fix hls timestamps (#598)

CHANGELOG.md

@@ -12,9 +12,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
   - `ts-legacy` for `MPEG-TS (Legacy)`
   - omitting the `mode` parameter returns each channel as configured
 - Link `File Not Found` health check to `Trash` page to allow deletion
-
-### Changed
-- Minor HLS Segmenter improvements
+- Fix `HLS Segmenter` streaming mode with multiple ffmpeg-based clients
+  - Jellyfin (web) and TiviMate (Android) were specifically tested
 
 ## [0.3.8-alpha] - 2022-01-23
 ### Fixed

ErsatzTV.Application/Streaming/HlsSessionWorker.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Diagnostics;
 using System.IO;
+using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using System.Timers;
@@ -132,12 +133,16 @@ namespace ErsatzTV.Application.Streaming
                 using IServiceScope scope = _serviceScopeFactory.CreateScope();
                 IMediator mediator = scope.ServiceProvider.GetRequiredService<IMediator>();
 
+                long ptsOffset = await GetPtsOffset(mediator, channelNumber, cancellationToken);
+                // _logger.LogInformation("PTS offset: {PtsOffset}", ptsOffset);
+
                 var request = new GetPlayoutItemProcessByChannelNumber(
                     channelNumber,
                     "segmenter",
                     firstProcess ? DateTimeOffset.Now : _transcodedUntil.AddSeconds(1),
                     !firstProcess,
-                    realtime);
+                    realtime,
+                    ptsOffset);
 
                 // _logger.LogInformation("Request {@Request}", request);
 
@@ -231,6 +236,28 @@ namespace ErsatzTV.Application.Streaming
                 _playlistStart = trimResult.PlaylistStart;
             }
         }
+        
+        private async Task<long> GetPtsOffset(IMediator mediator, string channelNumber, CancellationToken cancellationToken)
+        {
+            var directory = new DirectoryInfo(Path.Combine(FileSystemLayout.TranscodeFolder, channelNumber));
+            Option<FileInfo> lastSegment =
+                Optional(directory.GetFiles("*.ts").OrderByDescending(f => f.Name).FirstOrDefault());
+
+            long result = 0;
+            foreach (FileInfo segment in lastSegment)
+            {
+                Either<BaseError, PtsAndDuration> queryResult = await mediator.Send(
+                    new GetLastPtsDuration(segment.FullName),
+                    cancellationToken);
+
+                foreach (PtsAndDuration ptsAndDuration in queryResult.RightToSeq())
+                {
+                    result = ptsAndDuration.Pts + ptsAndDuration.Duration;
+                }
+            }
+
+            return result;
+        }
 
         private async Task<int> GetWorkAheadLimit()
         {

ErsatzTV.Application/Streaming/PtsAndDuration.cs

@@ -0,0 +1,12 @@
+namespace ErsatzTV.Application.Streaming;
+
+public record PtsAndDuration(long Pts, long Duration)
+{
+    public static PtsAndDuration From(string ffprobeLine)
+    {
+        string[] split = ffprobeLine.Split("|");
+        var left = long.Parse(split[0]);
+        var right = long.Parse(split[1]);
+        return new PtsAndDuration(left, right);
+    }
+}

ErsatzTV.Application/Streaming/Queries/FFmpegProcessRequest.cs

@@ -11,5 +11,6 @@ namespace ErsatzTV.Application.Streaming.Queries
         string Mode,
         DateTimeOffset Now,
         bool StartAtZero,
-        bool HlsRealtime) : IRequest<Either<BaseError, PlayoutItemProcessModel>>;
+        bool HlsRealtime,
+        long PtsOffset) : IRequest<Either<BaseError, PlayoutItemProcessModel>>;
 }

ErsatzTV.Application/Streaming/Queries/GetConcatProcessByChannelNumber.cs

@@ -9,7 +9,8 @@ namespace ErsatzTV.Application.Streaming.Queries
             "ts-legacy",
             DateTimeOffset.Now,
             false,
-            true)
+            true,
+            0)
         {
             Scheme = scheme;
             Host = host;

ErsatzTV.Application/Streaming/Queries/GetLastPtsDuration.cs

@@ -0,0 +1,7 @@
+using ErsatzTV.Core;
+using LanguageExt;
+using MediatR;
+
+namespace ErsatzTV.Application.Streaming.Queries;
+
+public record GetLastPtsDuration(string FileName) : IRequest<Either<BaseError, PtsAndDuration>>;

ErsatzTV.Application/Streaming/Queries/GetLastPtsDurationHandler.cs

@@ -0,0 +1,87 @@
+using System.Diagnostics;
+using System.IO;
+using System.Linq;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using ErsatzTV.Core;
+using ErsatzTV.Core.Domain;
+using ErsatzTV.Core.Interfaces.Repositories;
+using LanguageExt;
+using MediatR;
+
+namespace ErsatzTV.Application.Streaming.Queries;
+
+public class GetLastPtsDurationHandler : IRequestHandler<GetLastPtsDuration, Either<BaseError, PtsAndDuration>>
+{
+    private readonly IConfigElementRepository _configElementRepository;
+
+    public GetLastPtsDurationHandler(IConfigElementRepository configElementRepository)
+    {
+        _configElementRepository = configElementRepository;
+    }
+
+    public async Task<Either<BaseError, PtsAndDuration>> Handle(
+        GetLastPtsDuration request,
+        CancellationToken cancellationToken)
+    {
+        Validation<BaseError, RequestParameters> validation = await Validate(request);
+        return await validation.Match(
+            Handle,
+            error => Task.FromResult<Either<BaseError, PtsAndDuration>>(error.Join()));
+    }
+
+    private async Task<Validation<BaseError, RequestParameters>> Validate(GetLastPtsDuration request) =>
+        await ValidateFFprobePath()
+            .MapT(
+                ffprobePath => new RequestParameters(
+                    request.FileName,
+                    ffprobePath));
+
+    private async Task<Either<BaseError, PtsAndDuration>> Handle(RequestParameters parameters)
+    {
+        var startInfo = new ProcessStartInfo
+        {
+            FileName = parameters.FFprobePath,
+            RedirectStandardOutput = true,
+            RedirectStandardError = true,
+            UseShellExecute = false,
+            StandardOutputEncoding = Encoding.UTF8,
+            StandardErrorEncoding = Encoding.UTF8
+        };
+
+        startInfo.ArgumentList.Add("-v");
+        startInfo.ArgumentList.Add("0");
+        startInfo.ArgumentList.Add("-show_entries");
+        startInfo.ArgumentList.Add("packet=pts,duration");
+        startInfo.ArgumentList.Add("-of");
+        startInfo.ArgumentList.Add("compact=p=0:nk=1");
+        startInfo.ArgumentList.Add("-read_intervals");
+        startInfo.ArgumentList.Add("-999999");
+        startInfo.ArgumentList.Add(parameters.FileName);
+
+        var probe = new Process
+        {
+            StartInfo = startInfo
+        };
+
+        probe.Start();
+        return await probe.StandardOutput.ReadToEndAsync().MapAsync<string, Either<BaseError, PtsAndDuration>>(
+            async output =>
+            {
+                await probe.WaitForExitAsync();
+                return probe.ExitCode == 0
+                    ? PtsAndDuration.From(output.Split("\n").Filter(s => !string.IsNullOrWhiteSpace(s)).Last().Trim())
+                    : BaseError.New($"FFprobe at {parameters.FFprobePath} exited with code {probe.ExitCode}");
+            });
+    }
+
+    private Task<Validation<BaseError, string>> ValidateFFprobePath() =>
+        _configElementRepository.GetValue<string>(ConfigElementKey.FFprobePath)
+            .FilterT(File.Exists)
+            .Map(
+                ffprobePath =>
+                    ffprobePath.ToValidation<BaseError>("FFprobe path does not exist on the file system"));
+
+    private record RequestParameters(string FileName, string FFprobePath);
+}

ErsatzTV.Application/Streaming/Queries/GetPlayoutItemProcessByChannelNumber.cs

@@ -2,20 +2,15 @@
 
 namespace ErsatzTV.Application.Streaming.Queries
 {
-    public record GetPlayoutItemProcessByChannelNumber : FFmpegProcessRequest
-    {
-        public GetPlayoutItemProcessByChannelNumber(
-            string channelNumber,
-            string mode,
-            DateTimeOffset now,
-            bool startAtZero,
-            bool hlsRealtime) : base(
-            channelNumber,
-            mode,
-            now,
-            startAtZero,
-            hlsRealtime)
-        {
-        }
-    }
+    public record GetPlayoutItemProcessByChannelNumber(string ChannelNumber,
+        string Mode,
+        DateTimeOffset Now,
+        bool StartAtZero,
+        bool HlsRealtime,
+        long PtsOffset) : FFmpegProcessRequest(ChannelNumber,
+        Mode,
+        Now,
+        StartAtZero,
+        HlsRealtime,
+        PtsOffset);
 }

ErsatzTV.Application/Streaming/Queries/GetPlayoutItemProcessByChannelNumberHandler.cs

@@ -158,7 +158,8 @@ namespace ErsatzTV.Application.Streaming.Queries
                         request.HlsRealtime,
                         playoutItemWithPath.PlayoutItem.FillerKind,
                         playoutItemWithPath.PlayoutItem.InPoint,
-                        playoutItemWithPath.PlayoutItem.OutPoint);
+                        playoutItemWithPath.PlayoutItem.OutPoint,
+                        request.PtsOffset);
 
                     var result = new PlayoutItemProcessModel(process, playoutItemWithPath.PlayoutItem.FinishOffset);
 
@@ -193,7 +194,8 @@ namespace ErsatzTV.Application.Streaming.Queries
                                     channel,
                                     maybeDuration,
                                     "Channel is Offline",
-                                    request.HlsRealtime);
+                                    request.HlsRealtime,
+                                    request.PtsOffset);
                                 
                                 return new PlayoutItemProcessModel(errorProcess, finish);
                             }
@@ -212,7 +214,8 @@ namespace ErsatzTV.Application.Streaming.Queries
                                     channel,
                                     maybeDuration,
                                     error.Value,
-                                    request.HlsRealtime);
+                                    request.HlsRealtime,
+                                    request.PtsOffset);
 
                                 return new PlayoutItemProcessModel(errorProcess, finish);
                             }
@@ -231,7 +234,8 @@ namespace ErsatzTV.Application.Streaming.Queries
                                     channel,
                                     maybeDuration,
                                     "Channel is Offline",
-                                    request.HlsRealtime);
+                                    request.HlsRealtime,
+                                    request.PtsOffset);
 
                                 return new PlayoutItemProcessModel(errorProcess, finish);
                             }

ErsatzTV.Application/Streaming/Queries/GetWrappedProcessByChannelNumber.cs

@@ -9,7 +9,8 @@ namespace ErsatzTV.Application.Streaming.Queries
             "ts",
             DateTimeOffset.Now,
             false,
-            true)
+            true,
+            0)
         {
             Scheme = scheme;
             Host = host;

ErsatzTV.Core.Tests/FFmpeg/FFmpegPlaybackSettingsCalculatorTests.cs

@@ -16,6 +16,26 @@ namespace ErsatzTV.Core.Tests.FFmpeg
             private readonly FFmpegPlaybackSettingsCalculator _calculator;
 
             public CalculateSettings() => _calculator = new FFmpegPlaybackSettingsCalculator();
+            
+            [Test]
+            public void Should_Not_GenPts_ForHlsSegmenter()
+            {
+                FFmpegProfile ffmpegProfile = TestProfile();
+
+                FFmpegPlaybackSettings actual = _calculator.CalculateSettings(
+                    StreamingMode.HttpLiveStreamingSegmenter,
+                    ffmpegProfile,
+                    new MediaVersion(),
+                    new MediaStream(),
+                    new MediaStream(),
+                    DateTimeOffset.Now,
+                    DateTimeOffset.Now,
+                    TimeSpan.Zero,
+                    TimeSpan.Zero,
+                    false);
+
+                actual.FormatFlags.Should().NotContain("+genpts");
+            }
 
             [Test]
             public void Should_Not_UseSpecifiedThreadCount_ForTransportStream()

ErsatzTV.Core.Tests/FFmpeg/TranscodingTests.cs

@@ -214,7 +214,8 @@ namespace ErsatzTV.Core.Tests.FFmpeg
                 false,
                 FillerKind.None,
                 TimeSpan.Zero,
-                TimeSpan.FromSeconds(5));
+                TimeSpan.FromSeconds(5),
+                0);
 
             process.StartInfo.RedirectStandardError = true;
             

ErsatzTV.Core/FFmpeg/FFmpegPlaybackSettingsCalculator.cs

@@ -36,6 +36,12 @@ namespace ErsatzTV.Core.FFmpeg
             "+igndts"
         };
 
+        private static readonly List<string> SegmenterFormatFlags = new()
+        {
+            "+discardcorrupt",
+            "+igndts"
+        };
+
         public FFmpegPlaybackSettings ConcatSettings => new()
         {
             ThreadCount = 1,
@@ -56,7 +62,11 @@ namespace ErsatzTV.Core.FFmpeg
         {
             var result = new FFmpegPlaybackSettings
             {
-                FormatFlags = CommonFormatFlags,
+                FormatFlags = streamingMode switch
+                {
+                    StreamingMode.HttpLiveStreamingSegmenter => SegmenterFormatFlags,
+                    _ => CommonFormatFlags,
+                },
                 RealtimeOutput = streamingMode switch
                 {
                     StreamingMode.HttpLiveStreamingSegmenter => hlsRealtime,

ErsatzTV.Core/FFmpeg/FFmpegProcessBuilder.cs

@@ -21,6 +21,7 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Globalization;
 using System.IO;
 using System.Runtime.InteropServices;
 using System.Text;
@@ -387,7 +388,7 @@ namespace ErsatzTV.Core.FFmpeg
             return this;
         }
 
-        public FFmpegProcessBuilder WithHls(string channelNumber, Option<MediaVersion> mediaVersion)
+        public FFmpegProcessBuilder WithHls(string channelNumber, Option<MediaVersion> mediaVersion, long ptsOffset, Option<int> maybeTimeScale)
         {
             const int SEGMENT_SECONDS = 4;
 
@@ -412,10 +413,15 @@ namespace ErsatzTV.Core.FFmpeg
                 frameRate = fr;
             }
 
+            foreach (int timescale in maybeTimeScale)
+            {
+                _arguments.Add("-output_ts_offset");
+                _arguments.Add($"{(ptsOffset / (double)timescale).ToString(NumberFormatInfo.InvariantInfo)}");
+            }
+
             _arguments.AddRange(
                 new[]
                 {
-                    "-use_wallclock_as_timestamps", "1",
                     "-g", $"{frameRate * SEGMENT_SECONDS}",
                     "-keyint_min", $"{frameRate * SEGMENT_SECONDS}",
                     "-force_key_frames", $"expr:gte(t,n_forced*{SEGMENT_SECONDS})",
@@ -427,7 +433,6 @@ namespace ErsatzTV.Core.FFmpeg
                     Path.Combine(FileSystemLayout.TranscodeFolder, channelNumber, "live%06d.ts"),
                     "-hls_flags", "program_date_time+append_list+discont_start+omit_endlist+independent_segments",
                     "-mpegts_flags", "+initial_discontinuity",
-                    "-mpegts_copyts", "1",
                     Path.Combine(FileSystemLayout.TranscodeFolder, channelNumber, "live.m3u8")
                 });
 

ErsatzTV.Core/FFmpeg/FFmpegProcessService.cs

@@ -51,7 +51,8 @@ namespace ErsatzTV.Core.FFmpeg
             bool hlsRealtime,
             FillerKind fillerKind,
             TimeSpan inPoint,
-            TimeSpan outPoint)
+            TimeSpan outPoint,
+            long ptsOffset)
         {
             MediaStream videoStream = await _ffmpegStreamSelector.SelectVideoStream(channel, videoVersion);
             Option<MediaStream> maybeAudioStream = await _ffmpegStreamSelector.SelectAudioStream(channel, audioVersion);
@@ -158,7 +159,7 @@ namespace ErsatzTV.Core.FFmpeg
             {
                 // HLS needs to segment and generate playlist
                 case StreamingMode.HttpLiveStreamingSegmenter:
-                    return builder.WithHls(channel.Number, videoVersion)
+                    return builder.WithHls(channel.Number, videoVersion, ptsOffset, playbackSettings.VideoTrackTimeScale)
                         .Build();
                 default:
                     return builder.WithFormat("mpegts")
@@ -173,7 +174,8 @@ namespace ErsatzTV.Core.FFmpeg
             Channel channel,
             Option<TimeSpan> duration,
             string errorMessage,
-            bool hlsRealtime)
+            bool hlsRealtime,
+            long ptsOffset)
         {
             FFmpegPlaybackSettings playbackSettings =
                 _playbackSettingsCalculator.CalculateErrorSettings(channel.FFmpegProfile);
@@ -221,7 +223,7 @@ namespace ErsatzTV.Core.FFmpeg
             {
                 // HLS needs to segment and generate playlist
                 case StreamingMode.HttpLiveStreamingSegmenter:
-                    return builder.WithHls(channel.Number, None)
+                    return builder.WithHls(channel.Number, None, ptsOffset, playbackSettings.VideoTrackTimeScale)
                         .Build();
                 default:
                     return builder.WithFormat("mpegts")

ErsatzTV.Core/Interfaces/FFmpeg/IFFmpegProcessService.cs

@@ -27,14 +27,16 @@ namespace ErsatzTV.Core.Interfaces.FFmpeg
             bool hlsRealtime,
             FillerKind fillerKind,
             TimeSpan inPoint,
-            TimeSpan outPoint);
+            TimeSpan outPoint,
+            long ptsOffset);
 
         Task<Process> ForError(
             string ffmpegPath,
             Channel channel,
             Option<TimeSpan> duration,
             string errorMessage,
-            bool hlsRealtime);
+            bool hlsRealtime,
+            long ptsOffset);
 
         Process ConcatChannel(string ffmpegPath, bool saveReports, Channel channel, string scheme, string host);
 

ErsatzTV/Controllers/InternalController.cs

@@ -27,14 +27,14 @@ namespace ErsatzTV.Controllers
         public Task<IActionResult> GetConcatPlaylist(string channelNumber) =>
             _mediator.Send(new GetConcatPlaylistByChannelNumber(Request.Scheme, Request.Host.ToString(), channelNumber))
                 .ToActionResult();
-        
+
         [HttpGet("ffmpeg/stream/{channelNumber}")]
         public Task<IActionResult> GetStream(
             string channelNumber,
             [FromQuery]
             string mode = "mixed") =>
             _mediator.Send(
-                    new GetPlayoutItemProcessByChannelNumber(channelNumber, mode, DateTimeOffset.Now, false, true))
+                    new GetPlayoutItemProcessByChannelNumber(channelNumber, mode, DateTimeOffset.Now, false, true, 0))
                 .Map(
                     result =>
                         result.Match<IActionResult>(