feat: enhance WebRTC pipeline with improved logging and error handling

internal/api/preview.go

@@ -95,24 +95,24 @@ func (api *API) previewHandler(c echo.Context) error {
 
 	// on-negotiation-needed: Triggered when webrtcbin needs to create an offer or answer.
 	// In our case (server receiving an offer), this fires after the remote description is set.
-	previewPipeline.webrtcbin.Connect("on-negotiation-needed", func(self *gst.Element) {
+	if _, err := previewPipeline.webrtcbin.Connect("on-negotiation-needed", func(self *gst.Element) {
 		log.Info().Msg("Negotiation needed, creating answer")
 
 		// Create Answer
-		promise, err := self.Emit("create-answer")
+		promise := gst.NewPromise()
+		_, err := self.Emit("create-answer", nil, promise)
 		if err != nil {
 			log.Error().Err(err).Msg("Failed to emit create-answer")
 			return
 		}
-		if promise == nil {
-			log.Error().Msg("Emit create-answer returned nil promise")
-			return
-		}
 
 		// Handle the promise result (asynchronously)
-		promise.(*gst.Promise).Interrupt()                  // Interrupt any previous waits
+		promise.Interrupt()                                // Interrupt any previous waits
-		promise.(*gst.Promise).Await(c.Request().Context()) // Wait for the answer to be created
+		reply, err := promise.Await(c.Request().Context()) // Wait for the answer to be created
-		reply := promise.(*gst.Promise).GetReply()
+		if err != nil {
+			log.Error().Err(err).Msg("Failed to await create-answer promise")
+			return
+		}
 		if reply == nil {
 			log.Error().Msg("Promise reply for create-answer was nil")
 			return
@@ -132,16 +132,14 @@ func (api *API) previewHandler(c echo.Context) error {
 		log.Debug().Str("sdp", answer.SDP().String()).Msg("Answer created")
 
 		// Set Local Description
-		promise, err = self.Emit("set-local-description", answer)
+		descPromise := gst.NewPromise()
+		_, err = self.Emit("set-local-description", answer, descPromise)
 		if err != nil {
 			log.Error().Err(err).Msg("Failed to emit set-local-description")
 			return
 		}
-		if promise == nil {
+
-			log.Error().Msg("Emit set-local-description returned nil promise")
+		descPromise.Interrupt() // Interrupt any previous waits
-			return
-		}
-		promise.(*gst.Promise).Interrupt() // Interrupt any previous waits
 
 		log.Info().Msg("Set local description (answer)")
 
@@ -159,10 +157,12 @@ func (api *API) previewHandler(c echo.Context) error {
 		if err := conn.WriteMessage(websocket.TextMessage, msg); err != nil {
 			log.Error().Err(err).Msg("Failed to send answer over WebSocket")
 		}
-	})
+	}); err != nil {
+		log.Error().Err(err).Msg("Failed to connect on-negotiation-needed signal")
+	}
 
 	// on-ice-candidate: Triggered when webrtcbin generates a new ICE candidate.
-	previewPipeline.webrtcbin.Connect("on-ice-candidate", func(self *gst.Element, mlineindex uint, candidate string) {
+	if _, err := previewPipeline.webrtcbin.Connect("on-ice-candidate", func(self *gst.Element, mlineindex uint, candidate string, _ any) {
 		log.Debug().Uint("mlineindex", mlineindex).Str("candidate", candidate).Msg("🧊 Generated ICE candidate")
 		// Note: The 'sdpMid' is often derived from the mlineindex or context,
 		// but the signal itself only provides mlineindex and candidate string directly.
@@ -183,7 +183,9 @@ func (api *API) previewHandler(c echo.Context) error {
 		if err := conn.WriteMessage(websocket.TextMessage, msg); err != nil {
 			log.Error().Err(err).Msg("Failed to send ICE candidate over WebSocket")
 		}
-	})
+	}); err != nil {
+		log.Error().Err(err).Msg("Failed to connect on-ice-candidate signal")
+	}
 
 	// --- WebSocket Message Loop ---
 	for {
@@ -454,7 +456,6 @@ func (api *API) createPreviewPipeline(d Device) (*PreviewPipeline, error) {
 	}
 	log.Info().Str("pipeline", pipeline.GetName()).Msg("Preview pipeline state set to PLAYING")
 
-
 	return previewPipeline, nil
 }
 

internal/gstreamer/debug.go

@@ -2,23 +2,8 @@ package gstreamer
 
 import (
 	"github.com/go-gst/go-gst/gst"
-	"github.com/goccy/go-graphviz/cgraph"
 )
 
 func gstreamerBinToDot(bin *gst.Bin) string {
 	return bin.DebugBinToDotData(gst.DebugGraphShowAll)
 }
-
-func setFontSize(graph *cgraph.Graph, fontSize float64) {
-	graph.SetFontSize(20)
-	graph.Set("arrowSize", "3")
-	for node, err := graph.FirstNode(); err == nil && node != nil; node, err = graph.NextNode(node) {
-		node.SetFontSize(fontSize)
-		for edge, err := graph.FirstEdge(node); err == nil && edge != nil; edge, err = graph.NextEdge(edge, node) {
-			edge.SetFontSize(fontSize)
-		}
-	}
-	//for subGraph, err := graph.FirstSubGraph(); err == nil && subGraph != nil; subGraph, err = graph.NextSubGraph() {
-	//	setFontSize(subGraph, fontSize)
-	//}
-}

internal/ndi/device.go

@@ -5,6 +5,8 @@ import (
 	"github.com/go-gst/go-gst/gst"
 	"github.com/google/uuid"
 	"github.com/rs/zerolog/log"
+	"os"
+	"path/filepath"
 	"sync"
 )
 
@@ -92,6 +94,8 @@ func (d *Device) createPipeline() error {
 	d.Lock()
 	defer d.Unlock()
 
+	log.Debug().Str("name", d.name).Msg("Creating pipeline for device")
+
 	pipeline, err := gst.NewPipeline("ndi-" + d.name)
 	if err != nil {
 		return fmt.Errorf("creating pipeline: %w", err)
@@ -99,6 +103,10 @@ func (d *Device) createPipeline() error {
 	pipeline.ForceClock(gst.ObtainSystemClock().Clock)
 
 	input := d.gstDevice.CreateElement("")
+	if err := pipeline.Add(input); err != nil {
+		return fmt.Errorf("adding input to pipeline: %w", err)
+	}
+
 	inputQueue, err := gst.NewElementWithProperties("queue2",
 		map[string]interface{}{
 			"name":             "input-queue",
@@ -106,6 +114,13 @@ func (d *Device) createPipeline() error {
 			"max-size-bytes":   0,
 			"max-size-time":    40000000, // 40ms
 		})
+	if err != nil {
+		return fmt.Errorf("creating input-queue: %w", err)
+	}
+	if err := pipeline.Add(inputQueue); err != nil {
+		return fmt.Errorf("adding input-queue to pipeline: %w", err)
+	}
+
 	if err := input.Link(inputQueue); err != nil {
 		return fmt.Errorf("linking input to input input-queue: %w", err)
 	}
@@ -114,6 +129,9 @@ func (d *Device) createPipeline() error {
 	if err != nil {
 		return fmt.Errorf("creating ndisrcdemux: %w", err)
 	}
+	if err := pipeline.Add(ndiDemuxer); err != nil {
+		return fmt.Errorf("adding ndisrcdemux to pipeline: %w", err)
+	}
 
 	if err := inputQueue.Link(ndiDemuxer); err != nil {
 		return fmt.Errorf("linking input-queue to ndisrcdemux: %w", err)
@@ -123,14 +141,16 @@ func (d *Device) createPipeline() error {
 	if err != nil {
 		return fmt.Errorf("creating video-tee: %w", err)
 	}
+	if err := pipeline.Add(videoTee); err != nil {
+		return fmt.Errorf("adding video-tee to pipeline: %w", err)
+	}
 
 	audioTee, err := gst.NewElementWithName("tee", "audio-tee")
 	if err != nil {
 		return fmt.Errorf("creating audio-tee: %w", err)
 	}
-
+	if err := pipeline.Add(audioTee); err != nil {
-	if err := pipeline.AddMany(input, ndiDemuxer, videoTee, audioTee); err != nil {
+		return fmt.Errorf("adding audio-tee to pipeline: %w", err)
-		return fmt.Errorf("adding elements to pipeline: %w", err)
 	}
 
 	d.pipeline = pipeline
@@ -140,6 +160,18 @@ func (d *Device) createPipeline() error {
 	if _, err := ndiDemuxer.Connect("pad-added", d.onNdiSrcDemuxerPadAdded); err != nil {
 		return fmt.Errorf("connecting pad-added signal: %w", err)
 	}
+	cwd, err := os.Getwd()
+	if err != nil {
+		return fmt.Errorf("getting current working directory: %w", err)
+	}
+	log.Debug().Str("cwd", cwd).Msg("dumping pipeline to dot file")
+	filename := filepath.Join(cwd, "dumpDot", "ndi-pipeline.dot")
+	dot := pipeline.DebugBinToDotData(gst.DebugGraphShowAll)
+	if err := os.WriteFile(filename, []byte(dot), 0644); err != nil {
+		return fmt.Errorf("writing dot file: %w", err)
+	}
+
+	log.Debug().Str("name", d.name).Msg("Pipeline created")
 
 	return nil
 }
@@ -244,40 +276,10 @@ func (d *Device) setPipelineState(state gst.State) error {
 	}
 
 	log.Info().Str("pipeline", d.pipeline.GetName()).Str("target_state", state.String()).Msg("Setting pipeline state")
-	stateChangeReturn := d.pipeline.SetState(state)
+	if err := d.pipeline.SetState(state); err != nil {
-	if stateChangeReturn == gst.StateChangeFailure {
+		log.Error().Str("pipeline", d.pipeline.GetName()).Str("target_state", state.String()).Err(err).Msg("SetState failed")
-		log.Error().Str("pipeline", d.pipeline.GetName()).Str("target_state", state.String()).Msg("SetState returned failure")
+		return fmt.Errorf("setting pipeline state to %s: %w", state.String(), err)
-		return fmt.Errorf("setting pipeline state to %s failed", state.String())
 	}
-	if stateChangeReturn == gst.StateChangeNoPreroll {
-		log.Warn().Str("pipeline", d.pipeline.GetName()).Str("target_state", state.String()).Msg("SetState returned no-preroll")
-		// No-preroll might be acceptable depending on the pipeline, especially for live sources.
-	}
-
-
-	// Wait briefly for the state change to complete, especially important for PLAYING.
-	// Use a reasonable timeout (e.g., 2 seconds)
-	_, currentState, pendingState := d.pipeline.GetState(2 * gst.Second)
-	log.Debug().
-		Str("pipeline", d.pipeline.GetName()).
-		Str("target_state", state.String()).
-		Str("current_state", currentState.String()).
-		Str("pending_state", pendingState.String()).
-		Msg("Pipeline state after SetState attempt")
-
-	if currentState != state && pendingState != state {
-		// If neither current nor pending matches the target state after timeout, log a warning.
-		// This might indicate a problem, but we won't return an error yet,
-		// as some state transitions might take longer or settle asynchronously.
-		log.Warn().
-			Str("pipeline", d.pipeline.GetName()).
-			Str("target_state", state.String()).
-			Str("actual_state", currentState.String()).
-			Msg("Pipeline did not reach target state within timeout")
-	} else {
-		log.Info().Str("pipeline", d.pipeline.GetName()).Str("reached_state", state.String()).Msg("Pipeline state change successful or pending")
-	}
-
 
 	return nil
 }

webRTC-test/index.html

@@ -0,0 +1,15 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>WebRTC Video Preview</title>
+    <link rel="stylesheet" href="style.css">
+</head>
+<body>
+<h1>WebRTC Video Stream</h1>
+<video id="video" autoplay playsinline></video>
+
+<script src="script.js"></script>
+</body>
+</html>

webRTC-test/style.css

@@ -0,0 +1,15 @@
+body {
+    font-family: Arial, sans-serif;
+    text-align: center;
+}
+
+h1 {
+    color: #4CAF50;
+}
+
+#video {
+    width: 100%;
+    max-width: 600px;
+    border: 1px solid #ddd;
+    margin-top: 20px;
+}