Optimize short form content demo app

PiperOrigin-RevId: 592225900

demos/shortform/src/main/java/androidx/media3/demo/shortform/MediaSourceManager.kt

@@ -82,7 +82,7 @@ class MediaSourceManager(
     }
   }
 
-  operator fun get(mediaItem: MediaItem): MediaSource {
+  operator fun get(mediaItem: MediaItem): PreloadMediaSource {
     if (!sourceMap.containsKey(mediaItem)) {
       add(mediaItem)
     }

demos/shortform/src/main/java/androidx/media3/demo/shortform/PlayerPool.kt

@@ -19,6 +19,7 @@ import android.content.Context
 import android.os.Handler
 import android.os.Looper
 import androidx.annotation.OptIn
+import androidx.media3.common.Player
 import androidx.media3.common.util.UnstableApi
 import androidx.media3.exoplayer.ExoPlayer
 import androidx.media3.exoplayer.LoadControl
@@ -80,6 +81,25 @@ class PlayerPool(
     }
   }
 
+  /** Calls [Player.play()] for the given player and pauses all other players. */
+  fun play(player: Player) {
+    pauseAllPlayers(player)
+    player.play()
+  }
+
+  /**
+   * Pauses all players.
+   *
+   * @param keepOngoingPlayer The optional player that should keep playing if not paused.
+   */
+  fun pauseAllPlayers(keepOngoingPlayer: Player? = null) {
+    playerMap.values.forEach {
+      if (it != keepOngoingPlayer) {
+        it.pause()
+      }
+    }
+  }
+
   fun releasePlayer(token: Int, player: ExoPlayer?) {
     synchronized(playerMap) {
       // Remove token from set of views requesting players & remove potential callbacks

demos/shortform/src/main/java/androidx/media3/demo/shortform/viewpager/ViewPagerActivity.kt

@@ -43,20 +43,11 @@ class ViewPagerActivity : AppCompatActivity() {
     Log.d("viewpager", "Backward cache is of size: ${mediaItemDatabase.lCacheSize}")
     Log.d("viewpager", "Forward cache is of size: ${mediaItemDatabase.rCacheSize}")
     viewPagerView = findViewById(R.id.viewPager)
+    viewPagerView.offscreenPageLimit = 1
     viewPagerView.registerOnPageChangeCallback(
       object : ViewPager2.OnPageChangeCallback() {
-        override fun onPageScrolled(
-          position: Int,
-          positionOffset: Float,
-          positionOffsetPixels: Int
-        ) {}
-
-        override fun onPageScrollStateChanged(state: Int) {
-          Log.d("viewpager", "onPageScrollStateChanged: state=$state")
-        }
-
         override fun onPageSelected(position: Int) {
-          Log.d("viewpager", "onPageSelected: position=$position")
+          adapter.play(position)
         }
       }
     )

demos/shortform/src/main/java/androidx/media3/demo/shortform/viewpager/ViewPagerMediaAdapter.kt

@@ -30,7 +30,7 @@ import androidx.media3.demo.shortform.R
 import androidx.media3.exoplayer.DefaultLoadControl
 import androidx.media3.exoplayer.DefaultRenderersFactory
 import androidx.media3.exoplayer.ExoPlayer
-import androidx.media3.exoplayer.source.ProgressiveMediaSource
+import androidx.media3.exoplayer.source.DefaultMediaSourceFactory
 import androidx.media3.exoplayer.trackselection.DefaultTrackSelector
 import androidx.media3.exoplayer.upstream.DefaultBandwidthMeter
 import androidx.media3.exoplayer.util.EventLogger
@@ -47,6 +47,7 @@ class ViewPagerMediaAdapter(
   private val mediaSourceManager: MediaSourceManager
   private var viewCounter = 0
   private var playerPool: PlayerPool
+  private val holderMap: MutableMap<Int, ViewPagerMediaHolder>
 
   init {
     playbackThread.start()
@@ -61,9 +62,10 @@ class ViewPagerMediaAdapter(
         renderersFactory,
         DefaultBandwidthMeter.getSingletonInstance(context)
       )
+    holderMap = mutableMapOf()
     mediaSourceManager =
       MediaSourceManager(
-        ProgressiveMediaSource.Factory(DefaultDataSource.Factory(context)),
+        DefaultMediaSourceFactory(DefaultDataSource.Factory(context)),
         playbackThread.looper,
         loadControl.allocator,
         renderersFactory,
@@ -99,6 +101,14 @@ class ViewPagerMediaAdapter(
     mediaSourceManager.addAll(reachableMediaItems)
   }
 
+  override fun onViewAttachedToWindow(holder: ViewPagerMediaHolder) {
+    holderMap[holder.currentToken] = holder
+  }
+
+  override fun onViewDetachedFromWindow(holder: ViewPagerMediaHolder) {
+    holderMap.remove(holder.currentToken)
+  }
+
   override fun getItemCount(): Int {
     // Effectively infinite scroll
     return Int.MAX_VALUE
@@ -106,7 +116,6 @@ class ViewPagerMediaAdapter(
 
   override fun onViewRecycled(holder: ViewPagerMediaHolder) {
     super.onViewRecycled(holder)
-    Log.d("viewpager", "Recycling the view")
   }
 
   fun onDestroy() {
@@ -115,6 +124,10 @@ class ViewPagerMediaAdapter(
     mediaSourceManager.release()
   }
 
+  fun play(position: Int) {
+    holderMap[position]?.let { holder -> holder.player?.let { playerPool.play(it) } }
+  }
+
   inner class Factory : PlayerPool.PlayerFactory {
     private var playerCounter = 0
 
@@ -122,10 +135,10 @@ class ViewPagerMediaAdapter(
       val loadControl =
         DefaultLoadControl.Builder()
           .setBufferDurationsMs(
-            DefaultLoadControl.DEFAULT_MIN_BUFFER_MS,
-            DefaultLoadControl.DEFAULT_MAX_BUFFER_MS,
-            /* bufferForPlaybackMs= */ 0,
-            DefaultLoadControl.DEFAULT_BUFFER_FOR_PLAYBACK_AFTER_REBUFFER_MS
+            /* minBufferMs= */ 15_000,
+            /* maxBufferMs= */ 15_000,
+            /* bufferForPlaybackMs= */ 500,
+            /* bufferForPlaybackAfterRebufferMs= */ 1_000
           )
           .build()
       val player = ExoPlayer.Builder(context).setLoadControl(loadControl).build()

demos/shortform/src/main/java/androidx/media3/demo/shortform/viewpager/ViewPagerMediaHolder.kt

@@ -18,25 +18,27 @@ package androidx.media3.demo.shortform.viewpager
 import android.util.Log
 import android.view.View
 import androidx.annotation.OptIn
+import androidx.media3.common.Player
 import androidx.media3.common.util.UnstableApi
 import androidx.media3.demo.shortform.PlayerPool
 import androidx.media3.demo.shortform.R
 import androidx.media3.exoplayer.ExoPlayer
-import androidx.media3.exoplayer.source.MediaSource
+import androidx.media3.exoplayer.source.preload.PreloadMediaSource
 import androidx.media3.ui.PlayerView
 import androidx.recyclerview.widget.RecyclerView
 
+@OptIn(UnstableApi::class) // Using PreloadMediaSource.
 class ViewPagerMediaHolder(
   itemView: View,
   private val viewCounter: Int,
   private val playerPool: PlayerPool
 ) : RecyclerView.ViewHolder(itemView), View.OnAttachStateChangeListener {
   private val playerView: PlayerView = itemView.findViewById(R.id.player_view)
-  private var player: ExoPlayer? = null
+  private var exoPlayer: ExoPlayer? = null
   private var isInView: Boolean = false
   private var token: Int = -1
 
-  private lateinit var mediaSource: MediaSource
+  private lateinit var mediaSource: PreloadMediaSource
 
   init {
     // Define click listener for the ViewHolder's View
@@ -47,7 +49,16 @@ class ViewPagerMediaHolder(
     }
   }
 
-  @OptIn(UnstableApi::class)
+  val currentToken: Int
+    get() {
+      return token
+    }
+
+  val player: Player?
+    get() {
+      return exoPlayer
+    }
+
   override fun onViewAttachedToWindow(view: View) {
     Log.d("viewpager", "onViewAttachedToWindow: $viewCounter")
     isInView = true
@@ -59,36 +70,37 @@ class ViewPagerMediaHolder(
   override fun onViewDetachedFromWindow(view: View) {
     Log.d("viewpager", "onViewDetachedFromWindow: $viewCounter")
     isInView = false
-    releasePlayer(player)
+    releasePlayer(exoPlayer)
+    // This is a hacky way of keep preloading sources that are removed from players. This does only
+    // work because the demo app cycles endlessly through the same 5 URIs. Preloading is still
+    // uncoordinated meaning it just preloading as soon as this method is called.
+    mediaSource.preload(0)
   }
 
-  fun bindData(token: Int, mediaSource: MediaSource) {
+  fun bindData(token: Int, mediaSource: PreloadMediaSource) {
     this.mediaSource = mediaSource
     this.token = token
   }
 
-  @OptIn(UnstableApi::class)
   fun releasePlayer(player: ExoPlayer?) {
-    playerPool.releasePlayer(token, player ?: this.player)
-    this.player = null
+    playerPool.releasePlayer(token, player ?: exoPlayer)
+    this.exoPlayer = null
     playerView.player = null
   }
 
-  @OptIn(UnstableApi::class)
   fun setupPlayer(player: ExoPlayer) {
     if (!isInView) {
       releasePlayer(player)
     } else {
-      if (player != this.player) {
-        releasePlayer(this.player)
+      if (player != exoPlayer) {
+        releasePlayer(exoPlayer)
       }
 
       player.run {
         repeatMode = ExoPlayer.REPEAT_MODE_ONE
         setMediaSource(mediaSource)
         seekTo(currentPosition)
-        playWhenReady = true
-        this@ViewPagerMediaHolder.player = player
+        this@ViewPagerMediaHolder.exoPlayer = player
         player.prepare()
         playerView.player = player
       }