Class: Timecode

Inherits:
Object
  • Object
show all
Includes:
Comparable
Defined in:
lib/timecode.rb

Overview

Timecode is a convenience object for calculating SMPTE timecode natively. The promise is that you only have to store two values to know the timecode - the amount of frames and the framerate. An additional perk might be to save the dropframeness, but we avoid that at this point.

You can calculate in timecode objects ass well as with conventional integers and floats. Timecode is immutable and can be used as a value object. Timecode objects are sortable.

Here’s how to use it with ActiveRecord (your column names will be source_tc_frames_total and tape_fps)

composed_of :source_tc, :class_name => 'Timecode',
  :mapping => [%w(source_tc_frames total), %w(tape_fps fps)]

Defined Under Namespace

Classes: CannotParse, Error, RangeError, TimecodeLibError, WrongFramerate

Constant Summary collapse

VERSION = 
'0.1.4'
DEFAULT_FPS = 
25.0
NTSC_FPS =

:stopdoc:

(30.0 * 1000 / 1001).freeze
ALLOWED_FPS_DELTA = 
(0.001).freeze
COMPLETE_TC_RE = 
/^(\d{2}):(\d{2}):(\d{2}):(\d{2})$/
DF_TC_RE = 
/^(\d{1,2}):(\d{1,2}):(\d{1,2});(\d{2})$/
FRACTIONAL_TC_RE = 
/^(\d{2}):(\d{2}):(\d{2}).(\d{1,8})$/
WITH_FRACTIONS_OF_SECOND = 
"%02d:%02d:%02d.%02d"
WITH_FRAMES = 
"%02d:%02d:%02d:%02d"
TIME_FIELDS =

:nodoc:

7

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(total = 0, fps = DEFAULT_FPS) ⇒ Timecode

Initialize a new Timecode object with a certain amount of frames and a framerate will be interpreted as the total number of frames

Raises:



50
51
52
53
54
55
56
57
58
59
 
# File 'lib/timecode.rb', line 50

def initialize(total = 0, fps = DEFAULT_FPS)
  raise WrongFramerate, "FPS cannot be zero" if fps.zero?
  
  # If total is a string, use parse
  raise RangeError, "Timecode cannot be negative" if total.to_i < 0
  # Always cast framerate to float, and num of rames to integer
  @total, @fps = total.to_i, fps.to_f
  @value = validate!
  freeze
end

Class Method Details

.at(hrs, mins, secs, frames, with_fps = DEFAULT_FPS) ⇒ Object

Initialize a Timecode object at this specfic timecode



133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
 
# File 'lib/timecode.rb', line 133

def at(hrs, mins, secs, frames, with_fps = DEFAULT_FPS)
  case true
    when hrs > 99
      raise RangeError, "There can be no more than 99 hours, got #{hrs}"
    when mins > 59
      raise RangeError, "There can be no more than 59 minutes, got #{mins}"
    when secs > 59
      raise RangeError, "There can be no more than 59 seconds, got #{secs}"
    when frames > (with_fps -1)
      raise RangeError, "There can be no more than #{with_fps -1} frames @#{with_fps}, got #{frames}"
  end

  total = (hrs*(60*60*with_fps) +  mins*(60*with_fps) + secs*with_fps + frames).round
  new(total, with_fps)
end

.from_seconds(seconds_float, the_fps = DEFAULT_FPS) ⇒ Object

create a timecode from the number of seconds. This is how current time is supplied by QuickTime and other systems which have non-frame-based timescales



165
166
167
168
 
# File 'lib/timecode.rb', line 165

def from_seconds(seconds_float, the_fps = DEFAULT_FPS)
  total_frames = (seconds_float.to_f * the_fps.to_f).ceil
  new(total_frames, the_fps)
end

.from_uint(uint, fps = DEFAULT_FPS) ⇒ Object

Some systems (like SGIs) and DPX format store timecode as unsigned integer, bit-packed. This method unpacks such an integer into a timecode.



172
173
174
175
176
177
178
179
 
# File 'lib/timecode.rb', line 172

def from_uint(uint, fps = DEFAULT_FPS)
  tc_elements = (0..7).to_a.reverse.map do | multiplier | 
    ((uint >> (multiplier * 4)) & 0x0F)
  end.join.scan(/(\d{2})/).flatten.map{|e| e.to_i}

  tc_elements << fps
  at(*tc_elements)
end

.new(from, fps = DEFAULT_FPS) ⇒ Object

Use initialize for integers and parsing for strings



70
71
72
 
# File 'lib/timecode.rb', line 70

def new(from, fps = DEFAULT_FPS)
  from.is_a?(String) ? parse(from, fps) : super(from, fps)
end

.parse(input, with_fps = DEFAULT_FPS) ⇒ Object

Parse timecode entered by the user. Will raise if the string cannot be parsed. The following formats are supported:

  • 10h 20m 10s 1f (or any combination thereof) - will be disassembled to hours, frames, seconds and so on automatically

  • 123 - will be parsed as 00:00:01:23

  • 00:00:00:00 - will be parsed as zero TC

Raises:



84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
 
# File 'lib/timecode.rb', line 84

def parse(input, with_fps = DEFAULT_FPS)
  # Drop frame goodbye
  raise Error, "We do not support drop frame" if (input =~ /\;/)
  
  hrs, mins, secs, frames = 0,0,0,0
  atoms = []
  
  # 00:00:00:00
  if (input =~ COMPLETE_TC_RE)
    atoms = input.scan(COMPLETE_TC_RE).to_a.flatten
  # 00:00:00.0
  elsif input =~ FRACTIONAL_TC_RE
    parse_with_fractional_seconds(input, with_fps)
  # 10h 20m 10s 1f
  elsif input =~ /\s/
    return input.split.map{|part|  parse(part, with_fps) }.inject { |sum, p| sum + p.total }
  # 10s
  elsif input =~ /^(\d+)s$/
    return new(input.to_i * with_fps, with_fps)
  # 10h
  elsif input =~ /^(\d+)h$/i
    return new(input.to_i * 60 * 60 * with_fps, with_fps)
  # 20m
  elsif input =~ /^(\d+)m$/i
    return new(input.to_i * 60 * with_fps, with_fps)
  # 60f - 60 frames, or 2 seconds and 10 frames
  elsif input =~ /^(\d+)f$/i
    return new(input.to_i, with_fps)
  # A bunch of integers
  elsif (input =~ /^(\d+)$/)
    ints = input.split(//)
    atoms.unshift [ints.pop, ints.pop].reverse.join.to_i
    atoms.unshift [ints.pop, ints.pop].reverse.join.to_i
    atoms.unshift [ints.pop, ints.pop].reverse.join.to_i
    atoms.unshift [ints.pop, ints.pop].reverse.join.to_i
  else
    raise CannotParse, "Cannot parse #{input} into timecode, no match"
  end
  
  if atoms.any?
    hrs, mins, secs, frames = atoms.map{|e| e.to_i}
  else
    raise CannotParse, "Cannot parse #{input} into timecode, atoms were empty"
  end
  
  at(hrs, mins, secs, frames, with_fps)
end

.parse_with_fractional_seconds(tc_with_fractions_of_second, fps = DEFAULT_FPS) ⇒ Object

Parse a timecode with fractional seconds instead of frames. This is how ffmpeg reports a timecode



151
152
153
154
155
156
157
158
159
160
161
 
# File 'lib/timecode.rb', line 151

def parse_with_fractional_seconds(tc_with_fractions_of_second, fps = DEFAULT_FPS)
  fraction_expr = /\.(\d+)$/
  fraction_part = ('.' + tc_with_fractions_of_second.scan(fraction_expr)[0][0]).to_f

  seconds_per_frame = 1.0 / fps.to_f
  frame_idx = (fraction_part / seconds_per_frame).floor

  tc_with_frameno = tc_with_fractions_of_second.gsub(fraction_expr, ":%02d" % frame_idx)

  parse(tc_with_frameno, fps)
end

.soft_parse(input, with_fps = DEFAULT_FPS) ⇒ Object

Parse timecode and return zero if none matched



75
76
77
 
# File 'lib/timecode.rb', line 75

def soft_parse(input, with_fps = DEFAULT_FPS)
  parse(input) rescue new(0, with_fps)
end

Instance Method Details

#*(arg) ⇒ Object

Multiply the timecode by a number

Raises:



277
278
279
280
 
# File 'lib/timecode.rb', line 277

def *(arg)
  raise RangeError, "Timecode multiplier cannot be negative" if (arg < 0)
  Timecode.new(@total*arg.to_i, @fps)
end

#+(arg) ⇒ Object

add number of frames (or another timecode) to this one



255
256
257
258
259
260
261
262
263
 
# File 'lib/timecode.rb', line 255

def +(arg)
  if (arg.is_a?(Timecode) && framerate_in_delta(arg.fps, @fps))
    Timecode.new(@total+arg.total, @fps)
  elsif (arg.is_a?(Timecode))
    raise WrongFramerate, "You are calculating timecodes with different framerates"
  else
    Timecode.new(@total + arg, @fps)
  end
end

#-(arg) ⇒ Object

Subtract a number of frames



266
267
268
269
270
271
272
273
274
 
# File 'lib/timecode.rb', line 266

def -(arg)
  if (arg.is_a?(Timecode) &&  framerate_in_delta(arg.fps, @fps))
    Timecode.new(@total-arg.total, @fps)
  elsif (arg.is_a?(Timecode))
    raise WrongFramerate, "You are calculating timecodes with different framerates"
  else
    Timecode.new(@total-arg, @fps)
  end
end

#/(arg) ⇒ Object

Get the number of times a passed timecode fits into this time span (if performed with Timecode) or a Timecode that multiplied by arg will give this one



289
290
291
 
# File 'lib/timecode.rb', line 289

def /(arg)
  arg.is_a?(Timecode) ?  (@total / arg.total) : Timecode.new(@total /arg, @fps)
end

#<=>(other_tc) ⇒ Object

Timecodes can be compared to each other



294
295
296
297
298
299
300
 
# File 'lib/timecode.rb', line 294

def <=>(other_tc)
  if other_tc.is_a?(Timecode) && framerate_in_delta(fps, other_tc.fps)
    self.total <=> other_tc.total
  else
    self.total <=> other_tc
  end
end

#convert(new_fps) ⇒ Object

Convert to different framerate based on the total frames. Therefore, 1 second of PAL video will convert to 25 frames of NTSC (this is suitable for PAL to film TC conversions and back).



235
236
237
 
# File 'lib/timecode.rb', line 235

def convert(new_fps)
  self.class.new(@total, new_fps)
end

#fps ⇒ Object

get FPS



193
194
195
 
# File 'lib/timecode.rb', line 193

def fps
  @fps
end

#frame_interval ⇒ Object

get frame interval in fractions of a second



218
219
220
 
# File 'lib/timecode.rb', line 218

def frame_interval
  1.0/@fps
end

#framerate_in_delta(one, two) ⇒ Object

Validate that framerates are within a small delta deviation considerable for floats



314
315
316
 
# File 'lib/timecode.rb', line 314

def framerate_in_delta(one, two)
  (one.to_f - two.to_f).abs <= ALLOWED_FPS_DELTA
end

#frames ⇒ Object

get the number of frames



198
199
200
 
# File 'lib/timecode.rb', line 198

def frames
  value_parts[3]
end

#hours ⇒ Object

get the number of hours



213
214
215
 
# File 'lib/timecode.rb', line 213

def hours
  value_parts[0]
end

#inspect ⇒ Object

:nodoc:



61
62
63
 
# File 'lib/timecode.rb', line 61

def inspect # :nodoc:
  "#<Timecode:%s (%dF@%.2f)>" % [to_s, total, fps]
end

#minutes ⇒ Object

get the number of minutes



208
209
210
 
# File 'lib/timecode.rb', line 208

def minutes
  value_parts[1]
end

#seconds ⇒ Object

get the number of seconds



203
204
205
 
# File 'lib/timecode.rb', line 203

def seconds
  value_parts[2]
end

#succ ⇒ Object

Get the next frame



283
284
285
 
# File 'lib/timecode.rb', line 283

def succ
  self.class.new(@total + 1, @fps)
end

#to_f ⇒ Object

get total frames as float



245
246
247
 
# File 'lib/timecode.rb', line 245

def to_f
  @total
end

#to_i ⇒ Object

get total frames as integer



250
251
252
 
# File 'lib/timecode.rb', line 250

def to_i
  @total
end

#to_s ⇒ Object

get formatted SMPTE timecode



240
241
242
 
# File 'lib/timecode.rb', line 240

def to_s
  WITH_FRAMES % value_parts
end

#to_uint ⇒ Object

get the timecode as bit-packed unsigned 32 bit int (suitable for DPX and SGI)



223
224
225
226
227
228
229
230
 
# File 'lib/timecode.rb', line 223

def to_uint
  elements = (("%02d" * 4) % [hours,minutes,seconds,frames]).split(//).map{|e| e.to_i }
  uint = 0
  elements.reverse.each_with_index do | p, i |
    uint |= p << 4 * i 
  end
  uint
end

#total ⇒ Object

get total frame count



188
189
190
 
# File 'lib/timecode.rb', line 188

def total
  to_f
end

#with_frames_as_fraction ⇒ Object Also known as: with_fractional_seconds

FFmpeg expects a fraction of a second as the last element instead of number of frames. Use this method to get the timecode that adheres to that expectation. The return of this method can be fed to ffmpeg directly.

Timecode.parse("00:00:10:24", 25).with_frames_as_fraction #=> "00:00:10.96"



306
307
308
309
310
 
# File 'lib/timecode.rb', line 306

def with_frames_as_fraction
  vp = value_parts.dup
  vp[-1] = (100.0 / @fps) * vp[-1]
  WITH_FRACTIONS_OF_SECOND % vp
end

#zero? ⇒ Boolean

is the timecode at 00:00:00:00

Returns:

  • (Boolean) 


183
184
185
 
# File 'lib/timecode.rb', line 183

def zero?
  @total.zero?
end