sample: Add playback tutorial 3 sample

samples/Makefile.am

@@ -1,4 +1,4 @@
-TARGETS = playback.exe video-overlay.exe basic-tutorial-1.exe basic-tutorial-2.exe basic-tutorial-3.exe basic-tutorial-4.exe basic-tutorial-5.exe basic-tutorial-6.exe basic-tutorial-7.exe basic-tutorial-8.exe basic-tutorial-9.exe basic-tutorial-12.exe basic-tutorial-13.exe playback-tutorial-1.exe playback-tutorial-2.exe
+TARGETS = playback.exe video-overlay.exe basic-tutorial-1.exe basic-tutorial-2.exe basic-tutorial-3.exe basic-tutorial-4.exe basic-tutorial-5.exe basic-tutorial-6.exe basic-tutorial-7.exe basic-tutorial-8.exe basic-tutorial-9.exe basic-tutorial-12.exe basic-tutorial-13.exe playback-tutorial-1.exe playback-tutorial-2.exe playback-tutorial-3.exe
 
 DEBUGS = $(addsuffix .mdb, $(TARGETS))
 assemblies = 					\
@@ -54,6 +54,9 @@ playback-tutorial-1.exe: $(srcdir)/PlaybackTutorial1.cs $(assemblies)
 playback-tutorial-2.exe: $(srcdir)/PlaybackTutorial2.cs $(assemblies)
 	$(CSC) $(CSFLAGS) -out:playback-tutorial-2.exe $(references) $(GLIB_SHARP_LIBS) $(srcdir)/PlaybackTutorial2.cs
 
+playback-tutorial-3.exe: $(srcdir)/PlaybackTutorial3.cs $(assemblies)
+	$(CSC) $(CSFLAGS) -out:playback-tutorial-3.exe $(references) $(GLIB_SHARP_LIBS) $(srcdir)/PlaybackTutorial3.cs
+
 EXTRA_DIST = 				\
 	Playback.cs \
     VideoOverlay.cs \
@@ -69,4 +72,5 @@ EXTRA_DIST = 				\
     BasicTutorial12.cs \
     BasicTutorial13.cs \
     PlaybackTutorial1.cs \
-    PlaybackTutorial2.cs
+    PlaybackTutorial2.cs \
+    PlaybackTutorial3.cs

samples/PlaybackTutorial3.cs

@@ -0,0 +1,152 @@
+// Authors
+//   Copyright (C) 2014 Stephan Sundermann <stephansundermann@gmail.com>
+
+using System;
+using Gst;
+using System.Runtime.InteropServices;
+
+namespace GstreamerSharp
+{
+	class Playback
+	{
+		const int ChunkSize = 1024;
+		const int SampleRate = 44100;
+
+		static Gst.App.AppSrc AppSource;
+		static Element Pipeline;
+
+		static long NumSamples;   // Number of samples generated so far (for timestamp generation)
+		static float a, b, c, d;     // For waveform generation
+
+		static uint Sourceid;        // To control the GSource
+
+		static GLib.MainLoop MainLoop;  // GLib's Main Loop
+
+		// This method is called by the idle GSource in the mainloop, to feed CHUNK_SIZE bytes into appsrc.
+		// The idle handler is added to the mainloop when appsrc requests us to start sending data (need-data signal)
+		// and is removed when appsrc has enough data (enough-data signal).
+
+		static bool PushData () {
+			var numSamples = ChunkSize / 2; // Because each sample is 16 bits
+			MapInfo map;
+
+			// Create a new empty buffer
+			var buffer = new Gst.Buffer (null, ChunkSize, AllocationParams.Zero);
+
+			// Set its timestamp and duration
+			buffer.Pts = Util.Uint64Scale ((ulong)NumSamples, (ulong)Constants.SECOND, (ulong)SampleRate);
+			buffer.Dts = Util.Uint64Scale ((ulong)NumSamples, (ulong)Constants.SECOND, (ulong)SampleRate);
+			buffer.Duration = Util.Uint64Scale ((ulong)NumSamples, (ulong)Constants.SECOND, (ulong)SampleRate);
+
+			// Generate some psychodelic waveforms
+			buffer.Map (out map, MapFlags.Write);
+			c += d;
+			d -= c / 1000f;
+			var freq = 1100f + 1000f * d;
+			short[] data = new short[numSamples];
+			for (int i = 0; i < numSamples; i++) {
+				a += b;
+				b -= a / freq;
+				data[i] = (short)(500f * a);
+			}
+			// convert the short[] to a byte[] by marshalling
+			var native = Marshal.AllocHGlobal (data.Length * sizeof(short));
+			Marshal.Copy (data, 0, native, data.Length);
+			byte[] bytedata = new byte[2 * data.Length];
+			Marshal.Copy (native, bytedata, 0, data.Length * sizeof(short));
+
+			map.Data = bytedata;
+			buffer.Unmap (map);
+			NumSamples += numSamples;
+
+			// Push the buffer into the appsrc
+			var ret = AppSource.PushBuffer (buffer);
+
+			// Free the buffer now that we are done with it
+			buffer.Dispose ();
+
+			if (ret != FlowReturn.Ok) {
+				// We got some error, stop sending data
+				return false;
+			}
+			return true;
+		}
+
+		// This signal callback triggers when appsrc needs  Here, we add an idle handler
+		// to the mainloop to start pushing data into the appsrc
+		static void StartFeed (object sender, Gst.App.NeedDataArgs args) {
+			if (Sourceid == 0) {
+				Console.WriteLine ("Start feeding");
+				Sourceid = GLib.Idle.Add (PushData);
+			}
+		}
+
+		// This callback triggers when appsrc has enough data and we can stop sending.
+		// We remove the idle handler from the mainloop
+		static void StopFeed (object sender, EventArgs args) {
+			if (Sourceid != 0) {
+				Console.WriteLine ("Stop feeding");
+				GLib.Source.Remove (Sourceid);
+				Sourceid = 0;
+			}
+		}
+
+		// This function is called when playbin has created the appsrc element, so we have a chance to configure it.
+		static void SourceSetup (object sender, GLib.SignalArgs args) {
+			var info = Gst.Audio.AudioInfo.Zero;
+			var source = new Gst.App.AppSrc(((Element)args.Args [0]).Handle);
+			Console.WriteLine ("Source has been created. Configuring.");
+			AppSource = source;
+
+			// Configure appsrc
+			info.SetFormat (Gst.Audio.AudioFormat.S16, SampleRate, 1, (Gst.Audio.AudioChannelPosition)0);
+			var audioCaps = info.ToCaps ();
+			source ["caps"] = audioCaps;
+			source ["format"] = Format.Time;
+			source.NeedData += StartFeed;
+			source.EnoughData += StopFeed;
+		}
+
+		// This function is called when an error message is posted on the bus
+		static void HandleError (object sender, GLib.SignalArgs args) {
+			GLib.GException err;
+			string debug;
+			var msg = (Message) args.Args[0];
+
+			// Print error details on the screen
+			msg.ParseError (out err, out debug);
+			Console.WriteLine ("Error received from element {0}: {1}", msg.Src.Name, err.Message);
+			Console.WriteLine ("Debugging information: {0}", debug != null ? debug : "none");
+
+			MainLoop.Quit ();
+		}
+
+		public static void Main (string[] args)
+		{
+			b = 1;
+			d = 1;
+
+			// Initialize Gstreamer
+			Gst.Application.Init(ref args);
+
+			// Create the playbin element
+			Pipeline = Parse.Launch ("playbin uri=appsrc://");
+			Pipeline.Connect ("source-setup", SourceSetup);
+
+			// Instruct the bus to emit signals for each received message, and connect to the interesting signals
+			var bus = Pipeline.Bus;
+			bus.AddSignalWatch ();
+			bus.Connect ("message::error", HandleError);
+
+			// Start playing the pipeline
+			Pipeline.SetState (State.Playing);
+
+			// Create a GLib Main Loop and set it to run
+			MainLoop = new GLib.MainLoop ();
+			MainLoop.Run ();
+
+			// Free resources
+			Pipeline.SetState (State.Null);
+		}
+	}
+}