feat: vod dynamic playback rate buffer control (#6172)

Dynamically update playback rate to keep the buffer full. Related to #6131
shaka-project · Feb 2, 2024 · 8fc292b · 8fc292b
1 parent 278c7bc
commit 8fc292b
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Showing 4 changed files with 63 additions and 11 deletions.
diff --git a/demo/config.js b/demo/config.js
@@ -476,15 +476,23 @@ shakaDemo.Config = class {
             /* canBeZero= */ true)
         .addNumberInput_('Min playback rate for live sync',
             'streaming.liveSyncMinPlaybackRate',
-            /* canBeDecimal= */ true,
-            /* canBeZero= */ false)
+            /* canBeDecimal= */ true)
         .addBoolInput_('Live Sync Panic Mode', 'streaming.liveSyncPanicMode')
         .addNumberInput_('Live Sync Panic Mode Threshold',
             'streaming.liveSyncPanicThreshold')
         .addBoolInput_('Allow Media Source recoveries',
             'streaming.allowMediaSourceRecoveries')
         .addNumberInput_('Minimum time between recoveries',
-            'streaming.minTimeBetweenRecoveries');
+            'streaming.minTimeBetweenRecoveries')
+        .addBoolInput_('VOD Dynamic Playback Rate Buffer Control',
+            'streaming.vodDynamicPlaybackRate')
+        .addNumberInput_('VOD Dynamic Playback Rate Low Buffer Rate',
+            'streaming.vodDynamicPlaybackRateLowBufferRate',
+            /* canBeDecimal= */ true)
+        .addNumberInput_('VOD Dynamic Playback Rate Buffer Ratio',
+            'streaming.vodDynamicPlaybackRateBufferRatio',
+            /* canBeDecimal= */ true);
+
 
     if (!shakaDemoMain.getNativeControlsEnabled()) {
       this.addBoolInput_('Always Stream Text', 'streaming.alwaysStreamText');

diff --git a/externs/shaka/player.js b/externs/shaka/player.js
@@ -1171,7 +1171,10 @@ shaka.extern.ManifestConfiguration;
  *   liveSyncPanicMode: boolean,
  *   liveSyncPanicThreshold: number,
  *   allowMediaSourceRecoveries: boolean,
- *   minTimeBetweenRecoveries: number
+ *   minTimeBetweenRecoveries: number,
+ *   vodDynamicPlaybackRate: boolean,
+ *   vodDynamicPlaybackRateLowBufferRate: number,
+ *   vodDynamicPlaybackRateBufferRatio: number
  * }}
  *
  * @description
@@ -1338,6 +1341,17 @@ shaka.extern.ManifestConfiguration;
  *   The minimum time between recoveries when VIDEO_ERROR is reached, in
  *   seconds.
  *   Defaults to <code>5</code>.
+ * @property {boolean} vodDynamicPlaybackRate
+ *   Adapt the playback rate of the player to keep the buffer full. Defaults to
+ *   <code>false</code>.
+ * @property {number} vodDynamicPlaybackRateLowBufferRate
+ *   Playback rate to use if the buffer is too small. Defaults to
+ *   <code>0.95</code>.
+ * @property {number} vodDynamicPlaybackRateBufferRatio
+ *   Ratio of the <code>bufferingGoal</code> as the low threshold for
+ *   setting the playback rate to
+ *   <code>vodDynamicPlaybackRateLowBufferRate</code>.
+ *   Defaults to <code>0.5</code>.
  * @exportDoc
  */
 shaka.extern.StreamingConfiguration;

diff --git a/lib/player.js b/lib/player.js
@@ -2065,9 +2065,10 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
 
     const isLive = this.isLive();
 
-    if (isLive && (this.config_.streaming.liveSync ||
+    if ((isLive && (this.config_.streaming.liveSync ||
         this.manifest_.serviceDescription ||
-        this.config_.streaming.liveSyncPanicMode)) {
+        this.config_.streaming.liveSyncPanicMode)) ||
+        this.config_.streaming.vodDynamicPlaybackRate) {
       const onTimeUpdate = () => this.onTimeUpdate_();
       this.loadEventManager_.listen(mediaElement, 'timeupdate', onTimeUpdate);
     } else if (!isLive) {
@@ -2398,8 +2399,9 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
 
     const isLive = this.isLive();
 
-    if (isLive && (this.config_.streaming.liveSync ||
-        this.config_.streaming.liveSyncPanicMode)) {
+    if ((isLive && (this.config_.streaming.liveSync ||
+        this.config_.streaming.liveSyncPanicMode)) ||
+        this.config_.streaming.vodDynamicPlaybackRate) {
       const onTimeUpdate = () => this.onTimeUpdate_();
       this.loadEventManager_.listen(mediaElement, 'timeupdate', onTimeUpdate);
     } else if (!isLive) {
@@ -5672,15 +5674,41 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
   }
 
   /**
-   * Callback for liveSync
+   * Callback for liveSync and vodDynamicPlaybackRate
    *
    * @private
    */
   onTimeUpdate_() {
+    const playbackRate = this.video_.playbackRate;
+    const isLive = this.isLive();
+
+    if (this.config_.streaming.vodDynamicPlaybackRate && !isLive) {
+      const minPlaybackRate =
+        this.config_.streaming.vodDynamicPlaybackRateLowBufferRate;
+      const bufferFullness = this.getBufferFullness();
+      const bufferThreshold =
+        this.config_.streaming.vodDynamicPlaybackRateBufferRatio;
+
+      if (bufferFullness <= bufferThreshold) {
+        if (playbackRate != minPlaybackRate) {
+          shaka.log.debug('Buffer fullness ratio (' + bufferFullness + ') ' +
+            'is less than the vodDynamicPlaybackRateBufferRatio (' +
+            bufferThreshold + '). Updating playbackRate to ' + minPlaybackRate);
+          this.trickPlay(minPlaybackRate);
+        }
+      } else if (bufferFullness == 1) {
+        if (playbackRate !== this.playRateController_.getDefaultRate()) {
+          shaka.log.debug('Buffer is full. Cancel trick play.');
+          this.cancelTrickPlay();
+        }
+      }
+    }
+
     // If the live stream has reached its end, do not sync.
-    if (!this.isLive()) {
+    if (!isLive) {
       return;
     }
+
     const seekRange = this.seekRange();
     if (!Number.isFinite(seekRange.end)) {
       return;
@@ -5725,7 +5753,6 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
       }
     }
 
-    const playbackRate = this.video_.playbackRate;
     const latency = seekRange.end - this.video_.currentTime;
     let offset = 0;
     // In src= mode, the seek range isn't updated frequently enough, so we need

diff --git a/lib/util/player_configuration.js b/lib/util/player_configuration.js
@@ -235,6 +235,9 @@ shaka.util.PlayerConfiguration = class {
       liveSyncPanicThreshold: 60,
       allowMediaSourceRecoveries: true,
       minTimeBetweenRecoveries: 5,
+      vodDynamicPlaybackRate: false,
+      vodDynamicPlaybackRateLowBufferRate: 0.95,
+      vodDynamicPlaybackRateBufferRatio: 0.5,
     };
 
     // WebOS, Tizen, Chromecast and Hisense have long hardware pipelines