Android - wav 文件播放速度快

Posted 2023-02-25

【中文标题】Android - wav 文件播放速度快

【英文标题】：Android - wav file plays fast

【发布时间】：2012-12-20 06:59:40

【问题描述】：

我将麦克风的输入记录到 sample.wav。但是播放速度太快了。 10 秒文件在 3 秒内。

int RECORDER_SAMPLERATE = 44100;
int RECORDER_BitsPerSample = 16;
int RECORDER_CHANNELS = AudioFormat.CHANNEL_IN_MONO;
int RECORDER_AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT;

int channels = 2;
long byteRate = RECORDER_BPP * RECORDER_SAMPLERATE * channels / 8;

请说明哪里出错了。

byteRate 用于创建 wav 文件头。

wav 标头格式为 //RIFF/WAVE 标头

            header[0] = 'R'; 
    header[1] = 'I';
    header[2] = 'F';
    header[3] = 'F';
    header[4] = (byte) (totalDataLen & 0xff);
    header[5] = (byte) ((totalDataLen >> 8) & 0xff);
    header[6] = (byte) ((totalDataLen >> 16) & 0xff);
    header[7] = (byte) ((totalDataLen >> 24) & 0xff);
    header[8] = 'W';
    header[9] = 'A';
    header[10] = 'V';
    header[11] = 'E';
    header[12] = 'f'; // 'fmt ' chunk
    header[13] = 'm';
    header[14] = 't';
    header[15] = ' ';
    header[16] = 16; // 4 bytes: size of 'fmt ' chunk
    header[17] = 0;
    header[18] = 0;
    header[19] = 0;
    header[20] = 1; // format = 1
    header[21] = 0;
    header[22] = (byte) channels;
    header[23] = 0;
    header[24] = (byte) (longSampleRate & 0xff);
    header[25] = (byte) ((longSampleRate >> 8) & 0xff);
    header[26] = (byte) ((longSampleRate >> 16) & 0xff);
    header[27] = (byte) ((longSampleRate >> 24) & 0xff);
    header[28] = (byte) (byteRate & 0xff);
    header[29] = (byte) ((byteRate >> 8) & 0xff);
    header[30] = (byte) ((byteRate >> 16) & 0xff);
    header[31] = (byte) ((byteRate >> 24) & 0xff);
    header[32] = (byte) (2 * 16 / 8); // block align
    header[33] = 0;
    header[34] = RECORDER_BPP; // bits per sample
    header[35] = 0;
    header[36] = 'd';
    header[37] = 'a';
    header[38] = 't';
    header[39] = 'a';
    header[40] = (byte) (totalAudioLen & 0xff);
    header[41] = (byte) ((totalAudioLen >> 8) & 0xff);
    header[42] = (byte) ((totalAudioLen >> 16) & 0xff);
    header[43] = (byte) ((totalAudioLen >> 24) & 0xff);

【参考方案1】：

我找到了解决上述问题的方法。对于 AudioFormat.CHANNEL_IN_MONO，通道必须为 1。对于 AudioFormat.CHANNEL_IN_STEREO，通道必须为 2。

int channels = 1;
long byteRate = RECORDER_BPP * RECORDER_SAMPLERATE * channels / 8;

现在可以正常使用了。