Merge pull request #17537 from vdatanet/fix/pcm-wav-transcode

Fix PCM audio transcoding to wav returning HTTP 500 and headerless output

3 files changed, 50 insertions, 10 deletions

diff --git a/Jellyfin.Api/Helpers/StreamingHelpers.cs b/Jellyfin.Api/Helpers/StreamingHelpers.cs
index 6a6aac1327..60c5bb2ef6 100644
--- a/Jellyfin.Api/Helpers/StreamingHelpers.cs
+++ b/Jellyfin.Api/Helpers/StreamingHelpers.cs
@@ -198,11 +198,6 @@ public static class StreamingHelpers
             state.OutputAudioBitrate = encodingHelper.GetAudioBitrateParam(streamingRequest.AudioBitRate, streamingRequest.AudioCodec, state.AudioStream, state.OutputAudioChannels) ?? 0;
         }
 
-        if (outputAudioCodec.StartsWith("pcm_", StringComparison.Ordinal))
-        {
-            containerInternal = ".pcm";
-        }
-
         if (state.VideoRequest is not null)
         {
             state.OutputVideoCodec = state.Request.VideoCodec;
diff --git a/MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs b/MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs
index 1b0bbe9ea0..9a68889352 100644
--- a/MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs
+++ b/MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs
@@ -7864,10 +7864,16 @@ namespace MediaBrowser.Controller.MediaEncoding
                 audioTranscodeParams.Add("-acodec " + GetAudioEncoder(state));
             }
 
-            if (GetAudioEncoder(state).StartsWith("pcm_", StringComparison.Ordinal))
-            {
-                audioTranscodeParams.Add(string.Concat("-f ", GetAudioEncoder(state).AsSpan(4)));
-                audioTranscodeParams.Add("-ar " + state.BaseRequest.AudioBitRate);
+            // The pcm_* encoders emit raw samples that carry no header of their own, so the header
+            // has to come from the muxer. Only force the matching raw muxer when the client actually
+            // asked for a raw container (added in #10321 for I2S/MCU clients): applying it to every
+            // pcm_* codec also strips the RIFF header from a `stream.wav` request, which then serves
+            // headerless PCM behind an audio/wav content type.
+            var audioEncoder = GetAudioEncoder(state);
+            if (audioEncoder.StartsWith("pcm_", StringComparison.Ordinal)
+                && string.Equals(state.OutputContainer, "pcm", StringComparison.OrdinalIgnoreCase))
+            {
+                audioTranscodeParams.Add(string.Concat("-f ", audioEncoder.AsSpan(4)));
             }
 
             var sampleRate = state.OutputAudioSampleRate;
diff --git a/tests/Jellyfin.Controller.Tests/MediaEncoding/EncodingHelperTests.cs b/tests/Jellyfin.Controller.Tests/MediaEncoding/EncodingHelperTests.cs
index 71b6551d0f..2b009b4673 100644
--- a/tests/Jellyfin.Controller.Tests/MediaEncoding/EncodingHelperTests.cs
+++ b/tests/Jellyfin.Controller.Tests/MediaEncoding/EncodingHelperTests.cs
@@ -223,12 +223,51 @@ public class EncodingHelperTests
         Assert.Contains("-ar " + expectedSampleRate, args, StringComparison.Ordinal);
     }
 
-    private static EncodingJobInfo BuildAudioState(string audioCodec, int requestedSampleRate)
+    [Theory]
+    [InlineData("wav")]
+    [InlineData("flac")]
+    [InlineData("mp3")]
+    public void GetProgressiveAudioFullCommandLine_PcmInRealContainer_KeepsContainerMuxer(string outputContainer)
+    {
+        // A pcm_* encoder must not drag the raw muxer into a container that writes its own header,
+        // or the client gets headerless PCM behind the container's content type.
+        var state = BuildAudioState("pcm_s16le", 48000, outputContainer);
+        var args = CreateHelper().GetProgressiveAudioFullCommandLine(state, new EncodingOptions(), "/tmp/out");
+
+        Assert.DoesNotContain("-f s16le", args, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void GetProgressiveAudioFullCommandLine_PcmInPcmContainer_ForcesRawMuxer()
+    {
+        // The raw-PCM route added in #10321 for I2S/MCU clients must keep working.
+        var state = BuildAudioState("pcm_s16le", 48000, "pcm");
+        var args = CreateHelper().GetProgressiveAudioFullCommandLine(state, new EncodingOptions(), "/tmp/out");
+
+        Assert.Contains("-f s16le", args, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void GetProgressiveAudioFullCommandLine_PcmWithoutBitrate_EmitsNoEmptySampleRate()
+    {
+        // AudioBitRate is optional; it used to be emitted as `-ar <null>`, producing a bare `-ar`
+        // that made ffmpeg abort with "Expected number for ar" and the request fail with HTTP 500.
+        var state = BuildAudioState("pcm_s16le", 48000, "wav");
+        state.BaseRequest.AudioBitRate = null;
+        var args = CreateHelper().GetProgressiveAudioFullCommandLine(state, new EncodingOptions(), "/tmp/out");
+
+        Assert.DoesNotContain("-ar -", args, StringComparison.Ordinal);
+        Assert.DoesNotContain("-ar  ", args, StringComparison.Ordinal);
+        Assert.Contains("-ar 48000", args, StringComparison.Ordinal);
+    }
+
+    private static EncodingJobInfo BuildAudioState(string audioCodec, int requestedSampleRate, string? outputContainer = null)
     {
         var audio = new MediaStream { Index = 0, Type = MediaStreamType.Audio, Codec = "flac", SampleRate = 96000 };
 
         return new EncodingJobInfo(TranscodingJobType.Progressive)
         {
+            OutputContainer = outputContainer,
             MediaSource = new MediaSourceInfo
             {
                 Container = "flac",