GDP

#!/usr/bin/env python

""" Subscribe to a log and play audio data """

import gdp

import sys

import time

import json

import pyaudio

from threading import Lock

DELAY_RECS = 5

pcm_buf = ""

channels = None

sampleWidth = None

samplingRate = None

def playAudio(lh):

    print ">>>", "sampleWidth:", sampleWidth, "channels:", channels,

    print "samplingRate:", samplingRate

    def __helperCallback(in_data, frame_count, time_info, status):

        global pcm_buf

        ret_len = frame_count*channels*sampleWidth

        while len(pcm_buf)<ret_len:

            time.sleep(0.01)

        pcm_buf_lock.acquire()

        out_data = pcm_buf[:ret_len]

        pcm_buf = pcm_buf[ret_len:]

        pcm_buf_lock.release()

        return (out_data, pyaudio.paContinue)

    p = pyaudio.PyAudio()

    stream = p.open(format=p.get_format_from_width(sampleWidth),

                    channels=channels, rate=samplingRate,

                    input=False, output=True, stream_callback=__helperCallback)

    global pcm_buf

    pcm_buf_lock = Lock()

    # subscribe to the log

    lh.subscribe(-DELAY_RECS, 0, None)

    stream.start_stream()

    while True:

        event = gdp.GDP_GCL.get_next_event(None)

        pcm_buf_lock.acquire()

        pcm_buf += event['datum']['data']

        pcm_buf_lock.release()

    stream.stop_stream()

    stream.close()

    p.terminate()

def main(logname):

    gdp.gdp_init()

    lh = gdp.GDP_GCL(gdp.GDP_NAME(logname), gdp.GDP_MODE_RO)

    firstRecord = lh.read(1)

    audioParams = json.loads(firstRecord['data'])

    global sampleWidth

    global samplingRate

    global channels

    sampleWidth = audioParams['sampleWidth']

    samplingRate = audioParams['samplingRate']

    channels = audioParams['channels']

    playAudio(lh)

if __name__=="__main__":

    if len(sys.argv)<2:

        print "Usage: %s logname" % sys.argv[0]

        sys.exit(1)

    main(sys.argv[1])