From PiTiViWiKi
#!/usr/bin/env python
"""A short Audio-Video example"""
import gobject
gobject.threads_init()
import gst
import pygtk
pygtk.require("2.0")
import gtk
import sys
import os
from audio_video import AVDemo, create_decodebin
class AVCrossfade(AVDemo):
"""Base class implementing boring, boiler-plate code.
Sets up a basic gstreamer environment which includes:
* a window containing a drawing area and basic media controls
* a basic gstreamer pipeline using an ximagesink and an autoaudiosink
* connects the ximagesink to the window's drawing area
Derived classes need only override magic(), __name__,
and __usage__ to create new demos."""
__name__ = "AV Demo"
__usage__ = "python audio_video.py <filename>"
__def_win_size__ = (320, 240)
# this commment allows us to include only a portion of the file
# in the tutorial for this demo
def onPad(self, decoder, pad, target):
tpad = target.get_compatible_pad(pad)
if tpad:
pad.link(tpad)
def addVideoChain(self, pipeline, name, decoder, mixer):
alpha = gst.element_factory_make("alpha")
alpha.props.alpha = 1.0
videoscale = gst.element_factory_make("videoscale")
videorate = gst.element_factory_make("videorate")
colorspace = gst.element_factory_make("ffmpegcolorspace")
queue = gst.element_factory_make("queue")
pipeline.add(alpha, videoscale, videorate, colorspace, queue)
decoder.connect("pad-added", self.onPad, videorate)
videorate.link(videoscale)
videoscale.link(colorspace)
colorspace.link(queue)
queue.link(alpha)
alpha.link(mixer)
setattr(self, "alpha%s" % name, alpha)
def addAudioChain(self, pipeline, name, decoder, adder):
volume = gst.element_factory_make("volume")
volume.props.volume = 0.5
audioconvert = gst.element_factory_make("audioconvert")
audiorate = gst.element_factory_make("audioresample")
queue = gst.element_factory_make("queue")
pipeline.add(volume, audioconvert, audiorate, queue)
decoder.connect("pad-added", self.onPad, audioconvert)
audioconvert.link(audiorate)
audiorate.link(queue)
queue.link(volume)
volume.link(adder)
setattr(self, "vol%s" % name, volume)
def addSourceChain(self, pipeline, name, filename, mixer, adder):
src = gst.element_factory_make("filesrc")
src.props.location = filename
dcd = create_decodebin()
pipeline.add(src, dcd)
src.link(dcd)
self.addVideoChain(pipeline, name, dcd, mixer)
self.addAudioChain(pipeline, name, dcd, adder)
def magic(self, pipeline, (videosink, audiosink), args):
"""This is where the magic happens"""
mixer = gst.element_factory_make("videomixer")
adder = gst.element_factory_make("adder")
pipeline.add(mixer, adder)
mixer.link(videosink)
adder.link(audiosink)
self.addSourceChain(pipeline, "A", args[0], mixer, adder)
self.addSourceChain(pipeline, "B", args[1], mixer, adder)
self.alphaB.props.alpha = 0.5
def onValueChanged(self, adjustment):
balance = self.balance.get_value()
crossfade = self.crossfade.get_value()
self.volA.props.volume = (2 - balance) * (1 - crossfade)
self.volB.props.volume = balance * crossfade
self.alphaB.props.alpha = crossfade
def customWidgets(self):
self.crossfade = gtk.Adjustment(0.5, 0, 1.0)
self.balance = gtk.Adjustment(1.0, 0.0, 2.0)
crossfadeslider = gtk.HScale(self.crossfade)
balanceslider = gtk.HScale(self.balance)
self.crossfade.connect("value-changed", self.onValueChanged)
self.balance.connect("value-changed", self.onValueChanged)
ret = gtk.Table()
ret.attach(gtk.Label("Crossfade"), 0, 1, 0, 1)
ret.attach(crossfadeslider, 1, 2, 0, 1)
ret.attach(gtk.Label("Balance"), 0, 1, 1, 2)
ret.attach(balanceslider, 1, 2, 1, 2)
return ret
# if this file is being run directly, create the demo and run it
if __name__ == '__main__':
AVCrossfade().run()
