Initial audio filter implementation

Former-commit-id: 78a703fc93

FFMpegCore/FFMpeg/Arguments/AudioFiltersArgument.cs

@@ -0,0 +1,53 @@
+using System.Collections.Generic;
+using System.Drawing;
+using System.Linq;
+using FFMpegCore.Enums;
+using FFMpegCore.Exceptions;
+
+namespace FFMpegCore.Arguments
+{
+    public class AudioFiltersArgument : IArgument
+    {
+        public readonly AudioFilterOptions Options;
+
+        public AudioFiltersArgument(AudioFilterOptions options)
+        {
+            Options = options;
+        }
+
+        public string Text => GetText();
+
+        private string GetText()
+        {
+            if (!Options.Arguments.Any())
+                throw new FFMpegArgumentException("No audio-filter arguments provided");
+
+            var arguments = Options.Arguments
+                .Where(arg => !string.IsNullOrEmpty(arg.Value))
+                .Select(arg =>
+                {
+                    var escapedValue = arg.Value.Replace(",", "\\,");
+                    return string.IsNullOrEmpty(arg.Key) ? escapedValue : $"{arg.Key}={escapedValue}";
+                });
+
+            return $"-af \"{string.Join(", ", arguments)}\"";
+        }
+    }
+
+    public interface IAudioFilterArgument
+    {
+        public string Key { get; }
+        public string Value { get; }
+    }
+
+    public class AudioFilterOptions
+    {
+        public List<IAudioFilterArgument> Arguments { get; } = new List<IAudioFilterArgument>();
+     
+        private AudioFilterOptions WithArgument(IAudioFilterArgument argument)
+        {
+            Arguments.Add(argument);
+            return this;
+        }
+    }
+}

FFMpegCore/FFMpeg/FFMpegArgumentOptions.cs

@@ -43,6 +43,13 @@ public FFMpegArgumentOptions WithVideoFilters(Action<VideoFilterOptions> videoFi
             return WithArgument(new VideoFiltersArgument(videoFilterOptionsObj));
         }
 
+        public FFMpegArgumentOptions WithAudioFilters(Action<AudioFilterOptions> audioFilterOptions)
+        {
+            var audioFilterOptionsObj = new AudioFilterOptions();
+            audioFilterOptions(audioFilterOptionsObj);
+            return WithArgument(new AudioFiltersArgument(audioFilterOptionsObj));
+        }
+
         public FFMpegArgumentOptions WithFramerate(double framerate) => WithArgument(new FrameRateArgument(framerate));
         public FFMpegArgumentOptions WithoutMetadata() => WithArgument(new RemoveMetadataArgument());
         public FFMpegArgumentOptions WithSpeedPreset(Speed speed) => WithArgument(new SpeedPresetArgument(speed));