Make SilenceMediaSource add a media item to the timeline

PiperOrigin-RevId: 311295749

library/core/src/main/java/com/google/android/exoplayer2/source/SilenceMediaSource.java

@@ -15,10 +15,12 @@
  */
 package com.google.android.exoplayer2.source;
 
+import android.net.Uri;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.FormatHolder;
+import com.google.android.exoplayer2.MediaItem;
 import com.google.android.exoplayer2.SeekParameters;
 import com.google.android.exoplayer2.decoder.DecoderInputBuffer;
 import com.google.android.exoplayer2.trackselection.TrackSelection;
@@ -40,7 +42,7 @@ public final class SilenceMediaSource extends BaseMediaSource {
     @Nullable private Object tag;
 
     /**
-     * Sets the duration of the silent audio.
+     * Sets the duration of the silent audio. The value needs to be a positive value.
      *
      * @param durationUs The duration of silent audio to output, in microseconds.
      * @return This factory, for convenience.
@@ -63,12 +65,20 @@ public final class SilenceMediaSource extends BaseMediaSource {
       return this;
     }
 
-    /** Creates a new {@link SilenceMediaSource}. */
+    /**
+     * Creates a new {@link SilenceMediaSource}.
+     *
+     * @throws IllegalStateException if the duration is a non-positive value.
+     */
     public SilenceMediaSource createMediaSource() {
-      return new SilenceMediaSource(durationUs, tag);
+      Assertions.checkState(durationUs > 0);
+      return new SilenceMediaSource(durationUs, MEDIA_ITEM.buildUpon().setTag(tag).build());
     }
   }
 
+  /** The media id used by any media item of silence media sources. */
+  public static final String MEDIA_ID = "com.google.android.exoplayer2.source.SilenceMediaSource";
+
   private static final int SAMPLE_RATE_HZ = 44100;
   @C.PcmEncoding private static final int PCM_ENCODING = C.ENCODING_PCM_16BIT;
   private static final int CHANNEL_COUNT = 2;
@@ -79,11 +89,17 @@ public final class SilenceMediaSource extends BaseMediaSource {
           .setSampleRate(SAMPLE_RATE_HZ)
           .setPcmEncoding(PCM_ENCODING)
           .build();
+  private static final MediaItem MEDIA_ITEM =
+      new MediaItem.Builder()
+          .setMediaId(MEDIA_ID)
+          .setUri(Uri.EMPTY)
+          .setMimeType(FORMAT.sampleMimeType)
+          .build();
   private static final byte[] SILENCE_SAMPLE =
       new byte[Util.getPcmFrameSize(PCM_ENCODING, CHANNEL_COUNT) * 1024];
 
   private final long durationUs;
-  @Nullable private final Object tag;
+  private final MediaItem mediaItem;
 
   /**
    * Creates a new media source providing silent audio of the given duration.
@@ -91,13 +107,19 @@ public final class SilenceMediaSource extends BaseMediaSource {
    * @param durationUs The duration of silent audio to output, in microseconds.
    */
   public SilenceMediaSource(long durationUs) {
-    this(durationUs, /* tag= */ null);
+    this(durationUs, MEDIA_ITEM);
   }
 
-  private SilenceMediaSource(long durationUs, @Nullable Object tag) {
+  /**
+   * Creates a new media source providing silent audio of the given duration.
+   *
+   * @param durationUs The duration of silent audio to output, in microseconds.
+   * @param mediaItem The media item associated with this media source.
+   */
+  private SilenceMediaSource(long durationUs, MediaItem mediaItem) {
     Assertions.checkArgument(durationUs >= 0);
     this.durationUs = durationUs;
-    this.tag = tag;
+    this.mediaItem = mediaItem;
   }
 
   @Override
@@ -109,7 +131,7 @@ public final class SilenceMediaSource extends BaseMediaSource {
             /* isDynamic= */ false,
             /* isLive= */ false,
             /* manifest= */ null,
-            tag));
+            mediaItem));
   }
 
   @Override
@@ -123,6 +145,12 @@ public final class SilenceMediaSource extends BaseMediaSource {
   @Override
   public void releasePeriod(MediaPeriod mediaPeriod) {}
 
+  /** Returns the {@link MediaItem} of this media source. */
+  // TODO(bachinger): add @Override annotation once the method is defined by MediaSource.
+  public MediaItem getMediaItem() {
+    return mediaItem;
+  }
+
   @Override
   protected void releaseSourceInternal() {}
 

library/core/src/test/java/com/google/android/exoplayer2/source/SilenceMediaSourceTest.java

+/*
+ * Copyright 2020 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.source;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.assertThrows;
+
+import android.net.Uri;
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import com.google.android.exoplayer2.MediaItem;
+import com.google.android.exoplayer2.util.MimeTypes;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+/** Unit tests for {@link SilenceMediaSource}. */
+@RunWith(AndroidJUnit4.class)
+public class SilenceMediaSourceTest {
+
+  @Test
+  public void builder_setsMediaItem() {
+    SilenceMediaSource mediaSource =
+        new SilenceMediaSource.Factory().setDurationUs(1_000_000).createMediaSource();
+
+    MediaItem mediaItem = mediaSource.getMediaItem();
+
+    assertThat(mediaItem).isNotNull();
+    assertThat(mediaItem.mediaId).isEqualTo(SilenceMediaSource.MEDIA_ID);
+    assertThat(mediaItem.playbackProperties.uri).isEqualTo(Uri.EMPTY);
+    assertThat(mediaItem.playbackProperties.mimeType).isEqualTo(MimeTypes.AUDIO_RAW);
+  }
+
+  @Test
+  public void builderSetTag_setsTagOfMediaItem() {
+    Object tag = new Object();
+
+    SilenceMediaSource mediaSource =
+        new SilenceMediaSource.Factory().setTag(tag).setDurationUs(1_000_000).createMediaSource();
+
+    assertThat(mediaSource.getMediaItem().playbackProperties.tag).isEqualTo(tag);
+  }
+
+  @Test
+  public void builder_setDurationUsNotCalled_throwsIllegalStateException() {
+    assertThrows(IllegalStateException.class, new SilenceMediaSource.Factory()::createMediaSource);
+  }
+
+  @Test
+  public void builderSetDurationUs_nonPositiveValue_throwsIllegalStateException() {
+    SilenceMediaSource.Factory factory = new SilenceMediaSource.Factory().setDurationUs(-1);
+
+    assertThrows(IllegalStateException.class, factory::createMediaSource);
+  }
+
+  @Test
+  public void newInstance_setsMediaItem() {
+    SilenceMediaSource mediaSource = new SilenceMediaSource(1_000_000);
+
+    MediaItem mediaItem = mediaSource.getMediaItem();
+
+    assertThat(mediaItem).isNotNull();
+    assertThat(mediaItem.mediaId).isEqualTo(SilenceMediaSource.MEDIA_ID);
+    assertThat(mediaSource.getMediaItem().playbackProperties.uri).isEqualTo(Uri.EMPTY);
+    assertThat(mediaItem.playbackProperties.mimeType).isEqualTo(MimeTypes.AUDIO_RAW);
+  }
+}