rms_gst_example.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# Copyright 2018, Florent Thiery

import gi
import sys
gi.require_version('Gst', '1.0')
from gi.repository import Gst, GLib

Gst.init(None)

try:
    input_file = sys.argv[1]
except Exception:
    print('Need wave input file as argument')
    sys.exit()

p = "filesrc location=%s ! wavparse ! level ! fakesink" % input_file
print(p)

def _on_message(bus, message):
    if message.type == Gst.MessageType.ELEMENT:
        struct = message.get_structure()
        sname = struct.get_name()
        if sname == 'level':
            ts = struct.get_value("timestamp")
            # you need gst-python gio overrides for arrays
            rms_array = struct.get_value("rms")
            print(ts, rms_array)


pipeline = Gst.parse_launch(p)
bus = pipeline.get_bus()
bus.add_signal_watch()
bus.connect("message", _on_message)

GLib.idle_add(pipeline.set_state, Gst.State.PLAYING)
ml = GLib.MainLoop()

ml.run()