messaggeria/static/js/detto.js

// detto - cesco@ventuordici.org - 2020

/* THE CHINOTTO-WARE LICENSE" (Revision 42):
 * cesco@ventuordici.org wrote this code.
 * As long as you retain this notice you can do whatever you want with this stuff.
 * I reserve the right to do the absolute minimum provided by law, up to and including absolutely nothing.
 * If we meet some day, and you think this stuff is worth it, you can buy me a chinotto in return.
 */

var audioCtx;
const canvas = document.querySelector('.visualizer');
canvasCtx = canvas.getContext("2d");

document.addEventListener('DOMContentLoaded', function() {
	if(window.location.hash) {
		document.getElementById('visualizer').style.display = 'none';
		document.getElementById('record_audio').style.display = 'none';
		document.getElementById('url').style.display = 'none';
		document.getElementById('stop_record').style.display = 'none';

	        var downloadbutton = document.getElementById('download');
	        if (downloadbutton) { downloadbutton.addEventListener('click', content_download, false); }
	} else {
		document.getElementById('player').style.display = 'none';
		document.getElementById('download').style.display = 'none';
	        var recordbutton = document.getElementById('record_audio');
	        if (recordbutton) {
			recordbutton.addEventListener('click', processa_audio, false); 
		}

	        var stopbutton = document.getElementById('stop_record');
	        if (stopbutton) { stopbutton.addEventListener('click', stop_recorder, false); }
	}
}, false);

function processa_audio(){
        filename = "";
	fileext = ".webm";
	var constraints = { audio: true };
	var options = {
		audioBitsPerSecond : 64000,
		mimeType : 'audio/webm;codecs=opus'
	}
	audioCtx = new AudioContext();

	navigator.mediaDevices.getUserMedia(constraints).then(stream => {
		document.getElementById("record_audio").disabled = true;
		window.localStream = stream;
		const recorder = new MediaRecorder(stream, options);
		window.localRecorder = recorder;
		console.log("creato recorder " + recorder );
		visualize(stream);
		const chunks = [];

		recorder.ondataavailable = function(e) {
			// console.log("aggiungo chunk");
			chunks.push(e.data);
		}

		recorder.onstop = function(e) {
				console.log("stoppato recorder");
				const blob = new Blob(chunks, { type: 'audio/webm' });
				var reader = new FileReader();
				reader.onload = function(event) {
					console.log("reader loaded");
					var content = event.target.result;
					critta(content);
					document.getElementById("record_audio").disabled = false;
				}
				reader.readAsArrayBuffer(blob);
		}
	recorder.start(1000);

	});
}

function stop_recorder(stream){
	console.log("stopping");
	localRecorder.stop();
	localStream.getAudioTracks()[0].stop();
	localStream.getTracks().forEach(track => track.stop());
}

function visualize(stream) {
  console.log("start visualize");

  if(!audioCtx) {
    audioCtx = new AudioContext();
	console.log("creating audioctx" + audioCtx);
  }

  const source = audioCtx.createMediaStreamSource(stream);

  const analyser = audioCtx.createAnalyser();
  console.log("created analyser" + analyser);

  analyser.fftSize = 2048;
  const bufferLength = analyser.frequencyBinCount;
  const dataArray = new Uint8Array(bufferLength);

  source.connect(analyser);
  draw()

  function draw() {
    // console.log("start draw");
    WIDTH = canvas.width
    HEIGHT = canvas.height;

    requestAnimationFrame(draw);
    analyser.getByteTimeDomainData(dataArray);

    canvasCtx.fillStyle = 'rgb(255, 255, 255)';
    canvasCtx.fillRect(0, 0, WIDTH, HEIGHT);
    canvasCtx.lineWidth = 2;
    canvasCtx.strokeStyle = 'rgb(150, 0, 0)';

    canvasCtx.beginPath();

    let sliceWidth = WIDTH * 1.0 / bufferLength;
    let x = 0;


    for(let i = 0; i < bufferLength; i++) {

      let v = dataArray[i] / 128.0;
      let y = v * HEIGHT/2;

	if(i === 0) {
		canvasCtx.moveTo(x, y);
	} else {
		canvasCtx.lineTo(x, y);
	}
	x += sliceWidth;
    }

    canvasCtx.lineTo(canvas.width, canvas.height/2);
    canvasCtx.stroke();
  }
}