Question

我正在努力理解24位单声道PCM音频格式数据并以Java读取此数据。

我理解并且可以读取RIFF标头，但无法弄清楚如何读取24位PCM样本。我需要一一阅读PCM样本。

Answer 1

假设little-endian encoding，这应该使您入门：

// constant holding the minimum value of a signed 24bit sample: -2^22.
private static final int MIN_VALUE_24BIT = -2 << 22;

// constant holding the maximum value a signed 24bit sample can have, 2^(22-1).
private static final int MAX_VALUE_24BIT = -MIN_VALUE_24BIT-1;

[...]
// open your AudioInputStream using AudioSystem and read values into a buffer buf
[...]

final byte[] buf = ... ;      // your audio byte buffer
final int bytesPerSample = 3; // because 24 / 8 = 3

// read one sample:
int sample = 0;
for (int byteIndex = 0; byteIndex < bytesPerSample; byteIndex++) {
    final int aByte = buf[byteIndex] & 0xff;
    sample += aByte << 8 * (byteIndex);
}

// now handle the sign / valid range
final int threeByteSample = sample > MAX_VALUE_24BIT
    ? sample + MIN_VALUE_24BIT + MIN_VALUE_24BIT
    : sample;

// do something with your threeByteSample / read the next sample

有关PCM解码的更多常规处理，请参见jipes AudioSignalSource。

用Java读取24位单声道PCM

1 个答案: