How can I randomise a song when one has finished? [duplicate] - javascript

I'm planning out a project for a very simple audio streamer that would take a mysql database list of songs hosted on my local server, and then randomly stream a song from the list constantly throughout the day. This would be attached to a very simple frontend page that would display the name of the currently playing song.
I know how to get a random file from the database and stream it using a Javascript/HTML front end, but I'm getting lost on how to detect when a song is over - and then load the next song. Is there a simple way to do this? Can someone point me in the right direction?
EDIT: To elaborate on the frontend, I'd most likely be serving up the filename/location via PHP into the HTML5 audio tag (again I want this as simple as possible). I'm thinking the simplest way would be to play the audio file and then refresh the page and play the next file using the same audio tag and new filename - I just don't know how to cause that event to happen at the end of the song. Alternatively I could use a Javascript based player like JPlayer (http://www.jplayer.org/) if I need to.
I'm guessing there's a callback function of some kind I can use in conjunction with JQuery?

HTML5 audio tag has an event "onended" which is run when the media reaches its end, but since you wish to keep playing you should use the "onwaiting" event, which also fires when the media reaches its end, but keeps itself ready to accept a new track/data.
You can then use the XMLHttpRequest object to query for the next track to play, eg.
<script type="text/javascript">
function getNextTrack(e) {
var xhttp = new XMLHttpRequest();
xhttp.open("GET", "next_track.php", false);
xhttp.send("");
var playback = xhttp.responseXML.childNodes[0];
for(i = 0; i < playback.childNodes.length; ++i) {
if (playback.childNodes[i].nodeName != 'track') continue;
var value = playback.childNodes[i].childNodes[0].nodeValue;
e.currentTarget.src = value;
break;
}
}
</script>
<audio id="player" onwaiting="javascript: getNextTrack(e)" src="first_track.ogg"></audio>
The xml would be in the form of:
<?xml version="1.0" encoding="UTF-8" ?>
<playback>
<track>next_song.ogg</track>
</playback>

Related

Javascript: How to load updated audio file and play it

I am trying to play one audio file and so far I am able to do it by:
a = new Audio("audio.mp3");
a.load();
a.play();
But after playing it what I am trying to do is that I am creating new audio file with same name. Now again when I click one button and run this function to play audio, then it will play the previous file output rather than new one. So how I can re-upload the same file with same name so that new audio will be generated.
Thanks
The reason you keep getting the same audio file because of the browser cache, Since it's the same name the browser assumes the two files are the same. To prevent this, you can append a random query string to the filename so the browser thinks that you have a new file every time. But the down side of this is your user have to download the audio file every time, this could slow down your user loading time.
a = new Audio("audio.mp3?random=" + new Date().getTime());
a.load();
a.play();
If you have access to the uploaded time you can append that datetime instead of a random datetime, at least that force the browser to download the file only once per upload.
a = new Audio("audio.mp3?random=" + uploadDate.getTime());
a.load();
a.play();
In case to load another file with the same name (or even maybe with another name, in the same object), you need to remove the previous Object!
a.remove() will do the trick:
a = new Audio('a.mp3');
a.load();
a.play();
setTimeout(function(){a.pause();a.remove();a.load('a.mp3');a.play();},10000);
the above code loads a.mp3 plays it for 10 seconds. After 10 seconds it loads a.mp3 again whit what ever content there is in that file.
You need to be fast enough to replace the audio file with the same name in 10 seconds :D (or just raise the timeout seconds)

Is it possible to merge multiple webm blobs/clips into one sequential video clientside?

I already looked at this question -
Concatenate parts of two or more webm video blobs
And tried the sample code here - https://developer.mozilla.org/en-US/docs/Web/API/MediaSource -- (without modifications) in hopes of transforming the blobs into arraybuffers and appending those to a sourcebuffer for the MediaSource WebAPI, but even the sample code wasn't working on my chrome browser for which it is said to be compatible.
The crux of my problem is that I can't combine multiple blob webm clips into one without incorrect playback after the first time it plays. To go straight to the problem please scroll to the line after the first two chunks of code, for background continue reading.
I am designing a web application that allows a presenter to record scenes of him/herself explaining charts and videos.
I am using the MediaRecorder WebAPI to record video on chrome/firefox. (Side question - is there any other way (besides flash) that I can record video/audio via webcam & mic? Because MediaRecorder is not supported on not Chrome/Firefox user agents).
navigator.mediaDevices.getUserMedia(constraints)
.then(gotMedia)
.catch(e => { console.error('getUserMedia() failed: ' + e); });
function gotMedia(stream) {
recording = true;
theStream = stream;
vid.src = URL.createObjectURL(theStream);
try {
recorder = new MediaRecorder(stream);
} catch (e) {
console.error('Exception while creating MediaRecorder: ' + e);
return;
}
theRecorder = recorder;
recorder.ondataavailable =
(event) => {
tempScene.push(event.data);
};
theRecorder.start(100);
}
function finishRecording() {
recording = false;
theRecorder.stop();
theStream.getTracks().forEach(track => { track.stop(); });
while(tempScene[0].size != 1) {
tempScene.splice(0,1);
}
console.log(tempScene);
scenes.push(tempScene);
tempScene = [];
}
The function finishRecording gets called and a scene (an array of blobs of mimetype 'video/webm') gets saved to the scenes array. After it gets saved. The user can then record and save more scenes via this process. He can then view a certain scene using this following chunk of code.
function showScene(sceneNum) {
var sceneBlob = new Blob(scenes[sceneNum], {type: 'video/webm; codecs=vorbis,vp8'});
vid.src = URL.createObjectURL(sceneBlob);
vid.play();
}
In the above code what happens is the blob array for the scene gets turning into one big blob for which a url is created and pointed to by the video's src attribute, so -
[blob, blob, blob] => sceneBlob (an object, not array)
Up until this point everything works fine and dandy. Here is where the issue starts
I try to merge all the scenes into one by combining the blob arrays for each scene into one long blob array. The point of this functionality is so that the user can order the scenes however he/she deems fit and so he can choose not to include a scene. So they aren't necessarily in the same order as they were recorded in, so -
scene 1: [blob-1, blob-1] scene 2: [blob-2, blob-2]
final: [blob-2, blob-2, blob-1, blob-1]
and then I make a blob of the final blob array, so -
final: [blob, blob, blob, blob] => finalBlob
The code is below for merging the scene blob arrays
function mergeScenes() {
scenes[scenes.length] = [];
for(var i = 0; i < scenes.length - 1; i++) {
scenes[scenes.length - 1] = scenes[scenes.length - 1].concat(scenes[i]);
}
mergedScenes = scenes[scenes.length - 1];
console.log(scenes[scenes.length - 1]);
}
This final scene can be viewed by using the showScene function in the second small chunk of code because it is appended as the last scene in the scenes array. When the video is played with the showScene function it plays all the scenes all the way through. However, if I press play on the video after it plays through the first time, it only plays the last scene.
Also, if I download and play the video through my browser, the first time around it plays correctly - the subsequent times, I see the same error.
What am I doing wrong? How can I merge the files into one video containing all the scenes? Thank you very much for your time in reading this and helping me, and please let me know if I need to clarify anything.
I am using a element to display the scenes
The file's headers (metadata) should only be appended to the first chunk of data you've got.
You can't make an new video file by just pasting one after the other, they've got a structure.
So how to workaround this ?
If I understood correctly your problem, what you need is to be able to merge all the recorded videos, just like if it were only paused.
Well this can be achieved, thanks to the MediaRecorder.pause() method.
You can keep the stream open, and simply pause the MediaRecorder. At each pause event, you'll be able to generate a new video containing all the frames from the beginning of the recording, until this event.
Here is an external demo because stacksnippets don't works well with gUM...
And if ever you needed to also have shorter videos from between each resume and pause events, you could simply create new MediaRecorders for these smaller parts, while keeping the big one running.

Concerning Web Audio nodes, what does .connect() do?

Trying to follow the example here, which is basically a c&p of this
Think I got most of the parts down, except all the node.connect()'s
From what I understand, this sequence of code is needed to provide the audio analyzer with an audio stream:
var source = audioCtx.createMediaStreamSource(stream);
source.connect(analyser);
analyser.connect(audioCtx.destination);
I can't seem to make sense of it as it looks rather ouroboros-y to me.
And unfortunately, I can't seem to find any documentation on .connect() so quite lost and would appreciate any clarification!
Oh and I'm loading an .mp3 via pure javascript new Audio('db.mp3').play(); and am trying to use that as the source without creating an <audio> element.
Can a mediaStream object be created from this to feed into .createMediaStreamSource(stream)?
connect simply defines the output for the filters.
In this case, your source loads the stream into the buffer and writes to the input of the next filter which is defined by the connect function. This is repeated for your analyser filter.
Think of it as pipes.
here is a sample code snippet that I have written a few years back using web audio api.
this.scriptProcessor = this.audioContext.createScriptProcessor(this.scriptProcessorBufferSize,
this.scriptProcessorInputChannels,
this.scriptProcessorOutputChannels);
this.scriptProcessor.connect(this.audioContext.destination);
this.scriptProcessor.onaudioprocess = updateMediaControl.bind(this);
//Set up the Gain Node with a default value of 1(max volume).
this.gainNode = this.audioContext.createGain();
this.gainNode.connect(this.audioContext.destination);
this.gainNode.gain.value = 1;
sewi.AudioResourceViewer.prototype.playAudio = function(){
if(this.audioBuffer){
this.source = this.audioContext.createBufferSource();
this.source.buffer = this.audioBuffer;
this.source.connect(this.gainNode);
this.source.connect(this.scriptProcessor);
this.beginTime = Date.now();
this.source.start(0, this.offset);
this.isPlaying = true;
this.controls.update({playing: this.isPlaying});
updateGraphPlaybackPosition.call(this, this.offset);
}
};
So as you can see that my source is connected to a gainNode, which is connected to a scriptProcessor. When the audio starts playing, the data is passed from the source->gainNode->destination and source->scriptProcessor->destination. flowing through the "pipes" that connects them, which is defined by connect(). When the audio data pass through the gainNode, volume can be adjusted by changing the amplitude of the audio wave. After that it is passed to the script processor so that events can be attached and triggered while the audio is being processed.

Programm that tracks changes on web page

I have a web page that has several images on it and a script in it which changes picture of one random image once in some time interval. Script changes the image by rewtiting its file in the cash an updating it on the page. So url of the image picture doesnt chage in html code:
socket.on("banner", function(info) {
banName = "banner" + info.bid;
ban = document.getElementById(banName).getContext('2d');
var img = new Image();
img.src = 'data:image/jpg;base64,' + info.image;
img.onload = function(){ban.drawImage(img, 0, 0);};
});
How can I track image change using for example C#, when the page is in the browser?
As a last resort, retrieve the image periodically and load it into a byte array. Checking changes is just a matter of checking if the byte array has changed.
edit:
It seems the hard part is about how can one retrieve the image data. Without any javascript code in the browser, use C# to establish a websocket connection to mimic the behavior of javascript.
But I think it would be easier done by modifying the javascript code in the browser.

Stream audio file

So I am trying to stream and download audio file to the browser.
My files are stored on a seperate drive to the web application.
Currently I am using java to send the file:
public static Result recording(Long id) {
PhoneCall currentCall = PhoneCall.getCall(id);
if (currentCall != null) {
File wavFile = new File("D:\\audio\\"
+ currentCall.fileName);
return ok(wavFile);
} else {
return badRequest();
}
}
This works fine in that i can stream the audio and it plays nicely. And I am playing the audio through a html5 element.
But I am trying to use a slider control and using audio.currentTime to set the current time so a user can play midway through but it seems that I cannot set this value. I also cannot get the duration of the audio file using audio.duration.
Even when i use <audio controls="controls" it does not allow me to play midway through
Is there something I am missing? Can I get javascript to download the whole file before it starts playing so that i can get all this information? Or is there another way to send this using play framework?

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