Develop Reference

p5.js | Quality of image captured from camera feed, lower than actual camera feed?

With the code below, the quality of the video coming from my Mac's camera and shown inside <video> is great.
However the quality of the frame I capture and show in p5's canvas is pretty low, dark and grainy. Why is that and can I fix it ?
function setup() {
let canvas = createCanvas(canvasSize, canvasSize)
canvas.elt.width = canvasSize
canvas.elt.height = canvasSize
video = createCapture(VIDEO)
}
let PAUSE = false
async function draw() {
if (video && video.loadedmetadata) {
if (!PAUSE) {
// the quality of this image is much lower than what is shown inside p5's <video>
image(video.get(), 0, 0, canvasSize, canvasSize, x, y, canvasSize, canvasSize)
PAUSE = true
}
}
}

I found what the problem was.
It was not due to me setting the canvas.elt.width and canvas.elt.height, even though setting them is indeed redundant.
It's because in the code shown in the OP I was capturing the very first frame and this is too soon so the very first frame is still dark and blurry. Apparently the first few frames coming from the camera are like that.
If I give my code a delay of e.g. 5 seconds the frame it captures is then the exact same quality as the one coming from the video feed.
let video
let canvasWidth = 400
// set this to 10 on https://editor.p5js.org/ and you'll see the problem
const DELAY = 5000
function setup() {
let canvas = createCanvas(canvasWidth, canvasWidth)
canvas.elt.width = canvasWidth // redundant
canvas.elt.height = canvasWidth // redundant
video = createCapture(VIDEO)
}
let PAUSE = false
let start = Date.now()
async function draw() {
let delay = Date.now() - start
if (video && video.loadedmetadata) {
if (delay > DELAY && !PAUSE) {
PAUSE = true
let x = Math.round((video.width / 2) - (canvasWidth / 2))
let y = Math.round((video.height / 2) - (canvasWidth / 2))
// the quality of this image is now perfect
image(video.get(), 0, 0, canvasWidth, canvasWidth, x, y, canvasWidth, canvasWidth)
}
}
}

You should not be setting width/height this way. That will mess up the sizing on high DPI displays and cause your image to appear stretched and blurry.
const canvasSize = 500;
function setup() {
let canvas = createCanvas(canvasSize, canvasSize)
// Don't do this, it will mess up the sizing on high DPI displays:
// canvas.elt.width = canvasSize
// canvas.elt.height = canvasSize
video = createCapture(VIDEO)
}
let PAUSE = false;
function draw() {
if (video && video.loadedmetadata) {
if (!PAUSE) {
// the quality of this image is much lower than what is shown inside p5's <video>
image(video.get(), 0, 0, canvasSize, canvasSize, 0, 0, canvasSize, canvasSize)
}
}
}
function keyPressed() {
if (key === 'p') {
PAUSE = !PAUSE;
}
}
With this code I paused the video that was being rendered to p5.js and then took a screenshot. The version of the video displayed on the p5.js canvas wash indistinguishable from the live video.

HTML5 How to get first frame of a video

I am trying to get the first frame of a video in order to put it in a canvas, using this code but the canvas remains empty.
video.addEventListener("canplay",function () {
var $this = this;
console.log("canplay");
console.log(video.readyState);
canvas.getContext('2d').drawImage($this, 0, 0, canvas.width, canvas.height);
});
I also use this code to mirror the video in a canvas and it works.
video.addEventListener('play', function() {
var $this = this;
(function loop() {
if (!$this.paused && !$this.ended) {
context.save();
context.scale(-1, 1);
context.drawImage($this, 0, 0, mCanvas.width*-1, mCanvas.height);
context.restore();
setTimeout(loop, 1000 / 30); // drawing at 30fps
}
})();
}, 0);
How can I get the first frame of the video? Morevoer I have the possibility to change the URL dynamically: what should I do to get the first frame of the new video?

Show webcam / camera stream with delay - webrtc

I've made a simple setup, getting the webcam / phone camera stream and the passing it on , drawing on a html 2d canvas.
But ive been having trouble figuring out how to show the stream with a delay of few seconds. Kinda like a delay mirror.
I tried playing with ctx.globalAlpha = 0.005; but this gives me a ghosting effect rather than 'delaying' the stream.
Any idea how this can be achieved?
The snippet below doesnt work here probably because of security issues apparently but here's a pen:
https://codepen.io/farisk/pen/LvmGGQ
var width = 0, height = 0;
var canvas = document.createElement('canvas'),
ctx = canvas.getContext('2d');
document.body.appendChild(canvas);
var video = document.createElement('video'),
track;
video.setAttribute('autoplay',true);
window.vid = video;
function getWebcam(){
navigator.mediaDevices.getUserMedia({ video: true }).then(function(stream) {
var videoTracks = stream.getVideoTracks();
var newStream = new MediaStream(stream.getVideoTracks());
video.srcObject = newStream;
video.play();
track = stream.getTracks()[0];
}, function(e) {
console.error('Rejected!', e);
});
}
getWebcam();
var rotation = 0,
loopFrame,
centerX,
centerY,
twoPI = Math.PI * 2;
function loop(){
loopFrame = requestAnimationFrame(loop);
// ctx.globalAlpha = 0.005;
ctx.drawImage(video, 0, 0, width, height);
ctx.restore();
}
function startLoop(){
loopFrame = requestAnimationFrame(loop);
}
video.addEventListener('loadedmetadata',function(){
width = canvas.width = video.videoWidth;
height = canvas.height = video.videoHeight;
centerX = width / 2;
centerY = height / 2;
startLoop();
});
canvas.addEventListener('click',function(){
if ( track ) {
if ( track.stop ) { track.stop(); }
track = null;
} else {
getWebcam();
}
});
video,
canvas {
max-width: 100%;
height: auto;
}
The snippet below doesnt work here probably because of security issues apparently but here's a pen:
https://codepen.io/farisk/pen/LvmGGQ

You might want to consider storing the video data you get in an array of sorts. It might mean delaying the playback for n seconds at first.
Basically on frame 1, you store the video feed into an array, and draw nothing. This happened until frame 1000 (1 second). At that point start drawing based on the first element of the array.
Once you draw that frame, remove it from the array and add the new frame.

JavaScript audio.pause() and audio.play() not working in audio visualizer

I have an audio visualizer to which I'm attempting to add controls. Unfortunately, the problem cannot be easily replicated in a snippet because a special server must be setup to allow frequency access to the audio. However, I'll describe the problem the best I can.
All JavaScript for the project is below. I haven't tried skip functions yet but play/pause doesn't work.
This block handles all the play/pause.
function updatePlayState(){
//console.log(paused)
console.log(audio.paused)
//audio.play();
audio.pause();
console.log(audio.paused)
/*if(!paused){
paused = true;
audio.pause();
console.log(audio.src)
}else{
audio.play();
}*/
}
When I click the button, the console logs false and then true. However, it continues the same behavior after additional clicks. The audio also doesn't pause. The audio object I'm using is global so scope must not be the issue. I'm just wanting to get the audio to pause and then I'll move on to additional functionality.
//initialize global variables...
var audio, canvas, ctx, audioCtx, source, analyser, playlist_index = 0, full_screen = false, paused = false;
var playlist = [
//'http://localhost/audio-visualizer/audio/audio.mp3',
'http://localhost/audio-visualizer/audio/HaxPigMeow.mp3',
'http://localhost/audio-visualizer/audio/4ware.mp3',
'http://localhost/audio-visualizer/audio/Narwhals_song.mp3'
];
//when the page loads...
window.addEventListener('load', function() {
//initialize the canvas...
initializeCanvas();
//initialize audio...
initializeAudio();
//initialize audio analyzer (get frequency information)...
initializeAudioAnalyser();
//initialize audio controls...
initializeAudioControls();
});
//when the window is resized...
window.addEventListener('resize', function() {
resizeCanvas();
});
function initializeCanvas() {
//get the canvas...
canvas = document.getElementById('canvas');
//create a canvas context to draw graphics...
ctx = canvas.getContext('2d');
//resize the canvas to fit the window...
resizeCanvas();
}
function resizeCanvas() {
//set height of canvas...
canvas.width = window.innerWidth;
//set width of canvas...
canvas.height = window.innerHeight;
//set width of context...
ctx.width = window.innerWidth;
//set height of context...
ctx.height = window.innerHeight;
//reset drawing properties...
setCanvasDrawingProperties();
}
function initializeAudio() {
//load the audio...
audio = new Audio(playlist[playlist_index]);
//bypass CORS (Cross Origin Resource Sharing) restrictions...
audio.crossOrigin = 'anonymous';
//when the audio finishes playing; replay...
//audio.loop = true;
//play automatically...
//audio.autoplay = true;
//wait until audio fully loads before playing...
audio.oncanplaythrough = function() {
setTimeout(function() {
window.addEventListener('click',function(e){
audio.play();
//request full screen access...
if(e.target.tagName != 'INPUT'){
var root_element = document.documentElement;
rfs = root_element.requestFullscreen
|| root_element.webkitRequestFullScreen
|| root_element.mozRequestFullScreen
|| root_element.msRequestFullscreen
;
rfs.call(root_element);
}
//show audio controls....
document.getElementById('controlContainer').style.display = 'block';
setTimeout(function(){
document.getElementById('controlContainer').style.opacity = '1';
},500);
//hide the loading message...
document.getElementById('overlayLoadingMessage').style.opacity = '0';
window.setTimeout(function() {
document.getElementById('overlayLoadingMessage').style.display = 'none';
}, 500);
});
}, 1000);
};
audio.addEventListener('ended',function(){
skipForward();
playlist_index++;
if(playlist_index == playlist.length){
playlist_index = 0;
}
audio.src = playlist[playlist_index];
audio.crossOrigin = 'anonymous';
audio.play();
})
}
function initializeAudioControls(){
document.getElementById('skipBack').addEventListener('click',skipTrackBackward);
document.getElementById('skipForward').addEventListener('click',skipTrackForward);
document.getElementById('pause').addEventListener('click',updatePlayState);
function skipTrackForward(){
console.log('skip forward')
}
function skipTrackBackward(){
console.log('skip backward')
}
function updatePlayState(){
//console.log(paused)
console.log(audio.paused)
//audio.play();
audio.pause();
console.log(audio.paused)
/*if(!paused){
paused = true;
audio.pause();
console.log(audio.src)
}else{
audio.play();
}*/
}
}
function initializeAudioAnalyser() {
//create an audio context for browsers (including older webkit)...
if(window.webkitAudioContext){
//an older browser which needs to use the webkit audio constructor...
audioCtx = new window.webkitAudioContext;
}else{
//a newer browser which has full support for the audio context...
audioCtx = new window.AudioContext;
}
//create a new analyser...
analyser = audioCtx.createAnalyser();
//create new media source for the audio context...
source = audioCtx.createMediaElementSource(audio);
//connect the analyser to the source...
source.connect(analyser);
//connect audio output device information to the analyser to gather audio frequencies...
analyser.connect(audioCtx.destination);
//set drawing properties...
setCanvasDrawingProperties();
//let's do this thing (time to animate)...
animate();
}
function setCanvasDrawingProperties() {
//set background color of future drawing...
ctx.fillStyle = '#fff';
//blur radius (50px)...
ctx.shadowBlur = 50;
//shadow color...
ctx.shadowColor = "#ddd";
}
function animate() {
//clear canvas...
ctx.clearRect(0, 0, window.innerWidth, window.innerHeight);
//create new frequency array map...
frequencyBinaryCountArray = new Uint8Array(analyser.frequencyBinCount);
//input frequency data into the array map...
analyser.getByteFrequencyData(frequencyBinaryCountArray);
//calculate radius based on frequency information (uses channel 50 right now)..
var r = frequencyBinaryCountArray[50];
//set x of circle...
var x = (window.innerWidth / 2);
//set y of circle...
var y = (window.innerHeight / 2);
//set start angle (the circumference of the circle)...
var startAngle = 2 * Math.PI;
//set end angle (the end circumference of the circle)...
var endAngle = 0 * Math.PI;
//draw a circle; radius is based on frequency...
//begin the drawing...
ctx.beginPath();
//draw the circle...
ctx.arc(x, y, r, startAngle, endAngle);
//fill the circle with a color...
ctx.fill();
//close the path...
ctx.closePath();
//do it again (appx 60 times per second)...
requestAnimationFrame(animate);
}
Tested in Chrome 67.x (latest version as of this post) on macOS High Sierra.

I was stuck on it a while but, immediately after posting the question, I discovered the global click listener that starts playing the audio was also firing when I clicked the pause button. It was overriding the pause function. To fix it, I moved the audio play inside the e.target tagname exception. However, to prevent future confusion, I added a button to start the visualization rather than a global click event.
Thanks for looking.

Recording speed javascript

I am currently creating a project that supports video recording through my website.
I create a canvas and then push the recorded frames to it. The problem is, when I play the video after its recorded, it plays too fast. A 10 second long video plays in like 2 seconds. I have checked the playbackRate is set to 1. I save the recording to a database and its speeded up there aswell, so it has nothing to do with the browsers videoplayer.
I am relative new to AngularJS and javascript so im sorry if I left something important out.
I have tried changing alot of the values back and forth but I cant seem to find the cause for the problem. Any ideas?
Here is the code for the video recording:
scope.startRecording = function () {
if (mediaStream) {
var video = $('.video-capture')[0];
var canvas = document.createElement('canvas');
canvas.height = video.videoHeight;
canvas.width = video.videoWidth;
ctx = canvas.getContext('2d');
var CANVAS_WIDTH = canvas.width;
var CANVAS_HEIGHT = canvas.height;
function drawVideoFrame(time) {
videoRecorder = requestAnimationFrame(drawVideoFrame);
ctx.drawImage(video, 0, 0, CANVAS_WIDTH, CANVAS_HEIGHT);
recordedFrames.push(canvas.toDataURL('image/webp', 1));
}
videoRecorder = requestAnimationFrame(drawVideoFrame); // Note: not using vendor prefixes!
scope.recording = true;
}
};
scope.stopRecording = function () {
cancelAnimationFrame(videoRecorder); // Note: not using vendor prefixes!
// 2nd param: framerate for the video file.
scope.video.files = Whammy.fromImageArray(recordedFrames, 1000 / 30);
recordedVideoBlob = Whammy.fromImageArray(recordedFrames, 1000 / 30);
scope.videoMode = 'viewRecording';
scope.recording = false;
};

I am guess the culprit is requestAnimationFrame, left on it's own, you cannot tell at what intervals it keeps calling the callback, it can be as high as 60fps.
also looking at your code, I cannot tell how you came to the conclusion that frame rate = 1000/30
my advice( at least for your case) would be to go with $interval,
you can do something like:
scope.frameRate = 10, videoInterval; // the amount I consider ideal for client-side video recording.
scope.startRecording = function () {
if (mediaStream) {
var video = $('.video-capture')[0];
var canvas = document.createElement('canvas');
canvas.height = video.videoHeight;
canvas.width = video.videoWidth;
ctx = canvas.getContext('2d');
var CANVAS_WIDTH = canvas.width;
var CANVAS_HEIGHT = canvas.height;
function drawVideoFrame() {
ctx.drawImage(video, 0, 0, CANVAS_WIDTH, CANVAS_HEIGHT);
recordedFrames.push(canvas.toDataURL('image/webp', 1));
}
videoInterval = $interval(drawVideoFrame, 1000/scope.frameRate);
scope.recording = true;
}
};
scope.stopRecording = function () {
$interval.cancel(videoInterval);
// 2nd param: framerate for the video file.
scope.video.files = Whammy.fromImageArray(recordedFrames, scope.frameRate);
recordedVideoBlob = Whammy.fromImageArray(recordedFrames, scope.frameRate); // you can chage this to some file copy method, so leave out the duplicate processing of images into video.
scope.videoMode = 'viewRecording';
scope.recording = false;
};