Implement FfProbeKeyframeExtractor and add tests for it

3 files changed, 97 insertions, 7 deletions

diff --git a/src/Jellyfin.MediaEncoding.Hls/Playlist/DynamicHlsPlaylistGenerator.cs b/src/Jellyfin.MediaEncoding.Hls/Playlist/DynamicHlsPlaylistGenerator.cs
index 5411d5667..cbc62eb59 100644
--- a/src/Jellyfin.MediaEncoding.Hls/Playlist/DynamicHlsPlaylistGenerator.cs
+++ b/src/Jellyfin.MediaEncoding.Hls/Playlist/DynamicHlsPlaylistGenerator.cs
@@ -90,9 +90,11 @@ namespace Jellyfin.MediaEncoding.Hls.Playlist
                     .AppendLine();
             }
 
-            double currentRuntimeInSeconds = 0;
+            long currentRuntimeInSeconds = 0;
             foreach (var length in segments)
             {
+                // Manually convert to ticks to avoid precision loss when converting double
+                var lengthTicks = Convert.ToInt64(length * TimeSpan.TicksPerSecond);
                 builder.Append("#EXTINF:")
                     .Append(length.ToString("0.000000", CultureInfo.InvariantCulture))
                     .AppendLine(", nodesc")
@@ -101,12 +103,12 @@ namespace Jellyfin.MediaEncoding.Hls.Playlist
                     .Append(segmentExtension)
                     .Append(request.QueryString)
                     .Append("&runtimeTicks=")
-                    .Append(TimeSpan.FromSeconds(currentRuntimeInSeconds).Ticks)
+                    .Append(currentRuntimeInSeconds)
                     .Append("&actualSegmentLengthTicks=")
-                    .Append(TimeSpan.FromSeconds(length).Ticks)
+                    .Append(lengthTicks)
                     .AppendLine();
 
-                currentRuntimeInSeconds += length;
+                currentRuntimeInSeconds += lengthTicks;
             }
 
             builder.AppendLine("#EXT-X-ENDLIST");
@@ -122,6 +124,7 @@ namespace Jellyfin.MediaEncoding.Hls.Playlist
                 return false;
             }
 
+            var succeeded = false;
             var cachePath = GetCachePath(filePath);
             if (TryReadFromCache(cachePath, out var cachedResult))
             {
@@ -139,10 +142,14 @@ namespace Jellyfin.MediaEncoding.Hls.Playlist
                     return false;
                 }
 
-                CacheResult(cachePath, keyframeData);
+                succeeded = keyframeData.KeyframeTicks.Count > 0;
+                if (succeeded)
+                {
+                    CacheResult(cachePath, keyframeData);
+                }
             }
 
-            return keyframeData.KeyframeTicks.Count > 0;
+            return succeeded;
         }
 
         private void CacheResult(string cachePath, KeyframeData keyframeData)
diff --git a/src/Jellyfin.MediaEncoding.Keyframes/FfProbe/FfProbeKeyframeExtractor.cs b/src/Jellyfin.MediaEncoding.Keyframes/FfProbe/FfProbeKeyframeExtractor.cs
index e09b9da9a..351d880fe 100644
--- a/src/Jellyfin.MediaEncoding.Keyframes/FfProbe/FfProbeKeyframeExtractor.cs
+++ b/src/Jellyfin.MediaEncoding.Keyframes/FfProbe/FfProbeKeyframeExtractor.cs
@@ -1,4 +1,8 @@
 using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Globalization;
+using System.IO;
 
 namespace Jellyfin.MediaEncoding.Keyframes.FfProbe
 {
@@ -7,12 +11,85 @@ namespace Jellyfin.MediaEncoding.Keyframes.FfProbe
     /// </summary>
     public static class FfProbeKeyframeExtractor
     {
+        private const string DefaultArguments = "-v error -skip_frame nokey -show_entries format=duration -show_entries stream=duration -show_entries packet=pts_time,flags -select_streams v -of csv \"{0}\"";
+
         /// <summary>
         /// Extracts the keyframes using the ffprobe executable at the specified path.
         /// </summary>
         /// <param name="ffProbePath">The path to the ffprobe executable.</param>
         /// <param name="filePath">The file path.</param>
         /// <returns>An instance of <see cref="KeyframeData"/>.</returns>
-        public static KeyframeData GetKeyframeData(string ffProbePath, string filePath) => throw new NotImplementedException();
+        public static KeyframeData GetKeyframeData(string ffProbePath, string filePath)
+        {
+            using var process = new Process
+            {
+                StartInfo = new ProcessStartInfo
+                {
+                    FileName = ffProbePath,
+                    Arguments = string.Format(CultureInfo.InvariantCulture, DefaultArguments, filePath),
+
+                    CreateNoWindow = true,
+                    UseShellExecute = false,
+                    RedirectStandardOutput = true,
+
+                    WindowStyle = ProcessWindowStyle.Hidden,
+                    ErrorDialog = false,
+                },
+                EnableRaisingEvents = true
+            };
+
+            process.Start();
+
+            return ParseStream(process.StandardOutput);
+        }
+
+        internal static KeyframeData ParseStream(StreamReader reader)
+        {
+            var keyframes = new List<long>();
+            double streamDuration = 0;
+            double formatDuration = 0;
+
+            while (!reader.EndOfStream)
+            {
+                var line = reader.ReadLine().AsSpan();
+                if (line.IsEmpty)
+                {
+                    continue;
+                }
+
+                var firstComma = line.IndexOf(',');
+                var lineType = line[..firstComma];
+                var rest = line[(firstComma + 1)..];
+                if (lineType.Equals("packet", StringComparison.OrdinalIgnoreCase))
+                {
+                    if (rest.EndsWith(",K_"))
+                    {
+                        // Trim the flags from the packet line. Example line: packet,7169.079000,K_
+                        var keyframe = double.Parse(rest[..^3], NumberStyles.AllowDecimalPoint, CultureInfo.InvariantCulture);
+                        // Have to manually convert to ticks to avoid rounding errors as TimeSpan is only precise down to 1 ms when converting double.
+                        keyframes.Add(Convert.ToInt64(keyframe * TimeSpan.TicksPerSecond));
+                    }
+                }
+                else if (lineType.Equals("stream", StringComparison.OrdinalIgnoreCase))
+                {
+                    if (double.TryParse(rest, NumberStyles.AllowDecimalPoint, CultureInfo.InvariantCulture, out var streamDurationResult))
+                    {
+                        streamDuration = streamDurationResult;
+                    }
+                }
+                else if (lineType.Equals("format", StringComparison.OrdinalIgnoreCase))
+                {
+                    if (double.TryParse(rest, NumberStyles.AllowDecimalPoint, CultureInfo.InvariantCulture, out var formatDurationResult))
+                    {
+                        formatDuration = formatDurationResult;
+                    }
+                }
+            }
+
+            // Prefer the stream duration as it should be more accurate
+            var duration = streamDuration > 0 ? streamDuration : formatDuration;
+
+            return new KeyframeData(TimeSpan.FromSeconds(duration).Ticks, keyframes);
+        }
     }
 }
diff --git a/src/Jellyfin.MediaEncoding.Keyframes/Jellyfin.MediaEncoding.Keyframes.csproj b/src/Jellyfin.MediaEncoding.Keyframes/Jellyfin.MediaEncoding.Keyframes.csproj
index d3eb44d2b..22db10d72 100644
--- a/src/Jellyfin.MediaEncoding.Keyframes/Jellyfin.MediaEncoding.Keyframes.csproj
+++ b/src/Jellyfin.MediaEncoding.Keyframes/Jellyfin.MediaEncoding.Keyframes.csproj
@@ -20,4 +20,10 @@
     <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="5.0.0" />
   </ItemGroup>
 
+  <ItemGroup>
+    <AssemblyAttribute Include="System.Runtime.CompilerServices.InternalsVisibleTo">
+      <_Parameter1>Jellyfin.MediaEncoding.Keyframes.Tests</_Parameter1>
+    </AssemblyAttribute>
+  </ItemGroup>
+
 </Project>