allow older ffmpeg for testing (#1485)

* allow older ffmpeg for testing

* use proper option name

ErsatzTV.FFmpeg.Tests/PipelineBuilderBaseTests.cs

@@ -497,6 +497,7 @@ public class PipelineBuilderBaseTests
                 new System.Collections.Generic.HashSet<string>(),
                 new System.Collections.Generic.HashSet<string>(),
                 new System.Collections.Generic.HashSet<string>(),
+                new System.Collections.Generic.HashSet<string>(),
                 new System.Collections.Generic.HashSet<string>())
         {
         }

ErsatzTV.FFmpeg/Capabilities/FFmpegCapabilities.cs

@@ -9,17 +9,20 @@ public class FFmpegCapabilities : IFFmpegCapabilities
     private readonly IReadOnlySet<string> _ffmpegDecoders;
     private readonly IReadOnlySet<string> _ffmpegEncoders;
     private readonly IReadOnlySet<string> _ffmpegFilters;
+    private readonly IReadOnlySet<string> _ffmpegOptions;
 
     public FFmpegCapabilities(
         IReadOnlySet<string> ffmpegHardwareAccelerations,
         IReadOnlySet<string> ffmpegDecoders,
         IReadOnlySet<string> ffmpegFilters,
-        IReadOnlySet<string> ffmpegEncoders)
+        IReadOnlySet<string> ffmpegEncoders,
+        IReadOnlySet<string> ffmpegOptions)
     {
         _ffmpegHardwareAccelerations = ffmpegHardwareAccelerations;
         _ffmpegDecoders = ffmpegDecoders;
         _ffmpegFilters = ffmpegFilters;
         _ffmpegEncoders = ffmpegEncoders;
+        _ffmpegOptions = ffmpegOptions;
     }
 
     public bool HasHardwareAcceleration(HardwareAccelerationMode hardwareAccelerationMode)
@@ -43,6 +46,8 @@ public class FFmpegCapabilities : IFFmpegCapabilities
 
     public bool HasFilter(string filter) => _ffmpegFilters.Contains(filter);
 
+    public bool HasOption(string ffmpegOption) => _ffmpegOptions.Contains(ffmpegOption);
+
     public Option<IDecoder> SoftwareDecoderForVideoFormat(string videoFormat) =>
         videoFormat switch
         {

ErsatzTV.FFmpeg/Capabilities/HardwareCapabilitiesFactory.cs

@@ -46,8 +46,14 @@ public class HardwareCapabilitiesFactory : IHardwareCapabilitiesFactory
         IReadOnlySet<string> ffmpegDecoders = await GetFFmpegCapabilities(ffmpegPath, "decoders", ParseFFmpegLine);
         IReadOnlySet<string> ffmpegFilters = await GetFFmpegCapabilities(ffmpegPath, "filters", ParseFFmpegLine);
         IReadOnlySet<string> ffmpegEncoders = await GetFFmpegCapabilities(ffmpegPath, "encoders", ParseFFmpegLine);
-
-        return new FFmpegCapabilities(ffmpegHardwareAccelerations, ffmpegDecoders, ffmpegFilters, ffmpegEncoders);
+        IReadOnlySet<string> ffmpegOptions = await GetFFmpegOptions(ffmpegPath);
+
+        return new FFmpegCapabilities(
+            ffmpegHardwareAccelerations,
+            ffmpegDecoders,
+            ffmpegFilters,
+            ffmpegEncoders,
+            ffmpegOptions);
     }
 
     public async Task<IHardwareCapabilities> GetHardwareCapabilities(
@@ -185,6 +191,31 @@ public class HardwareCapabilitiesFactory : IHardwareCapabilitiesFactory
             .Bind(l => parseLine(l))
             .ToImmutableHashSet();
     }
+    
+    private async Task<IReadOnlySet<string>> GetFFmpegOptions(string ffmpegPath)
+    {
+        var cacheKey = string.Format(CultureInfo.InvariantCulture, FFmpegCapabilitiesCacheKeyFormat, "options");
+        if (_memoryCache.TryGetValue(cacheKey, out IReadOnlySet<string>? cachedCapabilities) &&
+            cachedCapabilities is not null)
+        {
+            return cachedCapabilities;
+        }
+
+        string[] arguments = { "-hide_banner", "-h", "long" };
+
+        BufferedCommandResult result = await Cli.Wrap(ffmpegPath)
+            .WithArguments(arguments)
+            .WithValidation(CommandResultValidation.None)
+            .ExecuteBufferedAsync(Encoding.UTF8);
+
+        string output = string.IsNullOrWhiteSpace(result.StandardOutput)
+            ? result.StandardError
+            : result.StandardOutput;
+
+        return output.Split("\n").Map(s => s.Trim())
+            .Bind(l => ParseFFmpegOptionLine(l))
+            .ToImmutableHashSet();
+    }
 
     private static Option<string> ParseFFmpegAccelLine(string input)
     {
@@ -200,6 +231,13 @@ public class HardwareCapabilitiesFactory : IHardwareCapabilitiesFactory
         return match.Success ? match.Groups[1].Value : Option<string>.None;
     }
 
+    private static Option<string> ParseFFmpegOptionLine(string input)
+    {
+        const string PATTERN = @"^-([a-z_]+)\s+.*";
+        Match match = Regex.Match(input, PATTERN);
+        return match.Success ? match.Groups[1].Value : Option<string>.None;
+    }
+    
     private async Task<IHardwareCapabilities> GetVaapiCapabilities(
         Option<string> vaapiDriver,
         Option<string> vaapiDevice)

ErsatzTV.FFmpeg/Capabilities/IFFmpegCapabilities.cs

@@ -8,5 +8,6 @@ public interface IFFmpegCapabilities
     bool HasDecoder(string decoder);
     bool HasEncoder(string encoder);
     bool HasFilter(string filter);
+    bool HasOption(string ffmpegOption);
     Option<IDecoder> SoftwareDecoderForVideoFormat(string videoFormat);
 }

ErsatzTV.FFmpeg/InputOption/ReadrateInputOption.cs

@@ -1,17 +1,26 @@
 using System.Globalization;
+using ErsatzTV.FFmpeg.Capabilities;
 using ErsatzTV.FFmpeg.Environment;
+using Microsoft.Extensions.Logging;
 
 namespace ErsatzTV.FFmpeg.InputOption;
 
 public class ReadrateInputOption : IInputOption
 {
+    private readonly IFFmpegCapabilities _ffmpegCapabilities;
     private readonly int _initialBurstSeconds;
+    private readonly ILogger _logger;
 
-    public ReadrateInputOption(int initialBurstSeconds = 0)
+    public ReadrateInputOption(
+        IFFmpegCapabilities ffmpegCapabilities,
+        int initialBurstSeconds,
+        ILogger logger)
     {
+        _ffmpegCapabilities = ffmpegCapabilities;
         _initialBurstSeconds = initialBurstSeconds;
+        _logger = logger;
     }
-    
+
     public IList<EnvironmentVariable> EnvironmentVariables => Array.Empty<EnvironmentVariable>();
 
     public IList<string> GlobalOptions => Array.Empty<string>();
@@ -22,6 +31,15 @@ public class ReadrateInputOption : IInputOption
 
         if (_initialBurstSeconds > 0)
         {
+            if (!_ffmpegCapabilities.HasOption("readrate_initial_burst"))
+            {
+                _logger.LogWarning(
+                    "FFmpeg is missing {Option} option; unable to transcode faster than realtime",
+                    "readrate_initial_burst");
+
+                return result;
+            }
+
             result.AddRange(
                 new[]
                 {

ErsatzTV.FFmpeg/Pipeline/PipelineBuilderBase.cs

@@ -84,7 +84,7 @@ public abstract class PipelineBuilderBase : IPipelineBuilder
         };
 
         concatInputFile.AddOption(new ConcatInputFormat());
-        concatInputFile.AddOption(new ReadrateInputOption());
+        concatInputFile.AddOption(new ReadrateInputOption(_ffmpegCapabilities, 0, _logger));
         concatInputFile.AddOption(new InfiniteLoopInputOption(HardwareAccelerationMode.None));
 
         foreach (int threadCount in ffmpegState.ThreadCount)
@@ -130,7 +130,7 @@ public abstract class PipelineBuilderBase : IPipelineBuilder
             new EncoderCopyAll()
         };
 
-        concatInputFile.AddOption(new ReadrateInputOption());
+        concatInputFile.AddOption(new ReadrateInputOption(_ffmpegCapabilities, 0, _logger));
 
         SetMetadataServiceProvider(ffmpegState, pipelineSteps);
         SetMetadataServiceName(ffmpegState, pipelineSteps);
@@ -640,8 +640,8 @@ public abstract class PipelineBuilderBase : IPipelineBuilder
             };
         }
 
-        _audioInputFile.Iter(a => a.AddOption(new ReadrateInputOption(initialBurst)));
-        videoInputFile.AddOption(new ReadrateInputOption(initialBurst));
+        _audioInputFile.Iter(a => a.AddOption(new ReadrateInputOption(_ffmpegCapabilities, initialBurst, _logger)));
+        videoInputFile.AddOption(new ReadrateInputOption(_ffmpegCapabilities, initialBurst, _logger));
     }
 
     private static void SetStillImageInfiniteLoop(