Gstreamer DTMF detection plugin in vala written by ChatGPT

gistfile1.txt

using Gst;
using GLib;

public class DtmfDetector : Element {
  private static const int SAMPLE_RATE = 8000;
  private static const int CHUNK_SIZE = 256;
  private static const int LOW_FREQUENCIES = [697, 770, 852, 941];
  private static const int HIGH_FREQUENCIES = [1209, 1336, 1477, 1633];

  private Gst.Pad sinkpad;
  private Gst.Pad srcpad;
  private GLib.Queue<char> tones;
  private GLib.Mutex mutex;

  public DtmfDetector(Gst.ElementFactory factory, string name) {
    this.tones = new GLib.Queue<char>();
    this.mutex = new GLib.Mutex();
    this.sinkpad = this.get_static_pad("sink");
    this.srcpad = this.get_static_pad("src");
    this.sinkpad.add_probe(PadProbeType.BUFFER, sink_probe);
  }

  private PadProbeReturn sink_probe(Pad pad, PadProbeInfo info) {
    var buffer = info.get_buffer();
    var data = buffer.extract_dup(0, buffer.get_size());
    var samples = data.get_int16_array();
    var magnitudes = new double[CHUNK_SIZE];
    for (int i = 0; i < CHUNK_SIZE; i++) {
      var sample = samples[i];
      var magnitude = 0.0;
      for (int j = 0; j < LOW_FREQUENCIES.length; j++) {
        var lowFrequency = LOW_FREQUENCIES[j];
        var highFrequency = HIGH_FREQUENCIES[j];
        var lowReal = Math.cos(2 * Math.PI * lowFrequency * i / SAMPLE_RATE);
        var lowImag = Math.sin(2 * Math.PI * lowFrequency * i / SAMPLE_RATE);
        var highReal = Math.cos(2 * Math.PI * highFrequency * i / SAMPLE_RATE);
        var highImag = Math.sin(2 * Math.PI * highFrequency * i / SAMPLE_RATE);
        magnitude += lowReal * sample + highReal * sample;
      }
      magnitudes[i] = magnitude;
    }
    var maxMagnitude = -1.0;
    var maxFrequency = -1;
    for (int i = 0; i < CHUNK_SIZE; i++) {
      var magnitude = magnitudes[i];
      if (magnitude > maxMagnitude) {
        maxMagnitude = magnitude;
        maxFrequency = i;
      }
    }
    var frequency = (maxFrequency / CHUNK_SIZE) * SAMPLE_RATE;
    var tone = '?';
    if (697 <= frequency && frequency <= 1209) {
      var row =
        if (697 <= frequency && frequency <= 770) {
          "1"
        } else if (770 <= frequency && frequency <= 852) {
          "2"
        } else if (852 <= frequency && frequency <= 941) {
          "3"
        } else {
          "A"
        };
      tone = row[0];
    } else if (1336 <= frequency && frequency <= 1477) {
      var column =
        if (1336 <= frequency && frequency <= 1477) {
          "4"
        } else if (1477 <= frequency && frequency <= 1633) {
          "5"
        } else {
          "6"
        };
      tone = column[0];
    } else if (1633 <= frequency && frequency <= 1209) {
      var row =
        if (1633 <= frequency && frequency <= 1750) {
          "7"
        } else if (1750 <= frequency && frequency <= 1865) {
          "8"
        } else if (1865 <= frequency && frequency <= 1976) {
          "9"
        } else {
          "*"
        };
      tone = row[0];
    } else if (2277 <= frequency && frequency <= 1633) {
      var column =
        if (2277 <= frequency && frequency <= 2024) {
          "0"
        } else {
          "#"
        };
      tone = column[0];
    }
    mutex.lock();
    tones.push_tail(tone);
    mutex.unlock();
    return PadProbeReturn.OK;
  }

  public char get_tone() {
    mutex.lock();
    var tone = tones.pop_head();
    mutex.unlock();
    return tone;
  }
}

public static int plugin_init(Plugin plugin) {
  return Element.register(plugin, "dtmfdetector", 0, DtmfDetector.GTYPE);
}


// Sample usage
Gst.init(ref args);

var pipeline = new Pipeline("pipeline");
var source = ElementFactory.make("autoaudiosrc", "source");
var dtmfdetector = ElementFactory.make("dtmfdetector", "dtmfdetector");
var sink = ElementFactory.make("autoaudiosink", "sink");
pipeline.add(source).add(dtmfdetector).add(sink);
source.link(dtmfdetector).link(sink);

pipeline.set_state(State.PLAYING);

while (true) {
  var tone = dtmfdetector.get_tone();
  stdout.printf("Detected tone: %c\n", tone);
}