fix qsv audio sync (#2090)

CHANGELOG.md

@@ -55,6 +55,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Fix HDR transcoding with NVIDIA accel for:
     - All NVIDIA docker users
     - Windows NVIDIA users who have set the `ETV_DISABLE_VULKAN` env var
+- Fix audio sync issue with QSV acceleration
 
 ## [25.2.0] - 2025-06-24
 ### Added

ErsatzTV.FFmpeg/Capabilities/HardwareCapabilitiesFactory.cs

@@ -135,7 +135,7 @@ public class HardwareCapabilitiesFactory : IHardwareCapabilitiesFactory
 
     public async Task<QsvOutput> GetQsvOutput(string ffmpegPath, Option<string> qsvDevice)
     {
-        var option = new QsvHardwareAccelerationOption(qsvDevice);
+        var option = new QsvHardwareAccelerationOption(qsvDevice, FFmpegCapability.Software);
         var arguments = option.GlobalOptions.ToList();
 
         arguments.AddRange(QsvArguments);

ErsatzTV.FFmpeg/GlobalOption/HardwareAcceleration/QsvHardwareAccelerationOption.cs

@@ -1,11 +1,10 @@
-using ErsatzTV.FFmpeg.Format;
+using ErsatzTV.FFmpeg.Capabilities;
+using ErsatzTV.FFmpeg.Format;
 
 namespace ErsatzTV.FFmpeg.GlobalOption.HardwareAcceleration;
 
-public class QsvHardwareAccelerationOption : GlobalOption
+public class QsvHardwareAccelerationOption(Option<string> device, FFmpegCapability decodeCapability) : GlobalOption
 {
-    private readonly Option<string> _qsvDevice;
-
     // TODO: read this from ffmpeg output
     private readonly List<string> _supportedFFmpegFormats = new()
     {
@@ -13,8 +12,6 @@ public class QsvHardwareAccelerationOption : GlobalOption
         FFmpegFormat.P010LE
     };
 
-    public QsvHardwareAccelerationOption(Option<string> qsvDevice) => _qsvDevice = qsvDevice;
-
     public override string[] GlobalOptions
     {
         get
@@ -29,9 +26,14 @@ public class QsvHardwareAccelerationOption : GlobalOption
                 "-hwaccel_output_format", "qsv"
             };
 
+            if (decodeCapability is not FFmpegCapability.Hardware)
+            {
+                result.Clear();
+            }
+
             if (OperatingSystem.IsLinux())
             {
-                foreach (string qsvDevice in _qsvDevice)
+                foreach (string qsvDevice in device)
                 {
                     if (!string.IsNullOrWhiteSpace(qsvDevice))
                     {

ErsatzTV.FFmpeg/Pipeline/QsvPipelineBuilder.cs

@@ -74,8 +74,6 @@ public class QsvPipelineBuilder : SoftwarePipelineBuilder
             encodeCapability = FFmpegCapability.Software;
         }
 
-        pipelineSteps.Add(new QsvHardwareAccelerationOption(ffmpegState.VaapiDevice));
-
         bool isHevcOrH264 = videoStream.Codec is /*VideoFormat.Hevc or*/ VideoFormat.H264;
         bool is10Bit = videoStream.PixelFormat.Map(pf => pf.BitDepth).IfNone(8) == 10;
 
@@ -85,6 +83,14 @@ public class QsvPipelineBuilder : SoftwarePipelineBuilder
             decodeCapability = FFmpegCapability.Software;
         }
 
+        // QSV cannot always decode properly when seeking, so use software
+        if (decodeCapability == FFmpegCapability.Hardware && ffmpegState.Start.Filter(s => s > TimeSpan.Zero).IsSome)
+        {
+            decodeCapability = FFmpegCapability.Software;
+        }
+
+        pipelineSteps.Add(new QsvHardwareAccelerationOption(ffmpegState.VaapiDevice, decodeCapability));
+
         // disable hw accel if decoder/encoder isn't supported
         return ffmpegState with
         {