将16位PCM到8位 [英] Convert 16 bit pcm to 8 bit

问题描述

我有存储在一个字节数组PCM音频。它是每个样本16位。我想让它每采样音频8位。

I have pcm audio stored in a byte array. It is 16 bits per sample. I want to make it 8 bit per sample audio.

任何人都可以提出一个很好的算法来做到这一点？

Can anyone suggest a good algorithm to do that?

我没有提到的比特率，因为我觉得它不是算法很重要 - 右

I haven't mentioned the bitrate because I think it isn't important for the algorithm - right?

推荐答案

我不明白现在为什么它是不够的，只是取上层字节，即舍弃低8位每个样品。

I can't see right now why it's not enough to just take the upper byte, i.e. discard the lower 8 bits of each sample.

这当然假定样本是线性的;如果他们不那么也许你需要做一些事情下探位之前，线性他们。

That of course assumes that the samples are linear; if they're not then maybe you need to do something to linearize them before dropping bits.

short sixteenBit = 0xfeed;
byte eightBit = sixteenBit >> 8;
// eightBit is now 0xfe.

作为评论建议的AShelly，它可能是圆一个不错的主意，即加1，如果我们丢弃的字节是其最大的一半高：

As suggested by AShelly in a comment, it might be a good idea to round, i.e. add 1 if the byte we're discarding is higher than half its maximum:

eightBit += eightBit < 0xff && ((sixteenBit & 0xff) > 0x80);

针对0xFF的工具测试夹具，所以我们不要冒险加1至0xFF，并包裹了为0x00，这将是坏的。

The test against 0xff implements clamping, so we don't risk adding 1 to 0xff and wrapping that to 0x00 which would be bad.

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