import gst, gobject

cap = 'video/x-raw-yuv,format=(fourcc)I420,width=640,height=480,framerate=(fraction)30000/1001'

def get_src(pattern):# creates videotestsrc->capfilter bin in a gnlsource
    bin  = gst.Bin()
    src  = gst.element_factory_make("videotestsrc")
    src.props.pattern = pattern
    caps = gst.element_factory_make("capsfilter")
    caps.props.caps = gst.Caps(cap)
    bin.add(src, caps)
    src.link(caps)
    bin.add_pad(gst.GhostPad("src", caps.get_pad("src")))
    gsrc = gst.element_factory_make("gnlsource")
    gsrc.add(bin)
    return gsrc

# create two gnlsources and make them play different patterns
gsrc1 = get_src("smpte")
gsrc2 = get_src("ball")

# set the two gnlsources to play serially
dur = 3
gsrc1.props.start          =   0 * gst.SECOND
gsrc1.props.duration       = dur * gst.SECOND
gsrc1.props.media_start    =   0 * gst.SECOND
gsrc1.props.media_duration = dur * gst.SECOND
gsrc2.props.start          = dur * gst.SECOND
gsrc2.props.duration       = dur * gst.SECOND
gsrc2.props.media_start    =   0 * gst.SECOND
gsrc2.props.media_duration = dur * gst.SECOND

# create a gnlcomposition to hold the two sources
comp  = gst.element_factory_make("gnlcomposition")
comp.add(gsrc1, gsrc2)

# put a caps filter on the output of the gnlcomposition
caps  = gst.element_factory_make("capsfilter")
caps.props.caps = gst.Caps(cap)

# create the pipeline
pipeline = gst.Pipeline()
pipeline.add(comp, caps)

# now create a backend. There are two different backend options. Change
# if state to True to enable an X11 backend or set it to false to enable
# an encoder backend.
if 0:
    sink = gst.element_factory_make("autovideosink")
    pipeline.add(sink)
    caps.link(sink)
else:
    enc  = gst.element_factory_make("ffenc_mpeg4")
    #enc  = gst.element_factory_make("x264enc")
    mux  = gst.element_factory_make("mp4mux")
    sink = gst.element_factory_make("filesink")
    sink.props.location = "test.mp4"
    pipeline.add(enc, mux, sink)
    gst.element_link_many(caps, enc, mux, sink)

# setup the gnlcomposition to link to the capsfilter when its pads get created
def on_pad(comp, pad, caps):
    pad.link(caps.get_compatible_pad(pad, pad.get_caps()))
comp.connect("pad-added", on_pad, caps)

# now run the pipeline
loop = gobject.MainLoop(is_running=True)
gobject.threads_init()
bus = pipeline.get_bus()
bus.add_signal_watch()
def on_message(bus, message, loop):
    if message.type == gst.MESSAGE_EOS:
        loop.quit()
    elif message.type == gst.MESSAGE_ERROR:
        print message
        loop.quit()
bus.connect("message", on_message, loop)
pipeline.set_state(gst.STATE_PLAYING)
loop.run()
pipeline.set_state(gst.STATE_NULL)