playbin example

examples/playbin/main.go

@@ -0,0 +1,92 @@
+// This example demonstrates GStreamer's playbin element.
+//
+// This element takes an arbitrary URI as parameter, and if there is a source
+// element within gstreamer, that supports this uri, the playbin will try
+// to automatically create a pipeline that properly plays this media source.
+// For this, the playbin internally relies on more bin elements, like the
+// autovideosink and the decodebin.
+// Essentially, this element is a single-element pipeline able to play
+// any format from any uri-addressable source that gstreamer supports.
+// Much of the playbin's behavior can be controlled by so-called flags, as well
+// as the playbin's properties and signals.
+package main
+
+import (
+	"errors"
+	"fmt"
+	"os"
+
+	"github.com/tinyzimmer/go-gst/examples"
+	"github.com/tinyzimmer/go-gst/gst"
+)
+
+var srcURI string
+
+func playbin(mainLoop *gst.MainLoop) error {
+	if len(os.Args) < 2 {
+		return errors.New("Usage: playbin <uri>")
+	}
+
+	gst.Init(nil)
+
+	// Create a new playbin and set the URI on it
+	playbin, err := gst.NewElement("playbin")
+	if err != nil {
+		return err
+	}
+	playbin.Set("uri", os.Args[1])
+
+	// The playbin element itself is a pipeline, so it can be used as one, despite being
+	// created from an element factory.
+	bus := playbin.GetBus()
+
+	playbin.SetState(gst.StatePlaying)
+
+	bus.AddWatch(func(msg *gst.Message) bool {
+		switch msg.Type() {
+		case gst.MessageEOS:
+			mainLoop.Quit()
+			return false
+		case gst.MessageError:
+			err := msg.ParseError()
+			fmt.Println("ERROR:", err.Error())
+			if debug := err.DebugString(); debug != "" {
+				fmt.Println("DEBUG")
+				fmt.Println(debug)
+			}
+			mainLoop.Quit()
+			return false
+		// Watch state change events
+		case gst.MessageStateChanged:
+			if _, newState := msg.ParseStateChanged(); newState == gst.StatePlaying {
+				bin := gst.BinFromElement(playbin)
+				// Generate a dot graph of the pipeline to GST_DEBUG_DUMP_DOT_DIR if defined
+				bin.DebugBinToDotFile(gst.DebugGraphShowAll, "PLAYING")
+			}
+
+		// Tag messages contain changes to tags on the stream. This can include metadata about
+		// the stream such as codecs, artists, albums, etc.
+		case gst.MessageTag:
+			tags := msg.ParseTags()
+			fmt.Println("Tags:")
+			if artist, ok := tags.GetString(gst.TagArtist); ok {
+				fmt.Println("  Artist:", artist)
+			}
+			if album, ok := tags.GetString(gst.TagAlbum); ok {
+				fmt.Println("  Album:", album)
+			}
+			if title, ok := tags.GetString(gst.TagTitle); ok {
+				fmt.Println("  Title:", title)
+			}
+		}
+		return true
+	})
+
+	mainLoop.Run()
+
+	return playbin.SetState(gst.StateNull)
+}
+
+func main() {
+	examples.RunLoop(playbin)
+}