Use Gstreamer unknown format video playback (python)

Use Gstreamer unknown format video playback (python)

1. Play Audio containing unknown format of video

  Gstreamer be implemented using the decodebin.
Codes are as follows:

import gi
gi.require_version('Gst', '1.0')
from gi.repository import Gst, GObject, GLib
Gst.init(None)
#decodebin产生新pad的回调函数
def cb_decodebin_newpad(src, pad, dst,dst2):
    caps = Gst.Pad.get_current_caps(pad)
    structure_name = caps.to_string()
    if structure_name.startswith("video"):
        videorate_pad = dst.get_static_pad("sink")
        pad.link(videorate_pad)

    elif structure_name.startswith("audio"):
        volume_pad = dst2.get_static_pad("sink")
        pad.link(volume_pad)


pipe = Gst.Pipeline.new("test")
src = Gst.ElementFactory.make("filesrc", "src")
queuev = Gst.ElementFactory.make("queue", "queue")
conv = Gst.ElementFactory.make("videoconvert", "conv")
sink = Gst.ElementFactory.make("xvimagesink", "sink")
decodebina = Gst.ElementFactory.make("decodebin", "decodea")
queuea = Gst.ElementFactory.make("queue", "queuea")
conva = Gst.ElementFactory.make("audioconvert", "conva")
sinka = Gst.ElementFactory.make("autoaudiosink", "sinka")

src.set_property("location", "a.mkv")
decodebina.connect("pad-added", cb_decodebin_newpad, queuev,queuea)

pipe.add(src)
pipe.add(queuev)
pipe.add(conv)
pipe.add(sink)
pipe.add(queuea)
pipe.add(decodebina)
pipe.add(conva)
pipe.add(sinka)

src.link(decodebina)
queuev.link(conv)
conv.link(sink)
queuea.link(conva)
conva.link(sinka)

pipe.set_state(Gst.State.PLAYING)

mainloop = GLib.MainLoop()
mainloop.run()

2. Play Audio's unknown whether it contains video

  Use liners and detection mechanisms in the blocking Gstreamer to complete.
  Currently the program is also a problem: no sound phenomenon may occur within a short time after the video starts playing. We are trying to solve.
Codes are as follows:

import gi
gi.require_version('Gst', '1.0')
from gi.repository import Gst, GObject, GLib

Gst.init(None)
a = 0
def cb_add_elements(src,pad):
    global a
    if a == 0:
        a = 1
        pipe.add(queuea)
        pipe.add(conva)
        pipe.add(sinka)
        queuea.link(conva)
        conva.link(sinka)
        return Gst.PadProbeReturn.PASS
    else:
        return Gst.PadProbeReturn.DROP

def cb_decodebin_newpad(src, pad):
    caps = Gst.Pad.get_current_caps(pad)
    structure_name = caps.to_string()
    if structure_name.startswith("video"):
        videorate_pad = queuev.get_static_pad("sink")
        pad.link(videorate_pad)

    elif structure_name.startswith("audio"):

        Gst.Pad.add_probe(pad, Gst.PadProbeType.IDLE, cb_add_elements)
        volume_pad = queuea.get_static_pad("sink")
        pad.link(volume_pad)


pipe = Gst.Pipeline.new("test")
src = Gst.ElementFactory.make("filesrc", "src")

queuev = Gst.ElementFactory.make("queue", "queue")
conv = Gst.ElementFactory.make("videoconvert", "conv")
sink = Gst.ElementFactory.make("xvimagesink", "sink")

decodebin = Gst.ElementFactory.make("decodebin", "decodea")
queuea = Gst.ElementFactory.make("queue", "queuea")
conva = Gst.ElementFactory.make("audioconvert", "conva")
sinka = Gst.ElementFactory.make("autoaudiosink", "sinka")

src.set_property("location", "a.mkv")
decodebin.connect("pad-added", cb_decodebin_newpad)
pipe.add(src)

pipe.add(queuev)
pipe.add(conv)
pipe.add(sink)
pipe.add(decodebin)

src.link(decodebin)
queuev.link(conv)
conv.link(sink)

pipe.set_state(Gst.State.PLAYING)

mainloop = GLib.MainLoop()
mainloop.run()

3. related study materials

Gsreamer dynamic connection information: gstreamer dynamic link
Gstreamer C language with Python control statements: Statement control