Add RFC7845 downmix algorithm (#12300)

1 files changed, 10 insertions, 18 deletions

diff --git a/MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs b/MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs
index 42b09a29e..2c3d44bf8 100644
--- a/MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs
+++ b/MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs
@@ -2666,28 +2666,17 @@ namespace MediaBrowser.Controller.MediaEncoding
 
             var filters = new List<string>();
 
-            if (channels.HasValue
-                && channels.Value == 2
-                && state.AudioStream is not null
-                && state.AudioStream.Channels.HasValue
-                && state.AudioStream.Channels.Value == 6)
+            if (channels is 2 && state.AudioStream?.Channels is > 2)
             {
-                if (!encodingOptions.DownMixAudioBoost.Equals(1))
+                var hasDownMixFilter = DownMixAlgorithmsHelper.AlgorithmFilterStrings.TryGetValue((encodingOptions.DownMixStereoAlgorithm, DownMixAlgorithmsHelper.InferChannelLayout(state.AudioStream)), out var downMixFilterString);
+                if (hasDownMixFilter)
                 {
-                    filters.Add("volume=" + encodingOptions.DownMixAudioBoost.ToString(CultureInfo.InvariantCulture));
+                    filters.Add(downMixFilterString);
                 }
 
-                switch (encodingOptions.DownMixStereoAlgorithm)
+                if (!encodingOptions.DownMixAudioBoost.Equals(1))
                 {
-                    case DownMixStereoAlgorithms.Dave750:
-                        filters.Add("pan=stereo|c0=0.5*c2+0.707*c0+0.707*c4+0.5*c3|c1=0.5*c2+0.707*c1+0.707*c5+0.5*c3");
-                        break;
-                    case DownMixStereoAlgorithms.NightmodeDialogue:
-                        filters.Add("pan=stereo|c0=c2+0.30*c0+0.30*c4|c1=c2+0.30*c1+0.30*c5");
-                        break;
-                    case DownMixStereoAlgorithms.None:
-                    default:
-                        break;
+                    filters.Add("volume=" + encodingOptions.DownMixAudioBoost.ToString(CultureInfo.InvariantCulture));
                 }
             }
 
@@ -7008,7 +6997,10 @@ namespace MediaBrowser.Controller.MediaEncoding
 
             var channels = state.OutputAudioChannels;
 
-            if (channels.HasValue && ((channels.Value != 2 && state.AudioStream?.Channels != 6) || encodingOptions.DownMixStereoAlgorithm == DownMixStereoAlgorithms.None))
+            var useDownMixAlgorithm = state.AudioStream is not null
+                                      && DownMixAlgorithmsHelper.AlgorithmFilterStrings.ContainsKey((encodingOptions.DownMixStereoAlgorithm, DownMixAlgorithmsHelper.InferChannelLayout(state.AudioStream)));
+
+            if (channels.HasValue && !useDownMixAlgorithm)
             {
                 args += " -ac " + channels.Value;
             }