Module: Captions::Util

Included in:
Base, Cue
Defined in:
lib/captions/util.rb

Constant Summary collapse

TIMECODE_REGEX =

TC should be HH:MM:SS:FF (frames) or HH:MM:SS.MSC (milliseconds). FF(2 digits) and MSC(3 digits) are optional.

/^-?([01]\d|2[0-3]):[0-5]\d:[0-5]\d(:\d{2}|\.\d{3})?$/

Instance Method Summary collapse

Instance Method Details

#convert_frame_rate(msec, old_fps, new_fps) ⇒ Object

Converts milliseconds calculated in one frame-rate to another frame-rate



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# File 'lib/captions/util.rb', line 46

def convert_frame_rate(msec, old_fps, new_fps)
  old_ms_per_frame = (1000.0 / old_fps)
  new_ms_per_frame = (1000.0 / new_fps)
  frames = (msec / old_ms_per_frame).round  # Number of frames in old fps
  sec = frames / old_fps
  frames = frames % old_fps
  new_frames = sec * new_fps
  new_frames += frames # Number of frames in new fps
  return (new_frames * new_ms_per_frame).round  # MSEC in new fps
end

#convert_to_msec(tc, ms_per_frame = 40) ⇒ Object

Currently considering frame rate as 25 Converts time-code in HH:MM:SS.MSEC (or) HH:MM:SS:FF (or) MM:SS.MSEC to milliseconds.



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# File 'lib/captions/util.rb', line 11

def convert_to_msec(tc, ms_per_frame=40)
  msec = 0
  negative_multiplier = 1
  if tc[0] == '-'
    tc = tc[1..-1]  # remove -ve sign
    negative_multiplier = -1
  end
  tc_split = tc.split('.')
  time_split = tc_split[0].split(':')

  # To handle MM:SS.MSEC format
  if time_split.length == 2
    time_split.unshift('00')
  end

  if tc_split[1]  # msec component exists
    msec = tc_split[1].ljust(3, '0').to_i  # pad with trailing 0s to make it 3 digit
  elsif time_split.length == 4  # FF (frame) component exists
    msec = time_split[-1].to_i * ms_per_frame.to_f
    time_split.pop  # so that below code can work from last index
  end

  min = 60
  hour = min * 60
  # Get HH:MM:SS in seconds
  sec = time_split[-1].to_i
  sec += time_split[-2].to_i * min
  sec += time_split[-3].to_i * hour

  msec += sec * 1000

  return (negative_multiplier * msec.round) # to be consistent with tc_to_frames which also rounds
end

#msec_to_timecode(milliseconds) ⇒ Object

Converts milliseconds to timecode format Currently returns HH:MM:SS.MSEC Supports upto 60 hours



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# File 'lib/captions/util.rb', line 60

def msec_to_timecode(milliseconds)
  seconds = milliseconds / 1000
  msec = milliseconds % 1000
  secs = seconds % 60

  seconds = seconds / 60
  mins = seconds % 60

  seconds = seconds / 60
  hours = seconds % 60

  format("%02d:%02d:%02d.%03d",hours, mins, secs ,msec)
end

#sanitize(time, frame_rate) ⇒ Object

Parses time-code and converts it to milliseconds. If time cannot be converted to milliseconds, it throws InvalidInput Error

Raises:



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# File 'lib/captions/util.rb', line 77

def sanitize(time, frame_rate)
  if time.is_a?(String)
    if TIMECODE_REGEX.match(time)
      time = convert_to_msec(time, frame_rate)
    end
  end
  raise InvalidInput, 'Input should be in Milliseconds or Timecode' unless time.is_a? (Fixnum)
  return time
end