Start Javascript audio according to the time - javascript

I installed the following JS library and I'm using the "player" samples.
https://github.com/goldfire/howler.js
Do you have any idea how to start the audio based on the time? I saw in the readme that they say to use the URL method with the seek parameter but I don't want to use a parameter in the URL but I want the time (in minutes or seconds) to be calculated when the site is accessed and for the audio to be started at that precise point.
I previously used this JS and it worked correctly:
var audio = new Audio();
audio.src = "MI24H.mp3";
ORA_ATTUALE_IN_SECONDI=(new Date().getHours()*60*60)+(new Date().getMinutes()*60)+(new Date().getSeconds());
audio.currentTime = ORA_ATTUALE_IN_SECONDI
audio.play();
function playAudio() {
audio.play();
}

I solved using the seek variable in this way:
TIME_IN_SECONDS=(new Date().getHours()*60*60)+(new Date().getMinutes()*60)+(new Date().getSeconds());
var seek = TIME_IN_SECONDS || 0;

Related

Web Audio API: createMediaStreamDestination().stream - no sound

I'm stuck with a problem in which whenever I pass the stream from createMediaStreamDestination to an audio element srcObject, no audio is being played. My implementation is based off of the response posted here Combine setSinkId with stereoPanner?
Initially, I have an audio element in which I isolate the sound so that it would only play from the left speaker
const audio = document.createElement('audio');
audio.src = audioUrl;
let audioContext = new AudioContext();
let source = audioContext.createMediaElementSource(audio);
let panner = audioContext.createStereoPanner();
let destination = audioContext.destination;
panner.pan.value = -1;
source.connect(panner).connect(destination);
The above plays sound fine when I add audio.play() but I want to be able to set specifically the speakers that the audio would play out of while keeping the panner changes. Since audioContext doesn't contain any possibility of setting the sinkId yet, I created a new audio element and mediastreamdestination and passed the mediaStream into the source object
const audio = document.createElement('audio');
audio.src = audioUrl;
let audioContext = new AudioContext();
let source = audioContext.createMediaElementSource(audio);
let panner = audioContext.createStereoPanner();
let destination = audioContext.createMediaStreamDestination();
panner.pan.value = -1;
source.connect(panner).connect(destination);
const outputAudio = new Audio();
outputAudio.srcObject = destination.stream;
outputAudio.setSinkId(audioSpeakerId);
outputAudio.play();
With the new code, however, when I start up my application, the outputAudio doesn't play any sound at all. Is there anything wrong with my code that is causing the outputAudio element not to play sound? I'm fairly new to web audio api and I tried implementing the code from the mentioned stackoverflow thread but it doesn't seem to be working for me. Any help would be appreciated!
In the description of your first code block you mention that you additionally also call audio.play() to start the audio. That's also necessary for the second code block to work. You need to start both audio elements.
Generally calling play() on an audio element and creating a new AudioContext should ideally happen in response to a user action to make sure the browser's autoplay policy doesn't block the audio.
If all goes well the state of your AudioContext should be "running".

Does R Shiny have the ability to start playing audio from a certain time stamp?

I'm building a Shiny app where users will be able to play snippets of an audio file. The time stamps are from a JSON file to mark each sentence in the audio file. To play the audio I was originally using runjs() like so:
in my input function:
tags$audio(id = "audio", controls = NA, autoplay = NA, src = "")
and in the server function:
observeEvent(input$select.file, {
runjs(sprintf("document.getElementById('audio').src = '%s';", input$select.file))
})
but I think this will not work for playing a certain segment of the audio. I have been looking at RStudio resources like this one on playing audio, but I haven't found anything showing how to play a section of the audio that doesn't necessarily start at the beginning.
This should work to skip e.g. the first 30 seconds:
observeEvent(input$select.file, {
runjs(sprintf("var myaudio = document.getElementById('audio');
myaudio.src = '%s';
myaudio.currentTime = 30;", input$select.file))
})

Use renderedBuffer as HTML5 Audio tag

So I've used WebAudioAPI to create a music from code. I've used OfflineAudioContext to create a music and it's oncomplete event is similar to this:
function(e) {
var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
var song = audioCtx.createBufferSource();
song.buffer = e.renderedBuffer;
song.connect(audioCtx.destination);
song.start();
}
Which plays the sound. And it works. But I would like to instead store it as an <audio> element, because it's easier to play, loop, pause and stop, which I need to reuse the song.
Is it possible? I'm googling for days, but I can't find how!
The idea was to use var song = new Audio() and something to copy the e.renderedBuffer to it.
Ok, so I found this code floating around: http://codedbot.com/questions-/911767/web-audio-api-output . I've created a copy here too: http://pastebin.com/rE9a1PaX .
I've managed to use this code to create and store an audio on the fly, using all the function provided in this link.
offaudioctx.oncomplete = function(e) {
var buffer = e.renderedBuffer;
var UintWave = createWaveFileData(buffer);
var base64 = btoa(uint8ToString(UintWave));
songsarr.push(document.createElement('audio'))
songsarr[songsarr.length-1].src = "data:audio/wav;base64," + base64;
console.log("completed!");
};
It's not pretty, but it works. I'm leaving everything here in case someone finds an easier way.

chrome audio analyzer breaking on audio switch

I'm creating an audio visualizer with webgl, and have been integrating soundcloud tracks into it. I want to no be able to switch tracks, but I can either get my visualizer to work and the audio to break, or I can get the audio to work and the visualizer to break.
The two ways that I've been able to make it work are
Audio working
delete audio element
append new audio element to body
trigger play
Visualizer working
stop audio
change source
trigger play
When I have the visualizer working, the audio is totally messed up. The buffers just sound wrong, and the audio has artifacts in it (noise, beeps and bloops).
When I have the audio working, when I call analyser.getByteFrequencyData, I get an array of 0's. I presume this is because the analyser is not hooked up correctly.
The code for the audio working looks like
$('#music').trigger("pause");
currentTrackNum = currentTrackNum + 1;
var tracks = $("#tracks").data("tracks")
var currentTrack = tracks[parseInt(currentTrackNum)%tracks.length];
// Begin audio switching
analyser.disconnect();
$('#music').remove();
$('body').append('<audio id="music" preload="auto" src="'+ currentTrack["download"].toString() + '?client_id=4c6187aeda01c8ad86e556555621074f"></audio>');
startWebAudio(),
(I don't think I need the pause call. Do I?)
when I want the visualizer to work, I use this code
currentTrackNum = currentTrackNum + 1;
var tracks = $("#tracks").data("tracks")
var currentTrack = tracks[parseInt(currentTrackNum)%tracks.length];
// Begin audio switching
$("#music").attr("src", currentTrack["download"].toString() + "?client_id=4c6187aeda01c8ad86e556555621074f");
$("#songTitle").text(currentTrack["title"]);
$('#music').trigger("play");
The startWebAudio function looks like this.
function startWebAudio() {
// Get our <audio> element
var audio = document.getElementById('music');
// Create a new audio context (that allows us to do all the Web Audio stuff)
var audioContext = new webkitAudioContext();
// Create a new analyser
analyser = audioContext.createAnalyser();
// Create a new audio source from the <audio> element
var source = audioContext.createMediaElementSource(audio);
// Connect up the output from the audio source to the input of the analyser
source.connect(analyser);
// Connect up the audio output of the analyser to the audioContext destination i.e. the speakers (The analyser takes the output of the <audio> element and swallows it. If we want to hear the sound of the <audio> element then we need to re-route the analyser's output to the speakers)
analyser.connect(audioContext.destination);
// Get the <audio> element started
audio.play();
var freqByteData = new Uint8Array(analyser.frequencyBinCount);
}
My suspicion is that the analyzer isn't hooked up correctly, but I can't figure out what to look at to figure it out. I have looked at the frequencyByteData output, and that seems to be indicative of something not being hooked up right. The analyser variable is global. If you would like more reference to the code, here's where it is on github
You can only create a single AudioContext per window. You should also be disconnecting the MediaElementSource when you're finished using it.
Here's an example that I used to answer a similar question: http://jsbin.com/acolet/1/

Javascript Audio Player - Adding .ogg to .mp3 array

I have my javascript audio player working with .mp3s, but I'm not sure how to add a second audio format (.ogg) so the files will also play in Firefox. Can anyone help with this. Here is the array code:
var urls = new Array();
urls[0] = 'audio/song1.mp3';
urls[1] = 'audio/song2.mp3';
urls[2] = 'audio/song3.mp3';
urls[3] = 'audio/song4.mp3';
var next = 0;
The easiest way to play sounds is with SoundManager 2 with uses Flash and HTML 5 when available.

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