Redirecting audio output from one function to another function in python
Suppose I have two functions drawn from two different APIs, function A and B.
By default, function A outputs audio data to a wav file.
By default, function B takes audio input from a wav file and process it.
Is it possible to stream the data from function A to B? If so, how do I do this? I work on lubuntu if that is relevant.
This is function A I'm thinking about from the PJSUA python API:
create_recorder(self, filename) Create WAV file recorder.
Keyword arguments filename -- WAV file name
Return: WAV recorder ID
And this is function B from the Pocketsphinx Python API
decode_raw(...)
Decode raw audio from a file. Parameters: fh (file) - Filehandle to read audio from. uttid (str) - Identifier to give to this utterance. maxsamps (int) - Maximum number of samples to read. If not specified or -1, the rest of the file will be read.
update:
When I try to pass the filename of a socket or named pipe, it outputs this error message, seems that the C function that the python bindings use doesn't like anything but .wav files... Why would that be?
pjsua_aud.c .pjsua_recorder_create() error: unable to determine file format for /tmp/t_fifo. Exception: Object: LIb, operation=create(recorder), error=Option/operation is not supported (PJ_ENOTSUP)
I need to use a value returned by create_recorder(), it is an int that is used to get the wav recorder id (which is not passed on directly to decode_raw() but rather passed on to some other function.
The answer is highly platform dependent and more details are required. Different Operating Systems have different ways of handling Interprocess Communication, or IPC.
If you're using a UNIXlike environment, there are a rich set of IPC primitives to work with. Pipes, SYS V Message Queues, shared memory, sockets, etc. In your case I think it would make sense to use a pipe or a socket, depending on whether the A and B are running in the same process or not.
Update:
In your case, I would use python's subprocess and or os module and a pipe. The idea here is to create calling contexts to the two APIs in processes which share a parent process, which has also created a unidirectional named pipe and passed it to its children. Then, data written to the named pipe in create_recorder will immediately be available for read()ing in the named pipe.
您可以使用命名管道os.mkfifo()并将函数移动到不同的线程/进程，例如：
import os
from multiprocessing import Process
os.mkfifo(filename)
try:
Process(target=obj.create_recorder, args=[filename]).start()
decode_raw(filename, ...)
finally:
os.remove(filename)
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