Simplify and improve text selection logic.

This changes the logic in the following ways:
 - If no preferred language is matched, prefer better scores for the selected
   audio language.
 - If a preferred language is matched, always prefer the better match
   irrespective of default or forced flags.
 - If a preferred language score and the isForced flag is the same, prefer
   tracks with a better selected audio language match.

PiperOrigin-RevId: 259707430
This commit is contained in:
tonihei 2019-07-24 11:05:27 +01:00 committed by Toni
parent feb807897f
commit e84d88e90f
2 changed files with 17 additions and 20 deletions

View File

@ -34,6 +34,8 @@
([#6153](https://github.com/google/ExoPlayer/issues/6153)).
* Add ability to specify a description when creating notification channels via
ExoPlayer library classes.
* Improve text selection logic to always prefer the better language matches
over other selection parameters.
### 2.10.3 ###

View File

@ -2536,9 +2536,9 @@ public class DefaultTrackSelector extends MappingTrackSelector {
private final boolean isWithinRendererCapabilities;
private final boolean isDefault;
private final boolean isForced;
private final boolean hasPreferredIsForcedFlag;
private final int preferredLanguageScore;
private final boolean isForcedAndSelectedAudioLanguage;
private final int selectedAudioLanguageScore;
public TextTrackScore(
Format format,
@ -2550,17 +2550,21 @@ public class DefaultTrackSelector extends MappingTrackSelector {
int maskedSelectionFlags =
format.selectionFlags & ~parameters.disabledTextTrackSelectionFlags;
isDefault = (maskedSelectionFlags & C.SELECTION_FLAG_DEFAULT) != 0;
isForced = (maskedSelectionFlags & C.SELECTION_FLAG_FORCED) != 0;
boolean isForced = (maskedSelectionFlags & C.SELECTION_FLAG_FORCED) != 0;
preferredLanguageScore =
getFormatLanguageScore(
format, parameters.preferredTextLanguage, parameters.selectUndeterminedTextLanguage);
// Prefer non-forced to forced if a preferred text language has been matched. Where both are
// provided the non-forced track will usually contain the forced subtitles as a subset.
// Otherwise, prefer a forced track.
hasPreferredIsForcedFlag =
(preferredLanguageScore > 0 && !isForced) || (preferredLanguageScore == 0 && isForced);
boolean selectedAudioLanguageUndetermined =
normalizeUndeterminedLanguageToNull(selectedAudioLanguage) == null;
int selectedAudioLanguageScore =
selectedAudioLanguageScore =
getFormatLanguageScore(format, selectedAudioLanguage, selectedAudioLanguageUndetermined);
isForcedAndSelectedAudioLanguage = isForced && selectedAudioLanguageScore > 0;
isWithinConstraints =
preferredLanguageScore > 0 || isDefault || isForcedAndSelectedAudioLanguage;
preferredLanguageScore > 0 || isDefault || (isForced && selectedAudioLanguageScore > 0);
}
/**
@ -2575,25 +2579,16 @@ public class DefaultTrackSelector extends MappingTrackSelector {
if (this.isWithinRendererCapabilities != other.isWithinRendererCapabilities) {
return this.isWithinRendererCapabilities ? 1 : -1;
}
if ((this.preferredLanguageScore > 0) != (other.preferredLanguageScore > 0)) {
return this.preferredLanguageScore > 0 ? 1 : -1;
if (this.preferredLanguageScore != other.preferredLanguageScore) {
return compareInts(this.preferredLanguageScore, other.preferredLanguageScore);
}
if (this.isDefault != other.isDefault) {
return this.isDefault ? 1 : -1;
}
if (this.preferredLanguageScore > 0) {
if (this.isForced != other.isForced) {
// Prefer non-forced to forced if a preferred text language has been specified. Where
// both are provided the non-forced track will usually contain the forced subtitles as
// a subset.
return !this.isForced ? 1 : -1;
}
return compareInts(this.preferredLanguageScore, other.preferredLanguageScore);
if (this.hasPreferredIsForcedFlag != other.hasPreferredIsForcedFlag) {
return this.hasPreferredIsForcedFlag ? 1 : -1;
}
if (this.isForcedAndSelectedAudioLanguage != other.isForcedAndSelectedAudioLanguage) {
return this.isForcedAndSelectedAudioLanguage ? 1 : -1;
}
return 0;
return compareInts(this.selectedAudioLanguageScore, other.selectedAudioLanguageScore);
}
}
}