Add DefaultMuxer forwarding to FrameworkMuxer

- The naming DefaultMuxer is more consistent with the rest of
Transformer codebase (e.g. DefaultEncoderFactory).
- By hiding the implementation details of DefaultMuxer, the transition
to in-app Muxer will be seamless for apps using DefaultMuxer.
- The current plan is that DefaultMuxer will become the in-app muxer.

PiperOrigin-RevId: 481838790
(cherry picked from commit b4d7f066dd31cce1e3d7ab14cc47d3b7be364a88)

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

@@ -0,0 +1,81 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * 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 com.google.android.exoplayer2.transformer;
+
+import android.os.ParcelFileDescriptor;
+import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.Format;
+import com.google.common.collect.ImmutableList;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+
+/** A default {@link Muxer} implementation. */
+public final class DefaultMuxer implements Muxer {
+
+  /** A {@link Muxer.Factory} for {@link DefaultMuxer}. */
+  public static final class Factory implements Muxer.Factory {
+    private final Muxer.Factory muxerFactory;
+
+    public Factory() {
+      this.muxerFactory = new FrameworkMuxer.Factory();
+    }
+
+    @Override
+    public Muxer create(String path, String outputMimeType) throws IOException {
+      return new DefaultMuxer(muxerFactory.create(path, outputMimeType));
+    }
+
+    @Override
+    public Muxer create(ParcelFileDescriptor parcelFileDescriptor, String outputMimeType)
+        throws IOException {
+      return new DefaultMuxer(muxerFactory.create(parcelFileDescriptor, outputMimeType));
+    }
+
+    @Override
+    public boolean supportsOutputMimeType(String mimeType) {
+      return muxerFactory.supportsOutputMimeType(mimeType);
+    }
+
+    @Override
+    public ImmutableList<String> getSupportedSampleMimeTypes(
+        @C.TrackType int trackType, String containerMimeType) {
+      return muxerFactory.getSupportedSampleMimeTypes(trackType, containerMimeType);
+    }
+  }
+
+  private final Muxer muxer;
+
+  private DefaultMuxer(Muxer muxer) {
+    this.muxer = muxer;
+  }
+
+  @Override
+  public int addTrack(Format format) throws MuxerException {
+    return muxer.addTrack(format);
+  }
+
+  @Override
+  public void writeSampleData(
+      int trackIndex, ByteBuffer data, boolean isKeyFrame, long presentationTimeUs)
+      throws MuxerException {
+    muxer.writeSampleData(trackIndex, data, isKeyFrame, presentationTimeUs);
+  }
+
+  @Override
+  public void release(boolean forCancellation) throws MuxerException {
+    muxer.release(forCancellation);
+  }
+}

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

@@ -124,7 +124,7 @@ public final class Transformer {
      */
     public Builder(Context context) {
       this.context = context.getApplicationContext();
-      muxerFactory = new FrameworkMuxer.Factory();
+      muxerFactory = new DefaultMuxer.Factory();
       looper = Util.getCurrentOrMainLooper();
       clock = Clock.DEFAULT;
       listeners = new ListenerSet<>(looper, clock, (listener, flags) -> {});
@@ -422,7 +422,7 @@ public final class Transformer {
     /**
      * Sets the factory for muxers that write the media container.
      *
-     * <p>The default value is a {@link FrameworkMuxer.Factory}.
+     * <p>The default value is a {@link DefaultMuxer.Factory}.
      *
      * @param muxerFactory A {@link Muxer.Factory}.
      * @return This builder.

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

@@ -856,15 +856,15 @@ public final class TransformerEndToEndTest {
 
   private final class TestMuxerFactory implements Muxer.Factory {
 
-    private final Muxer.Factory frameworkMuxerFactory;
+    private final Muxer.Factory defaultMuxerFactory;
 
     public TestMuxerFactory() {
-      frameworkMuxerFactory = new FrameworkMuxer.Factory();
+      defaultMuxerFactory = new DefaultMuxer.Factory();
     }
 
     @Override
     public Muxer create(String path, String outputMimeType) throws IOException {
-      testMuxer = new TestMuxer(path, outputMimeType, frameworkMuxerFactory);
+      testMuxer = new TestMuxer(path, outputMimeType, defaultMuxerFactory);
       return testMuxer;
     }
 
@@ -872,8 +872,7 @@ public final class TransformerEndToEndTest {
     public Muxer create(ParcelFileDescriptor parcelFileDescriptor, String outputMimeType)
         throws IOException {
       testMuxer =
-          new TestMuxer(
-              "FD:" + parcelFileDescriptor.getFd(), outputMimeType, frameworkMuxerFactory);
+          new TestMuxer("FD:" + parcelFileDescriptor.getFd(), outputMimeType, defaultMuxerFactory);
       return testMuxer;
     }
 
@@ -885,7 +884,7 @@ public final class TransformerEndToEndTest {
     @Override
     public ImmutableList<String> getSupportedSampleMimeTypes(
         @C.TrackType int trackType, String containerMimeType) {
-      return frameworkMuxerFactory.getSupportedSampleMimeTypes(trackType, containerMimeType);
+      return defaultMuxerFactory.getSupportedSampleMimeTypes(trackType, containerMimeType);
     }
   }
 }