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Correct tie-breaking rules when selecting fixed video track

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This commit is contained in:
Arnold Szabo 2020-05-31 23:40:10 +03:00
parent dfec0338c5
commit a1ebffd238
1 changed files with 43 additions and 21 deletions
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56
library/core/src/main/java/com/google/android/exoplayer2/trackselection/DefaultTrackSelector.java
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@ -1498,6 +1498,14 @@ public class DefaultTrackSelector extends MappingTrackSelector {
private static final float FRACTION_TO_CONSIDER_FULLSCREEN = 0.98f;
private static final int[] NO_TRACKS = new int[0];
private static final int WITHIN_RENDERER_CAPABILITIES_BONUS = 1000;
/**
* In case when both min and max constraints are set, give the track higher score which satisfies
* the max constraints, as it is more important to not violate the max constraints than min
* constraints, because it's more likely to play successfully when max constraints are satisfied.
*/
private static final int SATISFIES_MIN_CONSTRAINTS_BONUS = 1;
private static final int SATISFIES_MAX_CONSTRAINTS_BONUS = 2;
private final TrackSelection.Factory trackSelectionFactory;
private final AtomicReference<Parameters> parametersReference;
@ -2040,8 +2048,6 @@ public class DefaultTrackSelector extends MappingTrackSelector {
int selectedTrackScore = 0;
int selectedBitrate = Format.NO_VALUE;
int selectedPixelCount = Format.NO_VALUE;
boolean selectedSatisfiesMaxConstraints;
boolean selectedSatisfiesMinConstraints;
for (int groupIndex = 0; groupIndex < groups.length; groupIndex++) {
TrackGroup trackGroup = groups.get(groupIndex);
List<Integer> selectedTrackIndices = getViewportFilteredTrackIndices(trackGroup,
@ -2076,34 +2082,52 @@ public class DefaultTrackSelector extends MappingTrackSelector {
continue;
}
int trackScore = 1;
if (satisfiesMaxConstraints) {
trackScore += 1;
}
if (satisfiesMinConstraints) {
trackScore += 1;
}
boolean isWithinCapabilities = isSupported(trackFormatSupport[trackIndex], false);
if (isWithinCapabilities) {
trackScore += WITHIN_RENDERER_CAPABILITIES_BONUS;
}
if (satisfiesMaxConstraints) {
trackScore += SATISFIES_MAX_CONSTRAINTS_BONUS;
}
if (satisfiesMinConstraints) {
trackScore += SATISFIES_MIN_CONSTRAINTS_BONUS;
}
boolean selectTrack = trackScore > selectedTrackScore;
// Handling tie-breaking scenarios.
if (trackScore == selectedTrackScore) {
// TODO handle tie breaker cases correctly.
int bitrateComparison = compareFormatValues(format.bitrate, selectedBitrate);
if (params.forceLowestBitrate && bitrateComparison != 0) {
// Use bitrate as a tie breaker, preferring the lower bitrate.
selectTrack = bitrateComparison < 0;
} else {
// Use the pixel count as a tie breaker (or bitrate if pixel counts are tied). If
// we're within constraints prefer a higher pixel count (or bitrate), else prefer a
// lower count (or bitrate). If still tied then prefer the first track (i.e. the one
// that's already selected).
// Use the pixel count as a tie breaker (or bitrate if pixel counts are tied).
int formatPixelCount = format.getPixelCount();
int comparisonResult = formatPixelCount != selectedPixelCount
? compareFormatValues(formatPixelCount, selectedPixelCount)
: compareFormatValues(format.bitrate, selectedBitrate);
selectTrack = isWithinCapabilities && satisfiesMaxConstraints
? comparisonResult > 0 : comparisonResult < 0;
// If it's not within the capabilities, always pick lower quality because it's more
// likely to play successfully.
if (!isWithinCapabilities) {
selectTrack = comparisonResult < 0;
} else {
if (satisfiesMinConstraints && satisfiesMaxConstraints) {
// Both constraints are satisfied, pick higher quality.
selectTrack = comparisonResult > 0;
} else if (!satisfiesMinConstraints && satisfiesMaxConstraints) {
// Min constraints are not satisfied but the max constraints are, pick higher
// quality, because that's what gets us closest to satisfying the violated min
// constraints.
selectTrack = comparisonResult > 0;
} else if (satisfiesMinConstraints) {
// Min constraints are satisfied but not the max constraints, pick lower quality
// because that's what gets us closest to satisfying the violated max constraints.
selectTrack = comparisonResult > 0;
} else {
// Neither min or max constraints are not satisfied, pick lower quality because
// it's more likely to play successfully.
selectTrack = comparisonResult < 0;
}
}
}
}
if (selectTrack) {
@ -2112,8 +2136,6 @@ public class DefaultTrackSelector extends MappingTrackSelector {
selectedTrackScore = trackScore;
selectedBitrate = format.bitrate;
selectedPixelCount = format.getPixelCount();
selectedSatisfiesMaxConstraints = satisfiesMaxConstraints;
selectedSatisfiesMinConstraints = satisfiesMinConstraints;
}
}
}