Parse ffprobe keyframe output

kf.py

'''
 # Parse ffprobe keyframe output

 Run with 

     ffprobe -loglevel error -show_entries packet=pts_time,flags -of csv=print_section=0 -i <input file or stream> | python kf.py

 See  https://stackoverflow.com/a/18088156

'''

import sys

def delta_ms(timestamps):
  it = iter(timestamps)
  previous = next(it)
  for timestamp in it:
    yield int(1000 * (timestamp - previous)) # milliseconds
    previous = timestamp

def parse_keyframes(lines):
  for line in (raw.strip() for raw in lines):
    if len(line) == 0:
      continue

    #print(f"line ({len(line)}): {line}")

    ts, flags = line.split(',')
    if 'K' in flags:
        # confirmed it's a keyframe
        yield float(ts) # seconds

def main():
  for delta in delta_ms(parse_keyframes(sys.stdin)):
    print(f"{delta} ms")

if __name__ == '__main__':
  main()