path: root/voctogui/lib/audioleveldisplay.py

import logging, math
from gi.repository import Gst, Gtk

class AudioLevelDisplay(object):
    """ Displays a Level-Meter of another VideoDisplay into a GtkWidget """

    def __init__(self, drawing_area):
        self.log = logging.getLogger('AudioLevelDisplay[%s]' % drawing_area.get_name())

        self.drawing_area = drawing_area

        self.levelrms = []
        self.levelpeak = []
        self.leveldecay = []
        self.drawing_area.connect('draw', self.on_draw)

    def on_draw(self, widget, cr):
        channels = len(self.levelrms)

        if channels == 0:
            return

        width = self.drawing_area.get_allocated_width()
        height = self.drawing_area.get_allocated_height()
        margin = 2 # px

        channel_width = int((width - (margin * (channels - 1))) / channels)
        # self.log.debug(
        #   'width: %upx filled with %u channels of each %upx '
        #   'and %ux margin of %upx',
        #   width, channels, channel_width, channels-1, margin)

        rms_px   = [ self.normalize_db(db) * height for db in self.levelrms ]
        peak_px  = [ self.normalize_db(db) * height for db in self.levelpeak ]
        decay_px = [ self.normalize_db(db) * height for db in self.leveldecay ]

        cr.set_line_width(channel_width)
        for y in range(0, height):
            pct = y / height

            for channel in range(0, channels):
                x = (channel * channel_width) + (channel * margin)

                bright = 0.25
                if y < rms_px[channel]:
                    bright = 1
                # elif abs(y - peak_px[channel]) < 3:
                #   bright = 1.5
                elif y < decay_px[channel]:
                    bright = 0.75

                cr.set_source_rgb(pct * bright, (1-pct) * bright, 0 * bright)

                cr.move_to(x, height-y)
                cr.line_to(x + channel_width, height-y)
                cr.stroke()

        return True

    def normalize_db(self, db):
        # -60db -> 1.00 (very quiet)
        # -30db -> 0.75
        # -15db -> 0.50
        #  -5db -> 0.25
        #  -0db -> 0.00 (very loud)
        logscale = 1 - math.log10(-0.15 * db + 1)
        normalized = self.clamp(logscale, 0, 1)
        return normalized

    def clamp(self, value, min_value, max_value):
        return max(min(value, max_value), min_value)

    def level_callback(self, rms, peak, decay):
        self.levelrms = rms
        self.levelpeak = peak
        self.leveldecay = decay
        self.drawing_area.queue_draw()