From d10fdeb7b81c40fad927dea6555865753a77ec24 Mon Sep 17 00:00:00 2001
From: vaindil <vaindil@github.com>
Date: Sat, 6 Jan 2024 18:47:27 -0500
Subject: [PATCH] Fix VOD download trimming and quality selection (#936)

* fix streamOffsetSeconds calculation

* handle source quality streams

* check GroupId, add tests

* use `contains` instead of `equals`

Co-authored-by: Scrub <72096833+ScrubN@users.noreply.github.com>

---------

Co-authored-by: Scrub <72096833+ScrubN@users.noreply.github.com>
---
 .../M3U8ExtensionTests.cs                     | 24 +++++++++++++++++++
 .../Extensions/M3U8Extensions.cs              | 17 ++++++++++---
 TwitchDownloaderCore/VideoDownloader.cs       |  2 +-
 3 files changed, 39 insertions(+), 4 deletions(-)

diff --git a/TwitchDownloaderCore.Tests/M3U8ExtensionTests.cs b/TwitchDownloaderCore.Tests/M3U8ExtensionTests.cs
index be2a7f27..6c73cb37 100644
--- a/TwitchDownloaderCore.Tests/M3U8ExtensionTests.cs
+++ b/TwitchDownloaderCore.Tests/M3U8ExtensionTests.cs
@@ -99,6 +99,30 @@ public static void CorrectlyFindsStreamOfQualityFromOldM3U8Response(string quali
             Assert.Equal(expectedPath, selectedQuality.Path);
         }
 
+        [Theory]
+        [InlineData("1080", "1080p60")]
+        [InlineData("1080p", "1080p60")]
+        [InlineData("1080p60", "1080p60")]
+        [InlineData("720p60", "720p60")]
+        [InlineData("foo", "1080p60")]
+        public static void CorrectlyFindsStreamOfQualityFromM3U8ResponseWithoutFramerate(string qualityString, string expectedPath)
+        {
+            var m3u8 = new M3U8(new M3U8.Metadata(), new[]
+            {
+                new M3U8.Stream(
+                    new M3U8.Stream.ExtMediaInfo(M3U8.Stream.ExtMediaInfo.MediaType.Video, "chunked", "Source", true, true),
+                    new M3U8.Stream.ExtStreamInfo(0, 1, "avc1.4D401F,mp4a.40.2", (1920, 1080), "chunked", 0),
+                    "1080p60"),
+                new M3U8.Stream(
+                    new M3U8.Stream.ExtMediaInfo(M3U8.Stream.ExtMediaInfo.MediaType.Video, "720p60", "720p60", true, true),
+                    new M3U8.Stream.ExtStreamInfo(0, 1, "avc1.4D401F,mp4a.40.2", (1280, 720), "720p60", 58.644M),
+                    "720p60"),
+            });
+
+            var selectedQuality = m3u8.GetStreamOfQuality(qualityString);
+            Assert.Equal(expectedPath, selectedQuality.Path);
+        }
+
         [Theory]
         [InlineData("480p60", "1080p60")]
         [InlineData("852x480p60", "1080p60")]
diff --git a/TwitchDownloaderCore/Extensions/M3U8Extensions.cs b/TwitchDownloaderCore/Extensions/M3U8Extensions.cs
index 2a5371aa..d2db63cc 100644
--- a/TwitchDownloaderCore/Extensions/M3U8Extensions.cs
+++ b/TwitchDownloaderCore/Extensions/M3U8Extensions.cs
@@ -34,7 +34,7 @@ public static M3U8.Stream GetStreamOfQuality(this M3U8 m3u8, string qualityStrin
 
             if (qualityString is null)
             {
-                return streams.MaxBy(x => x.StreamInfo.Resolution.Width * x.StreamInfo.Resolution.Height * x.StreamInfo.Framerate);
+                return m3u8.BestQualityStream();
             }
 
             if (qualityString.Contains("audio", StringComparison.OrdinalIgnoreCase) &&
@@ -57,7 +57,7 @@ public static M3U8.Stream GetStreamOfQuality(this M3U8 m3u8, string qualityStrin
             var qualityStringMatch = UserQualityStringRegex.Match(qualityString);
             if (!qualityStringMatch.Success)
             {
-                return streams.MaxBy(x => x.StreamInfo.Resolution.Width * x.StreamInfo.Resolution.Height * x.StreamInfo.Framerate);
+                return m3u8.BestQualityStream();
             }
 
             var desiredWidth = qualityStringMatch.Groups["Width"];
@@ -74,7 +74,7 @@ public static M3U8.Stream GetStreamOfQuality(this M3U8 m3u8, string qualityStrin
             {
                 1 => filteredStreams[0],
                 2 when !desiredFramerate.Success => filteredStreams.First(x => Math.Abs(x.StreamInfo.Framerate - 30) <= 2),
-                _ => streams.MaxBy(x => x.StreamInfo.Resolution.Width * x.StreamInfo.Resolution.Height * x.StreamInfo.Framerate)
+                _ => m3u8.BestQualityStream()
             };
         }
 
@@ -118,5 +118,16 @@ public static string GetResolutionFramerateString(this M3U8.Stream stream)
 
             return $"{frameHeight}p{frameRate}";
         }
+
+        /// <summary>
+        /// Returns the best quality stream from the provided M3U8.
+        /// </summary>
+        public static M3U8.Stream BestQualityStream(this M3U8 m3u8)
+        {
+            var source = Array.Find(
+                m3u8.Streams, x => x.MediaInfo.Name.Contains("source", StringComparison.OrdinalIgnoreCase) ||
+                    x.MediaInfo.GroupId.Equals("chunked", StringComparison.OrdinalIgnoreCase));
+            return source ?? m3u8.Streams.MaxBy(x => x.StreamInfo.Resolution.Width * x.StreamInfo.Resolution.Height * x.StreamInfo.Framerate);
+        }
     }
 }
\ No newline at end of file
diff --git a/TwitchDownloaderCore/VideoDownloader.cs b/TwitchDownloaderCore/VideoDownloader.cs
index 3d1a5539..49a21527 100644
--- a/TwitchDownloaderCore/VideoDownloader.cs
+++ b/TwitchDownloaderCore/VideoDownloader.cs
@@ -88,7 +88,7 @@ public async Task DownloadAsync(CancellationToken cancellationToken)
                     .Take(videoListCrop.Start.Value)
                     .Sum(x => x.PartInfo.Duration);
 
-                startOffsetSeconds -= downloadOptions.CropBeginningTime;
+                startOffsetSeconds = downloadOptions.CropBeginningTime - startOffsetSeconds;
                 double seekDuration = Math.Round(downloadOptions.CropEndingTime - downloadOptions.CropBeginningTime);
 
                 string metadataPath = Path.Combine(downloadFolder, "metadata.txt");