const _self: Worker = self as any;
_self.onmessage = function (e) {
    transAudioData.transcode(e.data);
};

let transAudioData = {
   
    transcode(audioData) {
        let output: any = transAudioData.to16kHz(audioData);
        output = transAudioData.to16BitPCM(output);
        output = Array.from(new Uint8Array(output.buffer));
        _self.postMessage(output);
        // return output
    },
    to16kHz(audioData) {
        var data = new Float32Array(audioData);
        var fitCount = Math.round(data.length * (16000 / 44100));
        var newData = new Float32Array(fitCount);
        var springFactor = (data.length - 1) / (fitCount - 1);
        newData[0] = data[0];
        for (let i = 1; i < fitCount - 1; i++) {
            var tmp = i * springFactor;
            var before: any = Math.floor(tmp).toFixed();
            var after = Math.ceil(tmp).toFixed();
            var atPoint = tmp - before;
            newData[i] = data[before] + (data[after] - data[before]) * atPoint;
        }
        newData[fitCount - 1] = data[data.length - 1];
        return newData;
    },
    to16BitPCM(input) {
        var dataLength = input.length * (16 / 8);
        var dataBuffer = new ArrayBuffer(dataLength);
        var dataView = new DataView(dataBuffer);
        var offset = 0;
        for (var i = 0; i < input.length; i++, offset += 2) {
            var s = Math.max(-1, Math.min(1, input[i]));
            dataView.setInt16(offset, s < 0 ? s * 0x8000 : s * 0x7fff, true);
        }
        return dataView;
    },
};
export default null as any; // 默认导出以免爆 **.worker.ts is not a module 这样的错误