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python: Add gst_video_converter.py example
Add an example of using compositor and the samples-selected signal to do frame-by-frame animation by updating pad properties and the pad's GstVideoConverter configuration Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5187>
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Jan Schmidt
GStreamer Marge Bot
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commit
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1 changed files with 188 additions and 0 deletions
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subprojects/gst-python/examples/gst_video_converter.py
Executable file
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subprojects/gst-python/examples/gst_video_converter.py
Executable file
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#!/usr/bin/env python3
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# Demonstration of using compositor and the samples-selected
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# signal to do frame-by-frame updates and animation by
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# udpating compositor pad properties and the GstVideoConverter
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# config.
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#
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# Supply a URI argument to use a video file in the example,
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# or omit it to just animate a videotestsrc.
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import gi
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import math
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import sys
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gi.require_version('Gst', '1.0')
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gi.require_version('GstVideo', '1.0')
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gi.require_version('GLib', '2.0')
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gi.require_version('GObject', '2.0')
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from gi.repository import GLib, GObject, Gst, GstVideo
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def bus_call(bus, message, loop):
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t = message.type
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if t == Gst.MessageType.EOS:
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sys.stdout.write("End-of-stream\n")
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loop.quit()
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elif t == Gst.MessageType.ERROR:
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err, debug = message.parse_error()
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sys.stderr.write("Error: %s: %s\n" % (err, debug))
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loop.quit()
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return True
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def update_compositor(comp, seg, pts, dts, duration, info):
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sink = comp.get_static_pad("sink_1")
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# Can peek at the input sample(s) here to get the real video input caps
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sample = comp.peek_next_sample(sink)
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caps = sample.get_caps()
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in_w = caps[0]['width']
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in_h = caps[0]['height']
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dest_w = 160 + in_w * math.fabs(math.sin(pts / (10 * Gst.SECOND) * math.pi))
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dest_h = 120 + in_h * math.fabs(math.sin(pts / (11 * Gst.SECOND) * math.pi))
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x = (1920 - dest_w) * math.fabs(math.sin(pts / (5 * Gst.SECOND) * math.pi))
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y = (1080 - dest_h) * math.fabs(math.sin(pts / (7 * Gst.SECOND) * math.pi))
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sink.set_property("xpos", x)
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sink.set_property("ypos", y)
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sink.set_property("width", dest_w)
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sink.set_property("height", dest_h)
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# Update video-converter settings
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cfg = Gst.Structure.new_empty("GstVideoConverter")
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# When scaling down, switch to nearest-neighbour scaling, otherwise use bilinear
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if in_w < dest_w or in_h < dest_h:
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cfg.set_value(GstVideo.VIDEO_CONVERTER_OPT_RESAMPLER_METHOD, GstVideo.VideoResamplerMethod.NEAREST)
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cfg.set_value(GstVideo.VIDEO_CONVERTER_OPT_CHROMA_RESAMPLER_METHOD, GstVideo.VideoResamplerMethod.NEAREST)
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else:
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cfg.set_value(GstVideo.VIDEO_CONVERTER_OPT_RESAMPLER_METHOD, GstVideo.VideoResamplerMethod.LINEAR)
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cfg.set_value(GstVideo.VIDEO_CONVERTER_OPT_CHROMA_RESAMPLER_METHOD, GstVideo.VideoResamplerMethod.LINEAR)
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# Crop some from the top and bottom or sides of the source image
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crop = 64 * math.cos(pts / (4 * Gst.SECOND) * math.pi)
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if crop < 0:
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crop = min(in_w / 2, -crop)
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cfg.set_value(GstVideo.VIDEO_CONVERTER_OPT_SRC_X, int(crop))
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cfg.set_value(GstVideo.VIDEO_CONVERTER_OPT_SRC_WIDTH, int(in_w - 2 * crop))
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else:
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crop = min(in_h / 2, crop)
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cfg.set_value(GstVideo.VIDEO_CONVERTER_OPT_SRC_Y, int(crop))
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cfg.set_value(GstVideo.VIDEO_CONVERTER_OPT_SRC_HEIGHT, int(in_h - 2 * crop))
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# Add add some borders to the result by not filling the destination rect
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border = 64 * math.sin(pts / (4 * Gst.SECOND) * math.pi)
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if border < 0:
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border = min(in_w / 2, -border)
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cfg.set_value(GstVideo.VIDEO_CONVERTER_OPT_DEST_X, int(border))
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cfg.set_value(GstVideo.VIDEO_CONVERTER_OPT_DEST_WIDTH, int(dest_w - 2 * border))
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else:
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border = min(in_h / 2, border)
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cfg.set_value(GstVideo.VIDEO_CONVERTER_OPT_DEST_Y, int(border))
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cfg.set_value(GstVideo.VIDEO_CONVERTER_OPT_DEST_HEIGHT, int(dest_h - 2 * border))
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# Set the border colour. Need to set this into a GValue explicitly to ensure it's a uint
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argb = GObject.Value()
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argb.init(GObject.TYPE_UINT)
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argb.set_uint(0x80FF80FF)
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cfg.set_value(GstVideo.VIDEO_CONVERTER_OPT_BORDER_ARGB, argb)
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cfg.set_value(GstVideo.VIDEO_CONVERTER_OPT_FILL_BORDER, True)
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# When things get wide, do some dithering why not
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if dest_w > in_w:
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# Dither quantization must also be a uint
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dither = GObject.Value()
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dither.init(GObject.TYPE_UINT)
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dither.set_uint(64)
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cfg.set_value(GstVideo.VIDEO_CONVERTER_OPT_DITHER_METHOD, GstVideo.VideoDitherMethod.FLOYD_STEINBERG)
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cfg.set_value(GstVideo.VIDEO_CONVERTER_OPT_DITHER_QUANTIZATION, dither)
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else:
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dither = GObject.Value()
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dither.init(GObject.TYPE_UINT)
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dither.set_uint(1)
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# cfg.set_value(GstVideo.VIDEO_CONVERTER_OPT_DITHER_METHOD, GstVideo.VideoDitherMethod.NONE)
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cfg.set_value(GstVideo.VIDEO_CONVERTER_OPT_DITHER_QUANTIZATION, dither)
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# and fade it in and out every 13 seconds
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alpha = 0.25 + 0.75 * math.fabs(math.sin(pts / (13 * Gst.SECOND) * math.pi))
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# Use the video-converter to render alpha
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# cfg.set_value(GstVideo.VIDEO_CONVERTER_OPT_ALPHA_VALUE, alpha)
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# or use the pad's alpha setting is better because compositor can use it to skip rendering
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sink.set_property("alpha", alpha)
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# print(f"Setting config {cfg}")
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sink.set_property("converter-config", cfg)
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if __name__ == "__main__":
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Gst.init(sys.argv)
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pipeline = Gst.ElementFactory.make('pipeline', None)
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compositor = Gst.ElementFactory.make("compositor", None)
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compositor.set_property("emit-signals", True)
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compositor.set_property("background", "black")
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compositor.connect("samples-selected", update_compositor)
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cf = Gst.ElementFactory.make("capsfilter", None)
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# Need to make sure the output has RGBA or AYUV, or we can't do alpha blending / fades:
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caps = Gst.Caps.from_string("video/x-raw,width=1920,height=1080,framerate=25/1,format=RGBA")
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cf.set_property("caps", caps)
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conv = Gst.ElementFactory.make("videoconvert", None)
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sink = Gst.ElementFactory.make("autovideosink", None)
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pipeline.add(compositor, cf, conv, sink)
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Gst.Element.link_many(compositor, cf, conv, sink)
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bgsource = Gst.parse_bin_from_description("videotestsrc pattern=circular ! capsfilter name=cf", False)
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cfsrc = bgsource.get_by_name("cf")
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caps = Gst.Caps.from_string("video/x-raw,width=320,height=180,framerate=1/1,format=RGB")
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cfsrc.set_property("caps", caps)
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src = cfsrc.get_static_pad("src")
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bgsource.add_pad(Gst.GhostPad.new("src", src))
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pipeline.add(bgsource)
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bgsource.link(compositor)
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pad = compositor.get_static_pad("sink_0")
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pad.set_property("width", 1920)
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pad.set_property("height", 1080)
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if len(sys.argv) > 1:
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source = Gst.parse_bin_from_description("uridecodebin name=u ! capsfilter name=cf caps=video/x-raw", False)
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u = source.get_by_name("u")
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u.set_property("uri", sys.argv[1])
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cfsrc = source.get_by_name("cf")
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caps = Gst.Caps.from_string("video/x-raw")
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cfsrc.set_property("caps", caps)
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# Expose the capsfilter source pad as a ghost pad
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src = cfsrc.get_static_pad("src")
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source.add_pad(Gst.GhostPad.new("src", src))
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else:
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source = Gst.parse_bin_from_description("videotestsrc ! capsfilter name=cf", False)
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cfsrc = source.get_by_name("cf")
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caps = Gst.Caps.from_string("video/x-raw,width=320,height=240,framerate=30/1,format=I420")
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cfsrc.set_property("caps", caps)
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src = cfsrc.get_static_pad("src")
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source.add_pad(Gst.GhostPad.new("src", src))
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pipeline.add(source)
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source.link(compositor)
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pipeline.set_state(Gst.State.PLAYING)
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bus = pipeline.get_bus()
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bus.add_signal_watch()
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loop = GLib.MainLoop()
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bus.connect("message", bus_call, loop)
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loop.run()
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pipeline.set_state(Gst.State.NULL)
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pipeline.get_state(Gst.CLOCK_TIME_NONE)
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