Merge pull request #39 from viruslox/fix-srt-connection-15195665643207896187

Keep SRT connection alive with ffmpeg fifo and continuous audio

Author: viruslox

internal/modules/audiobridge/stream/mixer.go

@@ -94,6 +94,9 @@ func (m *Mixer) mixLoop() {
 	attackCoef := math.Exp(-1.0 / (sampleRate * (attackTimeMs / 1000.0)))
 	releaseCoef := math.Exp(-1.0 / (sampleRate * (releaseTimeMs / 1000.0)))
 
+	// Reusable zeroed chunk for sending silence
+	silentChunk := make([]byte, chunkSize)
+
 	for {
 		select {
 		case <-ticker.C:
@@ -117,6 +120,13 @@ func (m *Mixer) mixLoop() {
 						m.gateGain = releaseCoef * m.gateGain
 					}
 				}
+
+				// Send a chunk of silence to keep the SRT stream active
+				select {
+				case m.outChan <- silentChunk:
+				default:
+					log.Println("[AudioBridge] Warning: Mixer output channel blocked, dropping silent chunk")
+				}
 				continue
 			}
 

internal/modules/audiobridge/stream/srt.go

@@ -38,15 +38,20 @@ func (s *SRTManager) Start() error {
 		bitrate = "128k"
 	}
 
-	// Setup FFmpeg command
+	// Setup FFmpeg command with options to keep connection alive
 	s.cmd = exec.Command("ffmpeg",
 		"-f", "s16le", // raw 16-bit little-endian PCM
 		"-ar", "48000", // 48kHz sample rate
 		"-ac", "2", // 2 channels (stereo)
 		"-i", "pipe:0", // Read from stdin
 		"-c:a", "libopus", // Encode to Opus
 		"-b:a", bitrate,
-		"-f", "mpegts", // Container
+		// Apply fifo to abstract network output, adding reliability, dropped packets rather than blocking, and infinite reconnects
+		"-f", "fifo",
+		"-fifo_format", "mpegts",
+		"-drop_pkts_on_overflow", "1",
+		"-attempt_recovery", "1",
+		"-recovery_wait_time", "1",
 		s.cfg.Streaming.DestinationURL,
 	)