optimize transcoding speed (#1398)

* fix "empty trash" button blinking when loading trash page

* clean channel guide cache on startup

* only work-ahead in hls session for 2 minutes

CHANGELOG.md

@@ -22,6 +22,11 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ### Fixed
 - Fix subtitle scaling when using QSV hardware acceleration
 - Fix log viewer crash when log file contains invalid data
+- Clean channel guide cache on startup (delete channels that no longer exist)
+
+### Changed
+- Optimize transcoding session to only work ahead (at max speed) for 2 minutes before throttling to realtime
+  - This should *greatly* reduce cpu/gpu use when joining a channel, particularly with long content
 
 ## [0.8.1-beta] - 2023-08-07
 ### Added

ErsatzTV.Application/Streaming/HlsSessionWorkAheadState.cs

@@ -0,0 +1,8 @@
+namespace ErsatzTV.Application.Streaming;
+
+public enum HlsSessionWorkAheadState
+{
+    MaxSpeed,
+    SeekAndRealtime,
+    RealtimeFromZero
+}

ErsatzTV.Application/Streaming/HlsSessionWorker.cs

@@ -35,6 +35,7 @@ public class HlsSessionWorker : IHlsSessionWorker
     private Option<int> _targetFramerate;
     private Timer _timer;
     private DateTimeOffset _transcodedUntil;
+    private HlsSessionWorkAheadState _workAheadState;
 
     public HlsSessionWorker(
         IHlsPlaylistFilter hlsPlaylistFilter,
@@ -105,6 +106,7 @@ public class HlsSessionWorker : IHlsSessionWorker
     {
         _firstProcess = true;
         _seekNextItem = true;
+        _workAheadState = HlsSessionWorkAheadState.SeekAndRealtime;
     }
 
     public async Task Run(string channelNumber, TimeSpan idleTimeout, CancellationToken incomingCancellationToken)
@@ -149,6 +151,10 @@ public class HlsSessionWorker : IHlsSessionWorker
             _firstProcess = true;
 
             bool initialWorkAhead = Volatile.Read(ref _workAheadCount) < await GetWorkAheadLimit();
+            _workAheadState = initialWorkAhead
+                ? HlsSessionWorkAheadState.MaxSpeed
+                : HlsSessionWorkAheadState.SeekAndRealtime;
+
             if (!await Transcode(!initialWorkAhead, cancellationToken))
             {
                 return;
@@ -225,11 +231,24 @@ public class HlsSessionWorker : IHlsSessionWorker
             long ptsOffset = await GetPtsOffset(mediator, _channelNumber, cancellationToken);
             // _logger.LogInformation("PTS offset: {PtsOffset}", ptsOffset);
 
+            // this shouldn't happen, but respect realtime
+            if (realtime && _workAheadState is HlsSessionWorkAheadState.MaxSpeed)
+            {
+                _workAheadState = HlsSessionWorkAheadState.SeekAndRealtime;
+            }
+            
+            _logger.LogInformation("Work ahead state: {State}", _workAheadState);
+            
+            DateTimeOffset now = (_firstProcess || _workAheadState is HlsSessionWorkAheadState.MaxSpeed)
+                ? DateTimeOffset.Now
+                : _transcodedUntil.AddSeconds(_workAheadState is HlsSessionWorkAheadState.SeekAndRealtime ? 0 : 1);
+            bool startAtZero = _workAheadState is HlsSessionWorkAheadState.RealtimeFromZero && !_firstProcess;
+
             var request = new GetPlayoutItemProcessByChannelNumber(
                 _channelNumber,
                 "segmenter",
-                _firstProcess ? DateTimeOffset.Now : _transcodedUntil.AddSeconds(1),
-                !_firstProcess,
+                now,
+                startAtZero,
                 realtime,
                 ptsOffset,
                 _targetFramerate);
@@ -267,6 +286,7 @@ public class HlsSessionWorker : IHlsSessionWorker
                     if (commandResult.ExitCode == 0)
                     {
                         _logger.LogInformation("HLS process has completed for channel {Channel}", _channelNumber);
+                        _logger.LogDebug("Transcoded until: {Until}", processModel.Until);
                         _transcodedUntil = processModel.Until;
                         _firstProcess = false;
                         if (_seekNextItem)
@@ -275,6 +295,13 @@ public class HlsSessionWorker : IHlsSessionWorker
                             _seekNextItem = false;
                         }
 
+                        _workAheadState = _workAheadState switch
+                        {
+                            HlsSessionWorkAheadState.MaxSpeed => HlsSessionWorkAheadState.SeekAndRealtime,
+                            HlsSessionWorkAheadState.SeekAndRealtime => HlsSessionWorkAheadState.RealtimeFromZero,
+                            _ => _workAheadState
+                        };
+
                         _hasWrittenSegments = true;
                         return true;
                     }

ErsatzTV.Application/Streaming/Queries/GetPlayoutItemProcessByChannelNumberHandler.cs

@@ -172,6 +172,17 @@ public class GetPlayoutItemProcessByChannelNumberHandler : FFmpegProcessHandler<
                 .GetValue<bool>(ConfigElementKey.FFmpegSaveReports)
                 .Map(result => result.IfNone(false));
 
+            DateTimeOffset start = playoutItemWithPath.PlayoutItem.StartOffset;
+            DateTimeOffset finish = playoutItemWithPath.PlayoutItem.FinishOffset;
+            TimeSpan inPoint = playoutItemWithPath.PlayoutItem.InPoint;
+            TimeSpan outPoint = playoutItemWithPath.PlayoutItem.OutPoint;
+            DateTimeOffset effectiveNow = request.StartAtZero ? start : now;
+            if (!request.HlsRealtime && (outPoint - inPoint) > TimeSpan.FromMinutes(2))
+            {
+                finish = effectiveNow + TimeSpan.FromMinutes(2);
+                outPoint = finish - start + TimeSpan.FromMinutes(2);
+            }
+
             Command process = await _ffmpegProcessService.ForPlayoutItem(
                 ffmpegPath,
                 ffprobePath,
@@ -186,9 +197,9 @@ public class GetPlayoutItemProcessByChannelNumberHandler : FFmpegProcessHandler<
                 playoutItemWithPath.PlayoutItem.PreferredAudioTitle ?? channel.PreferredAudioTitle,
                 playoutItemWithPath.PlayoutItem.PreferredSubtitleLanguageCode ?? channel.PreferredSubtitleLanguageCode,
                 playoutItemWithPath.PlayoutItem.SubtitleMode ?? channel.SubtitleMode,
-                playoutItemWithPath.PlayoutItem.StartOffset,
-                playoutItemWithPath.PlayoutItem.FinishOffset,
-                request.StartAtZero ? playoutItemWithPath.PlayoutItem.StartOffset : now,
+                start,
+                finish,
+                request.StartAtZero ? start : now,
                 Optional(playoutItemWithPath.PlayoutItem.Watermark),
                 maybeGlobalWatermark,
                 channel.FFmpegProfile.VaapiDriver,
@@ -196,18 +207,14 @@ public class GetPlayoutItemProcessByChannelNumberHandler : FFmpegProcessHandler<
                 Optional(channel.FFmpegProfile.QsvExtraHardwareFrames),
                 request.HlsRealtime,
                 playoutItemWithPath.PlayoutItem.FillerKind,
-                playoutItemWithPath.PlayoutItem.InPoint,
-                playoutItemWithPath.PlayoutItem.OutPoint,
+                inPoint,
+                outPoint,
                 request.PtsOffset,
                 request.TargetFramerate,
                 playoutItemWithPath.PlayoutItem.DisableWatermarks,
                 _ => { });
 
-            var result = new PlayoutItemProcessModel(
-                process,
-                playoutItemWithPath.PlayoutItem.FinishOffset -
-                (request.StartAtZero ? playoutItemWithPath.PlayoutItem.StartOffset : now),
-                playoutItemWithPath.PlayoutItem.FinishOffset);
+            var result = new PlayoutItemProcessModel(process, finish - effectiveNow, finish);
 
             return Right<BaseError, PlayoutItemProcessModel>(result);
         }

ErsatzTV.Core/FFmpeg/FFmpegPlaybackSettingsCalculator.cs

@@ -21,6 +21,7 @@
 using ErsatzTV.Core.Domain;
 using ErsatzTV.Core.Interfaces.FFmpeg;
 using ErsatzTV.FFmpeg.Format;
+using Serilog;
 
 namespace ErsatzTV.Core.FFmpeg;
 
@@ -66,8 +67,7 @@ public class FFmpegPlaybackSettingsCalculator
             }
         };
 
-        // always use one thread with realtime output
-        result.ThreadCount = result.RealtimeOutput ? 1 : ffmpegProfile.ThreadCount;
+        result.ThreadCount = ffmpegProfile.ThreadCount;
 
         if (now != start || inPoint != TimeSpan.Zero)
         {

ErsatzTV/Pages/Trash.razor

@@ -70,21 +70,21 @@
                 <MudLink Class="ml-4" Href="@(_navigationManager.Uri.Split("#").Head() + "#songs")" Style="margin-bottom: auto; margin-top: auto">@_songs.Count Songs</MudLink>
             }
 
-            if (_movies?.Count == 0 && _shows?.Count == 0 && _seasons?.Count == 0 && _episodes?.Count == 0 && _artists?.Count == 0 && _musicVideos?.Count == 0 && _otherVideos?.Count == 0 && _songs?.Count == 0)
-            {
-                <MudText>Nothing to see here...</MudText>
-            }
-            else
+            if (IsNotEmpty)
             {
                 <div style="margin-left: auto">
-                    <MudButton Variant="Variant.Filled"
-                               Color="Color.Error"
+                    <MudButton Variant="@Variant.Filled"
+                               Color="@Color.Error"
                                StartIcon="@Icons.Material.Filled.DeleteForever"
                                OnClick="@(_ => EmptyTrash())">
                         Empty Trash
                     </MudButton>
                 </div>
             }
+            else
+            {
+                <MudText>Nothing to see here...</MudText>
+            }
         }
     </div>
 </MudPaper>
@@ -331,7 +331,7 @@
     private ArtistCardResultsViewModel _artists;
 
     protected override Task OnInitializedAsync() => RefreshData();
-
+    
     protected override async Task RefreshData()
     {
         _query = "state:FileNotFound";
@@ -348,6 +348,9 @@
         }
     }
 
+    private bool IsNotEmpty =>
+        _movies?.Count > 0 || _shows?.Count > 0 || _seasons?.Count > 0 || _episodes?.Count > 0 || _musicVideos?.Count > 0 || _otherVideos?.Count > 0 || _songs?.Count > 0 || _artists?.Count > 0;
+
     private void SelectClicked(MediaCardViewModel card, MouseEventArgs e)
     {
         List<MediaCardViewModel> GetSortedItems()

ErsatzTV/Services/RunOnce/CacheCleanerService.cs

@@ -41,6 +41,7 @@ public class CacheCleanerService : BackgroundService
             _logger.LogInformation("Migrating channel logos from legacy image cache folder");
 
             List<string> logos = await dbContext.Channels
+                .AsNoTracking()
                 .SelectMany(c => c.Artwork)
                 .Where(a => a.ArtworkKind == ArtworkKind.Logo)
                 .Map(a => a.Path)
@@ -67,5 +68,26 @@ public class CacheCleanerService : BackgroundService
             localFileSystem.EmptyFolder(FileSystemLayout.TranscodeFolder);
             _logger.LogInformation("Done emptying transcode cache folder");
         }
+
+        if (localFileSystem.FolderExists(FileSystemLayout.ChannelGuideCacheFolder))
+        {
+            _logger.LogInformation("Cleaning channel cache");
+
+            List<string> channelFiles = await dbContext.Channels
+                .AsNoTracking()
+                .Select(c => c.Number)
+                .Map(num => Path.Combine(FileSystemLayout.ChannelGuideCacheFolder, $"{num}.xml"))
+                .ToListAsync(cancellationToken);
+
+            foreach (string fileName in localFileSystem.ListFiles(FileSystemLayout.ChannelGuideCacheFolder))
+            {
+                if (fileName.Contains("channels") || channelFiles.Contains(fileName))
+                {
+                    continue;
+                }
+                
+                File.Delete(fileName);
+            }
+        }
     }
 }