问题
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 ?
回答1:
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.
回答2:
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.
来源：https://stackoverflow.com/questions/11182587/extract-audio-from-video-stream-using-javascript