使用SL4A使用Python获取录制声音的幅度

Question

I want to record sound for 1 second using a Python written app for SL4A and then find the max amplitude of the sound.

Is there any part of the SL4A API I can use or part of the Python APIs that can be used? Or is there any python module I can install for this matter?

I've searched the Python API from SL4A but haven't found anything related to amplitude. Maybe I just missed it.

I've managed to import the wave.py module into my code and try to open the recorded file. But when I access

wave.open("/sdcard/sl4aTemp/sound_sample.wav")

it throws this error,

File does not start with RIFF id

For those of you who are curious how my code looks here it is:

import android, audioop, time, wave

droid = android.Android()

print "Recording starts in: "
for i in range(0,5):
    time.sleep(1)
    print str(5-i)
time.sleep(1)

print "Speak!"
droid.recorderStartMicrophone('/sdcard/sl4aTemp/sound_sample.wav')
time.sleep(3)
droid.recorderStop()

print "Processing file in:"
for i in range(0,3):
    print str(3-i)
    time.sleep(1)

filename = "/sdcard/sl4aTemp/sound_sample.wav"

if wave.open(filename,"r") == True:
    print "Processing " + filename
else:
    print "File not processed"

FILE=wave.open(filename,"r")
rez=FILE.readframes(30)
print str(rez)

Answer 1

The standard answer to sound processing with python is PyAudio, which is separate package that actually depends on PortAudio, which probably hasn't been built for android so it's not really a good solution (unless you feel like being a hero and trying to get it to build).

Another option is the audioop module . The problem there is that you'll need to convert whatever format that file is saved as into the format audioop accepts (strings of 8/16/32bit wide signed integer samples). It's hard to say just how you'd do that, but if you're really lucky it'll be a .wav file and you can just use the wave module's readframes (which conveniently outputs the data as a string of bytes).

So, if SL4A implements all of the python core, you may be able to do it with no dependencies.