add pad_vaapi filter (#2036)

CHANGELOG.md

@@ -27,6 +27,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
   - NVIDIA may use hardware-accelerated tone mapping (when vulkan accel and libplacebo filter are also available)
   - QSV may use hardware-accelerated tone mapping (when hardware decoding is used)
   - In all other cases, HDR content will use a software pipeline and the clip algorithm
+- Use hardware-accelerated padding with VAAPI
 
 ### Changed
 - Start to make UI minimally responsive (functional on smaller screens)

ErsatzTV.FFmpeg/Filter/Vaapi/PadVaapiFilter.cs

@@ -0,0 +1,31 @@
+namespace ErsatzTV.FFmpeg.Filter.Vaapi;
+
+public class PadVaapiFilter : BaseFilter
+{
+    private readonly FrameState _currentState;
+    private readonly FrameSize _paddedSize;
+
+    public PadVaapiFilter(FrameState currentState, FrameSize paddedSize)
+    {
+        _currentState = currentState;
+        _paddedSize = paddedSize;
+    }
+
+    public override string Filter
+    {
+        get
+        {
+            var pad = $"pad_vaapi=w={_paddedSize.Width}:h={_paddedSize.Height}:x=-1:y=-1:color=black";
+
+            return _currentState.FrameDataLocation == FrameDataLocation.Hardware
+                ? pad
+                : $"format=nv12|p010le|vaapi,hwupload,{pad}";
+        }
+    }
+
+    public override FrameState NextState(FrameState currentState) => currentState with
+    {
+        PaddedSize = _paddedSize,
+        FrameDataLocation = FrameDataLocation.Hardware
+    };
+}

ErsatzTV.FFmpeg/Pipeline/VaapiPipelineBuilder.cs

@@ -536,7 +536,7 @@ public class VaapiPipelineBuilder : SoftwarePipelineBuilder
     {
         if (desiredState.CroppedSize.IsNone && currentState.PaddedSize != desiredState.PaddedSize)
         {
-            var padStep = new PadFilter(currentState, desiredState.PaddedSize);
+            var padStep = new PadVaapiFilter(currentState, desiredState.PaddedSize);
             currentState = padStep.NextState(currentState);
             videoInputFile.FilterSteps.Add(padStep);
         }