voctocore/videomix.py



import sys, inspect, math
from pprint import pprint
from gi.repository import GLib, Gst

class Videomix:
    # size of the monitor-streams
    # should be anamorphic PAL, beacuse we encode it to dv and send it to the mixer-gui
    monitorSize = (1024, 576)

    def __init__(self):
        # initialize an empty pipeline
        self.pipeline = Gst.Pipeline()

        # create audio and video mixer
        mixerbin = self.createMixer()

        # collection of video-sources to connect to the quadmix
        quadmixSources = []

        # create camera sources
        for camberabin in self.createDummyCamSources():
            # link camerasource to audiomixer
            camberabin.get_by_name('audio_src').link(self.pipeline.get_by_name('liveaudio'))

            # inject a ×2 distributor and link one end to the live-mixer
            distributor = self.createDistributor(camberabin.get_by_name('video_src'), camberabin.get_name())
            distributor.get_by_name('a').link(self.pipeline.get_by_name('livevideo'))

            # collect the other end to add it later to the quadmix
            quadmixSources.append(distributor.get_by_name('b'))

        # TODO: generate pause & slides with another generator here which only
        # yields if the respective files are present and which only have a video-pad

        # add all video-sources to the quadmix-monitor-screen
        self.addVideosToQuadmix(quadmixSources, self.pipeline.get_by_name('quadmix'))

        Gst.debug_bin_to_dot_file(self.pipeline, Gst.DebugGraphDetails.ALL, 'test')
        self.pipeline.set_state(Gst.State.PLAYING)

    # create audio and video mixer
    def createMixer(self):
        # create mixer-pipeline from string
        mixerbin = Gst.parse_bin_from_description("""
            videomixer name=livevideo ! autovideosink
            input-selector name=liveaudio ! autoaudiosink

            videotestsrc pattern="solid-color" foreground-color=0x808080 ! capsfilter name=filter ! videomixer name=quadmix ! autovideosink
        """, False)

        # define caps for the videotestsrc which generates the background-color for the quadmix
        bgcaps = Gst.Caps.new_empty_simple('video/x-raw')
        bgcaps.set_value('width', round(self.monitorSize[0]))
        bgcaps.set_value('height', round(self.monitorSize[1]))
        mixerbin.get_by_name('filter').set_property('caps', bgcaps)

        # name the bin, add and return it
        mixerbin.set_name('mixerbin')
        self.pipeline.add(mixerbin)
        return mixerbin

    # add all avaiable videosources to the quadmix
    def addVideosToQuadmix(self, videosources, quadmix):
        count = len(videosources)

        # coordinate of the cell where we place the next video
        place = [0, 0]
        
        # number of cells in the quadmix-monitor
        grid = [0, 0]
        grid[0] = math.ceil(math.sqrt(count))
        grid[1] = math.ceil(count / grid[0])

        # size of each cell in the quadmix-monitor
        cellSize = (
            self.monitorSize[0] / grid[0],
            self.monitorSize[1] / grid[1]
        )

        print("showing {} videosources in a {}×{} grid in a {}×{} px window, which gives cells of {}×{} px per videosource".format(
            count, grid[0], grid[1], self.monitorSize[0], self.monitorSize[1], cellSize[0], cellSize[1]))

        # iterate over all video-sources
        for idx, videosource in enumerate(videosources):
            # generate a pipeline for this videosource which
            # - scales the video to the request
            # - remove n px of the video (n = 5 if the video is highlighted else 0)
            # - add a colored border of n px of the video (n = 5 if the video is highlighted else 0)
            # - overlay the index of the video as text in the top left corner
            # - known & named output
            previewbin = Gst.parse_bin_from_description("""
                videoscale name=in !
                capsfilter name=caps !
                videobox name=crop top=0 left=0 bottom=0 right=0 !
                videobox fill=red top=-0 left=-0 bottom=-0 right=-0 name=add !
                textoverlay color=0xFFFFFFFF halignment=left valignment=top xpad=10 ypad=5 font-desc="sans 35" name=text !
                identity name=out
            """, False)

            # name the bin and add it
            self.pipeline.add(previewbin)
            previewbin.set_name('previewbin-{}'.format(idx))

            # set the overlay-text
            previewbin.get_by_name('text').set_property('text', str(idx))

            # query the video-source caps and extract its size
            caps = videosource.get_static_pad('src').query_caps(None)
            capsstruct = caps.get_structure(0)
            srcSize = (
                capsstruct.get_int('width')[1],
                capsstruct.get_int('height')[1],
            )

            # calculate the ideal scale factor and scale the sizes
            f = max(srcSize[0] / cellSize[0], srcSize[1] / cellSize[1])
            scaleSize = (
                srcSize[0] / f,
                srcSize[1] / f,
            )

            # calculate the top/left coordinate
            coord = (
                place[0] * cellSize[0] + (cellSize[0] - scaleSize[0]) / 2,
                place[1] * cellSize[1] + (cellSize[1] - scaleSize[1]) / 2,
            )

            print("placing videosrc {} of size {}×{} scaled by {} to {}×{} in a cell {}×{} px cell ({}/{}) at position ({}/{})".format(
                idx, srcSize[0], srcSize[1], f, scaleSize[0], scaleSize[1], cellSize[0], cellSize[1], place[0], place[1], coord[0], coord[1]))

            # link the videosource to the input of the preview-bin
            videosource.link(previewbin.get_by_name('in'))

            # create and set the caps for the preview-scaler
            scalecaps = Gst.Caps.new_empty_simple('video/x-raw')
            scalecaps.set_value('width', round(scaleSize[0]))
            scalecaps.set_value('height', round(scaleSize[1]))
            previewbin.get_by_name('caps').set_property('caps', scalecaps)

            # request a pad from the quadmixer and configure x/y position
            sinkpad = quadmix.get_request_pad('sink_%u')
            sinkpad.set_property('xpos', round(coord[0]))
            sinkpad.set_property('ypos', round(coord[1]))

            # link the output of the preview-bin to the mixer
            previewbin.get_by_name('out').link(quadmix)

            # increment grid position
            place[0] += 1
            if place[0] >= grid[0]:
                place[1] += 1
                place[0] = 0

    # create a simple ×2 distributor
    def createDistributor(self, videosource, name):
        distributor = Gst.parse_bin_from_description("""
            tee name=t
            t. ! queue name=a
            t. ! queue name=b
        """, False)

        # set a name and add to pipeline
        distributor.set_name('distributor({0})'.format(name))
        self.pipeline.add(distributor)

        # link input to the tee
        videosource.link(distributor.get_by_name('t'))
        return distributor

    # create test-video-sources from files or urls
    def createDummyCamSources(self):
        # TODO make configurable
        uris = ('file:///home/peter/122.mp4', 'file:///home/peter/10025.mp4',)
        for idx, uri in enumerate(uris):
            # create a bin for a simulated camera input
            # force the input resolution to 1024x576 because that way the following elements
            # in the pipeline cam know the size even if the file is not yet loaded. the quadmixer
            # is not resize-capable
            camberabin = Gst.parse_bin_from_description("""
                uridecodebin name=input
                input. ! videoconvert ! videoscale ! videorate ! video/x-raw,width=1024,height=576,framerate=25/1 ! identity name=video_src
                input. ! audioconvert name=audio_src
            """, False)

            # set name and uri
            camberabin.set_name('dummy-camberabin({0})'.format(uri))
            camberabin.get_by_name('input').set_property('uri', uri)

            # add to pipeline and pass the bin upstream
            self.pipeline.add(camberabin)
            yield camberabin


    # create real-video-sources from the bmd-drivers
    def createCamSources(self):
        # number of installed cams
        # TODO make configurable
        for cam in range(2):
            # create a bin for camera input
            camberabin = Gst.parse_bin_from_description("""
                decklinksrc name=input input=sdi input-mode=1080p25
                input. ! videoconvert ! videoscale ! videorate ! video/x-raw,width=1920,height=1080,framerate=25/1 ! identity name=video_src
                input. ! audioconvert name=audio_src
            """, False)

            # set name and subdevice
            camberabin.set_name('camberabin({0})'.format(cam))
            camberabin.get_by_name('input').set_property('subdevice', cam)

            # add to pipeline and pass the bin upstream
            self.pipeline.add(camberabin)
            yield camberabin