custom event example

examples/custom_events/main.go

@@ -0,0 +1,115 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/tinyzimmer/go-gst/examples"
+	"github.com/tinyzimmer/go-gst/gst"
+)
+
+type ExampleCustomEvent struct {
+	Count   int
+	SendEOS bool
+}
+
+func createPipeline() (*gst.Pipeline, error) {
+	gst.Init(nil)
+
+	// Create a new pipeline from a launch string
+	pipeline, err := gst.NewPipelineFromString(
+		"audiotestsrc name=src ! queue max-size-time=2000000000 ! fakesink name=sink sync=true",
+	)
+
+	// Retrieve the sink element
+	sinks, err := pipeline.GetSinkElements()
+	if err != nil {
+		return nil, err
+	} else if len(sinks) != 1 {
+		return nil, errors.New("Expected one sink back")
+	}
+	sink := sinks[0]
+
+	// Get the sink pad
+	sinkpad := sink.GetStaticPad("sink")
+
+	// Add a probe for out custom event
+	sinkpad.AddProbe(gst.PadProbeTypeEventDownstream, func(p *gst.Pad, info *gst.PadProbeInfo) gst.PadProbeReturn {
+		// Retrieve the event from the probe
+		ev := info.GetEvent()
+
+		// Extra check to make sure it is the right type.
+		if ev.Type() != gst.EventTypeCustomDownstream {
+			return gst.PadProbeUnhandled
+		}
+
+		// Unmarshal the event into our custom one
+		var customEvent ExampleCustomEvent
+		if err := ev.GetStructure().UnmarshalInto(&customEvent); err != nil {
+			fmt.Println("Could not parse the custom event!")
+			return gst.PadProbeUnhandled
+		}
+
+		// Log and act accordingly
+		fmt.Printf("Received custom event with count=%d send_eos=%v\n", customEvent.Count, customEvent.SendEOS)
+		if customEvent.SendEOS {
+			fmt.Println("Send EOS is true, sending eos")
+			if !pipeline.SendEvent(gst.NewEOSEvent()) {
+				fmt.Println("WARNING: Failed to send EOS to pipeline")
+			}
+		} else {
+			fmt.Println("Send EOS is false ignoring")
+		}
+		return gst.PadProbeOK
+	})
+
+	return pipeline, nil
+}
+
+func mainLoop(loop *gst.MainLoop, pipeline *gst.Pipeline) error {
+
+	// Start the pipeline
+	pipeline.SetState(gst.StatePlaying)
+
+	// Create a watch on the pipeline to kill the main loop when EOS is received
+	pipeline.GetPipelineBus().AddWatch(func(msg *gst.Message) bool {
+		switch msg.Type() {
+		case gst.MessageEOS:
+			pipeline.Destroy()
+			loop.Quit()
+		}
+		return true
+	})
+
+	// Loop and on the third iteration send the custom event.
+	ticker := time.NewTicker(time.Second * 2)
+	count := 0
+	for range ticker.C {
+		ev := ExampleCustomEvent{Count: count}
+		if count == 3 {
+			ev.SendEOS = true
+		}
+		st := gst.MarshalStructure(ev)
+		if !pipeline.SendEvent(gst.NewCustomEvent(gst.EventTypeCustomDownstream, st)) {
+			fmt.Println("Warning: failed to send custom event")
+		}
+		if count == 3 {
+			break
+		}
+		count++
+	}
+
+	return loop.RunError()
+}
+
+func main() {
+	examples.RunLoop(func(loop *gst.MainLoop) error {
+		var pipeline *gst.Pipeline
+		var err error
+		if pipeline, err = createPipeline(); err != nil {
+			return err
+		}
+		return mainLoop(loop, pipeline)
+	})
+}