无法在网页上获取 m4a 音频文件的长度

Question

I am trying to make a nodejs website that will return the length in seconds of any audio file a user chooses. So far I have it working with mp3, wav, and flac files. But it doesn't work for all .m4a or .aif files

The code for my HTML page with javascript is below:

choose audio file to get length:
<input style="cursor: pointer;" type="file" id="file" multiple="multiple" />

<script>

    //when files are selected:
    $("#file").change(async function (e) {
        console.log('file(s) selected')
        //get files 
        var files = e.currentTarget.files;
        //get number of files
        var numberOfFiles = files.length;
        //for each file
        for (i = 0; i < numberOfFiles; i++) {
            console.log(`songs[${i}].type=`, files[i].type)
            //get file length
            let songLength = await getSongLength(files[i]);
            console.log('songLength=', songLength)
        }

    });

    //recieve audio file, return length
    function getSongLength(song) {
        return new Promise(function (resolve, reject) {
            console.log('getSongLength() begin setup')
            //create objectURL and audio object for ssong
            objectURL = URL.createObjectURL(song);
            mySound = new Audio([objectURL])
            console.log('getSongLength() end setup')
            //when song metadata is loaded:
            mySound.addEventListener("canplaythrough", function (e) {
                console.log('getSongLength() canplaythrough')
                var seconds = e.currentTarget.duration;
                resolve(seconds)
            });

        });
    }

</script>

I gathered 6 different files for testing, and after running them on my above code have found out the following results:

• aif: not working
• flac: working
• m4a_file: not working
• m4a_file_from_comments_below:not working
• mp3: working
• wav: working

my test files for download: https://easyupload.io/m/la9xro

It seems like when I input my m4a file sample_M4A_file that it hangs inside the getSongLength() function and never enters the .addEventListener("canplaythrough" function, is there any alternative I can use to consistently get the duration in seconds for every audio file?

Answer 1

It's because your browser doesn't support Apple Lossless codecs. If you try in Safari, it will work.
If you attach an error event to your media element, you'll see it fires .

There is no real universal solution, apart from using an heavy machinery like mediainfo.js (2.4MB+) which should support most formats.

 const input = document.querySelector( "input" ); input.onchange = async (evt) => { const mediainfo = await new Promise( (res) => MediaInfo(null, res) ); const file = input.files[ 0 ]; const getSize = () => file.size; const readChunk = async (chunkSize, offset) => new Uint8Array( await file.slice(offset, offset + chunkSize).arrayBuffer() ); const info = await mediainfo.analyzeData(getSize, readChunk); // assumes we are only interested in audio duration const audio_track = info.media.track.find( (track) => track[ "@type" ] === "Audio" ); console.log( audio_track.Duration ); };

 <script src="https://unpkg.com/mediainfo.js@0.1.4/dist/mediainfo.min.js"></script> <input type="file">

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Ps: when using the media element solution, there is no need to wait for canplaythrough , just wait for loadedmetadata , and if you get Infinity, try this hack .