add software tonemap filter to support hdr content (#2027)

CHANGELOG.md

@@ -22,6 +22,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
   - As an example, if the current scheduling time is 6:02 AM and the next schedule item has a fixed start time of 6:00 AM
     - `Strict` will add nearly 24h (23:58) of unscheduled time so that it can start exactly at 6:00 AM the next day
     - `Flexible` will NOT add unscheduled time, and will schedule its item at 6:02 AM (which may also affect the scheduling of later items)
+- Add basic HDR transcoding support
+  - For this initial implementation, HDR content will *always* use a software pipeline
 
 ### Changed
 - Start to make UI minimally responsive (functional on smaller screens)

ErsatzTV.FFmpeg/Filter/TonemapFilter.cs

@@ -20,7 +20,7 @@ public class TonemapFilter : BaseFilter
             string pixelFormat = _currentState.PixelFormat.Match(pf => pf.FFmpegName, () => string.Empty);
 
             var tonemap =
-                $"setparams=colorspace=bt2020c,zscale=transfer=linear,tonemap=hable,zscale=transfer=bt709,format={_desiredPixelFormat.FFmpegName}";
+                $"zscale=transfer=linear,tonemap=hable,zscale=transfer=bt709,format={_desiredPixelFormat.FFmpegName}";
 
             if (_currentState.FrameDataLocation == FrameDataLocation.Hardware)
             {

ErsatzTV.FFmpeg/MediaStream.cs

@@ -30,6 +30,8 @@ public record VideoStream(
     Codec,
     StreamKind.Video)
 {
+    public ColorParams ColorParams { get; private set; } = ColorParams;
+
     public int BitDepth => PixelFormat.Map(pf => pf.BitDepth).IfNone(8);
 
     public string SampleAspectRatio
@@ -152,6 +154,8 @@ public record VideoStream(
         return result;
     }
 
+    public void ResetColorParams(ColorParams colorParams) => ColorParams = colorParams;
+
     private double GetSAR()
     {
         // some media servers don't provide sample aspect ratio so we have to calculate it

ErsatzTV.FFmpeg/Pipeline/NvidiaPipelineBuilder.cs

@@ -307,7 +307,7 @@ public class NvidiaPipelineBuilder : SoftwarePipelineBuilder
             // clearing color params will force it to be re-added
             if (videoStream.Codec == "vp9")
             {
-                videoStream = videoStream with { ColorParams = ColorParams.Unknown };
+                videoStream.ResetColorParams(ColorParams.Unknown);
             }
 
             if (!videoStream.ColorParams.IsBt709)

ErsatzTV.FFmpeg/Pipeline/PipelineBuilderFactory.cs

@@ -40,8 +40,23 @@ public class PipelineBuilderFactory : IPipelineBuilderFactory
             vaapiDriver,
             vaapiDevice);
 
+        bool isHdrContent = videoInputFile.Any(vif => vif.VideoStreams.Any(vs => vs.ColorParams.IsHdr));
+
         return hardwareAccelerationMode switch
         {
+            // force software pipeline when content is HDR
+            _ when isHdrContent => new SoftwarePipelineBuilder(
+                ffmpegCapabilities,
+                HardwareAccelerationMode.None,
+                videoInputFile,
+                audioInputFile,
+                watermarkInputFile,
+                subtitleInputFile,
+                concatInputFile,
+                reportsFolder,
+                fontsFolder,
+                _logger),
+
             HardwareAccelerationMode.Nvenc when capabilities is not NoHardwareCapabilities => new NvidiaPipelineBuilder(
                 ffmpegCapabilities,
                 capabilities,

ErsatzTV.FFmpeg/Pipeline/SoftwarePipelineBuilder.cs

@@ -104,6 +104,7 @@ public class SoftwarePipelineBuilder : PipelineBuilderBase
         {
             SetDeinterlace(videoInputFile, context, currentState);
 
+            currentState = SetTonemap(videoInputFile, videoStream, desiredState, currentState);
             currentState = SetScale(videoInputFile, videoStream, desiredState, currentState);
             currentState = SetPad(videoInputFile, videoStream, desiredState, currentState);
             currentState = SetCrop(videoInputFile, desiredState, currentState);
@@ -317,6 +318,26 @@ public class SoftwarePipelineBuilder : PipelineBuilderBase
         return currentState;
     }
 
+    private static FrameState SetTonemap(
+        VideoInputFile videoInputFile,
+        VideoStream videoStream,
+        FrameState desiredState,
+        FrameState currentState)
+    {
+        if (videoStream.ColorParams.IsHdr)
+        {
+            foreach (IPixelFormat pixelFormat in desiredState.PixelFormat)
+            {
+                var tonemapStep = new TonemapFilter(currentState, pixelFormat);
+                currentState = tonemapStep.NextState(currentState);
+                videoStream.ResetColorParams(ColorParams.Default);
+                videoInputFile.FilterSteps.Add(tonemapStep);
+            }
+        }
+
+        return currentState;
+    }
+
     private static FrameState SetScale(
         VideoInputFile videoInputFile,
         VideoStream videoStream,