fix image subtitle scaling (#949)

* properly scale image-based subtitles for nvidia and software

* fix vaapi image subtitle scaling

* fix qsv image subtitle scaling

* update changelog

CHANGELOG.md

@@ -11,6 +11,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - `VAAPI`: Downgrade libva from 2.15 to 2.14
 - Fix bug with XMLTV that caused some filler to display with primary content details
 - Multiple fixes for content scaling with `Nvidia`, `Qsv` and `Vaapi` accelerations
+- Properly scale image-based subtitles
 
 ### Added
 - Add `Preferred Audio Title` feature

ErsatzTV.Core.Tests/FFmpeg/TranscodingTests.cs

@@ -198,11 +198,11 @@ public class TranscodingTests
             [ValueSource(typeof(TestData), nameof(TestData.VideoFormats))]
             FFmpegProfileVideoFormat profileVideoFormat,
             // [ValueSource(typeof(TestData), nameof(TestData.NoAcceleration))] HardwareAccelerationKind profileAcceleration)
-            // [ValueSource(typeof(TestData), nameof(TestData.NvidiaAcceleration))] HardwareAccelerationKind profileAcceleration)
+            [ValueSource(typeof(TestData), nameof(TestData.NvidiaAcceleration))] HardwareAccelerationKind profileAcceleration)
         // [ValueSource(typeof(TestData), nameof(TestData.VaapiAcceleration))] HardwareAccelerationKind profileAcceleration)
         // [ValueSource(typeof(TestData), nameof(TestData.QsvAcceleration))] HardwareAccelerationKind profileAcceleration)
         // [ValueSource(typeof(TestData), nameof(TestData.VideoToolboxAcceleration))] HardwareAccelerationKind profileAcceleration)
-        [ValueSource(typeof(TestData), nameof(TestData.AmfAcceleration))] HardwareAccelerationKind profileAcceleration)
+        // [ValueSource(typeof(TestData), nameof(TestData.AmfAcceleration))] HardwareAccelerationKind profileAcceleration)
     {
         if (inputFormat.Encoder is "mpeg1video" or "msmpeg4v2" or "msmpeg4v3")
         {

ErsatzTV.Core/FFmpeg/FFmpegLibraryProcessService.cs

@@ -239,7 +239,8 @@ public class FFmpegLibraryProcessService : IFFmpegProcessService
             hlsPlaylistPath,
             hlsSegmentTemplate,
             ptsOffset,
-            playbackSettings.ThreadCount);
+            playbackSettings.ThreadCount,
+            128);
 
         _logger.LogDebug("FFmpeg desired state {FrameState}", desiredState);
 
@@ -363,7 +364,8 @@ public class FFmpegLibraryProcessService : IFFmpegProcessService
             hlsPlaylistPath,
             hlsSegmentTemplate,
             ptsOffset,
-            Option<int>.None);
+            Option<int>.None,
+            128);
 
         var ffmpegSubtitleStream = new ErsatzTV.FFmpeg.MediaStream(0, "ass", StreamKind.Video);
 

ErsatzTV.FFmpeg.Tests/PipelineBuilderTests.cs

@@ -70,6 +70,7 @@ public class PipelineGeneratorTests
             Option<string>.None,
             Option<string>.None,
             0,
+            Option<int>.None,
             Option<int>.None);
 
         var builder = new PipelineBuilder(
@@ -142,6 +143,7 @@ public class PipelineGeneratorTests
             Option<string>.None,
             Option<string>.None,
             0,
+            Option<int>.None,
             Option<int>.None);
 
         var builder = new PipelineBuilder(
@@ -240,6 +242,7 @@ public class PipelineGeneratorTests
             Option<string>.None,
             Option<string>.None,
             0,
+            Option<int>.None,
             Option<int>.None);
 
         var builder = new PipelineBuilder(
@@ -304,6 +307,7 @@ public class PipelineGeneratorTests
             Option<string>.None,
             Option<string>.None,
             0,
+            Option<int>.None,
             Option<int>.None);
 
         var builder = new PipelineBuilder(

ErsatzTV.FFmpeg/Encoder/AvailableEncoders.cs

@@ -43,14 +43,16 @@ public static class AvailableEncoders
                 new EncoderHevcQsv(
                     currentState,
                     maybeWatermarkInputFile,
-                    maybeSubtitleInputFile),
+                    maybeSubtitleInputFile,
+                    ffmpegState.QsvExtraHardwareFrames),
             (HardwareAccelerationMode.Qsv, VideoFormat.H264) when hardwareCapabilities.CanEncode(
                     VideoFormat.H264,
                     desiredState.PixelFormat) =>
                 new EncoderH264Qsv(
                     currentState,
                     maybeWatermarkInputFile,
-                    maybeSubtitleInputFile),
+                    maybeSubtitleInputFile,
+                    ffmpegState.QsvExtraHardwareFrames),
 
             (HardwareAccelerationMode.Vaapi, VideoFormat.Hevc) when hardwareCapabilities.CanEncode(
                     VideoFormat.Hevc,

ErsatzTV.FFmpeg/Encoder/Qsv/EncoderH264Qsv.cs

@@ -6,21 +6,26 @@ public class EncoderH264Qsv : EncoderBase
 {
     private readonly FrameState _currentState;
     private readonly Option<SubtitleInputFile> _maybeSubtitleInputFile;
+    private readonly int _extraHardwareFrames;
     private readonly Option<WatermarkInputFile> _maybeWatermarkInputFile;
 
     public EncoderH264Qsv(
         FrameState currentState,
         Option<WatermarkInputFile> maybeWatermarkInputFile,
-        Option<SubtitleInputFile> maybeSubtitleInputFile)
+        Option<SubtitleInputFile> maybeSubtitleInputFile,
+        int extraHardwareFrames)
     {
         _currentState = currentState;
         _maybeWatermarkInputFile = maybeWatermarkInputFile;
         _maybeSubtitleInputFile = maybeSubtitleInputFile;
+        _extraHardwareFrames = extraHardwareFrames;
     }
 
     public override string Name => "h264_qsv";
     public override StreamKind Kind => StreamKind.Video;
-    public override IList<string> OutputOptions => new[] { "-c:v", "h264_qsv", "-low_power", "0" };
+
+    public override IList<string> OutputOptions =>
+        new[] { "-c:v", "h264_qsv", "-low_power", "0", "-look_ahead", "0" };
 
     // need to upload if we're still in software and a watermark is used
     public override string Filter
@@ -37,11 +42,11 @@ public class EncoderH264Qsv : EncoderBase
                     // pixel format should already be converted to a supported format by QsvHardwareAccelerationOption
                     foreach (IPixelFormat pixelFormat in _currentState.PixelFormat)
                     {
-                        return $"format={pixelFormat.FFmpegName},hwupload=extra_hw_frames=64";
+                        return $"format={pixelFormat.FFmpegName},hwupload=extra_hw_frames={_extraHardwareFrames}";
                     }
 
                     // default to nv12
-                    return "format=nv12,hwupload=extra_hw_frames=64";
+                    return $"format=nv12,hwupload=extra_hw_frames={_extraHardwareFrames}";
                 }
             }
 

ErsatzTV.FFmpeg/Encoder/Qsv/EncoderHevcQsv.cs

@@ -6,21 +6,26 @@ public class EncoderHevcQsv : EncoderBase
 {
     private readonly FrameState _currentState;
     private readonly Option<SubtitleInputFile> _maybeSubtitleInputFile;
+    private readonly int _extraHardwareFrames;
     private readonly Option<WatermarkInputFile> _maybeWatermarkInputFile;
 
     public EncoderHevcQsv(
         FrameState currentState,
         Option<WatermarkInputFile> maybeWatermarkInputFile,
-        Option<SubtitleInputFile> maybeSubtitleInputFile)
+        Option<SubtitleInputFile> maybeSubtitleInputFile,
+        int extraHardwareFrames)
     {
         _currentState = currentState;
         _maybeWatermarkInputFile = maybeWatermarkInputFile;
         _maybeSubtitleInputFile = maybeSubtitleInputFile;
+        _extraHardwareFrames = extraHardwareFrames;
     }
 
     public override string Name => "hevc_qsv";
     public override StreamKind Kind => StreamKind.Video;
-    public override IList<string> OutputOptions => new[] { "-c:v", "hevc_qsv", "-low_power", "0" };
+
+    public override IList<string> OutputOptions =>
+        new[] { "-c:v", "hevc_qsv", "-low_power", "0", "-look_head", "0" };
 
     // need to upload if we're still in software and a watermark is used
     public override string Filter
@@ -37,11 +42,11 @@ public class EncoderHevcQsv : EncoderBase
                     // pixel format should already be converted to a supported format by QsvHardwareAccelerationOption
                     foreach (IPixelFormat pixelFormat in _currentState.PixelFormat)
                     {
-                        return $"format={pixelFormat.FFmpegName},hwupload=extra_hw_frames=64";
+                        return $"format={pixelFormat.FFmpegName},hwupload=extra_hw_frames={_extraHardwareFrames}";
                     }
 
                     // default to nv12
-                    return "format=nv12,hwupload=extra_hw_frames=64";
+                    return $"format=nv12,hwupload=extra_hw_frames={_extraHardwareFrames}";
                 }
             }
 

ErsatzTV.FFmpeg/FFmpegState.cs

@@ -18,8 +18,11 @@ public record FFmpegState(
     Option<string> HlsPlaylistPath,
     Option<string> HlsSegmentTemplate,
     long PtsOffset,
-    Option<int> ThreadCount)
+    Option<int> ThreadCount,
+    Option<int> MaybeQsvExtraHardwareFrames)
 {
+    public int QsvExtraHardwareFrames => MaybeQsvExtraHardwareFrames.IfNone(64);
+    
     public static FFmpegState Concat(bool saveReport, string channelName) =>
         new(
             saveReport,
@@ -37,5 +40,6 @@ public record FFmpegState(
             Option<string>.None,
             Option<string>.None,
             0,
+            Option<int>.None,
             Option<int>.None);
 }

ErsatzTV.FFmpeg/Filter/AvailableScaleFilters.cs

@@ -12,13 +12,14 @@ public static class AvailableScaleFilters
         HardwareAccelerationMode accelMode,
         FrameState currentState,
         FrameSize scaledSize,
-        FrameSize paddedSize) =>
+        FrameSize paddedSize,
+        int extraHardwareFrames) =>
         accelMode switch
         {
             HardwareAccelerationMode.Nvenc => new ScaleCudaFilter(currentState, scaledSize, paddedSize),
             HardwareAccelerationMode.Qsv when currentState.FrameDataLocation == FrameDataLocation.Hardware ||
                                               scaledSize == paddedSize =>
-                new ScaleQsvFilter(runtimeInfo, currentState, scaledSize, paddedSize),
+                new ScaleQsvFilter(runtimeInfo, currentState, scaledSize, paddedSize, extraHardwareFrames),
             HardwareAccelerationMode.Vaapi => new ScaleVaapiFilter(currentState, scaledSize, paddedSize),
             _ => new ScaleFilter(currentState, scaledSize, paddedSize)
         };

ErsatzTV.FFmpeg/Filter/AvailableSubtitleScaleFilters.cs

@@ -0,0 +1,24 @@
+using ErsatzTV.FFmpeg.Filter.Cuda;
+using ErsatzTV.FFmpeg.Filter.Qsv;
+
+namespace ErsatzTV.FFmpeg.Filter;
+
+public static class AvailableSubtitleScaleFilters
+{
+    public static IPipelineFilterStep ForAcceleration(
+        HardwareAccelerationMode accelMode,
+        FrameState currentState,
+        FrameSize scaledSize,
+        FrameSize paddedSize,
+        int extraHardwareFrames) =>
+        accelMode switch
+        {
+            HardwareAccelerationMode.Nvenc => new SubtitleScaleNppFilter(currentState, scaledSize, paddedSize),
+            HardwareAccelerationMode.Qsv => new SubtitleScaleQsvFilter(
+                currentState,
+                scaledSize,
+                paddedSize,
+                extraHardwareFrames),
+            _ => new ScaleImageFilter(paddedSize)
+        };
+}

ErsatzTV.FFmpeg/Filter/Cuda/SubtitleScaleNppFilter.cs

@@ -0,0 +1,40 @@
+using ErsatzTV.FFmpeg.Format;
+
+namespace ErsatzTV.FFmpeg.Filter.Cuda;
+
+public class SubtitleScaleNppFilter : BaseFilter
+{
+    private readonly FrameState _currentState;
+    private readonly FrameSize _paddedSize;
+    private readonly FrameSize _scaledSize;
+
+    public SubtitleScaleNppFilter(FrameState currentState, FrameSize scaledSize, FrameSize paddedSize)
+    {
+        _currentState = currentState;
+        _scaledSize = scaledSize;
+        _paddedSize = paddedSize;
+    }
+
+    public override string Filter
+    {
+        get
+        {
+            string scale = string.Empty;
+            if (_currentState.ScaledSize != _scaledSize)
+            {
+                string targetSize = $"{_paddedSize.Width}:{_paddedSize.Height}";
+                string format = string.Empty;
+                foreach (IPixelFormat pixelFormat in _currentState.PixelFormat)
+                {
+                    format = $":format={pixelFormat.FFmpegName}";
+                }
+
+                scale = $"scale_npp={targetSize}{format}";
+            }
+
+            return scale;
+        }
+    }
+
+    public override FrameState NextState(FrameState currentState) => currentState;
+}

ErsatzTV.FFmpeg/Filter/HardwareUploadFilter.cs

@@ -4,13 +4,16 @@ public class HardwareUploadFilter : BaseFilter
 {
     private readonly FFmpegState _ffmpegState;
 
-    public HardwareUploadFilter(FFmpegState ffmpegState) => _ffmpegState = ffmpegState;
+    public HardwareUploadFilter(FFmpegState ffmpegState)
+    {
+        _ffmpegState = ffmpegState;
+    }
 
     public override string Filter => _ffmpegState.EncoderHardwareAccelerationMode switch
     {
         HardwareAccelerationMode.None => string.Empty,
         HardwareAccelerationMode.Nvenc => "hwupload_cuda",
-        HardwareAccelerationMode.Qsv => "hwupload=extra_hw_frames=64",
+        HardwareAccelerationMode.Qsv => $"hwupload=extra_hw_frames={_ffmpegState.QsvExtraHardwareFrames}",
         HardwareAccelerationMode.Vaapi => "format=nv12|vaapi,hwupload",
         _ => "hwupload"
     };

ErsatzTV.FFmpeg/Filter/Qsv/DeinterlaceQsvFilter.cs

@@ -5,12 +5,17 @@ namespace ErsatzTV.FFmpeg.Filter.Qsv;
 public class DeinterlaceQsvFilter : BaseFilter
 {
     private readonly FrameState _currentState;
+    private readonly int _extraHardwareFrames;
 
-    public DeinterlaceQsvFilter(FrameState currentState) => _currentState = currentState;
+    public DeinterlaceQsvFilter(FrameState currentState, int extraHardwareFrames)
+    {
+        _currentState = currentState;
+        _extraHardwareFrames = extraHardwareFrames;
+    }
 
     // deinterlace_qsv seems to only support nv12, not p010le
     public override string Filter => _currentState.FrameDataLocation == FrameDataLocation.Software
-        ? "format=nv12,hwupload=extra_hw_frames=64,deinterlace_qsv"
+        ? $"format=nv12,hwupload=extra_hw_frames={_extraHardwareFrames},deinterlace_qsv"
         : "deinterlace_qsv";
 
     public override FrameState NextState(FrameState currentState)

ErsatzTV.FFmpeg/Filter/Qsv/ScaleQsvFilter.cs

@@ -10,13 +10,20 @@ public class ScaleQsvFilter : BaseFilter
     private readonly FrameState _currentState;
     private readonly FrameSize _scaledSize;
     private readonly FrameSize _paddedSize;
+    private readonly int _extraHardwareFrames;
 
-    public ScaleQsvFilter(IRuntimeInfo runtimeInfo, FrameState currentState, FrameSize scaledSize, FrameSize paddedSize)
+    public ScaleQsvFilter(
+        IRuntimeInfo runtimeInfo,
+        FrameState currentState,
+        FrameSize scaledSize,
+        FrameSize paddedSize,
+        int extraHardwareFrames)
     {
         _runtimeInfo = runtimeInfo;
         _currentState = currentState;
         _scaledSize = scaledSize;
         _paddedSize = paddedSize;
+        _extraHardwareFrames = extraHardwareFrames;
     }
 
     public override string Filter
@@ -57,10 +64,10 @@ public class ScaleQsvFilter : BaseFilter
             string initialPixelFormat = _currentState.PixelFormat.Match(pf => pf.FFmpegName, FFmpegFormat.NV12);
             if (!string.IsNullOrWhiteSpace(scale))
             {
-                return $"format={initialPixelFormat},hwupload=extra_hw_frames=64,{scale}";
+                return $"format={initialPixelFormat},hwupload=extra_hw_frames={_extraHardwareFrames},{scale}";
             }
 
-            return $"format={initialPixelFormat},hwupload=extra_hw_frames=64";
+            return $"format={initialPixelFormat},hwupload=extra_hw_frames={_extraHardwareFrames}";
         }
     }
 

ErsatzTV.FFmpeg/Filter/Qsv/SubtitleScaleQsvFilter.cs

@@ -0,0 +1,48 @@
+using ErsatzTV.FFmpeg.Format;
+
+namespace ErsatzTV.FFmpeg.Filter.Qsv;
+
+public class SubtitleScaleQsvFilter : BaseFilter
+{
+    private readonly FrameState _currentState;
+    private readonly FrameSize _scaledSize;
+    private readonly FrameSize _paddedSize;
+    private readonly int _extraHardwareFrames;
+
+    public SubtitleScaleQsvFilter(
+        FrameState currentState,
+        FrameSize scaledSize,
+        FrameSize paddedSize,
+        int extraHardwareFrames)
+    {
+        _currentState = currentState;
+        _scaledSize = scaledSize;
+        _paddedSize = paddedSize;
+        _extraHardwareFrames = extraHardwareFrames;
+    }
+
+    public override string Filter
+    {
+        get
+        {
+            string scale = string.Empty;
+            if (_currentState.ScaledSize != _scaledSize)
+            {
+                string targetSize = $"w={_paddedSize.Width}:h={_paddedSize.Height}";
+                
+                // use software scaling
+                scale = $"scale={targetSize}";
+            }
+
+            string initialPixelFormat = _currentState.PixelFormat.Match(pf => pf.FFmpegName, FFmpegFormat.NV12);
+            if (!string.IsNullOrWhiteSpace(scale))
+            {
+                return $"{scale},format={initialPixelFormat},hwupload=extra_hw_frames={_extraHardwareFrames}";
+            }
+
+            return $"format={initialPixelFormat},hwupload=extra_hw_frames={_extraHardwareFrames}";
+        }
+    }
+
+    public override FrameState NextState(FrameState currentState) => currentState;
+}

ErsatzTV.FFmpeg/Filter/SubtitleHardwareUploadFilter.cs

@@ -16,7 +16,7 @@ public class SubtitleHardwareUploadFilter : BaseFilter
         {
             HardwareAccelerationMode.None => string.Empty,
             HardwareAccelerationMode.Nvenc => "hwupload_cuda",
-            HardwareAccelerationMode.Qsv => "hwupload=extra_hw_frames=64",
+            HardwareAccelerationMode.Qsv => string.Empty,
 
             // leave vaapi in software since we don't (yet) use overlay_vaapi
             HardwareAccelerationMode.Vaapi when _currentState.FrameDataLocation == FrameDataLocation.Software =>

ErsatzTV.FFmpeg/Filter/SubtitlePixelFormatFilter.cs

@@ -6,20 +6,14 @@ public class SubtitlePixelFormatFilter : BaseFilter
 
     public SubtitlePixelFormatFilter(FFmpegState ffmpegState) => _ffmpegState = ffmpegState;
 
-    public override string Filter
-    {
-        get
-        {
-            Option<string> maybeFormat = _ffmpegState.EncoderHardwareAccelerationMode switch
-            {
-                HardwareAccelerationMode.Nvenc => "yuva420p",
-                HardwareAccelerationMode.Qsv => "yuva420p",
-                _ => None
-            };
+    public override string Filter => MaybeFormat.Match(f => $"format={f}", () => string.Empty);
 
-            return maybeFormat.Match(f => $"format={f}", () => string.Empty);
-        }
-    }
+    public Option<string> MaybeFormat =>_ffmpegState.EncoderHardwareAccelerationMode switch
+    {
+        HardwareAccelerationMode.Nvenc => "yuva420p",
+        HardwareAccelerationMode.Qsv => "yuva420p",
+        _ => None
+    }; 
 
     public override FrameState NextState(FrameState currentState) => currentState;
 }

ErsatzTV.FFmpeg/Filter/WatermarkHardwareUploadFilter.cs

@@ -15,7 +15,7 @@ public class WatermarkHardwareUploadFilter : BaseFilter
     {
         HardwareAccelerationMode.None => string.Empty,
         HardwareAccelerationMode.Nvenc => "hwupload_cuda",
-        HardwareAccelerationMode.Qsv => "hwupload=extra_hw_frames=64",
+        HardwareAccelerationMode.Qsv => $"hwupload=extra_hw_frames={_ffmpegState.QsvExtraHardwareFrames}",
 
         // leave vaapi in software since we don't (yet) use overlay_vaapi
         HardwareAccelerationMode.Vaapi when _currentState.FrameDataLocation == FrameDataLocation.Software =>

ErsatzTV.FFmpeg/Format/AvailablePixelFormats.cs

@@ -11,6 +11,7 @@ public static class AvailablePixelFormats
             PixelFormat.YUV420P10LE => new PixelFormatYuv420P10Le(),
             PixelFormat.YUVJ420P => new PixelFormatYuvJ420P(),
             PixelFormat.YUV444P => new PixelFormatYuv444P(),
+            PixelFormat.YUVA420P => new PixelFormatYuva420P(),
             _ => LogUnknownPixelFormat(pixelFormat, logger)
         };
 

ErsatzTV.FFmpeg/Format/FFmpegFormat.cs

@@ -4,6 +4,7 @@ public class FFmpegFormat
 {
     public const string YUV420P = "yuv420p";
     public const string YUV444P = "yuv444p";
+    public const string YUVA420P = "yuva420p";
     public const string P010LE = "p010le";
     public const string NV12 = "nv12";
 }

ErsatzTV.FFmpeg/Format/PixelFormat.cs

@@ -4,6 +4,7 @@ public static class PixelFormat
 {
     public const string YUV420P = "yuv420p";
     public const string YUV420P10LE = "yuv420p10le";
+    public const string YUVA420P = "yuva420p";
     public const string YUVJ420P = "yuvj420p";
     public const string YUV444P = "yuv444p";
     public const string YUV444P10LE = "yuv444p10le";

ErsatzTV.FFmpeg/Format/PixelFormatYuva420P.cs

@@ -0,0 +1,8 @@
+namespace ErsatzTV.FFmpeg.Format;
+
+public class PixelFormatYuva420P : IPixelFormat
+{
+    public string Name => PixelFormat.YUVA420P;
+    public string FFmpegName => FFmpegFormat.YUVA420P;
+    public int BitDepth => 8;
+}

ErsatzTV.FFmpeg/PipelineBuilder.cs

@@ -400,7 +400,8 @@ public class PipelineBuilder
                         ffmpegState.EncoderHardwareAccelerationMode,
                         currentState,
                         desiredState.ScaledSize,
-                        desiredState.PaddedSize);
+                        desiredState.PaddedSize,
+                        ffmpegState.QsvExtraHardwareFrames);
                     currentState = scaleFilter.NextState(currentState);
                     _videoInputFile.Iter(f => f.FilterSteps.Add(scaleFilter));
 
@@ -427,7 +428,8 @@ public class PipelineBuilder
                         ffmpegState.EncoderHardwareAccelerationMode,
                         currentState,
                         desiredState.ScaledSize,
-                        desiredState.PaddedSize);
+                        desiredState.PaddedSize,
+                        ffmpegState.QsvExtraHardwareFrames);
                     currentState = scaleFilter.NextState(currentState);
                     _videoInputFile.Iter(f => f.FilterSteps.Add(scaleFilter));
 
@@ -482,7 +484,8 @@ public class PipelineBuilder
                                     ffmpegState.EncoderHardwareAccelerationMode,
                                     currentState,
                                     desiredState.ScaledSize,
-                                    desiredState.PaddedSize);
+                                    desiredState.PaddedSize,
+                                    ffmpegState.QsvExtraHardwareFrames);
                                 currentState = scaleFilter.NextState(currentState);
                                 _videoInputFile.Iter(f => f.FilterSteps.Add(scaleFilter));
                             }
@@ -512,7 +515,8 @@ public class PipelineBuilder
                                 ffmpegState.EncoderHardwareAccelerationMode,
                                 currentState,
                                 desiredState.ScaledSize,
-                                desiredState.PaddedSize);
+                                desiredState.PaddedSize,
+                                ffmpegState.QsvExtraHardwareFrames);
                             currentState = scaleFilter.NextState(currentState);
                             videoInputFile.FilterSteps.Add(scaleFilter);
                         }
@@ -619,9 +623,35 @@ public class PipelineBuilder
                         _videoInputFile.Iter(f => f.FilterSteps.Add(downloadFilter));
                     }
 
-                    subtitleInputFile.FilterSteps.Add(new SubtitlePixelFormatFilter(ffmpegState));
+                    var pixelFormatFilter = new SubtitlePixelFormatFilter(ffmpegState);
+                    subtitleInputFile.FilterSteps.Add(pixelFormatFilter);
 
                     subtitleInputFile.FilterSteps.Add(new SubtitleHardwareUploadFilter(currentState, ffmpegState));
+
+                    FrameState fakeState = currentState;
+                    foreach (string format in pixelFormatFilter.MaybeFormat)
+                    {
+                        fakeState = fakeState with
+                        {
+                            PixelFormat = AvailablePixelFormats.ForPixelFormat(format, _logger)
+                        };
+                    }
+
+                    // hacky check for actual scaling or padding
+                    if (_videoInputFile.Exists(
+                            v => v.FilterSteps.Any(s => s.Filter.Contains(currentState.PaddedSize.Height.ToString()))))
+                    {
+                        // enable scaling the subtitle stream
+                        fakeState = fakeState with { ScaledSize = new FrameSize(1, 1) };
+                    }
+
+                    IPipelineFilterStep scaleFilter = AvailableSubtitleScaleFilters.ForAcceleration(
+                        ffmpegState.EncoderHardwareAccelerationMode,
+                        fakeState,
+                        desiredState.ScaledSize,
+                        desiredState.PaddedSize,
+                        ffmpegState.QsvExtraHardwareFrames);
+                    subtitleInputFile.FilterSteps.Add(scaleFilter);
                 }
                 else
                 {
@@ -639,7 +669,8 @@ public class PipelineBuilder
                             ffmpegState.EncoderHardwareAccelerationMode,
                             currentState,
                             desiredState.ScaledSize,
-                            desiredState.PaddedSize);
+                            desiredState.PaddedSize,
+                            ffmpegState.QsvExtraHardwareFrames);
                         currentState = scaleFilter.NextState(currentState);
                         _videoInputFile.Iter(f => f.FilterSteps.Add(scaleFilter));
                     }

ErsatzTV.sln.DotSettings

@@ -70,4 +70,5 @@
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=videotoolbox/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=xmltv/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=yadif/@EntryIndexedValue">True</s:Boolean>
+	<s:Boolean x:Key="/Default/UserDictionary/Words/=YUVA/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=YUVJ/@EntryIndexedValue">True</s:Boolean></wpf:ResourceDictionary>