Play audio and video with a Pipeline in Gstreamer

I've built an example video player that makes use of the elements you described.

It should show you how to connect the pads to eachother dynamically.

'''
Copyright (c) 2011 Joar Wandborg <http://wandborg.se>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

---

- A response to http://stackoverflow.com/questions/8187257/play-audio-and-video-with-a-pipeline-in-gstreamer-python/8197837
- Like it? Buy me a beer! https://flattr.com/thing/422997/Joar-Wandborg
'''

import gst
import gobject
gobject.threads_init()
import logging


logging.basicConfig()

_log = logging.getLogger(__name__)
_log.setLevel(logging.DEBUG)


class VideoPlayer(object):
    '''
    Simple video player
    '''

    source_file = None

    def __init__(self, **kwargs):
        self.loop = gobject.MainLoop()

        if kwargs.get('src'):
            self.source_file = kwargs.get('src')

        self.__setup()

    def run(self):
        self.loop.run()

    def stop(self):
        self.loop.quit()

    def __setup(self):
        _log.info('Setting up VideoPlayer...')
        self.__setup_pipeline()
        _log.info('Set up')

    def __setup_pipeline(self):
        self.pipeline = gst.Pipeline('video-player-pipeline')

        # Source element
        self.filesrc = gst.element_factory_make('filesrc')
        self.filesrc.set_property('location', self.source_file)
        self.pipeline.add(self.filesrc)

        # Demuxer
        self.decoder = gst.element_factory_make('decodebin2')
        self.decoder.connect('pad-added', self.__on_decoded_pad)
        self.pipeline.add(self.decoder)

        # Video elements
        self.videoqueue = gst.element_factory_make('queue', 'videoqueue')
        self.pipeline.add(self.videoqueue)

        self.autovideoconvert = gst.element_factory_make('autovideoconvert')
        self.pipeline.add(self.autovideoconvert)

        self.autovideosink = gst.element_factory_make('autovideosink')
        self.pipeline.add(self.autovideosink)

        # Audio elements
        self.audioqueue = gst.element_factory_make('queue', 'audioqueue')
        self.pipeline.add(self.audioqueue)

        self.audioconvert = gst.element_factory_make('audioconvert')
        self.pipeline.add(self.audioconvert)

        self.autoaudiosink = gst.element_factory_make('autoaudiosink')
        self.pipeline.add(self.autoaudiosink)

        self.progressreport = gst.element_factory_make('progressreport')
        self.progressreport.set_property('update-freq', 1)
        self.pipeline.add(self.progressreport)

        # Link source and demuxer
        linkres = gst.element_link_many(
            self.filesrc,
            self.decoder)

        if not linkres:
            _log.error('Could not link source & demuxer elements!\n{0}'.format(
                    linkres))

        linkres = gst.element_link_many(
            self.audioqueue,
            self.audioconvert,
            self.autoaudiosink)

        if not linkres:
            _log.error('Could not link audio elements!\n{0}'.format(
                    linkres))

        linkres = gst.element_link_many(
            self.videoqueue,
            self.progressreport,
            self.autovideoconvert,
            self.autovideosink)

        if not linkres:
            _log.error('Could not link video elements!\n{0}'.format(
                    linkres))

        self.bus = self.pipeline.get_bus()
        self.bus.add_signal_watch()
        self.bus.connect('message', self.__on_message)

        self.pipeline.set_state(gst.STATE_PLAYING)

    def __on_decoded_pad(self, pad, data):
        _log.debug('on_decoded_pad: {0}'.format(pad))

        if pad.get_caps()[0].to_string().startswith('audio'):
            pad.link(self.audioqueue.get_pad('sink'))
        else:
            pad.link(self.videoqueue.get_pad('sink'))

    def __on_message(self, bus, message):
        _log.debug(' - MESSAGE: {0}'.format(message))
        

if __name__ == '__main__':
    player = VideoPlayer(
        src='/home/joar/Videos/big_buck_bunny_1080p_stereo.avi')

    player.run()

queue is not a source element, you need to have either uridecodebin or decodebin or something simliar as the source element.

This is an example pipeline in the gst-launch format.

uridecodebin \
    uri="file:///home/joar/Dropbox/Music/04 - Deadmau5 - Clockwork (Jonas Steur Remix).mp3" \
! audioconvert ! autoaudiosink

it means that in the pipeline there is

• uridecodebin - A decoding bin, capable of decoding whatever source file is compatible with GStreamer, with the uri property set to file:///home/joar/Dropbox/Music/04 - Deadmau5 - Clockwork (Jonas Steur Remix).mp3.
• audioconvert - Converts audio between different formats
• autoaudiosink

If needed, you could add a queue element between the uridecodebin and the audioconvert.

---

Update

I can do what you describe using the following gst-launch command

gst-launch-0.10 filesrc \
    location="/home/joar/Dropbox/Skrillex vs. Adele - Set Fire to Everybody.mov" \
! decodebin name=dmux \
dmux. ! queue ! audioconvert ! autoaudiosink \
dmux. ! queue ! autovideoconvert ! autovideosink