Calculate output bitrate from output channel count

Jellyfin.Api/Helpers/DynamicHlsHelper.cs

@@ -223,7 +223,7 @@ public class DynamicHlsHelper
                     sdrVideoUrl += "&AllowVideoStreamCopy=false";
 
                     var sdrOutputVideoBitrate = _encodingHelper.GetVideoBitrateParamValue(state.VideoRequest, state.VideoStream, state.OutputVideoCodec);
-                    var sdrOutputAudioBitrate = _encodingHelper.GetAudioBitrateParam(state.VideoRequest, state.AudioStream) ?? 0;
+                    var sdrOutputAudioBitrate = _encodingHelper.GetAudioBitrateParam(state.VideoRequest, state.AudioStream, state.OutputAudioChannels) ?? 0;
                     var sdrTotalBitrate = sdrOutputAudioBitrate + sdrOutputVideoBitrate;
 
                     var sdrPlaylist = AppendPlaylist(builder, state, sdrVideoUrl, sdrTotalBitrate, subtitleGroup);

Jellyfin.Api/Helpers/StreamingHelpers.cs

@@ -183,7 +183,7 @@ public static class StreamingHelpers
 
         state.OutputContainer = (containerInternal ?? string.Empty).TrimStart('.');
 
-        state.OutputAudioBitrate = encodingHelper.GetAudioBitrateParam(streamingRequest.AudioBitRate, streamingRequest.AudioCodec, state.AudioStream);
+        state.OutputAudioBitrate = encodingHelper.GetAudioBitrateParam(streamingRequest.AudioBitRate, streamingRequest.AudioCodec, state.AudioStream, state.OutputAudioChannels);
 
         state.OutputAudioCodec = streamingRequest.AudioCodec;
 

MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs

@@ -2111,50 +2111,47 @@ namespace MediaBrowser.Controller.MediaEncoding
             return Convert.ToInt32(scaleFactor * bitrate);
         }
 
-        public int? GetAudioBitrateParam(BaseEncodingJobOptions request, MediaStream audioStream)
+        public int? GetAudioBitrateParam(BaseEncodingJobOptions request, MediaStream audioStream, int? outputAudioChannels)
         {
-            return GetAudioBitrateParam(request.AudioBitRate, request.AudioCodec, audioStream);
+            return GetAudioBitrateParam(request.AudioBitRate, request.AudioCodec, audioStream, outputAudioChannels);
         }
 
-        public int? GetAudioBitrateParam(int? audioBitRate, string audioCodec, MediaStream audioStream)
+        public int? GetAudioBitrateParam(int? audioBitRate, string audioCodec, MediaStream audioStream, int? outputAudioChannels)
         {
             if (audioStream is null)
             {
                 return null;
             }
 
-            if (audioBitRate.HasValue && string.IsNullOrEmpty(audioCodec))
+            var inputChannels = audioStream.Channels ?? 0;
+            var outputChannels = outputAudioChannels ?? 0;
+
+            if (audioBitRate.HasValue && (string.IsNullOrEmpty(audioCodec)
+                || string.Equals(audioCodec, "aac", StringComparison.OrdinalIgnoreCase)
+                || string.Equals(audioCodec, "mp3", StringComparison.OrdinalIgnoreCase)
+                || string.Equals(audioCodec, "opus", StringComparison.OrdinalIgnoreCase)
+                || string.Equals(audioCodec, "vorbis", StringComparison.OrdinalIgnoreCase)
+                || string.Equals(audioCodec, "ac3", StringComparison.OrdinalIgnoreCase)
+                || string.Equals(audioCodec, "eac3", StringComparison.OrdinalIgnoreCase)))
             {
-                return Math.Min(384000, audioBitRate.Value);
+                return (inputChannels, outputChannels) switch
+                {
+                    (>= 6, >= 6 or 0) => Math.Min(640000, audioBitRate.Value),
+                    (> 0, > 0) => Math.Min(outputChannels * 128000, audioBitRate.Value),
+                    (> 0, _) => Math.Min(inputChannels * 128000, audioBitRate.Value),
+                    (_, _) => Math.Min(384000, audioBitRate.Value)
+                };
             }
 
-            if (audioBitRate.HasValue && !string.IsNullOrEmpty(audioCodec))
+            if (audioBitRate.HasValue && (string.Equals(audioCodec, "flac", StringComparison.OrdinalIgnoreCase)
+                || string.Equals(audioCodec, "alac", StringComparison.OrdinalIgnoreCase)))
             {
-                if (string.Equals(audioCodec, "aac", StringComparison.OrdinalIgnoreCase)
-                    || string.Equals(audioCodec, "mp3", StringComparison.OrdinalIgnoreCase)
-                    || string.Equals(audioCodec, "opus", StringComparison.OrdinalIgnoreCase)
-                    || string.Equals(audioCodec, "vorbis", StringComparison.OrdinalIgnoreCase)
-                    || string.Equals(audioCodec, "ac3", StringComparison.OrdinalIgnoreCase)
-                    || string.Equals(audioCodec, "eac3", StringComparison.OrdinalIgnoreCase))
+                if ((audioStream.Channels ?? 0) >= 6)
                 {
-                    if ((audioStream.Channels ?? 0) >= 6)
-                    {
-                        return Math.Min(640000, audioBitRate.Value);
-                    }
-
-                    return Math.Min(384000, audioBitRate.Value);
+                    return Math.Min(3584000, audioBitRate.Value);
                 }
 
-                if (string.Equals(audioCodec, "flac", StringComparison.OrdinalIgnoreCase)
-                    || string.Equals(audioCodec, "alac", StringComparison.OrdinalIgnoreCase))
-                {
-                    if ((audioStream.Channels ?? 0) >= 6)
-                    {
-                        return Math.Min(3584000, audioBitRate.Value);
-                    }
-
-                    return Math.Min(1536000, audioBitRate.Value);
-                }
+                return Math.Min(1536000, audioBitRate.Value);
             }
 
             // Empty bitrate area is not allow on iOS