javascript .m4a和.aif视频文件无法获取时长

代码如下:

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>

原因

这是因为您的浏览器不支持Apple Lossless编解码器。如果您在Safari中尝试，则可以使用。
如果您将error事件附加到媒体元素，就会看到它触发了。

除了使用诸如mediainfo.js（2.4MB +）之类的笨重的机制，它应该支持大多数格式之外，没有真正的通用解决方案。

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">