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#pragma warning disable CS1591
using System;
using System.Collections.Generic;
using System.Linq;
using Jellyfin.Database.Implementations.Enums;
using Jellyfin.Extensions;
using MediaBrowser.Model.Entities;
namespace Emby.Server.Implementations.Library
{
public static class MediaStreamSelector
{
public static int? GetDefaultAudioStreamIndex(IReadOnlyList<MediaStream> streams, IReadOnlyList<string> preferredLanguages, bool preferDefaultTrack)
{
var sortedStreams = GetSortedStreams(streams, MediaStreamType.Audio, preferredLanguages).ToList();
if (preferDefaultTrack)
{
var defaultStream = sortedStreams.FirstOrDefault(i => i.IsDefault);
if (defaultStream is not null)
{
return defaultStream.Index;
}
}
return sortedStreams.FirstOrDefault()?.Index;
}
public static int? GetDefaultSubtitleStreamIndex(
IEnumerable<MediaStream> streams,
IReadOnlyList<string> preferredLanguages,
SubtitlePlaybackMode mode,
string audioTrackLanguage)
{
if (mode == SubtitlePlaybackMode.None)
{
return null;
}
// Sort in the following order: Default > No tag > Forced
var sortedStreams = streams
.Where(i => i.Type == MediaStreamType.Subtitle)
.OrderByDescending(x => x.IsExternal)
.ThenByDescending(x => x.IsDefault)
.ThenByDescending(x => !x.IsForced && MatchesPreferredLanguage(x.Language, preferredLanguages))
.ThenByDescending(x => x.IsForced && MatchesPreferredLanguage(x.Language, preferredLanguages))
.ThenByDescending(x => x.IsForced && IsLanguageUndefined(x.Language))
.ThenByDescending(x => x.IsForced)
.ToList();
MediaStream? stream = null;
if (mode == SubtitlePlaybackMode.Default)
{
// Load subtitles according to external, default and forced flags.
stream = sortedStreams.FirstOrDefault(x => x.IsExternal || x.IsDefault || x.IsForced);
}
else if (mode == SubtitlePlaybackMode.Smart)
{
// Only attempt to load subtitles if the audio language is not one of the user's preferred subtitle languages.
// If no subtitles of preferred language available, use none.
// If the audio language is one of the user's preferred subtitle languages behave like OnlyForced.
if (!preferredLanguages.Contains(audioTrackLanguage, StringComparison.OrdinalIgnoreCase))
{
stream = sortedStreams.FirstOrDefault(x => MatchesPreferredLanguage(x.Language, preferredLanguages));
}
else
{
stream = BehaviorOnlyForced(sortedStreams, preferredLanguages).FirstOrDefault();
}
}
else if (mode == SubtitlePlaybackMode.Always)
{
// Always load (full/non-forced) subtitles of the user's preferred subtitle language if possible, otherwise OnlyForced behaviour.
stream = sortedStreams.FirstOrDefault(x => !x.IsForced && MatchesPreferredLanguage(x.Language, preferredLanguages)) ??
BehaviorOnlyForced(sortedStreams, preferredLanguages).FirstOrDefault();
}
else if (mode == SubtitlePlaybackMode.OnlyForced)
{
// Load subtitles that are flagged forced of the user's preferred subtitle language or with an undefined language
stream = BehaviorOnlyForced(sortedStreams, preferredLanguages).FirstOrDefault();
}
return stream?.Index;
}
private static IEnumerable<MediaStream> GetSortedStreams(IEnumerable<MediaStream> streams, MediaStreamType type, IReadOnlyList<string> languagePreferences)
{
// Give some preference to external text subs for better performance
return streams
.Where(i => i.Type == type)
.OrderByDescending(i => GetStreamScore(i, languagePreferences));
}
public static void SetSubtitleStreamScores(
IReadOnlyList<MediaStream> streams,
IReadOnlyList<string> preferredLanguages,
SubtitlePlaybackMode mode,
string audioTrackLanguage)
{
if (mode == SubtitlePlaybackMode.None)
{
return;
}
var sortedStreams = GetSortedStreams(streams, MediaStreamType.Subtitle, preferredLanguages).ToList();
List<MediaStream>? filteredStreams = null;
if (mode == SubtitlePlaybackMode.Default)
{
// Prefer embedded metadata over smart logic
// Load subtitles according to external, default, and forced flags.
filteredStreams = sortedStreams.Where(s => s.IsExternal || s.IsDefault || s.IsForced)
.ToList();
}
else if (mode == SubtitlePlaybackMode.Smart)
{
// Prefer smart logic over embedded metadata
// Only attempt to load subtitles if the audio language is not one of the user's preferred subtitle languages, otherwise OnlyForced behavior.
if (!preferredLanguages.Contains(audioTrackLanguage, StringComparison.OrdinalIgnoreCase))
{
filteredStreams = sortedStreams.Where(s => MatchesPreferredLanguage(s.Language, preferredLanguages))
.ToList();
}
else
{
filteredStreams = BehaviorOnlyForced(sortedStreams, preferredLanguages);
}
}
else if (mode == SubtitlePlaybackMode.Always)
{
// Always load (full/non-forced) subtitles of the user's preferred subtitle language if possible, otherwise OnlyForced behavior.
filteredStreams = sortedStreams.Where(s => !s.IsForced && MatchesPreferredLanguage(s.Language, preferredLanguages))
.ToList() ?? BehaviorOnlyForced(sortedStreams, preferredLanguages);
}
else if (mode == SubtitlePlaybackMode.OnlyForced)
{
// Load subtitles that are flagged forced of the user's preferred subtitle language or with an undefined language
filteredStreams = BehaviorOnlyForced(sortedStreams, preferredLanguages);
}
// If filteredStreams is null, initialize it as an empty list to avoid null reference errors
filteredStreams ??= new List<MediaStream>();
foreach (var stream in filteredStreams)
{
stream.Score = GetStreamScore(stream, preferredLanguages);
}
}
private static bool MatchesPreferredLanguage(string language, IReadOnlyList<string> preferredLanguages)
{
// If preferredLanguages is empty, treat it as "any language" (wildcard)
return preferredLanguages.Count == 0 ||
preferredLanguages.Contains(language, StringComparison.OrdinalIgnoreCase);
}
private static bool IsLanguageUndefined(string language)
{
// Check for null, empty, or known placeholders
return string.IsNullOrEmpty(language) ||
language.Equals("und", StringComparison.OrdinalIgnoreCase) ||
language.Equals("unknown", StringComparison.OrdinalIgnoreCase) ||
language.Equals("undetermined", StringComparison.OrdinalIgnoreCase) ||
language.Equals("mul", StringComparison.OrdinalIgnoreCase) ||
language.Equals("zxx", StringComparison.OrdinalIgnoreCase);
}
private static List<MediaStream> BehaviorOnlyForced(IEnumerable<MediaStream> sortedStreams, IReadOnlyList<string> preferredLanguages)
{
return sortedStreams
.Where(s => s.IsForced && (MatchesPreferredLanguage(s.Language, preferredLanguages) || IsLanguageUndefined(s.Language)))
.OrderByDescending(s => MatchesPreferredLanguage(s.Language, preferredLanguages))
.ThenByDescending(s => IsLanguageUndefined(s.Language))
.ToList();
}
internal static int GetStreamScore(MediaStream stream, IReadOnlyList<string> languagePreferences)
{
var index = languagePreferences.FindIndex(x => string.Equals(x, stream.Language, StringComparison.OrdinalIgnoreCase));
var score = index == -1 ? 1 : 101 - index;
score = (score * 10) + (stream.IsForced ? 2 : 1);
score = (score * 10) + (stream.IsDefault ? 2 : 1);
score = (score * 10) + (stream.SupportsExternalStream ? 2 : 1);
score = (score * 10) + (stream.IsTextSubtitleStream ? 2 : 1);
score = (score * 10) + (stream.IsExternal ? 2 : 1);
return score;
}
}
}
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