add aac (latm) audio format (#2561)

* add aac (latm) audio format

* update changelog

CHANGELOG.md

@@ -27,6 +27,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
   - By default, poster will be added as image with type "poster" and thumbnail will be added as image with type "still"
   - Poster will continue to be added as icon by default
 - Add buttons to edit Jellyfin and Emby connection information in **Media Sources** > **Jellyfin** and **Media Sources** > **Emby**
+- Add audio format `aac (latm)` for DVB-C compatibility; `aac` uses ADTS by default which is required in most cases
 
 ### Fixed
 - Fix NVIDIA startup errors on arm64

ErsatzTV.Core/Domain/FFmpegProfileAudioFormat.cs

@@ -9,6 +9,7 @@ public enum FFmpegProfileAudioFormat
 
     Aac = 1,
     Ac3 = 2,
+    AacLatm = 3,
 
     Copy = 99
 }

ErsatzTV.Core/FFmpeg/FFmpegLibraryProcessService.cs

@@ -171,6 +171,7 @@ public class FFmpegLibraryProcessService : IFFmpegProcessService
         string audioFormat = playbackSettings.AudioFormat switch
         {
             FFmpegProfileAudioFormat.Aac => AudioFormat.Aac,
+            FFmpegProfileAudioFormat.AacLatm => AudioFormat.AacLatm,
             FFmpegProfileAudioFormat.Ac3 => AudioFormat.Ac3,
             FFmpegProfileAudioFormat.Copy => AudioFormat.Copy,
             _ => throw new ArgumentOutOfRangeException($"unexpected audio format {playbackSettings.VideoFormat}")
@@ -403,6 +404,27 @@ public class FFmpegLibraryProcessService : IFFmpegProcessService
             _ =>  Option<string>.None
         };
 
+        Option<string> hlsSegmentOptions = Option<string>.None;
+        if (outputFormat is OutputFormatKind.Hls)
+        {
+            string options = string.Empty;
+
+            if (ptsOffset == TimeSpan.Zero)
+            {
+                options += "+initial_discontinuity";
+            }
+
+            if (audioFormat == AudioFormat.AacLatm)
+            {
+                options += "+latm";
+            }
+
+            if (!string.IsNullOrWhiteSpace(options))
+            {
+                hlsSegmentOptions = $"mpegts_flags={options}";
+            }
+        }
+
         FrameSize scaledSize = ffmpegVideoStream.SquarePixelFrameSize(
             new FrameSize(channel.FFmpegProfile.Resolution.Width, channel.FFmpegProfile.Resolution.Height));
 
@@ -506,6 +528,7 @@ public class FFmpegLibraryProcessService : IFFmpegProcessService
             hlsPlaylistPath,
             hlsSegmentTemplate,
             hlsInitTemplate,
+            hlsSegmentOptions,
             ptsOffset,
             playbackSettings.ThreadCount,
             qsvExtraHardwareFrames,
@@ -583,6 +606,7 @@ public class FFmpegLibraryProcessService : IFFmpegProcessService
         string audioFormat = playbackSettings.AudioFormat switch
         {
             FFmpegProfileAudioFormat.Ac3 => AudioFormat.Ac3,
+            FFmpegProfileAudioFormat.AacLatm => AudioFormat.AacLatm,
             _ => AudioFormat.Aac
         };
 
@@ -645,6 +669,27 @@ public class FFmpegLibraryProcessService : IFFmpegProcessService
             _ =>  Option<string>.None
         };
 
+        Option<string> hlsSegmentOptions = Option<string>.None;
+        if (outputFormat is OutputFormatKind.Hls)
+        {
+            string options = string.Empty;
+
+            if (ptsOffset == TimeSpan.Zero)
+            {
+                options += "+initial_discontinuity";
+            }
+
+            if (audioFormat == AudioFormat.AacLatm)
+            {
+                options += "+latm";
+            }
+
+            if (!string.IsNullOrWhiteSpace(options))
+            {
+                hlsSegmentOptions = $"mpegts_options={options}";
+            }
+        }
+
         string videoPath = Path.Combine(FileSystemLayout.ResourcesCacheFolder, "background.png");
 
         var videoVersion = BackgroundImageMediaVersion.ForPath(videoPath, desiredResolution);
@@ -686,6 +731,7 @@ public class FFmpegLibraryProcessService : IFFmpegProcessService
             hlsPlaylistPath,
             hlsSegmentTemplate,
             hlsInitTemplate,
+            hlsSegmentOptions,
             ptsOffset,
             Option<int>.None,
             qsvExtraHardwareFrames,
@@ -778,6 +824,11 @@ public class FFmpegLibraryProcessService : IFFmpegProcessService
             $"http://localhost:{Settings.StreamingPort}/iptv/channel/{channel.Number}.m3u8?mode=segmenter{accessTokenQuery}",
             resolution);
 
+        if (channel.FFmpegProfile.AudioFormat is FFmpegProfileAudioFormat.AacLatm)
+        {
+            concatInputFile.AudioFormat = AudioFormat.AacLatm;
+        }
+
         IPipelineBuilder pipelineBuilder = await _pipelineBuilderFactory.GetBuilder(
             HardwareAccelerationMode.None,
             Option<VideoInputFile>.None,

ErsatzTV.FFmpeg.Tests/PipelineBuilderBaseTests.cs

@@ -91,6 +91,7 @@ public class PipelineBuilderBaseTests
             Option<string>.None,
             Option<string>.None,
             Option<string>.None,
+            Option<string>.None,
             TimeSpan.Zero,
             Option<int>.None,
             Option<int>.None,
@@ -190,6 +191,7 @@ public class PipelineBuilderBaseTests
             Option<string>.None,
             Option<string>.None,
             Option<string>.None,
+            Option<string>.None,
             TimeSpan.Zero,
             Option<int>.None,
             Option<int>.None,
@@ -347,6 +349,7 @@ public class PipelineBuilderBaseTests
             Option<string>.None,
             Option<string>.None,
             Option<string>.None,
+            Option<string>.None,
             TimeSpan.Zero,
             Option<int>.None,
             Option<int>.None,
@@ -440,6 +443,7 @@ public class PipelineBuilderBaseTests
             Option<string>.None,
             Option<string>.None,
             Option<string>.None,
+            Option<string>.None,
             TimeSpan.Zero,
             Option<int>.None,
             Option<int>.None,

ErsatzTV.FFmpeg/Decoder/DecoderAacLatm.cs

@@ -0,0 +1,24 @@
+using ErsatzTV.FFmpeg.Environment;
+using ErsatzTV.FFmpeg.InputOption;
+
+namespace ErsatzTV.FFmpeg.Decoder;
+
+public class DecoderAacLatm : IInputOption
+{
+    public EnvironmentVariable[] EnvironmentVariables => [];
+    public string[] GlobalOptions => [];
+    public string[] FilterOptions => [];
+    public string[] OutputOptions => [];
+
+    public string[] InputOptions(InputFile inputFile) => ["-c:a", "aac_latm"];
+
+    public FrameState NextState(FrameState currentState) => currentState;
+
+    public bool AppliesTo(AudioInputFile audioInputFile) => false;
+
+    public bool AppliesTo(VideoInputFile videoInputFile) => false;
+
+    public bool AppliesTo(ConcatInputFile concatInputFile) => true;
+
+    public bool AppliesTo(GraphicsEngineInput graphicsEngineInput) => false;
+}

ErsatzTV.FFmpeg/FFmpegState.cs

@@ -20,6 +20,7 @@ public record FFmpegState(
     Option<string> HlsPlaylistPath,
     Option<string> HlsSegmentTemplate,
     Option<string> HlsInitTemplate,
+    Option<string> HlsSegmentOptions,
     TimeSpan PtsOffset,
     Option<int> ThreadCount,
     Option<int> MaybeQsvExtraHardwareFrames,
@@ -49,6 +50,7 @@ public record FFmpegState(
             Option<string>.None,
             Option<string>.None,
             Option<string>.None,
+            Option<string>.None,
             TimeSpan.Zero,
             Option<int>.None,
             Option<int>.None,

ErsatzTV.FFmpeg/Format/AudioFormat.cs

@@ -4,6 +4,7 @@ public static class AudioFormat
 {
     public const string Aac = "aac";
     public const string Ac3 = "ac3";
+    public const string AacLatm = "aac-latm";
 
     public const string Copy = "copy";
 }

ErsatzTV.FFmpeg/InputFile.cs

@@ -28,6 +28,8 @@ public record ConcatInputFile(string Url, FrameSize Resolution) : InputFile(
             ScanKind.Unknown)
     })
 {
+    public Option<string> AudioFormat { get; set; }
+
     public void AddOption(IInputOption option)
     {
         if (option.AppliesTo(this))

ErsatzTV.FFmpeg/OutputFormat/OutputFormatHls.cs

@@ -11,6 +11,7 @@ public class OutputFormatHls : IPipelineStep
     private readonly bool _isTroubleshooting;
     private readonly Option<string> _mediaFrameRate;
     private readonly OutputFormatKind _outputFormat;
+    private readonly Option<string> _segmentOptions;
     private readonly bool _oneSecondGop;
     private readonly string _playlistPath;
     private readonly string _segmentTemplate;
@@ -20,6 +21,7 @@ public class OutputFormatHls : IPipelineStep
         FrameState desiredState,
         Option<string> mediaFrameRate,
         OutputFormatKind outputFormat,
+        Option<string> segmentOptions,
         string segmentTemplate,
         Option<string> initTemplate,
         string playlistPath,
@@ -30,6 +32,7 @@ public class OutputFormatHls : IPipelineStep
         _desiredState = desiredState;
         _mediaFrameRate = mediaFrameRate;
         _outputFormat = outputFormat;
+        _segmentOptions = segmentOptions;
         _segmentTemplate = segmentTemplate;
         _initTemplate = initTemplate;
         _playlistPath = playlistPath;
@@ -83,6 +86,11 @@ public class OutputFormatHls : IPipelineStep
                     break;
             }
 
+            foreach (string options in _segmentOptions)
+            {
+                result.AddRange("-hls_segment_options", options);
+            }
+
             string pdt = _isTroubleshooting ? string.Empty : "program_date_time+omit_endlist+";
 
             if (_isFirstTranscode)
@@ -108,7 +116,6 @@ public class OutputFormatHls : IPipelineStep
                         result.AddRange(
                         [
                             "-hls_flags", $"{pdt}append_list+discont_start{independentSegments}",
-                            "-mpegts_flags", "+initial_discontinuity",
                             _playlistPath
                         ]);
                         break;

ErsatzTV.FFmpeg/OutputOption/AudioChannelsOutputOption.cs

@@ -20,15 +20,17 @@ public class AudioChannelsOutputOption : OutputOption
     {
         get
         {
-            if (_sourceChannels != _desiredChannels || _audioFormat == Some(AudioFormat.Aac) && _desiredChannels > 2)
+            if (_sourceChannels != _desiredChannels ||
+                (_audioFormat == Some(AudioFormat.Aac) || _audioFormat == Some(AudioFormat.AacLatm)) &&
+                _desiredChannels > 2)
             {
-                return new[]
-                {
+                return
+                [
                     "-ac", _desiredChannels.ToString(CultureInfo.InvariantCulture)
-                };
+                ];
             }
 
-            return Array.Empty<string>();
+            return [];
         }
     }
 }

ErsatzTV.FFmpeg/Pipeline/PipelineBuilderBase.cs

@@ -162,6 +162,12 @@ public abstract class PipelineBuilderBase : IPipelineBuilder
             new EncoderCopyAll()
         };
 
+        // ffmpeg below 8 doesn't detect this without an explicit decoder
+        foreach (string _ in concatInputFile.AudioFormat.Where(af => af == AudioFormat.AacLatm))
+        {
+            concatInputFile.AddOption(new DecoderAacLatm());
+        }
+
         concatInputFile.AddOption(new ReadrateInputOption(1.0));
 
         SetMetadataServiceProvider(ffmpegState, pipelineSteps);
@@ -384,6 +390,7 @@ public abstract class PipelineBuilderBase : IPipelineBuilder
                                 desiredState,
                                 videoStream.FrameRate,
                                 ffmpegState.OutputFormat,
+                                ffmpegState.HlsSegmentOptions,
                                 segmentTemplate,
                                 ffmpegState.HlsInitTemplate,
                                 playlistPath,

ErsatzTV/Controllers/IptvController.cs

@@ -307,7 +307,7 @@ public class IptvController : StreamingControllerBase
             string audioCodec = streamingSpecs.AudioFormat switch
             {
                 FFmpegProfileAudioFormat.Ac3 => "ac-3",
-                FFmpegProfileAudioFormat.Aac => "mp4a.40.2",
+                FFmpegProfileAudioFormat.Aac or FFmpegProfileAudioFormat.AacLatm => "mp4a.40.2",
                 _ => string.Empty
             };
 

ErsatzTV/Pages/FFmpegEditor.razor

@@ -242,6 +242,7 @@
             <MudSelect @bind-Value="_model.AudioFormat" For="@(() => _model.AudioFormat)">
                 <MudSelectItem Value="@FFmpegProfileAudioFormat.Aac">aac</MudSelectItem>
                 <MudSelectItem Value="@FFmpegProfileAudioFormat.Ac3">ac3</MudSelectItem>
+                <MudSelectItem Value="@FFmpegProfileAudioFormat.AacLatm">aac (latm)</MudSelectItem>
             </MudSelect>
         </MudStack>
         <MudStack Row="true" Breakpoint="Breakpoint.SmAndDown" Class="form-field-stack gap-md-8 mb-5">