wx.playBackgroundAudio问题

setTimeout(() => {

    wx.playBackgroundAudio({

    dataUrl: url,

    title: ’ ',

    converImgUrl: ’ ',

    success: function(res){

        console.log(res)

    },

    fail: function(res){

        console.log(res)

    }

    })

}, 500);

有时候即使返回是成功状态，音频mp3还是播放不了，这是怎么回事?