fix segmenter timestamp continuity (#1610)

CHANGELOG.md

@@ -34,6 +34,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Automatically generate JWT tokens to allow channel previews of protected streams
 - Fix bug applying music video fallback metadata
 - Fix playback of media items with no audio streams
+- Fix timestamp continuity in `HLS Segmenter` sessions
+  - This should make *some* clients happier 
 
 ### Changed
 - Log search index updates under scanner category at debug level, to indicate a potential cause for the UI being out of date

ErsatzTV.Application/Channels/Mapper.cs

@@ -34,6 +34,9 @@ internal static class Mapper
             channel.PreferredAudioLanguageCode,
             GetStreamingMode(channel));
 
+    internal static ResolutionViewModel ProjectToViewModel(Resolution resolution) =>
+        new(resolution.Height, resolution.Width);
+
     private static string GetLogo(Channel channel) =>
         Optional(channel.Artwork.FirstOrDefault(a => a.ArtworkKind == ArtworkKind.Logo))
             .Match(a => a.Path, string.Empty);

ErsatzTV.Application/Channels/Queries/GetChannelResolution.cs

@@ -0,0 +1,3 @@
+namespace ErsatzTV.Application.Channels;
+
+public record GetChannelResolution(string ChannelNumber) : IRequest<Option<ResolutionViewModel>>;

ErsatzTV.Application/Channels/Queries/GetChannelResolutionHandler.cs

@@ -0,0 +1,25 @@
+using ErsatzTV.Core.Domain;
+using ErsatzTV.Infrastructure.Data;
+using ErsatzTV.Infrastructure.Extensions;
+using Microsoft.EntityFrameworkCore;
+
+namespace ErsatzTV.Application.Channels;
+
+public class GetChannelResolutionHandler(IDbContextFactory<TvContext> dbContextFactory)
+    : IRequestHandler<GetChannelResolution, Option<ResolutionViewModel>>
+{
+    public async Task<Option<ResolutionViewModel>> Handle(
+        GetChannelResolution request,
+        CancellationToken cancellationToken)
+    {
+        await using TvContext dbContext = await dbContextFactory.CreateDbContextAsync(cancellationToken);
+
+        Option<Channel> maybeChannel = await dbContext.Channels
+            .AsNoTracking()
+            .Include(c => c.FFmpegProfile)
+            .ThenInclude(ff => ff.Resolution)
+            .SelectOneAsync(c => c.Number, c => c.Number == request.ChannelNumber);
+
+        return maybeChannel.Map(c => Mapper.ProjectToViewModel(c.FFmpegProfile.Resolution));
+    }
+}

ErsatzTV.Application/Channels/ResolutionViewModel.cs

@@ -0,0 +1,3 @@
+namespace ErsatzTV.Application.Channels;
+
+public record ResolutionViewModel(int Height, int Width);

ErsatzTV.Application/Streaming/HlsSessionWorker.cs

@@ -181,7 +181,6 @@ public class HlsSessionWorker : IHlsSessionWorker
                 _logger.LogError("Transcode folder is NOT empty!");
             }
 
-
             Touch();
             _transcodedUntil = DateTimeOffset.Now;
             PlaylistStart = _transcodedUntil;
@@ -577,7 +576,7 @@ public class HlsSessionWorker : IHlsSessionWorker
 
             foreach ((long pts, long duration) in queryResult.RightToSeq())
             {
-                result = pts + duration;
+                result = pts + duration + 1;
             }
 
             return result;

ErsatzTV.FFmpeg/OutputFormat/OutputFormatHls.cs

@@ -8,6 +8,7 @@ public class OutputFormatHls : IPipelineStep
     private readonly Option<string> _mediaFrameRate;
     private readonly bool _oneSecondGop;
     private readonly string _playlistPath;
+    private readonly bool _isFirstTranscode;
     private readonly string _segmentTemplate;
 
     public OutputFormatHls(
@@ -15,12 +16,14 @@ public class OutputFormatHls : IPipelineStep
         Option<string> mediaFrameRate,
         string segmentTemplate,
         string playlistPath,
-        bool oneSecondGop = false)
+        bool isFirstTranscode,
+        bool oneSecondGop)
     {
         _desiredState = desiredState;
         _mediaFrameRate = mediaFrameRate;
         _segmentTemplate = segmentTemplate;
         _playlistPath = playlistPath;
+        _isFirstTranscode = isFirstTranscode;
         _oneSecondGop = oneSecondGop;
     }
 
@@ -38,8 +41,8 @@ public class OutputFormatHls : IPipelineStep
 
             int gop = _oneSecondGop ? frameRate : frameRate * SEGMENT_SECONDS;
 
-            return new[]
-            {
+            List<string> result =
+            [
                 "-g", $"{gop}",
                 "-keyint_min", $"{frameRate * SEGMENT_SECONDS}",
                 "-force_key_frames", $"expr:gte(t,n_forced*{SEGMENT_SECONDS})",
@@ -48,11 +51,28 @@ public class OutputFormatHls : IPipelineStep
                 "-hls_list_size", "0",
                 "-segment_list_flags", "+live",
                 "-hls_segment_filename",
-                _segmentTemplate,
+                _segmentTemplate
+            ];
+
+            if (_isFirstTranscode)
+            {
+                result.AddRange(
+                [
+                    "-hls_flags", "program_date_time+append_list+omit_endlist+independent_segments",
+                    _playlistPath
+                ]);
+            }
+            else
+            {
+                result.AddRange(
+                [
                     "-hls_flags", "program_date_time+append_list+discont_start+omit_endlist+independent_segments",
                     "-mpegts_flags", "+initial_discontinuity",
                     _playlistPath
-            };
+                ]);
+            }
+
+            return result.ToArray();
         }
     }
 

ErsatzTV.FFmpeg/Pipeline/PipelineBuilderBase.cs

@@ -275,6 +275,7 @@ public abstract class PipelineBuilderBase : IPipelineBuilder
                                 videoStream.FrameRate,
                                 segmentTemplate,
                                 playlistPath,
+                                isFirstTranscode: ffmpegState.PtsOffset == 0,
                                 ffmpegState.EncoderHardwareAccelerationMode is HardwareAccelerationMode.Qsv));
                     }
                 }

ErsatzTV/Controllers/IptvController.cs

@@ -191,6 +191,7 @@ public class IptvController : ControllerBase
         switch (mode)
         {
             case "segmenter":
+                string multiVariantPlaylist = await GetMultiVariantPlaylist(channelNumber);
                 _logger.LogDebug("Maybe starting ffmpeg session for channel {Channel}", channelNumber);
                 Either<BaseError, Unit> result = await _mediator.Send(new StartFFmpegSession(channelNumber, false));
                 return result.Match<IActionResult>(
@@ -199,7 +200,7 @@ public class IptvController : ControllerBase
                         _logger.LogDebug(
                             "Session started; returning multi-variant playlist for channel {Channel}",
                             channelNumber);
-                        return Content(GetMultiVariantPlaylist(channelNumber), "application/vnd.apple.mpegurl");
+                        return Content(multiVariantPlaylist, "application/vnd.apple.mpegurl");
                         // return Redirect($"~/iptv/session/{channelNumber}/hls.m3u8");
                     },
                     error =>
@@ -210,7 +211,7 @@ public class IptvController : ControllerBase
                                 _logger.LogDebug(
                                     "Session is already active; returning multi-variant playlist for channel {Channel}",
                                     channelNumber);
-                                return Content(GetMultiVariantPlaylist(channelNumber), "application/vnd.apple.mpegurl");
+                                return Content(multiVariantPlaylist, "application/vnd.apple.mpegurl");
                             // return RedirectPreserveMethod($"iptv/session/{channelNumber}/hls.m3u8");
                             default:
                                 _logger.LogWarning(
@@ -246,12 +247,20 @@ public class IptvController : ControllerBase
             Right: r => new PhysicalFileResult(r.FileName, r.MimeType));
     }
 
-    // TODO: include resolution here?
-    private string GetMultiVariantPlaylist(string channelNumber) =>
-        $@"#EXTM3U
+    private async Task<string> GetMultiVariantPlaylist(string channelNumber)
+    {
+        Option<ResolutionViewModel> maybeResolution = await _mediator.Send(new GetChannelResolution(channelNumber));
+        string resolution = string.Empty;
+        foreach (ResolutionViewModel res in maybeResolution)
+        {
+            resolution = $",RESOLUTION={res.Width}x{res.Height}";
+        }
+        
+        return $@"#EXTM3U
 #EXT-X-VERSION:3
-#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=10000000
+#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=10000000{resolution}
 {Request.Scheme}://{Request.Host}/iptv/session/{channelNumber}/hls.m3u8{AccessTokenQuery()}";
+    }
 
     private string AccessTokenQuery() => string.IsNullOrWhiteSpace(Request.Query["access_token"])
         ? string.Empty