字节序-优快云博客

本文链接：https://blog.youkuaiyun.com/ffmpeg4976/article/details/52289008

本文详细解释了计算机系统中数据存储的两种主要方式：大端模式和小端模式，并通过具体的例子进行说明。此外，还提供了将小端模式的字节数组转换为Short类型的Java代码示例，并展示了如何检查平台的字节顺序。

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什么是大小端？

例如：
90AB12CD
In big endian, you store the most significant byte in the smallest address. Here’s how it would look:

Address	Value
1000	90
1001	AB
1002	12
1003	CD

In little endian, you store the least significant byte in the smallest address. Here’s how it would look:

Address	Value
1000	CD
1001	12
1002	AB
1003	90

从Audio Recorder里读出来的byte array 数据是小端的, 可以用以下的代码转成Short

    public static short[] bytesToShorts(byte[] b) {
        short[] s = new short[b.length / 2];
        for (int i = 0; i < s.length; i++) {
            s[i] = (short) ((b[i * 2] & 0xff) | ((b[i * 2 + 1] << 8) & 0xff00));
        }
        return s;
    }

AudioRecord还可以直接读short

int read (short[] audioData, int offsetInShorts, int sizeInShorts)

write code to check the platform endian:

Suppose we are on a 32-bit machine.

If it is little endian, the x in the memory will be something like:

   higher memory
      ----->
+----+----+----+----+
|0x01|0x00|0x00|0x00|
+----+----+----+----+
A
|

so (char*)(*x) == 1

If it is big endian, it will be:

+----+----+----+----+
|0x00|0x00|0x00|0x01|
+----+----+----+----+
A
|

so this one will be ‘0’.