gstreamer/subprojects/gstreamer-sharp/samples/BasicTutorial8.cs

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// 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.AppSink AppSink;
static Gst.App.AppSrc AppSource;
static Element Pipeline, Tee, AudioQueue, AudioConvert1, AudioResample, AudioSink;
static Element VideoQueue, AudioConvert2, Visual, VideoConvert, VideoSink;
static Element AppQueue;
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;
}
}
// The appsink has received a buffer
static void NewSample (object sender, GLib.SignalArgs args) {
var sink = (Gst.App.AppSink)sender;
// Retrieve the buffer
var sample = sink.PullSample ();
if (sample != null) {
// The only thing we do in this example is print a * to indicate a received buffer
Console.Write ("*");
sample.Dispose ();
}
}
// 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;
Gst.Audio.AudioInfo info = new Gst.Audio.AudioInfo();
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// Initialize Gstreamer
Gst.Application.Init(ref args);
// Create the elements
AppSource = new Gst.App.AppSrc ("app_src");
Tee = ElementFactory.Make ("tee", "tee");
AudioQueue = ElementFactory.Make ("queue", "audio_queue");
AudioConvert1 = ElementFactory.Make ("audioconvert", "audio_convert1");
AudioResample = ElementFactory.Make ("audioresample", "audio_resample");
AudioSink = ElementFactory.Make ("autoaudiosink", "audio_sink");
VideoQueue = ElementFactory.Make ("queue", "video_queue");
AudioConvert2 = ElementFactory.Make ("audioconvert", "audio_convert2");
Visual = ElementFactory.Make ("wavescope", "visual");
VideoConvert = ElementFactory.Make ("videoconvert", "video_convert");
VideoSink = ElementFactory.Make ("autovideosink", "video_sink");
AppQueue = ElementFactory.Make ("queue", "app_queue");
AppSink = new Gst.App.AppSink ("app_sink");
// Create the empty pipeline
var pipeline = new Pipeline ("test-pipeline");
if (AppSource == null || Tee == null || AudioQueue == null || AudioConvert1 == null || AudioResample == null ||
AudioSink == null || VideoQueue == null || AudioConvert2 == null || Visual == null || VideoConvert == null ||
AppQueue == null || AppSink == null ||pipeline == null) {
Console.WriteLine ("Not all elements could be created.");
return;
}
// Configure wavescope
Visual ["shader"] = 0;
Visual ["style"] = 0;
// Configure appsrc
Gst.Audio.AudioChannelPosition[] position = {};
info.SetFormat (Gst.Audio.AudioFormat.S16, SampleRate, 1, position);
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var audioCaps = info.ToCaps ();
AppSource ["caps"] = audioCaps;
AppSource ["format"] = Format.Time;
AppSource.NeedData += StartFeed;
AppSource.EnoughData += StopFeed;
// Configure appsink
AppSink ["emit-signals"] = true;
AppSink ["caps"] = audioCaps;
AppSink.NewSample += NewSample;
// Link all elements that can be automatically linked because they have "Always" pads
pipeline.Add (AppSource, Tee, AudioQueue, AudioConvert1, AudioResample,
AudioSink, VideoQueue, AudioConvert2, Visual, VideoConvert, VideoSink, AppQueue, AppSink);
if (!Element.Link (AppSource, Tee) ||
!Element.Link (AudioQueue, AudioConvert1, AudioResample, AudioSink) ||
!Element.Link (VideoQueue, AudioConvert2, Visual, VideoConvert, VideoSink) ||
!Element.Link (AppQueue, AppSink)) {
Console.WriteLine ("Elements could not be linked.");
return;
}
// Manually link the Tee, which has "Request" pads
var teeSrcPadTemplate = Tee.GetPadTemplate ("src_%u");
var teeAudioPad = Tee.RequestPad (teeSrcPadTemplate);
Console.WriteLine ("Obtained request pad {0} for audio branch.", teeAudioPad.Name);
var queueAudioPad = AudioQueue.GetStaticPad ("sink");
var teeVideoPad = Tee.RequestPad (teeSrcPadTemplate);
Console.WriteLine ("Obtained request pad {0} for video branch.", teeVideoPad.Name);
var queueVideoPad = VideoQueue.GetStaticPad ("sink");
var teeAppPad = Tee.RequestPad (teeSrcPadTemplate);
Console.WriteLine ("Obtained request pad {0} for app branch.", teeAppPad.Name);
var queueAppPad = AppQueue.GetStaticPad ("sink");
if (teeAudioPad.Link (queueAudioPad) != PadLinkReturn.Ok ||
teeVideoPad.Link (queueVideoPad) != PadLinkReturn.Ok ||
teeAppPad.Link (queueAppPad) != PadLinkReturn.Ok) {
Console.WriteLine ("Tee could not be linked");
return;
}
// 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 ();
// Release the request pads from the Tee, and unref them
Tee.ReleaseRequestPad(teeAudioPad);
Tee.ReleaseRequestPad(teeVideoPad);
Tee.ReleaseRequestPad(teeAppPad);
// Free resources
pipeline.SetState (State.Null);
Gst.Global.Deinit();
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}
}
}