Support chaining async GlTextureProcessors in FrameProcessorChain.

After this change, FrameProcessorChain chains any GlTextureProcessors
instead of only SingleFrameGlTextureProcessors.

The GlTextureProcessors are chained in a bidirectional manner using
ChainingGlTextureProcessorListener to feed input and output related
events forward and release events backwards.

PiperOrigin-RevId: 456478414

demos/transformer/src/main/java/com/google/android/exoplayer2/transformerdemo/TransformerActivity.java

@@ -17,6 +17,7 @@ package com.google.android.exoplayer2.transformerdemo;
 
 import static android.Manifest.permission.READ_EXTERNAL_STORAGE;
 import static com.google.android.exoplayer2.util.Assertions.checkNotNull;
+import static com.google.android.exoplayer2.util.Assertions.checkState;
 
 import android.app.Activity;
 import android.content.Context;
@@ -421,9 +422,28 @@ public final class TransformerActivity extends AppCompatActivity {
 
   private final class DemoDebugViewProvider implements Transformer.DebugViewProvider {
 
+    private @MonotonicNonNull SurfaceView surfaceView;
+    private int width;
+    private int height;
+
+    public DemoDebugViewProvider() {
+      width = C.LENGTH_UNSET;
+      height = C.LENGTH_UNSET;
+    }
+
     @Nullable
     @Override
     public SurfaceView getDebugPreviewSurfaceView(int width, int height) {
+      checkState(
+          surfaceView == null || (this.width == width && this.height == height),
+          "Transformer should not change the output size mid-transformation.");
+      if (surfaceView != null) {
+        return surfaceView;
+      }
+
+      this.width = width;
+      this.height = height;
+
       // Update the UI on the main thread and wait for the output surface to be available.
       CountDownLatch surfaceCreatedCountDownLatch = new CountDownLatch(1);
       SurfaceView surfaceView = new SurfaceView(/* context= */ TransformerActivity.this);
@@ -460,6 +480,7 @@ public final class TransformerActivity extends AppCompatActivity {
         Thread.currentThread().interrupt();
         return null;
       }
+      this.surfaceView = surfaceView;
       return surfaceView;
     }
   }

library/transformer/src/main/java/com/google/android/exoplayer2/transformer/SingleFrameGlTextureProcessor.java

@@ -73,6 +73,16 @@ public abstract class SingleFrameGlTextureProcessor implements GlTextureProcesso
     this.listener = listener;
   }
 
+  /**
+   * Returns whether the {@code SingleFrameGlTextureProcessor} can accept an input frame.
+   *
+   * <p>If this method returns {@code true}, the next call to {@link #maybeQueueInputFrame(
+   * TextureInfo, long)} will also return {@code true}.
+   */
+  public boolean acceptsInputFrame() {
+    return !outputTextureInUse;
+  }
+
   @Override
   public final boolean maybeQueueInputFrame(TextureInfo inputTexture, long presentationTimeUs) {
     if (outputTextureInUse) {

library/transformer/src/main/java/com/google/android/exoplayer2/transformer/VideoTranscodingSamplePipeline.java

@@ -17,7 +17,6 @@
 package com.google.android.exoplayer2.transformer;
 
 import static com.google.android.exoplayer2.util.Assertions.checkNotNull;
-import static com.google.android.exoplayer2.util.Assertions.checkStateNotNull;
 
 import android.content.Context;
 import android.media.MediaCodec;
@@ -32,7 +31,6 @@ import com.google.common.collect.ImmutableList;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.List;
-import java.util.concurrent.atomic.AtomicReference;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.checkerframework.dataflow.qual.Pure;
 
@@ -91,8 +89,6 @@ import org.checkerframework.dataflow.qual.Pure;
       effectsListBuilder.add(Presentation.createForHeight(transformationRequest.outputHeight));
     }
 
-    AtomicReference<TransformationException> encoderInitializationException =
-        new AtomicReference<>();
     encoderWrapper =
         new EncoderWrapper(
             encoderFactory,
@@ -100,9 +96,8 @@ import org.checkerframework.dataflow.qual.Pure;
             allowedOutputMimeTypes,
             transformationRequest,
             fallbackListener,
-            encoderInitializationException);
+            asyncErrorListener);
 
-    @Nullable FrameProcessorChain frameProcessorChain;
     try {
       frameProcessorChain =
           FrameProcessorChain.create(
@@ -137,12 +132,6 @@ import org.checkerframework.dataflow.qual.Pure;
           e, TransformationException.ERROR_CODE_GL_INIT_FAILED);
     }
 
-    if (frameProcessorChain == null) {
-      // Failed to create FrameProcessorChain because the encoder could not provide a surface.
-      throw checkStateNotNull(encoderInitializationException.get());
-    }
-    this.frameProcessorChain = frameProcessorChain;
-
     decoder =
         decoderFactory.createForVideoDecoding(
             inputFormat,
@@ -266,7 +255,7 @@ import org.checkerframework.dataflow.qual.Pure;
     }
 
     if (maxPendingFrameCount != Codec.UNLIMITED_PENDING_FRAME_COUNT
-        && frameProcessorChain.getPendingFrameCount() == maxPendingFrameCount) {
+        && frameProcessorChain.getPendingInputFrameCount() == maxPendingFrameCount) {
       return false;
     }
 
@@ -303,7 +292,7 @@ import org.checkerframework.dataflow.qual.Pure;
     private final List<String> allowedOutputMimeTypes;
     private final TransformationRequest transformationRequest;
     private final FallbackListener fallbackListener;
-    private final AtomicReference<TransformationException> encoderInitializationException;
+    private final Transformer.AsyncErrorListener asyncErrorListener;
 
     private @MonotonicNonNull SurfaceInfo encoderSurfaceInfo;
 
@@ -317,14 +306,14 @@ import org.checkerframework.dataflow.qual.Pure;
         List<String> allowedOutputMimeTypes,
         TransformationRequest transformationRequest,
         FallbackListener fallbackListener,
-        AtomicReference<TransformationException> encoderInitializationException) {
+        Transformer.AsyncErrorListener asyncErrorListener) {
 
       this.encoderFactory = encoderFactory;
       this.inputFormat = inputFormat;
       this.allowedOutputMimeTypes = allowedOutputMimeTypes;
       this.transformationRequest = transformationRequest;
       this.fallbackListener = fallbackListener;
-      this.encoderInitializationException = encoderInitializationException;
+      this.asyncErrorListener = asyncErrorListener;
     }
 
     @Override
@@ -365,7 +354,7 @@ import org.checkerframework.dataflow.qual.Pure;
         encoder =
             encoderFactory.createForVideoEncoding(requestedEncoderFormat, allowedOutputMimeTypes);
       } catch (TransformationException e) {
-        encoderInitializationException.set(e);
+        asyncErrorListener.onTransformationException(e);
         return null;
       }
       Format encoderSupportedFormat = encoder.getConfigurationFormat();

library/transformer/src/test/java/com/google/android/exoplayer2/transformer/VideoEncoderWrapperTest.java

@@ -29,7 +29,6 @@ import com.google.android.exoplayer2.util.Clock;
 import com.google.android.exoplayer2.util.ListenerSet;
 import com.google.common.collect.ImmutableList;
 import java.util.List;
-import java.util.concurrent.atomic.AtomicReference;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -52,7 +51,7 @@ public final class VideoEncoderWrapperTest {
           /* allowedOutputMimeTypes= */ ImmutableList.of(),
           emptyTransformationRequest,
           fallbackListener,
-          new AtomicReference<>());
+          mock(Transformer.AsyncErrorListener.class));
 
   @Before
   public void registerTrack() {