer extends BaseRenderer {
       return false;
     }
 
+    if (outputMode == VpxDecoder.OUTPUT_MODE_NONE) {
+      // Skip frames in sync with playback, so we'll be at the right frame if the mode changes.
+      if (outputBuffer.timeUs <= positionUs) {
+        skipBuffer();
+        return true;
+      }
+      return false;
+    }
+
     // Drop the frame if we're joining and are more than 30ms late, or if we have the next frame
     // and that's also late. Else we'll render what we have.
     if ((joiningDeadlineMs != C.TIME_UNSET && outputBuffer.timeUs < positionUs - 30000)
         || (nextOutputBuffer != null && !nextOutputBuffer.isEndOfStream()
         && nextOutputBuffer.timeUs < positionUs)) {
-      decoderCounters.droppedOutputBufferCount++;
+      dropBuffer();
-      droppedFrames++;
-      consecutiveDroppedFrameCount++;
-      decoderCounters.maxConsecutiveDroppedOutputBufferCount = Math.max(
-          consecutiveDroppedFrameCount,
-          decoderCounters.maxConsecutiveDroppedOutputBufferCount);
-      if (droppedFrames == maxDroppedFramesToNotify) {
-        maybeNotifyDroppedFrames();
-      }
-      outputBuffer.release();
-      outputBuffer = null;
       return true;
     }
 
-    // If we have not rendered any frame so far (either initially or immediately following a seek),
+    // If we have yet to render a frame to the current output (either initially or immediately
-    // render one frame irrespective of the state or current position.
+    // following a seek), render one irrespective of the state or current position.
     if (!renderedFirstFrame
         || (getState() == STATE_STARTED && outputBuffer.timeUs <= positionUs + 30000)) {
       renderBuffer();
@@ -300,27 +281,44 @@ public final class LibvpxVideoRenderer extends BaseRenderer {
   }
 
   private void renderBuffer() {
-    decoderCounters.renderedOutputBufferCount++;
+    int bufferMode = outputBuffer.mode;
-    consecutiveDroppedFrameCount = 0;
+    boolean renderRgb = bufferMode == VpxDecoder.OUTPUT_MODE_RGB && surface != null;
-    maybeNotifyVideoSizeChanged(outputBuffer.width, outputBuffer.height);
+    boolean renderYuv = bufferMode == VpxDecoder.OUTPUT_MODE_YUV && outputBufferRenderer != null;
-    if (outputBuffer.mode == VpxDecoder.OUTPUT_MODE_RGB && surface != null) {
+    if (!renderRgb && !renderYuv) {
-      renderRgbFrame(outputBuffer, scaleToFit);
+      dropBuffer();
-      if (!renderedFirstFrame) {
-        renderedFirstFrame = true;
-        eventDispatcher.renderedFirstFrame(surface);
-      }
-      outputBuffer.release();
-    } else if (outputBuffer.mode == VpxDecoder.OUTPUT_MODE_YUV && outputBufferRenderer != null) {
-      // The renderer will release the buffer.
-      outputBufferRenderer.setOutputBuffer(outputBuffer);
-      if (!renderedFirstFrame) {
-        renderedFirstFrame = true;
-        eventDispatcher.renderedFirstFrame(null);
-      }
     } else {
+      maybeNotifyVideoSizeChanged(outputBuffer.width, outputBuffer.height);
+      if (renderRgb) {
+        renderRgbFrame(outputBuffer, scaleToFit);
         outputBuffer.release();
+      } else /* renderYuv */ {
+        outputBufferRenderer.setOutputBuffer(outputBuffer);
+        // The renderer will release the buffer.
       }
       outputBuffer = null;
+      consecutiveDroppedFrameCount = 0;
+      decoderCounters.renderedOutputBufferCount++;
+      maybeNotifyRenderedFirstFrame();
+    }
+  }
+
+  private void dropBuffer() {
+    decoderCounters.droppedOutputBufferCount++;
+    droppedFrames++;
+    consecutiveDroppedFrameCount++;
+    decoderCounters.maxConsecutiveDroppedOutputBufferCount = Math.max(
+        consecutiveDroppedFrameCount, decoderCounters.maxConsecutiveDroppedOutputBufferCount);
+    if (droppedFrames == maxDroppedFramesToNotify) {
+      maybeNotifyDroppedFrames();
+    }
+    outputBuffer.release();
+    outputBuffer = null;
+  }
+
+  private void skipBuffer() {
+    decoderCounters.skippedOutputBufferCount++;
+    outputBuffer.release();
+    outputBuffer = null;
   }
 
   private void renderRgbFrame(VpxOutputBuffer outputBuffer, boolean scale) {
@@ -420,7 +418,7 @@ public final class LibvpxVideoRenderer extends BaseRenderer {
       return false;
     }
     if (format != null && (isSourceReady() || outputBuffer != null)
-        && (renderedFirstFrame || !isRendererAvailable())) {
+        && (renderedFirstFrame || outputMode == VpxDecoder.OUTPUT_MODE_NONE)) {
       // Ready. If we were joining then we've now joined, so clear the joining deadline.
       joiningDeadlineMs = C.TIME_UNSET;
       return true;
@@ -551,32 +549,23 @@ public final class LibvpxVideoRenderer extends BaseRenderer {
   private void setOutput(Surface surface, VpxOutputBufferRenderer outputBufferRenderer) {
     // At most one output may be non-null. Both may be null if the output is being cleared.
     Assertions.checkState(surface == null || outputBufferRenderer == null);
-    // Clear state so that we always call the event listener with the video size and when a frame
-    // is rendered, even if the output hasn't changed.
-    renderedFirstFrame = false;
-    clearReportedVideoSize();
     // We only need to update the decoder if the output has changed.
     if (this.surface != surface || this.outputBufferRenderer != outputBufferRenderer) {
       this.surface = surface;
       this.outputBufferRenderer = outputBufferRenderer;
       outputMode = outputBufferRenderer != null ? VpxDecoder.OUTPUT_MODE_YUV
           : surface != null ? VpxDecoder.OUTPUT_MODE_RGB : VpxDecoder.OUTPUT_MODE_NONE;
-      updateDecoder();
+      // If outputMode is OUTPUT_MODE_NONE we leave the mode of the underlying decoder unchanged in
-    }
+      // anticipation that a subsequent output will likely be of the same type as the one that was
-  }
+      // set previously.
-
+      if (decoder != null && outputMode != VpxDecoder.OUTPUT_MODE_NONE) {
-  private void updateDecoder() {
-    if (decoder != null) {
-      if (outputMode == VpxDecoder.OUTPUT_MODE_NONE) {
-        releaseDecoder();
-      } else {
         decoder.setOutputMode(outputMode);
       }
     }
-  }
+    // Clear state so that we always call the event listener with the video size and when a frame
-
+    // is rendered, even if the output hasn't changed.
-  private boolean isRendererAvailable() {
+    renderedFirstFrame = false;
-    return surface != null || outputBufferRenderer != null;
+    clearReportedVideoSize();
   }
 
   private void clearReportedVideoSize() {
@@ -584,6 +573,13 @@ public final class LibvpxVideoRenderer extends BaseRenderer {
     reportedHeight = Format.NO_VALUE;
   }
 
+  private void maybeNotifyRenderedFirstFrame() {
+    if (!renderedFirstFrame) {
+      renderedFirstFrame = true;
+      eventDispatcher.renderedFirstFrame(surface);
+    }
+  }
+
   private void maybeNotifyVideoSizeChanged(int width, int height) {
     if (reportedWidth != width || reportedHeight != height) {
       reportedWidth = width;