Add a waveform streamer

scripts/itm-to-pcm.py

@@ -9,11 +9,25 @@ itm-to-pcm.py dump.txt dump.wav
 import wave
 import sys
 
-def read_itm(file_in):
+class Fifo(object):
+    def __init__(self, size):
+        self._size = size
+        self._buffer = []
+
+    def append(self, v):
+        self._buffer.append(v)
+        if len(self._buffer) > self._size:
+            del self._buffer[0]
+
+    def list(self):
+        return self._buffer
+
+def stream_itm(file_in):
+    #f = open(file_in, 'rb')
     f = open(file_in, 'rb')
     while True:
         samples = f.read(2)
-        if not samples: break
+        if len(samples) < 2: break
         #if len(set(samples)) != 1: continue # corrupted
         #yield samples[0]
         yield samples[0] + 0x100*samples[1]
@@ -25,6 +39,20 @@ def read_itm(file_in):
     #    except:
     #        pass
 
+def med_filt_stream(stream, kernel=5):
+    # n.b. introduces a delay of kernel/2
+    accum = Fifo(kernel)
+    for f in stream:
+        accum.append(f)
+        yield median(accum.list())
+
+def dc_filt_stream(stream, kernel=2):
+    accum = Fifo(kernel)
+    for f in stream:
+        accum.append(f)
+        dc = sum(accum.list()) / len(accum.list())
+        yield f - dc
+
 def frames_from_samples(itm):
     b = bytearray()
     for sample in itm:
@@ -36,35 +64,44 @@ def frames_from_samples(itm):
 
     return b
 
-def clean_frames(frames):
-    # Run a median filter over the frames to clean outliers:
-    post_med = [0]*len(frames)
-    for i, _ in enumerate(frames):
-        left = max(0, i-2)
-        right = min(len(frames), i+3)
-        post_med[i] = median(frames[left:right])
-    # Remove DC component
-    dc = sum(post_med) / len(post_med)
-    post_dc = [f - dc for f in post_med]
-    # Amplify to [-0x7fff, 0x7fff]
-    prev_max = max(abs(f) for f in post_dc)
-    amp_factor = 0x7fff / prev_max
-    post_amp = [f*amp_factor for f in post_dc]
-    # Round to int
-    return [int(round(f)) for f in post_amp]
-
 def median(samples):
     x = list(sorted(samples))
     return x[len(x) // 2]
 
-def main():
+def stream_to_wav(file_in, file_out):
-    _self, file_in, file_out = sys.argv
+    # broken
-    itm = clean_frames(list(read_itm(file_in)))
+    itm_stream = stream_itm(file_in)
+    clean_stream = dc_filt_stream(med_filt_stream(itm_stream))
     wave_out = wave.open(file_out, 'wb')
     wave_out.setnchannels(1)
     wave_out.setsampwidth(2)
     wave_out.setframerate(1000)
-    wave_out.writeframes(frames_from_samples(itm))
+    wave_out.writeframes(frames_from_samples(list(clean_stream)))
+
+def stream_to_term(file_in):
+    stream = dc_filt_stream(med_filt_stream(stream_itm(file_in)))
+    for f in stream:
+        print(ansi_rgb(color_for_sample(f), '█'), end='')
+
+def ansi_rgb(color, text):
+    r, g, b = color
+    return '\033[38;2;{r};{g};{b}m{text}\033[0m'.format(**locals())
+
+def color_for_sample(sample):
+    r, g, b = 0, 0, 0
+    if sample < 0:
+        b = int(-sample)
+    else:
+        r = int(sample)
+    #return (128, 0, 0)
+    return r, g, b
+
+def main():
+    if len(sys.argv) == 3:
+        _self, file_in, file_out = sys.argv
+        stream_to_wav(file_in, file_out)
+    if len(sys.argv) == 1:
+        stream_to_term('/dev/stdin')
 
 if __name__ == "__main__":
     main()