python - 加快Python中wav的读取速度

Question

晚上，

我正在开发一个项目，需要我读取 32 位 float 的多 channel wav 文件。当我将一个特定文件(1 分钟长，6 个 channel ，48k fs)读入 Matlab 并使用 tic/toc 对其进行测量时，它会在 2.456482 秒内解析该文件。

测量文件读取速度的Matlab代码 抽动症 wavread('C:/data/testData/6ch.wav'); 目录

当我在 python 中执行此操作时(请注意，我对 python 非常不熟悉)，需要 18.1655315617 秒!在我看来，我这样做的方式效率很低(我确实把它从 28 降到了 18，但仍然太多了......)

我将代码剥离为与该主题相关的内容:

文件读取速度测量的Python代码

import wave32
import struct
import time
import numpy as np

def getWavData(inFile)
    wavFile = wave32.open(inFile, 'r')
    wavParams = wavFile.getparams()
    nChannels = wavParams[0]
    byteDepth = wavParams[1]
    nFrames = wavParams[3]
    wavData = np.empty([nFrames, nChannels], np.float32)
    frames = wavFile.readframes(nFrames) 
    for i in range(nFrames):
        for j in range(nChannels):
            start = ( i * nChannels + j ) * byteDepth
            stop = start + byteDepth
            wavData[i][j] = struct.unpack('<f', frames[start:stop])[0]
    return wavData

inFile = 'C:/data/testData/6ch.wav'
start = time.clock() 
data2 = getWavData(inFile)
elapsed = time.clock()
elapsedNew = elapsed - start
print str(elapsedNew)

请注意，wav32 是我必须在 wave.py 上执行的一个小 hack，以启用 32 位浮点读取。

"""Stuff to parse WAVE files.

Usage.

Reading WAVE files:
      f = wave.open(file, 'r')
where file is either the name of a file or an open file pointer.
The open file pointer must have methods read(), seek(), and close().
When the setpos() and rewind() methods are not used, the seek()
method is not  necessary.

This returns an instance of a class with the following public methods:
      getnchannels()  -- returns number of audio channels (1 for
                         mono, 2 for stereo)
      getsampwidth()  -- returns sample width in bytes
      getframerate()  -- returns sampling frequency
      getnframes()    -- returns number of audio frames
      getcomptype()   -- returns compression type ('NONE' for linear samples)
      getcompname()   -- returns human-readable version of
                         compression type ('not compressed' linear samples)
      getparams()     -- returns a tuple consisting of all of the
                         above in the above order
      getmarkers()    -- returns None (for compatibility with the
                         aifc module)
      getmark(id)     -- raises an error since the mark does not
                         exist (for compatibility with the aifc module)
      readframes(n)   -- returns at most n frames of audio
      rewind()        -- rewind to the beginning of the audio stream
      setpos(pos)     -- seek to the specified position
      tell()          -- return the current position
      close()         -- close the instance (make it unusable)
The position returned by tell() and the position given to setpos()
are compatible and have nothing to do with the actual position in the
file.
The close() method is called automatically when the class instance
is destroyed.

Writing WAVE files:
      f = wave.open(file, 'w')
where file is either the name of a file or an open file pointer.
The open file pointer must have methods write(), tell(), seek(), and
close().

This returns an instance of a class with the following public methods:
      setnchannels(n) -- set the number of channels
      setsampwidth(n) -- set the sample width
      setframerate(n) -- set the frame rate
      setnframes(n)   -- set the number of frames
      setcomptype(type, name)
                      -- set the compression type and the
                         human-readable compression type
      setparams(tuple)
                      -- set all parameters at once
      tell()          -- return current position in output file
      writeframesraw(data)
                      -- write audio frames without pathing up the
                         file header
      writeframes(data)
                      -- write audio frames and patch up the file header
      close()         -- patch up the file header and close the
                         output file
You should set the parameters before the first writeframesraw or
writeframes.  The total number of frames does not need to be set,
but when it is set to the correct value, the header does not have to
be patched up.
It is best to first set all parameters, perhaps possibly the
compression type, and then write audio frames using writeframesraw.
When all frames have been written, either call writeframes('') or
close() to patch up the sizes in the header.
The close() method is called automatically when the class instance
is destroyed.
"""

import __builtin__

__all__ = ["open", "openfp", "Error"]

class Error(Exception):
    pass

WAVE_FORMAT_PCM = 0x0001
WAVE_FORMAT_IEEE_FLOAT = 0x0003

_array_fmts = None, 'b', 'h', None, 'l'

# Determine endian-ness
import struct
if struct.pack("h", 1) == "\000\001":
    big_endian = 1
else:
    big_endian = 0

from chunk import Chunk

class Wave_read:
    """Variables used in this class:

    These variables are available to the user though appropriate
    methods of this class:
    _file -- the open file with methods read(), close(), and seek()
              set through the __init__() method
    _nchannels -- the number of audio channels
              available through the getnchannels() method
    _nframes -- the number of audio frames
              available through the getnframes() method
    _sampwidth -- the number of bytes per audio sample
              available through the getsampwidth() method
    _framerate -- the sampling frequency
              available through the getframerate() method
    _comptype -- the AIFF-C compression type ('NONE' if AIFF)
              available through the getcomptype() method
    _compname -- the human-readable AIFF-C compression type
              available through the getcomptype() method
    _soundpos -- the position in the audio stream
              available through the tell() method, set through the
              setpos() method

    These variables are used internally only:
    _fmt_chunk_read -- 1 iff the FMT chunk has been read
    _data_seek_needed -- 1 iff positioned correctly in audio
              file for readframes()
    _data_chunk -- instantiation of a chunk class for the DATA chunk
    _framesize -- size of one frame in the file
    """

    def initfp(self, file):
        self._convert = None
        self._soundpos = 0
        self._file = Chunk(file, bigendian = 0)
        if self._file.getname() != 'RIFF':
            raise Error, 'file does not start with RIFF id'
        if self._file.read(4) != 'WAVE':
            raise Error, 'not a WAVE file'
        self._fmt_chunk_read = 0
        self._data_chunk = None
        while 1:
            self._data_seek_needed = 1
            try:
                chunk = Chunk(self._file, bigendian = 0)
            except EOFError:
                break
            chunkname = chunk.getname()
            if chunkname == 'fmt ':
                self._read_fmt_chunk(chunk)
                self._fmt_chunk_read = 1
            elif chunkname == 'data':
                if not self._fmt_chunk_read:
                    raise Error, 'data chunk before fmt chunk'
                self._data_chunk = chunk
                self._nframes = chunk.chunksize // self._framesize
                self._data_seek_needed = 0
                break
            chunk.skip()
        if not self._fmt_chunk_read or not self._data_chunk:
            raise Error, 'fmt chunk and/or data chunk missing'

    def __init__(self, f):
        self._i_opened_the_file = None
        if isinstance(f, basestring):
            f = __builtin__.open(f, 'rb')
            self._i_opened_the_file = f
        # else, assume it is an open file object already
        try:
            self.initfp(f)
        except:
            if self._i_opened_the_file:
                f.close()
            raise

    def __del__(self):
        self.close()
    #
    # User visible methods.
    #
    def getfp(self):
        return self._file

    def rewind(self):
        self._data_seek_needed = 1
        self._soundpos = 0

    def close(self):
        if self._i_opened_the_file:
            self._i_opened_the_file.close()
            self._i_opened_the_file = None
        self._file = None

    def tell(self):
        return self._soundpos

    def getnchannels(self):
        return self._nchannels

    def getnframes(self):
        return self._nframes

    def getsampwidth(self):
        return self._sampwidth

    def getframerate(self):
        return self._framerate

    def getcomptype(self):
        return self._comptype

    def getcompname(self):
        return self._compname

    def getparams(self):
        return self.getnchannels(), self.getsampwidth(), \
               self.getframerate(), self.getnframes(), \
               self.getcomptype(), self.getcompname()

    def getmarkers(self):
        return None

    def getmark(self, id):
        raise Error, 'no marks'

    def setpos(self, pos):
        if pos < 0 or pos > self._nframes:
            raise Error, 'position not in range'
        self._soundpos = pos
        self._data_seek_needed = 1

    def readframes(self, nframes):
        if self._data_seek_needed:
            self._data_chunk.seek(0, 0)
            pos = self._soundpos * self._framesize
            if pos:
                self._data_chunk.seek(pos, 0)
            self._data_seek_needed = 0
        if nframes == 0:
            return ''
        if self._sampwidth > 1 and big_endian:
            # unfortunately the fromfile() method does not take
            # something that only looks like a file object, so
            # we have to reach into the innards of the chunk object
            import array
            chunk = self._data_chunk
            data = array.array(_array_fmts[self._sampwidth])
            nitems = nframes * self._nchannels
            if nitems * self._sampwidth > chunk.chunksize - chunk.size_read:
                nitems = (chunk.chunksize - chunk.size_read) / self._sampwidth
            data.fromfile(chunk.file.file, nitems)
            # "tell" data chunk how much was read
            chunk.size_read = chunk.size_read + nitems * self._sampwidth
            # do the same for the outermost chunk
            chunk = chunk.file
            chunk.size_read = chunk.size_read + nitems * self._sampwidth
            data.byteswap()
            data = data.tostring()
        else:
            data = self._data_chunk.read(nframes * self._framesize)
        if self._convert and data:
            data = self._convert(data)
        self._soundpos = self._soundpos + len(data) // (self._nchannels * self._sampwidth)
        return data

    #
    # Internal methods.
    #
    def _read_fmt_chunk(self, chunk):
        wFormatTag, self._nchannels, self._framerate, dwAvgBytesPerSec, wBlockAlign = struct.unpack('<hhllh', chunk.read(14))
        if wFormatTag == WAVE_FORMAT_PCM or wFormatTag==WAVE_FORMAT_IEEE_FLOAT:
            sampwidth = struct.unpack('<h', chunk.read(2))[0]
            self._sampwidth = (sampwidth + 7) // 8
        else:
            #sampwidth = struct.unpack('<h', chunk.read(2))[0]
            #self._sampwidth = (sampwidth + 7) // 8
            raise Error, 'unknown format: %r' % (wFormatTag,)
        self._framesize = self._nchannels * self._sampwidth
        self._comptype = 'NONE'
        self._compname = 'not compressed'

class Wave_write:
    """Variables used in this class:

    These variables are user settable through appropriate methods
    of this class:
    _file -- the open file with methods write(), close(), tell(), seek()
              set through the __init__() method
    _comptype -- the AIFF-C compression type ('NONE' in AIFF)
              set through the setcomptype() or setparams() method
    _compname -- the human-readable AIFF-C compression type
              set through the setcomptype() or setparams() method
    _nchannels -- the number of audio channels
              set through the setnchannels() or setparams() method
    _sampwidth -- the number of bytes per audio sample
              set through the setsampwidth() or setparams() method
    _framerate -- the sampling frequency
              set through the setframerate() or setparams() method
    _nframes -- the number of audio frames written to the header
              set through the setnframes() or setparams() method

    These variables are used internally only:
    _datalength -- the size of the audio samples written to the header
    _nframeswritten -- the number of frames actually written
    _datawritten -- the size of the audio samples actually written
    """

    def __init__(self, f):
        self._i_opened_the_file = None
        if isinstance(f, basestring):
            f = __builtin__.open(f, 'wb')
            self._i_opened_the_file = f
        try:
            self.initfp(f)
        except:
            if self._i_opened_the_file:
                f.close()
            raise

    def initfp(self, file):
        self._file = file
        self._convert = None
        self._nchannels = 0
        self._sampwidth = 0
        self._framerate = 0
        self._nframes = 0
        self._nframeswritten = 0
        self._datawritten = 0
        self._datalength = 0
        self._headerwritten = False

    def __del__(self):
        self.close()

    #
    # User visible methods.
    #
    def setnchannels(self, nchannels):
        if self._datawritten:
            raise Error, 'cannot change parameters after starting to write'
        if nchannels < 1:
            raise Error, 'bad # of channels'
        self._nchannels = nchannels

    def getnchannels(self):
        if not self._nchannels:
            raise Error, 'number of channels not set'
        return self._nchannels

    def setsampwidth(self, sampwidth):
        if self._datawritten:
            raise Error, 'cannot change parameters after starting to write'
        if sampwidth < 1 or sampwidth > 4:
            raise Error, 'bad sample width'
        self._sampwidth = sampwidth

    def getsampwidth(self):
        if not self._sampwidth:
            raise Error, 'sample width not set'
        return self._sampwidth

    def setframerate(self, framerate):
        if self._datawritten:
            raise Error, 'cannot change parameters after starting to write'
        if framerate <= 0:
            raise Error, 'bad frame rate'
        self._framerate = framerate

    def getframerate(self):
        if not self._framerate:
            raise Error, 'frame rate not set'
        return self._framerate

    def setnframes(self, nframes):
        if self._datawritten:
            raise Error, 'cannot change parameters after starting to write'
        self._nframes = nframes

    def getnframes(self):
        return self._nframeswritten

    def setcomptype(self, comptype, compname):
        if self._datawritten:
            raise Error, 'cannot change parameters after starting to write'
        if comptype not in ('NONE',):
            raise Error, 'unsupported compression type'
        self._comptype = comptype
        self._compname = compname

    def getcomptype(self):
        return self._comptype

    def getcompname(self):
        return self._compname

    def setparams(self, params):
        nchannels, sampwidth, framerate, nframes, comptype, compname = params
        if self._datawritten:
            raise Error, 'cannot change parameters after starting to write'
        self.setnchannels(nchannels)
        self.setsampwidth(sampwidth)
        self.setframerate(framerate)
        self.setnframes(nframes)
        self.setcomptype(comptype, compname)

    def getparams(self):
        if not self._nchannels or not self._sampwidth or not self._framerate:
            raise Error, 'not all parameters set'
        return self._nchannels, self._sampwidth, self._framerate, \
              self._nframes, self._comptype, self._compname

    def setmark(self, id, pos, name):
        raise Error, 'setmark() not supported'

    def getmark(self, id):
        raise Error, 'no marks'

    def getmarkers(self):
        return None

    def tell(self):
        return self._nframeswritten

    def writeframesraw(self, data):
        self._ensure_header_written(len(data))
        nframes = len(data) // (self._sampwidth * self._nchannels)
        if self._convert:
            data = self._convert(data)
        if self._sampwidth > 1 and big_endian:
            import array
            data = array.array(_array_fmts[self._sampwidth], data)
            data.byteswap()
            data.tofile(self._file)
            self._datawritten = self._datawritten + len(data) * self._sampwidth
        else:
            self._file.write(data)
            self._datawritten = self._datawritten + len(data)
        self._nframeswritten = self._nframeswritten + nframes

    def writeframes(self, data):
        self.writeframesraw(data)
        if self._datalength != self._datawritten:
            self._patchheader()

    def close(self):
        if self._file:
            self._ensure_header_written(0)
            if self._datalength != self._datawritten:
                self._patchheader()
            self._file.flush()
            self._file = None
        if self._i_opened_the_file:
            self._i_opened_the_file.close()
            self._i_opened_the_file = None

    #
    # Internal methods.
    #

    def _ensure_header_written(self, datasize):
        if not self._headerwritten:
            if not self._nchannels:
                raise Error, '# channels not specified'
            if not self._sampwidth:
                raise Error, 'sample width not specified'
            if not self._framerate:
                raise Error, 'sampling rate not specified'
            self._write_header(datasize)

    def _write_header(self, initlength):
        assert not self._headerwritten
        self._file.write('RIFF')
        if not self._nframes:
            self._nframes = initlength / (self._nchannels * self._sampwidth)
        self._datalength = self._nframes * self._nchannels * self._sampwidth
        self._form_length_pos = self._file.tell()
        self._file.write(struct.pack('<l4s4slhhllhh4s',
            36 + self._datalength, 'WAVE', 'fmt ', 16,
            WAVE_FORMAT_PCM, self._nchannels, self._framerate,
            self._nchannels * self._framerate * self._sampwidth,
            self._nchannels * self._sampwidth,
            self._sampwidth * 8, 'data'))
        self._data_length_pos = self._file.tell()
        self._file.write(struct.pack('<l', self._datalength))
        self._headerwritten = True

    def _patchheader(self):
        assert self._headerwritten
        if self._datawritten == self._datalength:
            return
        curpos = self._file.tell()
        self._file.seek(self._form_length_pos, 0)
        self._file.write(struct.pack('<l', 36 + self._datawritten))
        self._file.seek(self._data_length_pos, 0)
        self._file.write(struct.pack('<l', self._datawritten))
        self._file.seek(curpos, 0)
        self._datalength = self._datawritten

def open(f, mode=None):
    if mode is None:
        if hasattr(f, 'mode'):
            mode = f.mode
        else:
            mode = 'rb'
    if mode in ('r', 'rb'):
        return Wave_read(f)
    elif mode in ('w', 'wb'):
        return Wave_write(f)
    else:
        raise Error, "mode must be 'r', 'rb', 'w', or 'wb'"

openfp = open # B/W compatibility

抱歉，代码很长:)

<小时/>

所以我的问题是:wave.py 模块本质上很慢(有解决这个问题的替代方法吗？)还是我在做一些效率低下的事情？

我想我可以使用自定义函数读取 wav header 并以不同的方式读取文件，但这似乎需要大量工作，特别是因为我知道的不多关于 1) python 和 2) 文件处理

亲切的问候，

K.

<小时/>

编辑:我尝试了 unutbu 的建议，但这不起作用，因为 scipy 不接受 >16 位。

当我尝试通过 scipy wavreader 解析 wav 文件时，我收到此消息:

C:\Users\King Broos\AppData\Local\Enthought\Canopy32\System\lib\site-packages\scipy\io\wavfile.py:31: WavFileWarning: Unfamiliar format bytes
  warnings.warn("Unfamiliar format bytes", WavFileWarning)

C:\Users\King Broos\AppData\Local\Enthought\Canopy32\System\lib\site-packages\scipy\io\wavfile.py:121: WavFileWarning: chunk not understood
  warnings.warn("chunk not understood", WavFileWarning)

查看 wavfile.py 的代码，这是抛出异常的行:

    if (comp != 1 or size > 16):
    warnings.warn("Unfamiliar format bytes", WavFileWarning)

我确实需要 24 位或 32 位，所以我猜 scipy 不是一个选择？

Answer 1

如果您可以安装或拥有 scipy ，然后使用wavfile.read :

import scipy.io.wavfile as wavfile
sample_rate, x = wavfile.read(filename)

您可能还想研究 source code, here .

<小时/>

请注意，scipy.io.wavfile 不使用 Python 的 wave 模块。我不确定它是否读取您的 IEEE_FLOAT 格式，但它不会执行与 wave.py 相同的检查:

    if wFormatTag == WAVE_FORMAT_PCM or wFormatTag==WAVE_FORMAT_IEEE_FLOAT:
        sampwidth = struct.unpack('<h', chunk.read(2))[0]
        self._sampwidth = (sampwidth + 7) // 8
    else:
        #sampwidth = struct.unpack('<h', chunk.read(2))[0]
        #self._sampwidth = (sampwidth + 7) // 8
        raise Error, 'unknown format: %r' % (wFormatTag,)

所以也许它可以开箱即用。

<小时/>

顺便说一句，您可以使用 Monkey，而不是制作自己的模块 wave32.py(它与标准库中的 wave.py 几乎完全相同) - 修补:

import wave
import struct

WAVE_FORMAT_IEEE_FLOAT = 0x0003
def _read_fmt_chunk(self, chunk):
    wFormatTag, self._nchannels, self._framerate, dwAvgBytesPerSec, wBlockAlign = struct.unpack('<hhllh', chunk.read(14))
    if wFormatTag == WAVE_FORMAT_PCM or wFormatTag == WAVE_FORMAT_IEEE_FLOAT:
        sampwidth = struct.unpack('<h', chunk.read(2))[0]
        self._sampwidth = (sampwidth + 7) // 8
    else:
        raise Error, 'unknown format: %r' % (wFormatTag,)
    self._framesize = self._nchannels * self._sampwidth
    self._comptype = 'NONE'
    self._compname = 'not compressed'

wave.Wave_read._read_fmt_chunk = _read_fmt_chunk