- 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 = []
- # register on_draw handler
- self.drawing_area.connect('draw', self.on_draw)
- def on_draw(self, widget, cr):
- # number of audio-channels
- channels = len(self.levelrms)
- if channels == 0:
- return
- width = self.drawing_area.get_allocated_width()
- height = self.drawing_area.get_allocated_height()
- # space between the channels in px
- margin = 2
- # 1 channel -> 0 margins, 2 channels -> 1 margin, 3 channels…
- 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)
- # normalize db-value to 0…1 and multiply with the height
- 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 ]
- # set the line-width >1, to get a nice overlap
- cr.set_line_width(2)
- # iterate over all pixels
- for y in range(0, height):
- # calculate our place in the color-gradient, clamp to 0…1
- # 0 -> green, 0.5 -> yellow, 1 -> red
- color = self.clamp(((y / height) - 0.6) / 0.42)
- for channel in range(0, channels):
- # start-coordinate for this channel
- x = (channel * channel_width) + (channel * margin)
- # calculate the brightness based on whether this line is in the
- # active region
- # default to 0.25, dark
- bright = 0.25
- if int(y - decay_px[channel]) in range(0, 2):
- # decay marker, 2px wide, extra bright
- bright = 1.5
- elif y < rms_px[channel]:
- # rms bar, full bright
- bright = 1
- elif y < peak_px[channel]:
- # peak bar, a little darker
- bright = 0.75
- # set the color with a little reduced green
- cr.set_source_rgb(
- color * bright,
- (1-color) * bright * 0.75,
- 0
- )
- # draw the marker
- cr.move_to(x, height-y)
- cr.line_to(x + channel_width, height-y)
- cr.stroke()
- # draw a black line for the margin
- cr.set_source_rgb(0,0,0)
- cr.move_to(x + channel_width, height-y)
- cr.line_to(x + channel_width + margin, height-y)
- cr.stroke()
- # draw db text-markers
- cr.set_source_rgb(1, 1, 1)
- for db in [-40, -20, -10, -5, -4, -3, -2, -1]:
- text = str(db)
- xbearing, ybearing, textwidth, textheight, xadvance, yadvance = (
- cr.text_extents(text))
- y = self.normalize_db(db) * height
- cr.move_to((width-textwidth) / 2, height - y - textheight)
- cr.show_text(text)
- 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)
- return self.clamp(logscale)
- def clamp(self, value, min_value=0, max_value=1):
- 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()
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