112:
signal, and can be treated as an audio signal in regards to distribution. Like audio, LTC can be distributed by standard audio wiring, connectors, distribution amplifiers, and patchbays, and can be ground-isolated with audio transformers. It can also be distributed via 75 ohm video cable and video distribution amplifiers, although the voltage attenuation caused by using a 75 ohm system may cause the signal to drop to a level that can not be read by some equipment.
154:
799:
bit. Since the sync code includes an odd number of 1 bits, it is an odd parity bit over the data.) This keeps the phase of each frame consistent, so it always starts with a rising edge at the beginning of bit 0. This allows seamless splicing of different time codes, and lets it be more easily read
111:
Made up of 80 bits per frame, where there may be 24, 25 or 30 frames per second, LTC timecode varies from 960 Hz (binary zeros at 24 frames/s) to 2400 Hz (binary ones at 30 frames/s), and thus is comfortably in the audio frequency range. LTC can exist as either a balanced or unbalanced
107:
When synchronizing multiple clock-dependent digital devices together with video, such as digital audio recorders, the devices must be connected to a common word clock signal that is derived from the house black burst signal. This can be accomplished by using a generator that generates both black
795:"Polarity correction bit" (bit 59 at 25 frame/s, bit 27 at other rates): this bit is chosen to provide an even number of 0 bits in the whole frame, including the sync code. (Since the frame is an even number of bits long, this implies an even number of 1 bits, and is thus an
807:"Binary group flag" bits BGF0 and BGF2 (bits 27 and 43 at 25 frame/s, bits 43 and 59 at other rates): these indicate the format of the user bits. Both 0 indicates no (or unspecified) format. Only BGF0 set indicates four 8-bit characters (transmitted
819:
The sync pattern in bits 64 through 79 includes 12 consecutive 1 bits, which cannot appear anywhere else in the time code. Assuming all user bits are set to 1, the longest run of 1 bits that can appear elsewhere in the time code is 10, bits 9 to 18
816:
Bit 58, unused in earlier versions of the specification, is now defined as "binary group flag 1" and indicates that the time code is synchronized to an external clock. if zero, the time origin is arbitrary.
108:
burst and video-resolved word clock, or by synchronizing the master digital device to video, and synchronizing all subsequent devices to the word clock output of the master digital device (and to LTC).
766:
numbering is in use; frame numbers 0 and 1 are skipped during the first second of every minute, except multiples of 10 minutes. This converts 30 frame/second time code to the 29.97 frame/second
898:
Recommendation ITU-R BR.780-2: Time and control code standards, for production applications in order to facilitate the international exchange of television programmes on magnetic tapes
54:): a 0 bit has a single transition at the start of the bit period. A 1 bit has two transitions, at the beginning and middle of the period. This encoding is
145:
Longitudinal SMPTE timecode should be played back at a middle-level when recorded on an audio track, as both low and high levels will introduce distortion.
161:
The basic format is an 80-bit code that gives the time of day to the second, and the frame number within the second. Values are stored in
823:
The sync pattern is preceded by 00 and followed by 01. This is used to determine whether an audio tape is running forward or backward.
930:
This is an example of the 25 frame/s bit assignments, which are different from the more commonly seen 30/29.97/24 bit assignments.
115:
Care has to be taken with analog audio to avoid audible 'breakthrough' (aka "crosstalk") from the LTC track to the audio tracks.
103:
In broadcast video situations, the LTC generator should be tied into house black burst, as should all devices using timecode,
843:
84:
The sound of linear timecode is a jarring and distinctive noise and has been used as a sound-effects shorthand to imply
1019:
918:
Indian
Standard IS: 12429 (Part 1) Time and Control Code for Video Tape Recorders: Part 1 Longitudinal Time Code (LTC)
777:
bit, is set to 1 if the time code is synchronized to a color video signal. The frame number modulo 2 (for NTSC and
857:
792:
Bits 27, 43, and 59 differ between 25 frame/s time code, and other frame rates (30, 29.97, or 24). The bits are:
1004:
948:
The time code reader uses the direction sense bits to determine whether the tape is running forward or backward.
940:
165:, least significant bit first. There are thirty-two bits of user data, usually used for a reel number and date.
999:
862:
1014:
925:
867:
833:
763:
590:
786:
916:
162:
8:
1009:
39:
896:
838:
81:
bit, ensures that there are an even number of AC transitions in each timecode frame.
47:
157:
Linear timecode waveform as displayed in
Audacity with 80 bit data frame highlighted
961:
105:
to ensure correct color framing and correct synchronization of all digital clocks.
853:
63:
31:
993:
848:
808:
774:
55:
801:
35:
796:
785:) should be preserved across cuts in order to avoid phase jumps in the
59:
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71:
27:
984:
95:
As of 2019-01-21, this recommendation was withdrawn by ITU-R
46:
track or other storage media. The bits are encoded using the
778:
67:
767:
128:
Never process an LTC with noise reduction, eq or compressor
902:
782:
134:
To create negative time code add one hour to time (avoid
43:
148:
991:
962:"Synchronisation and SMPTE timecode (time code)"
811:). The combinations with BGF2 set are reserved.
77:A special bit in the linear timecode frame, the
98:
38:, as defined in SMPTE 12M specification. The
286:
891:
889:
887:
885:
883:
985:LGPL library to en/decode LTC in software
946:. TimeLine Vista, Inc. 1996. p. 11.
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141:Always put slowest device as a master
959:
125:Avoid percussive sounds close to LTC
844:Control track longitudinal timecode
16:Timecode encoded as an audio signal
13:
14:
1031:
978:
149:Longitudinal timecode data format
62:' which has a special predefined
58:. Each frame is terminated by a '
42:signal is commonly recorded on a
20:Linear (or Longitudinal) Timecode
858:Differential Manchester encoding
960:Rees, Phil (15 November 2013).
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1:
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863:Rewritable consumer timecode
131:Allow pre roll and post roll
7:
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99:Generation and Distribution
10:
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926:Bureau of Indian Standards
868:Vertical interval timecode
215:
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1020:Film and video technology
834:AES-EBU embedded timecode
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79:biphase mark correction
1005:Electrical engineering
928:. 2002 . pp. 1–3.
787:chrominance subcarrier
762:Bit 10 is set to 1 if
169:SMPTE linear timecode
158:
66:relationship with any
1000:Broadcast engineering
156:
163:binary-coded decimal
941:"SMPTR Made Simple"
781:) or modulo 4 (for
631:"Color frame" flag
170:
649:(flag, see below)
643:(flag, see below)
637:(flag, see below)
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1015:Recording devices
839:Burnt-in timecode
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48:biphase mark code
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854:Manchester code
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136:midnight effect
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50:(also known as
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979:External links
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905:. 2005-04-08 .
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32:SMPTE timecode
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849:MIDI timecode
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809:little-endian
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775:color framing
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56:self-clocking
53:
49:
45:
41:
37:
33:
29:
25:
21:
965:. Retrieved
955:
947:
935:
917:
911:
897:
802:oscilloscope
773:Bit 11, the
502:Frame number
235:Frame number
160:
144:
135:
118:
117:
114:
110:
104:
102:
94:
89:
85:
83:
78:
76:
51:
36:audio signal
23:
19:
18:
797:even parity
614:Clock flag
541:tens (0-2)
504:tens (0-2)
34:data in an
994:Categories
967:2016-12-25
874:References
820:inclusive.
764:drop frame
591:Drop frame
295:1111 1101
287:Sync word,
1010:Timecodes
770:standard.
687:User bits
679:User bits
671:User bits
663:User bits
423:User bits
415:User bits
407:User bits
399:User bits
293:0011 1111
289:fixed bit
90:computers
86:telemetry
74:content.
60:sync word
828:See also
800:with an
689:field 8
681:field 6
673:field 4
665:field 2
425:field 7
417:field 5
409:field 3
401:field 1
224:Meaning
213:Meaning
202:Meaning
191:Meaning
180:Meaning
119:LTC care
28:encoding
26:) is an
526:Minutes
513:Seconds
291:pattern
261:Minutes
248:Seconds
593:flag.
530:(0–5)
517:(0–5)
278:(0–9)
265:(0–9)
252:(0–9)
239:(0–9)
210:Weight
199:Weight
188:Weight
177:Weight
944:(PDF)
922:(PDF)
779:SECAM
539:Hours
276:units
274:Hours
263:units
250:units
237:units
221:Value
68:video
40:audio
768:NTSC
611:BGF1
528:tens
515:tens
72:film
64:sync
903:ITU
783:PAL
749:63
746:47
743:31
740:15
729:62
726:46
723:30
720:14
709:61
706:45
703:29
700:13
605:40
599:40
573:20
567:20
561:20
555:20
485:55
482:39
479:23
476:07
465:54
462:38
459:22
456:06
445:53
442:37
439:21
436:05
218:Bit
207:Bit
196:Bit
185:Bit
174:Bit
88:or
70:or
44:VTR
30:of
24:LTC
996::
924:.
901:.
882:^
856:,
755:1
752:79
735:0
732:78
715:1
712:77
695:1
692:76
684:60
676:44
668:28
660:12
655:1
652:75
646:59
640:43
634:27
625:11
620:1
617:74
608:58
602:42
596:26
584:10
579:1
576:73
570:57
564:41
558:25
552:09
547:1
544:72
536:10
533:56
523:10
520:40
510:10
507:24
499:10
496:08
491:1
488:71
471:1
468:70
451:1
448:69
431:1
428:68
420:52
412:36
404:20
396:04
391:1
388:67
385:8
382:51
379:8
376:35
373:8
370:19
367:8
364:03
359:1
356:66
353:4
350:50
347:4
344:34
341:4
338:18
335:4
332:02
327:0
324:65
321:2
318:49
315:2
312:33
309:2
306:17
303:2
300:01
281:64
268:48
255:32
242:16
229:00
121::
92:.
52:FM
970:.
804:.
789:.
628:C
587:D
284:0
271:1
258:1
245:1
232:1
138:)
22:(
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
