scope.py

#!/usr/bin/env python
import numpy as np
import cv2
import sys
import scipy.io.wavfile
import scipy.signal


MIDDLE_RANGE = 2**15
ARBITRARY_MAX_RANGE = 65600  # we use 65600 instead of 65536 so we don't go off the edge
MAGIC_NUMBER = 48000

FRAME_RATE = 20

DIMENSION = 800


def sample_to_xy(x0, y0):
    """
    bias towards the middle of the image
    """
    x1 = int((MIDDLE_RANGE - x0) * (DIMENSION / ARBITRARY_MAX_RANGE))
    y1 = int((MIDDLE_RANGE - x1) * (DIMENSION / ARBITRARY_MAX_RANGE))
    return x1, y1


if __name__ == '__main__':
    _, IN_FILE, OUT_FILE = sys.argv
    # Needs to be a regular wav file, not wavex
    # Also, assuming PCM, 2 channels, 16-bit
    fs, data = scipy.io.wavfile.read(IN_FILE, 'rb')

    print('data shape: {}'.format(data.shape))

    if False:
        ratio = int(fs / MAGIC_NUMBER)
        new_fs = fs / ratio
        print('fs was {} decimating to {}'.format(fs, new_fs))
        fs = new_fs
        data = scipy.signal.decimate(data, ratio, axis=0)

    print('data shape: {}'.format(data.shape))

    # create an empty dimension x dimension bgr image
    vis = np.zeros((DIMENSION, DIMENSION, 3), np.uint8)

    fourcc = cv2.VideoWriter_fourcc(*'XVID')
    vwobj = cv2.VideoWriter(OUT_FILE, fourcc, FRAME_RATE, (DIMENSION, DIMENSION))

    samples_per_frame = int(fs / FRAME_RATE)

    total_samples = data.shape[0]

    print('Starting loop {} total samples'.format(total_samples))
    print('{} samples per frame'.format(samples_per_frame))

    old_point = (0, 0)

    for sample_count, sample_pair in enumerate(data):
        point = sample_to_xy(*sample_pair)

        # Draw a green line segment from old_point to point
        cv2.line(vis, old_point, point, (0, 255, 0))
        old_point = point
        if (sample_count % 1000) == 0:
            print('{} samples so far'.format(sample_count))
        if (sample_count % samples_per_frame) == 0:
            cv2.imshow('foo', vis)
            cv2.waitKey(1)
            print('Frame out {} samples so far'.format(sample_count))
        vwobj.write(vis)
        vis *= 0.5