force hw accel to use one thread (#1327)

CHANGELOG.md

@@ -15,6 +15,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Rework startup process to show UI as early as possible
   - A minimal UI will indicate when the database and search index are initializing
   - The UI will automatically refresh when the initialization processes have completed
+- Force ffmpeg to use one thread when hardware acceleration is used since hardware acceleration does not support multiple threads
 
 ## [0.8.0-beta] - 2023-06-23
 ### Added

ErsatzTV.FFmpeg/Pipeline/PipelineBuilderBase.cs

@@ -616,7 +616,16 @@ public abstract class PipelineBuilderBase : IPipelineBuilder
 
     private void SetThreadCount(FFmpegState ffmpegState, FrameState desiredState, IList<IPipelineStep> pipelineSteps)
     {
-        if (ffmpegState.Start.Exists(s => s > TimeSpan.Zero) && desiredState.Realtime)
+        if (ffmpegState.DecoderHardwareAccelerationMode != HardwareAccelerationMode.None ||
+            ffmpegState.EncoderHardwareAccelerationMode != HardwareAccelerationMode.None)
+        {
+            _logger.LogInformation(
+                "Forcing {Threads} ffmpeg thread when hardware acceleration is used",
+                1);
+
+            pipelineSteps.Insert(0, new ThreadCountOption(1));
+        }
+        else if (ffmpegState.Start.Exists(s => s > TimeSpan.Zero) && desiredState.Realtime)
         {
             _logger.LogInformation(
                 "Forcing {Threads} ffmpeg thread due to buggy combination of stream seek and realtime output",