added get_freq_bits example

pysstv/examples/get_freq_bits.py

@@ -0,0 +1,24 @@
+#!/usr/bin/env python
+
+"""
+This example streams the raw floating point (freq, msec) tuples to stdout
+in 4-byte single precision format (8 bytes per tuple), so that it can be
+processed outside PySSTV.
+
+Usage example using unixsstv/gen_values:
+get_freq_bits.py | gen_values 44100 | play -r 44100 -t f32 -c 1 --norm -
+"""
+
+from pysstv.sstv import SSTV
+from PIL import Image
+from pysstv.color import MartinM1
+import struct, sys
+
+def main():
+    img = Image.open("320x256rgb.png")
+    sstv = MartinM1(img, 44100, 16)
+    for freq, msec in sstv.gen_freq_bits():
+        sys.stdout.write(struct.pack('ff', freq, msec))
+
+if __name__ == '__main__':
+    main()