聲音信號處理的筆記

02-25

MINES A3 課程，不定期更新

課程代碼地址：boisgera/audio-notebooks

課程地址： Digital Audio Coding

02/09/2018

mac 上安裝 audio

先安裝 Pyaudio，然後安裝audio

brew install portaudiopip2.7 install pyaudiosudo pip2.7 install --upgrade audio

測試

import audio.wavefrom audio.bitstream import BitStreamBitStream([False, True])

Binary Data

In [1]: bin(42)Out[1]: 0b101010In [2]: hex(42)Out[2]: 0x2aIn [5]: 5 // 2Out[5]: 2In [6]: 5 % 2Out[6]: 1In [7]: 5 ** 2Out[7]: 25

Binary Arithmetic

In [8]: 42 | 7Out[8]: 47In [9]: 42 ^ 7Out[9]: 45In [10]: 0b101010 ^ 0b000111 # where ^ is XOROut[10]: 45In [11]: 42 & 7 Out[11]: 2In [12]: 0b101010 & 0b000111Out[12]: 2In [13]: bin(0b101010 << 3)Out[13]: 0b101010000In [14]: bin(0b101010 >> 3)Out[14]: 0b101

integer types

numpy.int8(255)numpy.int8(128)>>> numpy.int8(255)-1>>> numpy.int8(128)-128

int8 規則下

0b10000000 代表 $-2^7$

0b11111111 代表 -1

0b01111111 代表 $(2^7 - 1)$

BitStream

# a sample transform integer to 0b streamimport numpy as npfrom audio.bitstream import BitStreamdef write_uint8(stream, integers): integers = np.array(integers) for integer in integers: mask = 0b10000000 while mask != 0: stream.write((integer & mask) != 0) mask = mask >> 1 print stream.read()if __name__ == __main__: write_uint8(BitStream(), [1,2,32,54,225])