From 418726d04ba228add8d27381663fc3d56d2cdfe4 Mon Sep 17 00:00:00 2001
From: tonihei <tonihei@google.com>
Date: Mon, 14 Feb 2022 12:39:14 +0000
Subject: [PATCH] Make usage of live minDurationForQualityIncrease more
 consistent

We have two ways to choose the minDurationForQualityIncreaseMs value in
AdaptiveTrackSelection: use the configured value for non-live or when
enough buffered data is available, or use a fraction of the available
duration to allow switching when playing close to the live edge.

The decision point when to use which value isn't quite consistent because
we compare against availableDurationUs before making the adjustments. This
means there is range of values where no up-switching is possible despite
perfect buffering. Fix this by choosing the minimum of both values.

Issue: google/ExoPlayer#9784

#minor-release

PiperOrigin-RevId: 428474332
---
 .../trackselection/AdaptiveTrackSelection.java       | 11 ++++++-----
 .../trackselection/AdaptiveTrackSelectionTest.java   | 12 +++++++++---
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/trackselection/AdaptiveTrackSelection.java b/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/trackselection/AdaptiveTrackSelection.java
index 40dfa34a12d..0d1c02e80f6 100644
--- a/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/trackselection/AdaptiveTrackSelection.java
+++ b/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/trackselection/AdaptiveTrackSelection.java
@@ -16,6 +16,7 @@
 package androidx.media3.exoplayer.trackselection;
 
 import static java.lang.Math.max;
+import static java.lang.Math.min;
 
 import androidx.annotation.CallSuper;
 import androidx.annotation.Nullable;
@@ -605,10 +606,8 @@ private int determineIdealSelectedIndex(long nowMs, long chunkDurationUs) {
   }
 
   private long minDurationForQualityIncreaseUs(long availableDurationUs, long chunkDurationUs) {
-    boolean isAvailableDurationTooShort =
-        availableDurationUs != C.TIME_UNSET
-            && availableDurationUs <= minDurationForQualityIncreaseUs;
-    if (!isAvailableDurationTooShort) {
+    if (availableDurationUs == C.TIME_UNSET) {
+      // We are not in a live stream. Use the configured value.
       return minDurationForQualityIncreaseUs;
     }
     if (chunkDurationUs != C.TIME_UNSET) {
@@ -619,7 +618,9 @@ private long minDurationForQualityIncreaseUs(long availableDurationUs, long chun
       // actually achievable.
       availableDurationUs -= chunkDurationUs;
     }
-    return (long) (availableDurationUs * bufferedFractionToLiveEdgeForQualityIncrease);
+    long adjustedMinDurationForQualityIncreaseUs =
+        (long) (availableDurationUs * bufferedFractionToLiveEdgeForQualityIncrease);
+    return min(adjustedMinDurationForQualityIncreaseUs, minDurationForQualityIncreaseUs);
   }
 
   /**
diff --git a/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/trackselection/AdaptiveTrackSelectionTest.java b/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/trackselection/AdaptiveTrackSelectionTest.java
index f2915110f96..b8cc647d9f2 100644
--- a/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/trackselection/AdaptiveTrackSelectionTest.java
+++ b/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/trackselection/AdaptiveTrackSelectionTest.java
@@ -175,7 +175,9 @@ public void updateSelectedTrack_liveStream_switchesUpWhenBufferedFractionToLiveE
     when(mockBandwidthMeter.getBitrateEstimate()).thenReturn(1000L, 2000L);
     AdaptiveTrackSelection adaptiveTrackSelection =
         prepareAdaptiveTrackSelectionWithBufferedFractionToLiveEdgeForQualiyIncrease(
-            trackGroup, /* bufferedFractionToLiveEdgeForQualityIncrease= */ 0.75f);
+            trackGroup,
+            /* bufferedFractionToLiveEdgeForQualityIncrease= */ 0.75f,
+            /* minDurationForQualityIncreaseMs= */ 5000);
 
     // Not buffered close to live edge yet.
     adaptiveTrackSelection.updateSelectedTrack(
@@ -188,6 +190,8 @@ public void updateSelectedTrack_liveStream_switchesUpWhenBufferedFractionToLiveE
     assertThat(adaptiveTrackSelection.getSelectedFormat()).isEqualTo(format2);
 
     // Buffered all possible chunks (except for newly added chunk of 2 seconds).
+    // Intentionally choose a situation where availableDurationUs > minDurationForQualityIncreaseMs
+    // to ensure the live calculation is used regardless.
     adaptiveTrackSelection.updateSelectedTrack(
         /* playbackPositionUs= */ 0,
         /* bufferedDurationUs= */ 3_600_000,
@@ -768,14 +772,16 @@ private AdaptiveTrackSelection prepareAdaptiveTrackSelectionWithMaxResolutionToD
 
   private AdaptiveTrackSelection
       prepareAdaptiveTrackSelectionWithBufferedFractionToLiveEdgeForQualiyIncrease(
-          TrackGroup trackGroup, float bufferedFractionToLiveEdgeForQualityIncrease) {
+          TrackGroup trackGroup,
+          float bufferedFractionToLiveEdgeForQualityIncrease,
+          long minDurationForQualityIncreaseMs) {
     return prepareTrackSelection(
         new AdaptiveTrackSelection(
             trackGroup,
             selectedAllTracksInGroup(trackGroup),
             TrackSelection.TYPE_UNSET,
             mockBandwidthMeter,
-            AdaptiveTrackSelection.DEFAULT_MIN_DURATION_FOR_QUALITY_INCREASE_MS,
+            minDurationForQualityIncreaseMs,
             AdaptiveTrackSelection.DEFAULT_MAX_DURATION_FOR_QUALITY_DECREASE_MS,
             AdaptiveTrackSelection.DEFAULT_MIN_DURATION_TO_RETAIN_AFTER_DISCARD_MS,
             AdaptiveTrackSelection.DEFAULT_MAX_WIDTH_TO_DISCARD,