Alsaaudio 模組，錄製特定時間

下面的程式碼記錄了一段時間的音頻（我不知道多少）如何計算其記錄的總時間？

例如，如果我只想錄製一分鐘，那麼我將如何限制它的時間？

#!/usr/bin/env python

## recordtest.py
##
## This is an example of a simple sound capture script.
##
## The script opens an ALSA pcm forsound capture. Set
## various attributes of the capture, and reads in a loop,
## writing the data to standard out.
##
## To test it out do the following:
## python recordtest.py out.raw # talk to the microphone
## aplay -r 8000 -f S16_LE -c 1 out.raw


# Footnote: I'd normally use print instead of sys.std(out|err).write,
# but we're in the middle of the conversion between python 2 and 3
# and this code runs on both versions without conversion

import sys
import time
import getopt
import alsaaudio

def usage():
   sys.stderr.write('usage: recordtest.py [-c <card>] <file>\n')
   sys.exit(2)

if __name__ == '__main__':

   card = 'sysdefault:CARD=Device'

   opts, args = getopt.getopt(sys.argv[1:], 'c:')
   for o, a in opts:
       if o == '-c':
           card = a

   if not args:
       usage()

   f = open(args[0], 'wb')

   # Open the device in nonblocking capture mode. The last argument could
   # just as well have been zero for blocking mode. Then we could have
   # left out the sleep call in the bottom of the loop
   inp = alsaaudio.PCM(alsaaudio.PCM_CAPTURE, alsaaudio.PCM_NONBLOCK, card)

   # Set attributes: Mono, 44100 Hz, 16 bit little endian samples
   inp.setchannels(1)
   inp.setrate(44100)
   inp.setformat(alsaaudio.PCM_FORMAT_S16_LE)

   # The period size controls the internal number of frames per period.
   # The significance of this parameter is documented in the ALSA api.
   # For our purposes, it is suficcient to know that reads from the device
   # will return this many frames. Each frame being 2 bytes long.
   # This means that the reads below will return either 320 bytes of data
   # or 0 bytes of data. The latter is possible because we are in nonblocking
   # mode.
   inp.setperiodsize(160)

   loops = 1000000
   while loops > 0:
       loops -= 1
       # Read data from device
       l, data = inp.read()

       if l:
           f.write(data)
           time.sleep(.001)

每秒，您記錄 44100 幀（或您設置的任何採樣率）。

只需將讀取的幀數相加，並在記錄 60*44100 幀時停止：

total = 0
while total < 60 * 44100:
   l, data = inp.read()
   if l:
       total += l
       f.write(data)
       time.sleep(.001)

引用自：https://unix.stackexchange.com/questions/92852