Add beep generating tool

diff --git a/tools/gen_sound.py b/tools/gen_sound.py
new file mode 100644 (file)
index 0000000..6efc05e
--- /dev/null
+++ b/tools/gen_sound.py
@@ -0,0 +1,54 @@
+# Generate imperfect sine waves
+# 
+# Design notes. Produces ~= (user requested) s of raw audio
+# We're aiming for an 8-bit'ish effect, so we're going with
+# 8125 Hz, 8 bit sampling, but faking it out to
+# CDDA output (44100 Hz, 16 bit signed) for easier conversion to ogg
+# by multiply the value by 256 (after roundin) and repeating it 4 times.
+
+import sys
+import math
+import struct
+
+OUTPUT_RATE = 8125
+MAX = 95
+
+def gen_sine(freq, secs):
+    filename = 'beep%s.pcm' % freq
+    # We generate freq cycles and sample that OUTPUT_RATE times
+    per_cycle = OUTPUT_RATE / freq
+    data = []
+    for x in range(per_cycle):
+        rad = float(x) / per_cycle * 2 * math.pi
+        y = 256 * int(MAX * math.sin(rad))
+        data.extend([struct.pack('<i', y)] * 4)
+    output = open(filename, 'w')
+    # This is correct because OUTPUT_RATE = CDDA rate / 4 and we repeat
+    # the samples 4 times, so this works out to CDDA rate
+    for x in range(int(freq * secs)):
+        output.write(''.join(data))
+    output.close()
+    print 'Wrote output to %s' % filename
+
+
+def usage():
+    print 'Unexpected input'
+    print 'Usage gen_sound <freq> [<length>]'
+    print ' where <freq> is the frequency in Hz (int)'
+    print ' and [<length>] is the time in seconds (float) - default 0.25'
+
+
+if __name__ == "__main__":
+    try:
+       freq = int(sys.argv[1])
+       if len(sys.argv) > 2:
+          secs = float(sys.argv[2])
+       else:
+          secs = 0.25
+    except Exception, exc:
+       usage()
+       print 'Error was', exc
+       sys.exit(1)
+
+    gen_sine(freq, secs)
+