fix_timestamps.py

import logging
logger = logging.getLogger()
import numpy as np
from scipy.interpolate import UnivariateSpline
import sys

def sanitize_timestamps(ts):
    logger.debug("Checking %s timestamps for monotony in direction and smoothness"%ts.shape[0])
    avg_frame_time = (ts[-1] - ts[0])/ts.shape[0]
    logger.debug('average_frame_time: %s'%(1./avg_frame_time))

    raw_ts = ts #only needed for visualization
    runs = 0
    while True:
        #forward check for non monotonic increasing behaviour
        clean = np.ones((ts.shape[0]),dtype=np.bool)
        damper  = 0
        for idx in range(ts.shape[0]-1):
            if ts[idx] >= ts[idx+1]: #not monotonically increasing timestamp
                damper = 50
            clean[idx] = damper <= 0
            damper -=1

        #backward check to smooth timejumps forward
        damper  = 0
        for idx in range(ts.shape[0]-1)[::-1]:
            if ts[idx+1]-ts[idx]>1: #more than one second forward jump
                damper = 50
            clean[idx] &= damper <= 0
            damper -=1

        if clean.all() == True:
            if runs >0:
                logger.debug("Timestamps were bad but are ok now. Correction runs: %s"%runs)
                # from matplotlib import pyplot as plt
                # plt.plot(frames,raw_ts)
                # plt.plot(frames,ts)
                # # plt.scatter(frames[~clean],ts[~clean])
                # plt.show()
            else:
                logger.debug("Timestamps are clean.")
            return ts

        runs +=1
        if runs > 4:
            logger.error("Timestamps could not be fixed!")
            return ts

        logger.warning("Timestamps are not sane. We detected non monotitc or jumpy timestamps. Fixing them now")
        frames = np.arange(len(ts))
        s = UnivariateSpline(frames[clean],ts[clean],s=0)
        ts = s(frames)

if __name__ == '__main__':
    logging.basicConfig(level=logging.DEBUG)
    ts_file_path = sys.argv[1]
    ts_file = np.load(ts_file_path)
    ts_file = sanitize_timestamps(ts_file)
    np.save(ts_file_path,ts_file)