Javascript frequency analyzer using chart library - javascript

I'm currently trying to make a frequency analyzer using web technologies, especially Meteor.
For now, I tried to use the Google Charts library that create SVG pictures. The chart needs to be refreshed about 10 times by second and the performance aren't satisfying. It takes all the CPU resource.
I'm a bit new to web development (especially in graphical and performances issues) so if you could point into the right direction to make my research, I'd appreciate it.

I ended up using the library CanvasJs which appears to be one of the fastest. There is an option interactivityEnabled: false to disable interactions with the chart which increase performance.
Even if there is yet no direct Meteor integration, just put the js file in the ./client/compatibility and it works fine.

You could very easily accomplish this with ZingChart. We don't have a Meteor integration (yet), but the demo below should be a good start for you. Run the snippet below to see it live.
I'm on the ZingChart team! Let me know if you have questions.
var MAXVALUES = 100;
var myConfig = {
type: "line",
series : [
{
values : []
}
]
};
zingchart.render({
id : 'myChart',
data : myConfig,
height: 400,
width: 600
});
var myValues = [];
setInterval(function(){
myValues.push( Math.floor(Math.random() * 10 ) );
if(myValues.length == MAXVALUES+1){
myValues.shift();
}
console.log(myValues)
zingchart.exec('myChart', 'setseriesvalues', {
values : [myValues]
})
},60)
<script src="http://cdn.zingchart.com/zingchart.min.js"></script>
<div id='myChart'></div>

Use the canvas element. You should be able to get 60 per second and if it's a audio source the Audio API provides a DSP for spectral analysis.
Here is an example audio spectrum visualizer

Related

HERE Maps JS API Routing with ABR and Height limitations

I've recently came across a problem I'm using here maps JS api routing in specifically, and I am trying to add restrictions for example using height or weight. For some reason it ignores it, I'm using fleet telematics tiles as well from HERE, so its showing me relative information regarding here.
my options are:
let routingParameters = {
'routingMode': 'short',
'transportMode': 'truck',
'origin': locationPoints.A.lat+','+locationPoints.A.lon,
'destination': locationPoints.B.lat+','+locationPoints.B.lon,
'truck': {
'height': 600,
'grossWeight': 22000
},
'return': 'polyline,summary'
};
Everything is fine with routing itself, maybe I am missing something? Is there an option to avoid those things?
Logically speaking, it wouldn't be possible to drive trough a 4.5 under tunnel with 6m of height, so it shouldn't be an option even if there wouldnt be a good road for it routing wise.
I managed to figure it out, seems like they key has to be in the key itself, for example.
let routingParameters = {
'routingMode': 'short',
'transportMode': 'truck',
'origin': locationPoints.A.lat+','+locationPoints.A.lon,
'destination': locationPoints.B.lat+','+locationPoints.B.lon,
'truck[height]': 600,
'return': 'polyline,summary'
};
Will most definetely work. Who ever will run across the same problem.

Is it possible to select a quality for the azure media player using its javascript API?

Looking to implement azure media player for a project. But we need to use our existing custom video controls. Is it possible to control the quality selector by javascript? Have not been able to find anything concerning this in the documentation..
Does anyone have experience with this?
Any help would be appreciated!
Could also be worth noting that this is a react.js project.
Thanks,
You can specify the heuristic profile (HighQuality, Hybrid, LowLatency, QuickStart):
http://amp.azure.net/libs/amp/latest/docs/index.html#amp.player.heuristicprofile
http://amp.azure.net/libs/amp/latest/docs/#amp.videostream.selecttrackbyindex
try something like this:
myPlayer.addEventListener(amp.eventName.loadedmetadata,
function() {
var stream = myPlayer.currentVideoStreamList().streams ?
myPlayer.currentVideoStreamList().streams[0] :
undefined;
if (stream) {
stream.selectTrackByIndex(0);
}
});
myPlayer.src([{
src: "[srcuri]",
type: "application/vnd.ms-sstr+xml"
}]);

Phantomjs: take screenshot of the current page?

I'm trying to use Phantomjs to capture a screenshot from the same page that the user is on.
For example, A user is on my-page.html and has made some changes to the elements of this page, now I need to take a screenshot of an element (DIV) inside this page (my-page.html) and save it.
I found a few examples of Phantomjs and php which I tested and worked on my server and it stores the image on my server too BUT all of the examples I found are for taking screenshots of external pages/URLs and not the 'current page'.
This is fairly a straight forward process in Html2canvas but the quality of the produced image is not good at all so I decided to use Phantomjs to produce higher quality screenshots AND also it allows me to zoom in on the page.
Here is a simple example of using Phantomjs for taking screenshot of External URL's:
var system = require("system");
if (system.args.length > 0) {
var page = require('webpage').create();
page.open(system.args[1], function() {
//viewportSize being the actual size of the headless browser
page.viewportSize = { width: 3000, height: 3000 };
//the clipRect is the portion of the page you are taking a screenshot of
page.clipRect = { top: 0, left: 0, width: 3000, height: 3000 };
page.zoomFactor = 300.0/72.0;
var pageTitle = system.args[1].replace(/http.*\/\//g, "").replace("www.", "").split("/")[0]
var filePath = "img/" + pageTitle + '.png';
page.render(filePath);
console.log(filePath);
phantom.exit();
});
}
Could someone please let me know if this is possible at all?
EDIT (Answer to my own question),
it turns out that you cannot take a screenshot of the current page if the page's elements have been edited by the user on the live basis. the only screenshots you can take with phantomjs is a bare bone of the page.
Reason: phantomjs is a headless browser and uses QtWebKit which runs on the server and it is not a javascript library same as html2canvas.
Explained and experienced by others HERE:
Another use case that is an issue for a project I’m working on is that you need drag and drop. Headless drivers have some basic functionality, but if you need to be able to set precise coordinates you’re stuck with Selenium.
For taking screenshot of current page you must pass the correct URL to Phantom script
Syntax :
phantomjs <"Phantom code url(as in documentation report.js)"> <"page url of which you want to take scrrenshot"> <"result saving url">
Now assuming you are passing correct URL :
In my case I was unable to take screenshot of my page as there was a spring security annotation to it, so it was not letting me to proceed so Please check for any security you added to your page if yes then remove it and then try again.
If case 1 does not apply to you surely there is an problem with URL you are passing please double check it.
Please let me know if problem still persist please post any errors(if occurring) you are getting.

Jquery Flot Slow & freezes IE

I currently have to plot in the neighborhood of 8000 - 32000 points (4 lines * 8000 points) I am getting my data via a JSON request and that works perfectly actually the data is returned to me in less than a second. However whenever I get to the $.plot point it freezes IE8 and it takes forever to load that many points. Here is my code:
var data = [];
function onDataReceived(seriesData) {
var p = $.plot(placeholder, seriesData.seriesData, options);
}
$.ajax({
url: '/Charts/LineChart?DataTypesToGraph=' + dataTypes + '&DatePull=' + chartDate + '&AssetID=' + $('#AssetID').val(),
method: 'GET',
async: true,
cache: true,
dataType: 'json',
success: onDataReceived
});
How can I speed up my $.plot to make it load a lot faster. Also is there a way I can do it so it does not freeze IE8?
Thanks so much!
You're seeing a 'freeze' because Flot doesn't (yet) support incremental drawing; it renders the entire plot before giving control back to the browser. There's no way around that besides hacking the code, but there are two things you can do to help:
You're probably using Excanvas; try switching to Flashcanvas. In my experience it works just as well with Flot, and delivers dramatically better performance. The $31 necessary to license the 'pro' version is not going to break most budgets.
You have 8000 points per line, and most displays max out at 1920 pixels wide, with the average being more like 1280. If you're showing the whole line, without some sort of zoom/pan, then you're rendering 4-6 times more data than is actually visible onscreen. Some server-side filtering/aggregation to bring the number of points down to 2k would dramatically improve performance.
But no matter what you do, you're never going to get great performance on IE8 with large datasets. It's an almost four-year-old browser, released before the JavaScript performance wars, using an emulated canvas; you can only do so much.

Sound effects in JavaScript / HTML5

I'm using HTML5 to program games; the obstacle I've run into now is how to play sound effects.
The specific requirements are few in number:
Play and mix multiple sounds,
Play the same sample multiple times, possibly overlapping playbacks,
Interrupt playback of a sample at any point,
Preferably play WAV files containing (low quality) raw PCM, but I can convert these, of course.
My first approach was to use the HTML5 <audio> element and define all sound effects in my page. Firefox plays the WAV files just peachy, but calling #play multiple times doesn't really play the sample multiple times. From my understanding of the HTML5 spec, the <audio> element also tracks playback state, so that explains why.
My immediate thought was to clone the audio elements, so I created the following tiny JavaScript library to do that for me (depends on jQuery):
var Snd = {
init: function() {
$("audio").each(function() {
var src = this.getAttribute('src');
if (src.substring(0, 4) !== "snd/") { return; }
// Cut out the basename (strip directory and extension)
var name = src.substring(4, src.length - 4);
// Create the helper function, which clones the audio object and plays it
var Constructor = function() {};
Constructor.prototype = this;
Snd[name] = function() {
var clone = new Constructor();
clone.play();
// Return the cloned element, so the caller can interrupt the sound effect
return clone;
};
});
}
};
So now I can do Snd.boom(); from the Firebug console and play snd/boom.wav, but I still can't play the same sample multiple times. It seems that the <audio> element is really more of a streaming feature rather than something to play sound effects with.
Is there a clever way to make this happen that I'm missing, preferably using only HTML5 and JavaScript?
I should also mention that, my test environment is Firefox 3.5 on Ubuntu 9.10. The other browsers I've tried - Opera, Midori, Chromium, Epiphany - produced varying results. Some don't play anything, and some throw exceptions.
HTML5 Audio objects
You don't need to bother with <audio> elements. HTML 5 lets you access Audio objects directly:
var snd = new Audio("file.wav"); // buffers automatically when created
snd.play();
There's no support for mixing in current version of the spec.
To play same sound multiple times, create multiple instances of the Audio object. You could also set snd.currentTime=0 on the object after it finishes playing.
Since the JS constructor doesn't support fallback <source> elements, you should use
(new Audio()).canPlayType("audio/ogg; codecs=vorbis")
to test whether the browser supports Ogg Vorbis.
If you're writing a game or a music app (more than just a player), you'll want to use more advanced Web Audio API, which is now supported by most browsers.
Web Audio API
Edit: As of December 2021, Web Audio API is essentially supported in Chrome, Firefox, Safari and all the other major browsers (excluding IE, of course).
As of July 2012, the Web Audio API is now supported in Chrome, and at least partly supported in Firefox, and is slated to be added to IOS as of version 6.
Although the Audio element is robust enough to be used programmatically for basic tasks, it was never meant to provide full audio support for games and other complex applications. It was designed to allow a single piece of media to be embedded in a page, similar to an img tag. There are a lot of issues with trying to use the it for games:
Timing slips are common with Audio elements
You need an Audio element for each instance of a sound
Load events aren't totally reliable, yet
No common volume controls, no fading, no filters/effects
Here are some good resources to get started with the Web Audio API:
MDN documentaion
Getting Started With WebAudio article
The FieldRunners WebAudio Case Study is also a good read
howler.js
For game authoring, one of the best solutions is to use a library which solves the many problems we face when writing code for the web, such as howler.js. howler.js abstracts the great (but low-level) Web Audio API into an easy to use framework. It will attempt to fall back to HTML5 Audio Element if Web Audio API is unavailable.
var sound = new Howl({
urls: ['sound.mp3', 'sound.ogg']
}).play();
// it also provides calls for spatial/3d audio effects (most browsers)
sound.pos3d(0.1,0.3,0.5);
wad.js
Another great library is wad.js, which is especially useful for producing synth audio, such as music and effects. For example:
var saw = new Wad({source : 'sawtooth'})
saw.play({
volume : 0.8,
wait : 0, // Time in seconds between calling play() and actually triggering the note.
loop : false, // This overrides the value for loop on the constructor, if it was set.
pitch : 'A4', // A4 is 440 hertz.
label : 'A', // A label that identifies this note.
env : {hold : 9001},
panning : [1, -1, 10],
filter : {frequency : 900},
delay : {delayTime : .8}
})
Sound for Games
Another library similar to Wad.js is "Sound for Games", it has more focus on effects production, while providing a similar set of functionality through a relatively distinct (and perhaps more concise feeling) API:
function shootSound() {
soundEffect(
1046.5, //frequency
0, //attack
0.3, //decay
"sawtooth", //waveform
1, //Volume
-0.8, //pan
0, //wait before playing
1200, //pitch bend amount
false, //reverse bend
0, //random pitch range
25, //dissonance
[0.2, 0.2, 2000], //echo array: [delay, feedback, filter]
undefined //reverb array: [duration, decay, reverse?]
);
}
Summary
Each of these libraries are worth a look, whether you need to play back a single sound file, or perhaps create your own html-based music editor, effects generator, or video game.
You may also want to use this to detect HTML 5 audio in some cases:
http://diveintohtml5.ep.io/everything.html
HTML 5 JS Detect function
function supportsAudio()
{
var a = document.createElement('audio');
return !!(a.canPlayType && a.canPlayType('audio/mpeg;').replace(/no/, ''));
}
Here's one method for making it possible to play even same sound simultaneously. Combine with preloader, and you're all set. This works with Firefox 17.0.1 at least, haven't tested it with anything else yet.
// collection of sounds that are playing
var playing={};
// collection of sounds
var sounds={step:"knock.ogg",throw:"swing.ogg"};
// function that is used to play sounds
function player(x)
{
var a,b;
b=new Date();
a=x+b.getTime();
playing[a]=new Audio(sounds[x]);
// with this we prevent playing-object from becoming a memory-monster:
playing[a].onended=function(){delete playing[a]};
playing[a].play();
}
Bind this to a keyboard key, and enjoy:
player("step");
To play the same sample multiple times, wouldn't it be possible to do something like this:
e.pause(); // Perhaps optional
e.currentTime = 0;
e.play();
(e is the audio element)
Perhaps I completely misunderstood your problem, do you want the sound effect to play multiple times at the same time? Then this is completely wrong.
Sounds like what you want is multi-channel sounds. Let's suppose you have 4 channels (like on really old 16-bit games), I haven't got round to playing with the HTML5 audio feature yet, but don't you just need 4 <audio> elements, and cycle which is used to play the next sound effect? Have you tried that? What happens? If it works: To play more sounds simultaneously, just add more <audio> elements.
I have done this before without the HTML5 <audio> element, using a little Flash object from http://flash-mp3-player.net/ - I wrote a music quiz (http://webdeavour.appspot.com/) and used it to play clips of music when the user clicked the button for the question. Initially I had one player per question, and it was possible to play them over the top of each other, so I changed it so there was only one player, which I pointed at different music clips.
Have a look at the jai (-> mirror) (javascript audio interface) site. From looking at their source, they appear to be calling play() repeatedly, and they mention that their library might be appropriate for use in HTML5-based games.
You can fire multiple audio events
simultaneously, which could be used
for creating Javascript games, or
having a voice speaking over some
background music
Here's an idea. Load all of your audio for a certain class of sounds into a single individual audio element where the src data is all of your samples in a contiguous audio file (probably want some silence between so you can catch and cut the samples with a timeout with less risk of bleeding to the next sample). Then, seek to the sample and play it when needed.
If you need more than one of these to play you can create an additional audio element with the same src so that it is cached. Now, you effectively have multiple "tracks". You can utilize groups of tracks with your favorite resource allocation scheme like Round Robin etc.
You could also specify other options like queuing sounds into a track to play when that resource becomes available or cutting a currently playing sample.
http://robert.ocallahan.org/2011/11/latency-of-html5-sounds.html
http://people.mozilla.org/~roc/audio-latency-repeating.html
Works OK in Firefox and Chrome for me.
To stop a sound that you started, do
var sound = document.getElementById("shot").cloneNode(true);
sound.play();
and later
sound.pause();
I would recommend using SoundJS, a library I've help develop. It allows you to write a single code base that works everywhere, with SoundJS picking web audio, html audio, or flash audio as appropriate.
It will allow you to do all of the thing you want:
Play and mix multiple sounds,
Play the same sample multiple times, possibly overlapping playbacks
Interrupt playback of a sample at any point
play WAV files containing (depending on browser support)
Hope that helps.
It's not possible to do multi-shot playing with a single <audio> element. You need to use multiple elements for this.
I ran into this while programming a musicbox card generator. Started with different libraries but everytime there was a glitch somehow. The lag on normal audio implementation was bad, no multiple plays... eventually ended up using lowlag library + soundmanager:
http://lowlag.alienbill.com/
and
http://www.schillmania.com/projects/soundmanager2/
You can check out the implementation here:
http://musicbox.grit.it/
I generated wav + ogg files for multi browser plays. This musicbox player works responsive on ipad, iphone, Nexus, mac, pc,... works for me.
var AudioContextFunc = window.AudioContext || window.webkitAudioContext;
var audioContext = new AudioContextFunc();
var player=new WebAudioFontPlayer();
var instrumVox,instrumApplause;
var drumClap,drumLowTom,drumHighTom,drumSnare,drumKick,drumCrash;
loadDrum(21,function(s){drumClap=s;});
loadDrum(30,function(s){drumLowTom=s;});
loadDrum(50,function(s){drumHighTom=s;});
loadDrum(15,function(s){drumSnare=s;});
loadDrum(5,function(s){drumKick=s;});
loadDrum(70,function(s){drumCrash=s;});
loadInstrument(594,function(s){instrumVox=s;});
loadInstrument(1367,function(s){instrumApplause=s;});
function loadDrum(n,callback){
var info=player.loader.drumInfo(n);
player.loader.startLoad(audioContext, info.url, info.variable);
player.loader.waitLoad(function () {callback(window[info.variable])});
}
function loadInstrument(n,callback){
var info=player.loader.instrumentInfo(n);
player.loader.startLoad(audioContext, info.url, info.variable);
player.loader.waitLoad(function () {callback(window[info.variable])});
}
function uhoh(){
var when=audioContext.currentTime;
var b=0.1;
player.queueWaveTable(audioContext, audioContext.destination, instrumVox, when+b*0, 60, b*1);
player.queueWaveTable(audioContext, audioContext.destination, instrumVox, when+b*3, 56, b*4);
}
function applause(){
player.queueWaveTable(audioContext, audioContext.destination, instrumApplause, audioContext.currentTime, 54, 3);
}
function badumtss(){
var when=audioContext.currentTime;
var b=0.11;
player.queueWaveTable(audioContext, audioContext.destination, drumSnare, when+b*0, drumSnare.zones[0].keyRangeLow, 3.5);
player.queueWaveTable(audioContext, audioContext.destination, drumLowTom, when+b*0, drumLowTom.zones[0].keyRangeLow, 3.5);
player.queueWaveTable(audioContext, audioContext.destination, drumSnare, when+b*1, drumSnare.zones[0].keyRangeLow, 3.5);
player.queueWaveTable(audioContext, audioContext.destination, drumHighTom, when+b*1, drumHighTom.zones[0].keyRangeLow, 3.5);
player.queueWaveTable(audioContext, audioContext.destination, drumSnare, when+b*3, drumSnare.zones[0].keyRangeLow, 3.5);
player.queueWaveTable(audioContext, audioContext.destination, drumKick, when+b*3, drumKick.zones[0].keyRangeLow, 3.5);
player.queueWaveTable(audioContext, audioContext.destination, drumCrash, when+b*3, drumCrash.zones[0].keyRangeLow, 3.5);
}
<script src='https://surikov.github.io/webaudiofont/npm/dist/WebAudioFontPlayer.js'></script>
<button onclick='badumtss();'>badumtss</button>
<button onclick='uhoh();'>uhoh</button>
<button onclick='applause();'>applause</button>
<br/><a href='https://github.com/surikov/webaudiofont'>More sounds</a>
I know this is a total hack but thought I should add this sample open source audio library I put on github awhile ago...
https://github.com/run-time/jThump
After clicking the link below, type on the home row keys to play a blues riff (also type multiple keys at the same time etc.)
Sample using jThump library >> http://davealger.com/apps/jthump/
It basically works by making invisible <iframe> elements that load a page that plays a sound onReady().
This is certainly not ideal but you could +1 this solution based on creativity alone (and the fact that it is open source and works in any browser that I've tried it on) I hope this gives someone else searching some ideas at least.
:)
You can always try AudioContext it has limited support but it's a part of the web audio api working draft. It might be worth it if you are planing to release something in the future. And if you are only programing for chrome and Firefox you're golden.
Web Audio API is right tool for this job. There is little bit of work involved in loading sounds files and playing it. Luckily there are plenty of libraries out there that simplify the job. Being interested in sounds I also created a library called musquito you can check out that as well.
Currently it supports only fading sound effect and I'm working on other things like 3D spatialization.
The selected answer will work in everything except IE. I wrote a tutorial on how to make it work cross browser. Here is the function I wrote:
function playSomeSounds(soundPath) {
var trident = !!navigator.userAgent.match(/Trident\/7.0/);
var net = !!navigator.userAgent.match(/.NET4.0E/);
var IE11 = trident && net
var IEold = (navigator.userAgent.match(/MSIE/i) ? true : false);
if (IE11 || IEold) {
document.all.sound.src = soundPath;
} else {
var snd = new Audio(soundPath); // buffers automatically when created
snd.play();
}
}
You also need to add the following tag to the html page:
<bgsound id="sound">
Finally you can call the function and simply pass through the path here:
playSomeSounds("sounds/welcome.wav");

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