diff --git a/internal/ingest/decoder/fallback/ffmpeg.go b/internal/ingest/decoder/fallback/ffmpeg.go
index 6dc4198..27f10ee 100644
--- a/internal/ingest/decoder/fallback/ffmpeg.go
+++ b/internal/ingest/decoder/fallback/ffmpeg.go
@@ -81,7 +81,16 @@ func (d *FFmpegDecoder) DecodeStream(ctx context.Context, r io.Reader, meta deco
 		}
 	}()
 
-	stderrData, _ := io.ReadAll(stderr)
+	// DEADLOCK FIX: stderr and stdout must be drained concurrently.
+	// Reading stderr synchronously before readPCM means ffmpeg blocks when
+	// stdout's pipe buffer fills (typically 64KB), which prevents it from
+	// closing stderr, which prevents ReadAll from returning — deadlock.
+	var stderrData []byte
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		stderrData, _ = io.ReadAll(stderr)
+	}()
 	readErr := d.readPCM(ctx, stdout, sampleRate, channels, meta.SourceID, emit)
 	waitErr := cmd.Wait()
 	wg.Wait()