added option for multiple channels

pysstv/__main__.py

@@ -29,6 +29,8 @@ def main():
                         help='add VOX tones at the beginning')
     parser.add_argument('--fskid', dest='fskid',
                         help='add FSKID at the end')
+    parser.add_argument('--chan', dest='chan', type=int,
+                        help='number of channels (default: mono)')
     args = parser.parse_args()
     image = Image.open(args.img_file)
     mode = module_map[args.mode]
@@ -40,6 +42,8 @@ def main():
     s.vox_enabled = args.vox
     if args.fskid:
         s.add_fskid_text(args.fskid)
+    if args.chan:
+        s.nchannels = args.chan
     s.write_wav(args.wav_file)
 
 

pysstv/sstv.py

@@ -32,6 +32,7 @@ class SSTV(object):
         self.bits = bits
         self.vox_enabled = False
         self.fskid_payload = ''
+        self.nchannels = 1
 
     BITS_TO_STRUCT = {8: 'b', 16: 'h'}
 
@@ -40,7 +41,7 @@ class SSTV(object):
         fmt = '<' + self.BITS_TO_STRUCT[self.bits]
         data = ''.join(struct.pack(fmt, b) for b in self.gen_samples())
         with closing(wave.open(filename, 'wb')) as wav:
-            wav.setnchannels(1)
+            wav.setnchannels(self.nchannels)
             wav.setsampwidth(self.bits // 8)
             wav.setframerate(self.samples_per_sec)
             wav.writeframes(data)
@@ -56,9 +57,11 @@ class SSTV(object):
         amp = max_value / 2
         lowest = -amp
         highest = amp - 1
+        chans = range(self.nchannels)
         for value in self.gen_values():
             sample = int(round(value * amp + alias * (random() - 0.5)))
-            yield max(min(highest, sample), lowest)
+            for chan in chans:
+                yield max(min(highest, sample), lowest)
 
     def gen_values(self):
         """generates samples between -1 and +1 from gen_freq_bits()