Spectrum.py
Revision as of 13:10, 1 June 2009 by Michael Murtaugh (talk | contribs) (→Visualizing the data with PyGame)
Getting the data from gstreamer
import pygst
pygst.require("0.10")
import gst, gobject
import time, thread
class Spectrum:
def __init__(self):
# Create a gstreamer pipeline, listen to it's messages via on_message callback
# listener_desc = 'alsasrc ! spectrum ! fakesink'
listener_desc = 'alsasrc ! spectrum bands=64 ! fakesink'
self.listener = gst.parse_launch(listener_desc)
bus = self.listener.get_bus()
bus.add_signal_watch()
bus.connect("message", self.on_message)
def on_message (self, bus, message):
""" callback function for gstreamer messages """
s = message.structure
# print "message.name", s.get_name()
# print "message.structure.keys", s.keys()
if s and s.get_name() == "spectrum":
# spectrum messages have 'endtime', 'timestamp', 'stream-time', 'running-time', 'duration', 'magnitude'
# print len(s['magnitude'])
print "data: " + " ".join([str(x) for x in s['magnitude']])
return True
def start(self):
self.listener.set_state(gst.STATE_PLAYING)
while True:
time.sleep(1)
# Run the Spectrum object in it's own thread, then start the gobject.MainLoop as required
spectrum = Spectrum()
thread.start_new_thread(spectrum.start, ())
gobject.threads_init()
loop = gobject.MainLoop()
loop.run()
Visualizing the data with PyGame
Pipe the level data into a PyGame script, that uses RelativeValue.py to filter and display the data.
To run, we pipe the data from the above into the below, using "unbuffered" python...
python -u spectrum.py | python -u spectrum_display.py
#!/usr/bin/python
import sys
import pygame
from pygame.locals import *
from pygame.time import Clock
from time import sleep
import thread
from RelativeValue import RelativeValue
def main():
pygame.init()
rvals = []
NUM_BANDS = 64
for i in range(NUM_BANDS):
rvals.append(RelativeValue())
# screen = pygame.display.set_mode((640, 480), FULLSCREEN, 32)
screen = pygame.display.set_mode((640, 480), 0, 32)
SCREEN_WIDTH = screen.get_width()
SCREEN_HEIGHT = screen.get_height()
BAR_WIDTH = SCREEN_WIDTH / NUM_BANDS
pygame.display.set_caption("spectrum")
clock = Clock()
level = 0.0
while True:
# TIMING
clock.tick(30)
# PROCESS EVENTS
for event in pygame.event.get():
if event.type==QUIT or \
(event.type == KEYDOWN and event.key == K_ESCAPE):
sys.exit()
elif event.type == KEYDOWN and event.key == K_f:
pygame.display.toggle_fullscreen()
elif event.type == USEREVENT:
for (i, val) in enumerate(event.data):
rvals[i].setvalue(val)
screen.fill((0, 0, 0))
# if mfullimage: screen.blit(subimage, (mx, my))
for (i, rval) in enumerate(rvals):
max_height = SCREEN_HEIGHT / 2
bar_height = rval.slider * max_height
bar_rect = (i*BAR_WIDTH, SCREEN_HEIGHT / 2, BAR_WIDTH-1, bar_height)
bar_color = (255, 0, 0)
pygame.draw.rect(screen, bar_color, bar_rect)
pygame.display.update()
# Start the PyGame display in it's own thread...
thread.start_new_thread(main, ())
# ... and then READ DATA FROM STDIN, sending data to PyGame as "events"
print "Press ctrl-c to stop..."
while 1:
line = sys.stdin.readline()
if (not line): break
line = line.strip()
try:
if line.startswith("data:"):
data = line.split()[1:]
data = [float(x) for x in data] # parse data as floats
# create a custom "event" and send it (post it) to the pygame loop
evt = pygame.event.Event(USEREVENT, {"data" : data})
pygame.event.post(evt)
except ValueError:
print "bad data", line