Use the content URI as well as mediaId for the auto-generated ad ID

MediaItem.mediaId used to default to the content URI, but this changed:
cc26a92

Before the mediaId change linked above, a playlist of different content
all with the same ad URI would play the ads for every item. After the
change the ad would only play once (because mediaId == "" for every
item, so they're all the same). This change restores roughly the
original behaviour by always considering both mediaId and the content
URI.

Issue: #9106
PiperOrigin-RevId: 382763618

RELEASENOTES.md

@@ -35,6 +35,10 @@
         ([#9004](https://github.com/google/ExoPlayer/issues/9004)).
     *   Forward the FRAME-RATE value from the master playlist to renditions.
         ([#8960](https://github.com/google/ExoPlayer/issues/8960)).
+*   Ad playback:
+    *   Use the content URI when auto-generating an ad ID (in addition to the
+        media ID and ad tag URI)
+        ([#9106](https://github.com/google/ExoPlayer/issues/9106).
 *   DRM:
     *   Allow repeated provisioning in `DefaultDrmSession(Manager)`.
 *   Metadata:

docs/ad-insertion.md

@@ -67,12 +67,12 @@ described below.
 ### Playlists with ads ###
 
 When playing a [playlist][] with multiple media items, the default behavior is
-to request the ad tag and store ad playback state once for each media ID and ad
-tag URI combination. This means that users will see ads for every media item
-with ads that has a distinct media ID, even if the ad tag URIs match. If a
-media item is repeated, the user will see the corresponding ads only once (the
-ad playback state stores whether ads have been played, so they are skipped
-after their first occurrence).
+to request the ad tag and store ad playback state once for each media ID,
+content URI and ad tag URI combination. This means that users will see ads for
+every media item with ads that has a distinct media ID or content URI, even if
+the ad tag URIs match. If a media item is repeated, the user will see the
+corresponding ads only once (the ad playback state stores whether ads have been
+played, so they are skipped after their first occurrence).
 
 It's possible to customize this behavior by passing an opaque ads identifier
 with which ad playback state for a given media item is linked, based on object

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

@@ -18,7 +18,6 @@
 import static com.google.android.exoplayer2.util.Util.castNonNull;
 
 import android.content.Context;
-import android.util.Pair;
 import android.util.SparseArray;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
@@ -40,6 +39,7 @@
 import com.google.android.exoplayer2.util.Log;
 import com.google.android.exoplayer2.util.MimeTypes;
 import com.google.android.exoplayer2.util.Util;
+import com.google.common.collect.ImmutableList;
 import java.util.Arrays;
 import java.util.List;
 
@@ -427,7 +427,8 @@ private MediaSource maybeWrapWithAdsMediaSource(MediaItem mediaItem, MediaSource
         new DataSpec(adsConfiguration.adTagUri),
         /* adsId= */ adsConfiguration.adsId != null
             ? adsConfiguration.adsId
-            : Pair.create(mediaItem.mediaId, adsConfiguration.adTagUri),
+            : ImmutableList.of(
+                mediaItem.mediaId, mediaItem.playbackProperties.uri, adsConfiguration.adTagUri),
         /* adMediaSourceFactory= */ this,
         adsLoader,
         adViewProvider);