feat(restream): extend ProcessHooks with OnInputStart for WHIP ingest input legs

restream/restream.go

@@ -60,9 +60,11 @@ type Restreamer interface {
 
 // ProcessStartHook is invoked synchronously inside startProcess just
 // before FFmpeg is started. It receives a pointer to the task config;
-// returning a non-empty slice of ConfigIO appends those output legs to
-// cfg.Output and causes the FFmpeg command to be rebuilt before
-// Start(). Returning a non-nil error aborts the start.
+// returning a non-empty slice of ConfigIO causes the command to be
+// rebuilt before Start(). Returning a non-nil error aborts the start.
+//
+// For OnStart the returned ConfigIO slices are appended to cfg.Output.
+// For OnInputStart the returned ConfigIO slices are prepended to cfg.Input.
 //
 // Hooks run with the restream write lock held, so they must not call
 // back into the Restreamer interface (it would deadlock). They can,
@@ -76,9 +78,15 @@ type ProcessStopHook func(id string)
 
 // ProcessHooks bundles the lifecycle callbacks a sibling subsystem
 // (currently: app/webrtc) installs via SetHooks.
+//
+// OnStart returns ConfigIO entries appended to cfg.Output (WHEP RTP egress legs).
+// OnInputStart returns ConfigIO entries prepended to cfg.Input (WHIP RTP ingest legs).
+// OnStop and OnInputStop are called after FFmpeg stops.
 type ProcessHooks struct {
 	OnStart      ProcessStartHook
 	OnStop       ProcessStopHook
+	OnInputStart ProcessStartHook // WHIP ingest: returned legs prepended to cfg.Input
+	OnInputStop  ProcessStopHook  // WHIP ingest: teardown notification
 }
 
 // Config is the required configuration for a new restreamer instance.
@@ -1098,10 +1106,24 @@ func (r *restream) startProcess(id string) error {
 
 	task.process.Order = "start"
 
-	// Invoke the per-process start hook (used by app/webrtc to append
-	// RTP output legs). If it returns ConfigIO entries, append them to
-	// the output list and rebuild the FFmpeg process with the new
-	// command before we start it.
+	// Invoke the per-process lifecycle hooks. OnInputStart returns
+	// ConfigIO entries prepended to cfg.Input (WHIP ingest legs);
+	// OnStart returns ConfigIO entries appended to cfg.Output (WHEP
+	// egress legs). Both rebuild the FFmpeg process if non-empty.
+	needsRebuild := false
+
+	if r.hooks.OnInputStart != nil {
+		inputExtras, err := r.hooks.OnInputStart(task.id, task.config)
+		if err != nil {
+			r.logger.WithField("id", task.id).WithError(err).Error().Log("WHIP input hook aborted process start")
+			return err
+		}
+		if len(inputExtras) > 0 {
+			task.config.Input = append(inputExtras, task.config.Input...)
+			needsRebuild = true
+		}
+	}
+
 	if r.hooks.OnStart != nil {
 		extras, err := r.hooks.OnStart(task.id, task.config)
 		if err != nil {
@@ -1110,6 +1132,11 @@ func (r *restream) startProcess(id string) error {
 		}
 		if len(extras) > 0 {
 			task.config.Output = append(task.config.Output, extras...)
+			needsRebuild = true
+		}
+	}
+
+	if needsRebuild {
 		task.command = task.config.CreateCommand()
 
 		newFFmpeg, ferr := r.ffmpeg.New(ffmpeg.ProcessConfig{
@@ -1124,12 +1151,11 @@ func (r *restream) startProcess(id string) error {
 			Logger:         task.logger,
 		})
 		if ferr != nil {
-				r.logger.WithField("id", task.id).WithError(ferr).Error().Log("Failed to rebuild FFmpeg after start hook")
+			r.logger.WithField("id", task.id).WithError(ferr).Error().Log("Failed to rebuild FFmpeg after hooks")
 			return ferr
 		}
 		task.ffmpeg = newFFmpeg
 	}
-	}
 
 	task.ffmpeg.Start()
 
@@ -1175,11 +1201,14 @@ func (r *restream) stopProcess(id string) error {
 	r.nProc--
 
 	// Notify subsystems (app/webrtc) that this process has been
-	// stopped so they can tear down any per-process state. Hook is
+	// stopped so they can tear down any per-process state. Hooks are
 	// best-effort: errors are the hook's problem to log.
 	if r.hooks.OnStop != nil {
 		r.hooks.OnStop(task.id)
 	}
+	if r.hooks.OnInputStop != nil {
+		r.hooks.OnInputStop(task.id)
+	}
 
 	return nil
 }