subprojects/gst-python/examples/plugins/python/mixer.py

   1 '''
   2 Simple mixer element, accepts 320 x 240 RGBA at 30 fps
   3 on any number of sinkpads.
   4
   5 Requires PIL (Python Imaging Library)
   6
   7 Example pipeline:
   8
   9 gst-launch-1.0 py_videomixer name=mixer ! videoconvert ! autovideosink \
  10         videotestsrc ! mixer. \
  11         videotestsrc pattern=ball ! mixer. \
  12         videotestsrc pattern=snow ! mixer.
  13 '''
  14
  15 import gi
  16
  17 gi.require_version('Gst', '1.0')
  18 gi.require_version('GstBase', '1.0')
  19 gi.require_version('GObject', '2.0')
  20
  21 from gi.repository import Gst, GObject, GstBase
  22
  23 Gst.init_python()
  24
  25 try:
  26     from PIL import Image
  27 except ImportError:
  28     Gst.error('py_videomixer requires PIL')
  29     raise
  30
  31 # Completely fixed input / output
  32 ICAPS = Gst.Caps(Gst.Structure('video/x-raw',
  33                                format='RGBA',
  34                                width=320,
  35                                height=240,
  36                                framerate=Gst.Fraction(30, 1)))
  37
  38 OCAPS = Gst.Caps(Gst.Structure('video/x-raw',
  39                                format='RGBA',
  40                                width=320,
  41                                height=240,
  42                                framerate=Gst.Fraction(30, 1)))
  43
  44 class BlendData:
  45     def __init__(self, outimg):
  46         self.outimg = outimg
  47         self.pts = 0
  48         self.eos = True
  49
  50 class Videomixer(GstBase.Aggregator):
  51     __gstmetadata__ = ('Videomixer','Video/Mixer', \
  52                       'Python video mixer', 'Mathieu Duponchelle')
  53
  54     __gsttemplates__ = (
  55             Gst.PadTemplate.new_with_gtype("sink_%u",
  56                                 Gst.PadDirection.SINK,
  57                                 Gst.PadPresence.REQUEST,
  58                                 ICAPS,
  59                                 GstBase.AggregatorPad.__gtype__),
  60             Gst.PadTemplate.new_with_gtype("src",
  61                                 Gst.PadDirection.SRC,
  62                                 Gst.PadPresence.ALWAYS,
  63                                 OCAPS,
  64                                 GstBase.AggregatorPad.__gtype__)
  65     )
  66
  67     def mix_buffers(self, agg, pad, bdata):
  68         buf = pad.pop_buffer()
  69         _, info = buf.map(Gst.MapFlags.READ)
  70
  71         img = Image.frombuffer('RGBA', (320, 240), info.data, "raw", 'RGBA', 0, 1)
  72
  73         bdata.outimg = Image.blend(bdata.outimg, img, alpha=0.5)
  74         bdata.pts = buf.pts
  75
  76         buf.unmap(info)
  77
  78         bdata.eos = False
  79
  80         return True
  81
  82     def do_aggregate(self, timeout):
  83         outimg = Image.new('RGBA', (320, 240), 0x00000000)
  84
  85         bdata = BlendData(outimg)
  86
  87         self.foreach_sink_pad(self.mix_buffers, bdata)
  88
  89         data = bdata.outimg.tobytes()
  90
  91         outbuf = Gst.Buffer.new_allocate(None, len(data), None)
  92         outbuf.fill(0, data)
  93         outbuf.pts = bdata.pts
  94         self.finish_buffer (outbuf)
  95
  96         # We are EOS when no pad was ready to be aggregated,
  97         # this would obviously not work for live
  98         if bdata.eos:
  99             return Gst.FlowReturn.EOS
 100
 101         return Gst.FlowReturn.OK
 102
 103 GObject.type_register(Videomixer)
 104 __gstelementfactory__ = ("py_videomixer", Gst.Rank.NONE, Videomixer)