fix merge conflict

LICENSE.txt

@@ -0,0 +1,22 @@
+Copyright (c) 2013 Andras Veres-Szentkiralyi
+
+Permission is hereby granted, free of charge, to any person
+obtaining a copy of this software and associated documentation
+files (the "Software"), to deal in the Software without
+restriction, including without limitation the rights to use,
+copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the
+Software is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.

README.md

@@ -0,0 +1,71 @@
+SSTV generator in pure Python
+=============================
+
+PySSTV generates SSTV modulated WAV files from any image that PIL can open
+(PNG, JPEG, GIF, and many others). These WAV files then can be played by any
+audio player connected to a shortwave radio for example.
+
+My main motivation was to understand the internals of SSTV in practice, so
+performance is far from optimal. I tried keeping the code readable, and only
+performed such optimizations that wouldn't have complicated the codebase.
+
+Command line usage
+------------------
+
+    usage: run.py [-h]
+                  [--mode {MartinM2,MartinM1,Robot24BW,ScottieS2,ScottieS1,Robot8BW}]
+                  [--rate RATE] [--bits BITS]
+                  image.png output.wav
+
+    Converts an image to an SSTV modulated WAV file.
+
+    positional arguments:
+      image.png             input image file name
+      output.wav            output WAV file name
+
+    optional arguments:
+      -h, --help            show this help message and exit
+      --mode {MartinM2,MartinM1,Robot24BW,ScottieS2,ScottieS1,Robot8BW}
+                            image mode (default: Martin M1)
+      --rate RATE           sampling rate (default: 48000)
+      --bits BITS           bits per sample (default: 16)
+
+Python interface
+----------------
+
+The `SSTV` class in the `sstv` module implements basic SSTV-related
+functionality, and the classes of other modules such as `grayscale` and
+`color` extend this. Most instances implement the following methods:
+
+ - `__init__` takes a PIL image, the samples per second, and the bits per
+   sample as a parameter, but doesn't perform any hard calculations
+ - `gen_freq_bits` generates tuples that describe a sine wave segment with
+   frequency in Hz and duration in ms
+ - `gen_values` generates samples between -1 and +1, performing sampling
+   according to the samples per second value given during construction
+ - `gen_samples` generates discrete samples, performing quantization
+   according to the bits per sample value given during construction
+ - `write_wav` writes the whole image to a Microsoft WAV file
+
+The above methods all build upon those above them, for example `write_wav`
+calls `gen_samples`, while latter calls `gen_values`, so typically, only
+the first and the last, maybe the last two should be called directly, the
+others are just listed here for the sake of completeness and to make the
+flow easier to understand.
+
+License
+-------
+
+The whole project is available under MIT license.
+
+Useful links
+------------
+
+ - receive-only "counterpart": https://github.com/windytan/slowrx
+ - free SSTV handbook: http://www.sstv-handbook.com/
+
+Dependencies
+------------
+
+ - Python 2.7 (tested on 2.7.5)
+ - Python Imaging Library (Debian/Ubuntu package: `python-imaging`)

color.py

@@ -70,3 +70,5 @@ class ScottieS2(ScottieS1):
 	VIS_CODE = 0x38
 	SCAN = 88.064 - ScottieS1.INTER_CH_GAP
 	WIDTH = 160
+
+MODES = (MartinM1, MartinM2, ScottieS1, ScottieS2)

grayscale.py

@@ -26,8 +26,8 @@ class Robot8BW(GrayscaleSSTV):
 	VIS_CODE = 0x02
 	WIDTH = 160
 	HEIGHT = 120
-	SYNC = 10
-	SCAN = 56
+	SYNC = 7
+	SCAN = 60
 
 
 class Robot24BW(GrayscaleSSTV):
@@ -36,3 +36,5 @@ class Robot24BW(GrayscaleSSTV):
 	HEIGHT = 240
 	SYNC = 12
 	SCAN = 93
+
+MODES = (Robot8BW, Robot24BW)

run.py

@@ -0,0 +1,44 @@
+#!/usr/bin/env python
+
+from __future__ import print_function
+from PIL import Image
+from argparse import ArgumentParser
+from sys import stderr
+import color, grayscale
+
+SSTV_MODULES = [color, grayscale]
+
+def main():
+	module_map = build_module_map()
+	parser = ArgumentParser(
+			description='Converts an image to an SSTV modulated WAV file.')
+	parser.add_argument('img_file', metavar='image.png',
+			help='input image file name')
+	parser.add_argument('wav_file', metavar='output.wav',
+			help='output WAV file name')
+	parser.add_argument('--mode', dest='mode', default='MartinM1', choices=module_map,
+			help='image mode (default: Martin M1)')
+	parser.add_argument('--rate', dest='rate', type=int, default=48000,
+			help='sampling rate (default: 48000)')
+	parser.add_argument('--bits', dest='bits', type=int, default=16,
+			help='bits per sample (default: 16)')
+	args = parser.parse_args()
+	image = Image.open(args.img_file)
+	mode = module_map[args.mode]
+	if not all(i >= m for i, m in zip(image.size, (mode.WIDTH, mode.HEIGHT))):
+		print(('Image must be at least {m.WIDTH} x {m.HEIGHT} pixels '
+				'for mode {m.__name__}').format(m=mode), file=stderr)
+		raise SystemExit(1)
+	s = mode(image, args.rate, args.bits)
+	s.write_wav(args.wav_file)
+
+def build_module_map():
+	module_map = {}
+	for module in SSTV_MODULES:
+		for mode in module.MODES:
+			module_map[mode.__name__] = mode
+	return module_map
+
+
+if __name__ == '__main__':
+	main()

sstv.py

@@ -3,7 +3,8 @@
 from __future__ import division, with_statement
 from math import sin, pi, floor
 from random import random
-import struct
+from contextlib import closing
+import struct, wave
 
 FREQ_VIS_BIT1 = 1100
 FREQ_SYNC = 1200
@@ -25,23 +26,13 @@ class SSTV(object):
 
 	BITS_TO_STRUCT = {8: 'b', 16: 'h'}
 	def write_wav(self, filename):
-		bytes_per_sec = self.bits // 8
 		fmt = '<' + self.BITS_TO_STRUCT[self.bits]
 		data = ''.join(struct.pack(fmt, b) for b in self.gen_samples())
-		payload = ''.join((
-				'WAVE',
-				'fmt ',
-				struct.pack('<IHHIIHH', 16, 1, 1, self.samples_per_sec,
-					self.samples_per_sec * bytes_per_sec, bytes_per_sec,
-					self.bits),
-				'data',
-				struct.pack('<I', len(data))
-				))
-		header = 'RIFF' + struct.pack('<I', len(payload) + len(data))
-		with file(filename, 'wb') as wav:
-			wav.write(header)
-			wav.write(payload)
-			wav.write(data)
+		with closing(wave.open(filename, 'wb')) as wav:
+			wav.setnchannels(1)
+			wav.setsampwidth(self.bits // 8)
+			wav.setframerate(self.samples_per_sec)
+			wav.writeframes(data)
 
 	def gen_samples(self):
 		"""generates bits from gen_values"""
@@ -93,11 +84,3 @@ class SSTV(object):
 
 def byte_to_freq(value):
 	return FREQ_BLACK + FREQ_RANGE * value / 255
-
-
-if __name__ == '__main__':
-	from PIL import Image
-	from color import MartinM1
-	image = Image.open('320x256.png')
-	s = MartinM1(image, 48000, 16)
-	s.write_wav('test.wav')