(function () {
    const self = this;
    const transAudioData = {
        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 = 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;
        },
        transcode(audioData) {
            let output = transAudioData.to16kHz(audioData);
            output = transAudioData.to16BitPCM(output);
            output = Array.from(new Uint8Array(output.buffer));
            self.postMessage(output);
            // return output
        }
    };
    this.onmessage = function (e) {
        transAudioData.transcode(e.data);
    };
})()