go-gst/examples/custom_events/main.go

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)
	})
}