Extract audio from video stream using javascript - javascript

I want to extract audio from a video file using javascript, is it possible to make a mp3 file or any format so that i can play it in an audio tag in html5 ? if yes how? OR what API should I use ?

JavaScript is a script running at the client-end for handling user interactions usually. Long computations cause the browser to halt the script anyway and can turn the page unresponsive. Besides, it is not suitable for video encoding/decoding.
You should use a Java applet for video processing/audio extraction. That way, processing is still offloaded to the client. Processing on the server is expensive in terms of memory and processor cycles. Not Recommended.

Sooo, this is NOT an optimal solution. It is sort of terrible actually since you will forcing users to download a video without seeing it. What you could do is play the file as HTML5 video and just hide the video display then show controls as if it were just audio. This is sort of like playing a video, but just not watching the video while listening to the audio.
Checkout jPlayer: http://jplayer.org/
It will let you play an MP4 basically on any browser by telling it to use flash then falling back to HTML5 when you need it to. Then you can just style things how you want using CSS/HTML/Images.
You might want to try a small test first to see if the display:none; css style will also prevent the video's audio from playing. If that is the case you could also use height:0;;
Once again, this is sub-optimal since you are taking up the user's bandwidth. There are other solutions out there that could potentially strip out just the audio for you in a streaming environment.

Related

How to disable video/audio downloading in web pages?

I have a website that I put my videos/audios on it.
I use HTML5 and tag to show videos.
But videos/audios can be downloaded if client opens view source page and then copy the file address.
How can I disable downloading these files, I just want client to see videos/hear audios in the web page.
Many online video/audio services like Youtube disabled downloading videos by this way. How they did that? What is a working way to disable, or at least make this progress much harder?
Youtube encodes their video into the MPEG-DASH format, which plays back through byte streams via the browser's implementation of the Media Source Extensions API. See See more on Wikipedia.
You can do the same by encoding your video into MPEG-DASH files, then playing it back in your code through a library like dash.js. Watch how the dash.js player works live by checking out the DASH Reference Client.
I've encoded MPEG-DASH video using Sorenson Squeeze, but there are other encoders you could use.
And just to clarify... this will make downloading more difficult... but will NOT provide a real DRM solution. For that you need to check out EME.
MPEG-DASH seems like a nice solution but is definitely not perfect. There are many ways to bypass this and still being able to download the video. On the other hand putting a lot of effort in protection might not be worth it since people can always make screen recordings etc.
But if you still want to go for a more secure option you can try using
Encrypted Media Extensions i.e. with Amazon s3 cloud.

Detect if any type of audio if playing in browser

I need to build a Javascript tracker that will log a user's radio listening session. A website will generally embed their radio streams into many type of HTML elements, such as the video or audio tag.
I need to detect any form of live audio (i.e. radio stream) that is playing on a website's page. Audios have different formats such as mp3, aac, m3u8, etc. Most of the time, websites use the video or audio tag, and these tags are easily retrievable in Javascript. I can also use the paused attribute to acknowledge if it is playing or not.
My problem is to detect audios that use old technologies like Flash. I don't know where to start to handle these cases. Are there some standards regarding Flash? How can I find the Flash's object and detecting if it is playing or not? Can I find its url?

Seeking HTML5 audio element causes delay (breaks sync)

I'm developing a collaborative audio recording platform for musicians (something like a cloud DAW married with GitHub).
In a nutshell, a session (song) is made of a series of audio tracks, encoded in AAC and played through HTML5 <audio> elements. Each track is connected to the Web Audio API through a MediaElementAudioSourceNode and routed through a series of nodes (gain and pan, at the moment) until the destination. So far so good.
I am able to play them in sync, pause, stop and seek with no problems at all, and successfully implemented the usual mute, solo functionalities of the common DAW, as well as waveform visualization and navigation. This is the playback part.
As for the recording part, I connected the output from getUserMedia() to a MediaStreamAudioSourceNode, which is then routed to a ScriptProcessorNode that writes the recorded buffer to an array, using a web worker.
When the recording process ends, the recorded buffer is written into a PCM wave file and uploaded to the server, but, at the same time, hooked up to a <audio> element for immediate playback (otherwise I would have to wait for the wav file to be uploaded to the server to be available).
Here is the problem: I can play the recorded track in perfect sync with the previous ones if I play them from the beginning, but I can't seek properly. If I change the currentTime property of the newly recorded track, it becomes messy and terribly out of sync — I repeat that this happens only when the "local" track is added, as the other tracks behave just fine when I change their position.
Does anyone have any idea of what may be causing this? Is there any other useful information I can provide?
Thank you in advance.
Fundamentally, there's no guarantee that elements will sync properly. If you really want audio to be in sync, you'll have to load the audio files into AudioBuffers and play them with BufferSourceNodes.
You'll find in some relatively straightforward circumstances you can get them to sync - but it won't necessarily work across devices and OSes, and once you start trying to seek, as you found, it will fall apart. The way wraps downloading, decoding and playing into one step doesn't lend itself to syncing.

Feed video byte data to flash player from javascript?

Is it possible to, using javascript, either create video data on the fly, or more likely download pieces of video data from various sources and feed them to a flash player instance.
Even better, is it possible to feed a html5 video stream from locally executed javascript?
Short answer: no.
Long answer:
To pass the data directly from JavaScript into Flash, such as by ExternalInterface, you would need to serialize the video data as a byte stream. This means JS must be able to access video frame data, convert it to a String, and send it to Flash.
Serializing video data in the browser with JS would take some pretty fancy footwork; given the way HTML5 video works, I don't think any mainstream web browser supports this.
As a suggestion - you can use JS to feed URLs of video files to Flash where Flash can open the connection and access the data itself. In general Flash is vastly better at manipulating media data like videos and images. If you're already planning to using Flash you're better off cutting JS out of that process anyway.

How can I provide a 1 minute preview of a live flash video stream using Javascript?

I have a site that is streaming live videos, and I want to offer a one minute free preview to users before they pay for a stream. I am using JW Player - I was thinking of triggering a timer when the play button is clicked, and then removing a div containing the player once the timer is finished. I am already using jQuery on this page.
What methods can I take to secure this? Is there another way to do this - I am using a CDN so server-side is somewhat limited.
It's not possible to build a secure 60-seconds-only preview of the full video that way; the only way to be sure that no one could exploit the javascript code and see the entire video is to create a separate video file of 60 seconds only and to play that one instead of the real full video.
This is so because the javascript code is run on the client and it would be pretty easy to disable, edit it or, even simpler, to spot the URL of the full version of the video in the code.
Moreover it's better to protect the download of the full video file checking that every HTTP request made to download it corresponds to a user who has paid for it.
Unless you're using proper streaming (eg RTMP), the whole file will be accessible for direct download by users with access to this pseudo-preview. To properly limit access, you'll want to either implement streaming and limit the free stream server side, or use a one minute file and a protected full video.
To solve this I used JW Player's events to fire a setTimeout call for 60 seconds later. I then hid the player and popped up a modal jQuery UI dialog over the screen. It's not particularly secure but is sufficient for my needs.

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