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Search episodes in O(n) instead of O(n^2) time

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This commit is contained in:
ConfusedPolarBear 2022-08-27 01:58:46 -05:00
parent f92eea20b3
commit 874f77f94c
2 changed files with 49 additions and 83 deletions
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31
ConfusedPolarBear.Plugin.IntroSkipper/Data/SeasonHistogram.cs
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@ -1,31 +0,0 @@
#pragma warning disable CA1815 // Override equals and operator equals on value types
using System;
using System.Collections.ObjectModel;
namespace ConfusedPolarBear.Plugin.IntroSkipper;
/// <summary>
/// Histogram entry for episodes in a season.
/// </summary>
public struct SeasonHistogram
{
/// <summary>
/// Initializes a new instance of the <see cref="SeasonHistogram"/> struct.
/// </summary>
/// <param name="firstEpisode">First episode seen with this duration.</param>
public SeasonHistogram(Guid firstEpisode)
{
Episodes.Add(firstEpisode);
}
/// <summary>
/// Gets episodes with this duration.
/// </summary>
public Collection<Guid> Episodes { get; } = new Collection<Guid>();
/// <summary>
/// Gets the number of times an episode with an intro of this duration has been seen.
/// </summary>
public int Count => Episodes?.Count ?? 0;
}

97
ConfusedPolarBear.Plugin.IntroSkipper/ScheduledTasks/AnalyzeEpisodesTask.cs
View File

@ -1,5 +1,6 @@
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Numerics;
using System.Threading;
using System.Threading.Tasks;
@ -146,9 +147,11 @@ public class AnalyzeEpisodesTask : IScheduledTask
try
{
var episodes = new Collection<QueuedEpisode>(season.Value);
// Increment totalProcessed by the number of episodes in this season that were actually analyzed
// (instead of just using the number of episodes in the current season).
var analyzed = AnalyzeSeason(season.Value, cancellationToken);
var analyzed = AnalyzeSeason(episodes, cancellationToken);
Interlocked.Add(ref totalProcessed, analyzed);
writeEdl = analyzed > 0 || Plugin.Instance!.Configuration.RegenerateEdlFiles;
}
@ -219,9 +222,6 @@ public class AnalyzeEpisodesTask : IScheduledTask
return previous;
}
// TODO: restore warning
#pragma warning disable CA1002
/// <summary>
/// Fingerprints all episodes in the provided season and stores the timestamps of all introductions.
/// </summary>
@ -229,19 +229,26 @@ public class AnalyzeEpisodesTask : IScheduledTask
/// <param name="cancellationToken">Cancellation token provided by the scheduled task.</param>
/// <returns>Number of episodes from the provided season that were analyzed.</returns>
private int AnalyzeSeason(
List<QueuedEpisode> episodes,
Collection<QueuedEpisode> episodes,
CancellationToken cancellationToken)
{
// All intros for this season.
var seasonIntros = new Dictionary<Guid, Intro>();
// Cache of all fingerprints for this season.
var fingerprintCache = new Dictionary<Guid, uint[]>();
// Total episodes in this season. Counted at the start of this function as episodes
// are popped from here during analysis.
var episodeCount = episodes.Count;
/* Don't analyze specials or seasons with an insufficient number of episodes.
* A season with only 1 episode can't be analyzed as it would compare the episode to itself,
* which would result in the entire episode being marked as an introduction, as the audio is identical.
*/
if (episodes.Count < 2 || episodes[0].SeasonNumber == 0)
{
return episodes.Count;
return episodeCount;
}
var first = episodes[0];
@ -252,7 +259,7 @@ public class AnalyzeEpisodesTask : IScheduledTask
first.SeriesName,
first.SeasonNumber);
// Cache all fingerprints
// Compute fingerprints for all episodes in the season
foreach (var episode in episodes)
{
try
@ -263,60 +270,52 @@ public class AnalyzeEpisodesTask : IScheduledTask
{
_logger.LogWarning("Caught fingerprint error: {Ex}", ex);
// fallback to an empty fingerprint
// Fallback to an empty fingerprint on any error
fingerprintCache[episode.EpisodeId] = Array.Empty<uint>();
}
}
// TODO: implementing bucketing
/* Theory of operation:
* Episodes are analyzed in the same order that Jellyfin displays them in and are
* sorted into buckets based off of the intro sequence that the episode contains.
*
* Jellyfin's episode ordering is used because it is assumed that the introduction
* in each season of a show will likely either:
* - remain constant throughout the entire season
* - remain constant in subranges of the season (e.g. episodes 1 - 5 and 6 - 10 share intros)
* If the intros do not follow this pattern, the plugin should still find most
* of them.
*/
// For all episodes
foreach (var outer in episodes)
// While there are still episodes in the queue
while (episodes.Count > 0)
{
// Compare the outer episode to all other episodes
foreach (var inner in episodes)
{
// Don't compare the episode to itself
if (outer.EpisodeId == inner.EpisodeId)
{
continue;
}
// Pop the first episode from the queue
var currentEpisode = episodes[0];
episodes.RemoveAt(0);
// Fingerprint both episodes
Intro outerIntro;
Intro innerIntro;
(outerIntro, innerIntro) = CompareEpisodes(
outer.EpisodeId,
fingerprintCache[outer.EpisodeId],
inner.EpisodeId,
fingerprintCache[inner.EpisodeId]);
if (!outerIntro.Valid)
// Search through all remaining episodes.
foreach (var remainingEpisode in episodes)
{
continue;
}
// Compare the current episode to all remaining episodes in the queue.
var (currentIntro, remainingIntro) = CompareEpisodes(
currentEpisode.EpisodeId,
fingerprintCache[currentEpisode.EpisodeId],
remainingEpisode.EpisodeId,
fingerprintCache[remainingEpisode.EpisodeId]);
// Save this intro if:
// - it is the first one we've seen for this episode
// - OR it is longer than the previous one
if (
!seasonIntros.TryGetValue(outer.EpisodeId, out var currentOuterIntro) ||
outerIntro.Duration > currentOuterIntro.Duration)
// If we found an intro, save it.
if (currentIntro.Valid)
{
seasonIntros[outer.EpisodeId] = outerIntro;
}
seasonIntros[currentIntro.EpisodeId] = currentIntro;
seasonIntros[remainingIntro.EpisodeId] = remainingIntro;
if (
!seasonIntros.TryGetValue(inner.EpisodeId, out var currentInnerIntro) ||
innerIntro.Duration > currentInnerIntro.Duration)
{
seasonIntros[inner.EpisodeId] = innerIntro;
}
break;
}
}
// TODO: analysisStatistics.TotalAnalyzedEpisodes.Add(2);
// If no intro is found at this point, the popped episode is not reinserted into the queue.
}
// Ensure only one thread at a time can update the shared intro dictionary.
lock (_introsLock)
@ -332,11 +331,9 @@ public class AnalyzeEpisodesTask : IScheduledTask
Plugin.Instance!.SaveTimestamps();
}
return episodes.Count;
return episodeCount;
}
#pragma warning restore CA1002
/// <summary>
/// Analyze two episodes to find an introduction sequence shared between them.
/// </summary>