#!/usr/bin/env python
"""
Change the speed of an audio file without changing its pitch (with GStreamer).
"""
import argparse
import os
import sys
import gi
gi.require_version('Gst', '1.0')
# pylint: disable=wrong-import-position
from gi.repository import Gst, GObject
Gst.init(sys.argv)
import audiotsm.gstreamer.wsola # pylint: disable=unused-import
# pylint: enable=wrong-import-position
class Pipeline(Gst.Pipeline):
"""A gstreamer pipeline that changes the speed of an audio file, write the
output to another file, and quit the main gobject loop with this is done.
:param tsm_description: the description used to create the tsm element of
the pipeline. This will be used as input of the
:func:`Gst.parse_launch` function.
"""
def __init__(self, tsm_description="audiotsm-wsola"):
super().__init__()
self._speed = 0
# Create the playbin, that will handle the decoding of the audio files
self.playbin = Gst.ElementFactory.make('playbin', 'playbin')
self.add(self.playbin)
# Create the audiotsm bin, that will handle the TSM
audiotsmbin = Gst.Bin('audiotsm')
# Create the elements of the audiotsm bin, add them, and link them
self.tsm = Gst.parse_launch(tsm_description)
converter = Gst.ElementFactory.make('audioconvert', 'converter')
encoder = Gst.ElementFactory.make('wavenc', 'encoder')
self.sink = Gst.ElementFactory.make('filesink', 'sink')
audiotsmbin.add(self.tsm)
audiotsmbin.add(converter)
audiotsmbin.add(encoder)
audiotsmbin.add(self.sink)
self.tsm.link(converter)
converter.link(encoder)
encoder.link(self.sink)
# Add the sink pad of the TSM plugin to the audiotsm bin.
self.tsm_sink_pad = Gst.GhostPad.new(
'sink', self.tsm.get_static_pad('sink'))
audiotsmbin.add_pad(self.tsm_sink_pad)
# And link it to the playbin
self.playbin.set_property("audio-sink", audiotsmbin)
bus = self.get_bus()
bus.add_signal_watch()
bus.connect("message::error", self._on_error)
bus.connect("message::eos", self._on_eos)
def _on_error(self, _, message):
"""Called when there is an error during the playback."""
# pylint: disable=no-self-use
err, debug = message.parse_error()
print("Error: %s" % err, debug)
sys.exit()
def _on_eos(self, _1, _2):
"""Called when the end of the audio file is reached."""
# pylint: disable=no-self-use
sys.exit()
def set_speed(self, speed):
"""Set the speed ratio."""
self._speed = speed
def save(self, path):
"""Save the output of the TSM procedure to path, then quit the GObject
loop."""
self.sink.set_property('location', path)
self.set_state(Gst.State.PAUSED)
self.get_state(Gst.CLOCK_TIME_NONE)
self.playbin.seek(self._speed, Gst.Format.BYTES, Gst.SeekFlags.FLUSH,
Gst.SeekType.SET, 0, Gst.SeekType.NONE, -1)
self.set_state(Gst.State.PLAYING)
def set_src_uri(self, uri):
"""Set the uri of the source audio file."""
self.playbin.set_property("uri", uri)
def main():
"""Change the speed of an audio file without changing its pitch."""
parser = argparse.ArgumentParser(description=(
"Change the speed of an audio file without changing its pitch."))
parser.add_argument(
'-s', '--speed', metavar="S", type=float, default=1.,
help="Set the speed ratio (e.g 0.5 to play at half speed)")
parser.add_argument(
'input_filename', metavar='INPUT_FILENAME', type=str,
help="The audio input file")
parser.add_argument(
'output_filename', metavar='OUTPUT_FILENAME', type=str,
help="The audio output file")
args = parser.parse_args()
if not os.path.isfile(args.input_filename):
parser.error(
'The input file "{}" does not exist.'.format(args.input_filename))
pipeline = Pipeline()
pipeline.set_speed(args.speed)
pipeline.set_src_uri('file:///' + os.path.realpath(args.input_filename))
pipeline.save(args.output_filename)
loop = GObject.MainLoop()
loop.run()
if __name__ == '__main__':
main()
