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javascriptaudiohtml5-audio

JavaScript audio duration not working for ALAC files (HTML audio duration property)

I am using the following implementation in some JS code to get durations of audio files loaded in: http://jsfiddle.net/derickbailey/s4P2v/ (Taken from https://lostechies.com/derickbailey/2013/09/23/getting-audio-file-information-with-htmls-file-api-and-audio-element/.)

My implementation is the same, even using createObjectURL. It works with MP3, AAC (.m4a), and FLAC fine, but not ALAC (also .m4a).

let length = 0;
let url = URL.createObjectURL(file);
let audio = new Audio(url);
audio.addEventListener('loadeddata', function () {
    length = audio.duration;
}

Does anyone know how I can get the duration of ALAC files using pure JavaScript? I am not using any frameworks and am new to JS.

Thanks

Solution

  • I think only Safari is able to natively decode ALAC codec, and there, it works.

    But in all other browsers, since they can't decode it, they won't be able to give you the correct duration.

    ffmpeg seems to be able to decode it though and to get its duration, so you may want to grab this info from server side, or have a look at this project which aims to port ffmpeg to js.
    I never tried it myself, but it claims to have ported the mp4 decoder, so you might have some luck in there.