CA1135840A - Apparatus for generating time code signals - Google Patents
Apparatus for generating time code signalsInfo
- Publication number
- CA1135840A CA1135840A CA000325717A CA325717A CA1135840A CA 1135840 A CA1135840 A CA 1135840A CA 000325717 A CA000325717 A CA 000325717A CA 325717 A CA325717 A CA 325717A CA 1135840 A CA1135840 A CA 1135840A
- Authority
- CA
- Canada
- Prior art keywords
- time code
- signal
- bit
- recording
- code signal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/14—Digital recording or reproducing using self-clocking codes
- G11B20/1403—Digital recording or reproducing using self-clocking codes characterised by the use of two levels
- G11B20/1407—Digital recording or reproducing using self-clocking codes characterised by the use of two levels code representation depending on a single bit, i.e. where a one is always represented by a first code symbol while a zero is always represented by a second code symbol
- G11B20/1419—Digital recording or reproducing using self-clocking codes characterised by the use of two levels code representation depending on a single bit, i.e. where a one is always represented by a first code symbol while a zero is always represented by a second code symbol to or from biphase level coding, i.e. to or from codes where a one is coded as a transition from a high to a low level during the middle of a bit cell and a zero is encoded as a transition from a low to a high level during the middle of a bit cell or vice versa, e.g. split phase code, Manchester code conversion to or from biphase space or mark coding, i.e. to or from codes where there is a transition at the beginning of every bit cell and a one has no second transition and a zero has a second transition one half of a bit period later or vice versa, e.g. double frequency code, FM code
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
- G11B27/02—Editing, e.g. varying the order of information signals recorded on, or reproduced from, record carriers
- G11B27/022—Electronic editing of analogue information signals, e.g. audio or video signals
- G11B27/024—Electronic editing of analogue information signals, e.g. audio or video signals on tapes
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
- G11B27/02—Editing, e.g. varying the order of information signals recorded on, or reproduced from, record carriers
- G11B27/022—Electronic editing of analogue information signals, e.g. audio or video signals
- G11B27/028—Electronic editing of analogue information signals, e.g. audio or video signals with computer assistance
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
- G11B27/02—Editing, e.g. varying the order of information signals recorded on, or reproduced from, record carriers
- G11B27/022—Electronic editing of analogue information signals, e.g. audio or video signals
- G11B27/029—Insert-editing
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
- G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
- G11B27/19—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier
- G11B27/28—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording
- G11B27/32—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording on separate auxiliary tracks of the same or an auxiliary record carrier
- G11B27/322—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording on separate auxiliary tracks of the same or an auxiliary record carrier used signal is digitally coded
- G11B27/323—Time code signal, e.g. on a cue track as SMPTE- or EBU-time code
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B2220/00—Record carriers by type
- G11B2220/90—Tape-like record carriers
Abstract
ABSTRACT OF THE DISCLOSURE
An apparatus for generating a recording time code signal having a time code data signal generator and a time code signal forming circuit which is supplied with a time code data signal from the time code data signal generator and produces a recording time code signal consisting of bi-phase coded signals, in which the above recording time code signal is corresponded to an information signal and then recorded on a recording medium continuously at word unit. In this case, the polarity of a speci-fic bit signal of a fixed binary bit or value in the above recording time code signal of word unit is discriminated, and a changing circuit is provided in the time code signal forming circuit which changing circuit changes the above fixed binary bit in accordance with the polarity of the specific bit signal. Thus, a recording time code signal of word unit, which has a constant polarity of bit signals after the above specific bit signal, is derived from the time code signal forming circuit.
An apparatus for generating a recording time code signal having a time code data signal generator and a time code signal forming circuit which is supplied with a time code data signal from the time code data signal generator and produces a recording time code signal consisting of bi-phase coded signals, in which the above recording time code signal is corresponded to an information signal and then recorded on a recording medium continuously at word unit. In this case, the polarity of a speci-fic bit signal of a fixed binary bit or value in the above recording time code signal of word unit is discriminated, and a changing circuit is provided in the time code signal forming circuit which changing circuit changes the above fixed binary bit in accordance with the polarity of the specific bit signal. Thus, a recording time code signal of word unit, which has a constant polarity of bit signals after the above specific bit signal, is derived from the time code signal forming circuit.
Description
BACKGROUND OF THE INVENTION
This invention relates to appiaratus for generatillg coded characters and, more particularly, to such apparatus wherein a bi-phase coded character is generated ha~ing a constant relation between the phases at the beginning and end of each coded chiaracter regardless of the number o~ "1 " s and "0" s included in that character.
In accordance witn a specific aspect of this invention, an SMPTE time code character is generated having ~ level transition at the start thereof which is of the sanrle phase, or polarity, as the leveI transition at the end thereot.
With the advent of lrideo recording alld playback devices9 such as the ~ideo tape recorder (VTR~9 ~arious situations may arise wh~rein a recorded medium, such as recorded video tape, should be edited such that a certain iniormation thereon is replac0d by other, desired infor-~ ~ mation, or that a certialn additional information is recorded immediately *~1 2 :~L13~
, following a previously recorded segment. The former editing ope-ration is known as an insert edit whereinJ for example, one or more frames of video signals which are recorded on one video tape are replaced by an equal number of l~rames of video signals which has been recorded on another video tape. The latter edit operation is known as an assemble edit where-in one of more frames of video signals which had been recorded on another video tape are transferred, or re~recorded, onto the main video tapeJ
whereby an entire program may be "assembled".
As may be appreciated, in order to carry out an insert edit or an assemble edit operationJ that is, an operation wherein video signals which had been recorded on a secondary tape are transferredJ or re-recorded, onto a primary tape J two separate VrrR ' s are needed for controlling the respective playback and recording operations of the seconclary and primary tapes. The secondary VTR must be operated to ascertain those frames containing the video information which must be transferred to the primary tape and the primary VTR must be controlled so as to ascertain the precise location on the primary tape at which the secondary information is to be recorded. FurthermoreJ both VTR ' s must be operated in synchronism with each other.
In order to facilitate such editing operationsJ and particularly, to identify the specific frames of video signals which are to be edited, a standardi~ed code has been de~eloped, known as the SMPTE time code~
This SMPTE time code is a serial code formed of a predetermined number of binary bits which are recorded as phase-modulated, or bi-phase signals.
In accordance with the present standardJ the SMPTE time code cvntains eighty bi-phase bits which representJ in BCD format~ an inclication of the time at which each frame of ~ideo signals is recorded, a frame count and optional binary word information. This time code also includes a sixteen bit synchroni~ing word and a number of so called binary groups which may be used either for future information or as the user of the video , . .~. . . . . :
tape so desires. A more complete description of this ~MPTE
time code is described in "Standardization for Time and ~ontrol Code for Video Tape and Audio Recorders" by E~ K. Dahlin, I)ecember 1970, Journal of the S~IPTE, Volurnne 79~ page 1086. Another proposal for a standardized time code for viàeo recording is the EBU time code .
In the bi-phase representation of binary bits, the beginning of each bit period is marked by a level transition, either a positive transition ïrom a lower to a higher level or a negative transitionO
A binary "1 " is represented by yet another level transition during the bit period, while a binary "0" is represented by the absence of any additional bit transitions throughout the bit period. In recording the SMPTE time code on a video tape~ the bi-phase signals are record-ed in seriatum along a longitudinal edge of the tape such that the begin-ning of an SMPTE character starts at the beginning of the frame of video signals and ends at the end of that frame of signals. Thus, the end of one SMPTE character is coincident with the beginning of the next following SMPTE character,. Accordingly, it is important that the phase of the beginning of an SMPTE character, that is, the direction of the level transition at the start of the SMPTE character, be con-sistent, or compatible, with the phase at the end of the preceding SMPTE
character. This means that if the preceding SMPIE character ends with a negative-going transition, the next following SMPTE character should start with a negative-going transition.
In the insert edit operation wherein video signals which had been recorded on the primary tape are replaced by ~ideo si~nals which are played back from the secondary tape, that is, the secondary video signals are "insertec~" between two existing segments on the primary tape, the SMPTE time code characters which had been recorded for the particular segment on the primary tape which is being replaced ~ l n~rmally remain on the primary tape. Thus, in the insert edit opera tion, there is no change in the recorded SMPTE characters and, there-fore, there is no problem in making sure that the phase at the end of a preceding SMPTE character is compatible with the phase at the begin-ning of the next following SMPTE character. However, in the assemble edit operation, a new SMPTE time code is recorded together with the new video signals which are recorded from the secondary video tape~ Since the new SMPTE time code characters are not recorded during the same operation that the preceding SMPTE time code charac-ters were recorded! it is possible `that tlle phase at the beginning oî
a new character may not be compatible with the phase at the end of the preceding, previously recorded character. It has been thought that this problem can be solved by, for examplel reading the next-to last SMPTE time code character which is recorded on the primary tape just prior to the assemble edit location thereon and then interpolate the information represented by the read character such that the content of ;-the last character can be ascertained, and thus the phase at the end of that last character will be known. Once this phase is known, the new SMPTE time code characters can be generated so as to be compatible therewith. However, this assumes that the last few frames of the previously recorded video signals on the primary tape has been recorded in successionO Thus, the frame count contained in the last character will be one greater than the frame count included in the preceding charac-ter, and so on. This technique is not successful if successive frames of video signals are assembled on a frame-by-frame basis, such as for assembling an animat0d video picture. In that event, the content of the last-recorded SMPTE time code character will not merely be one frame greater than the SMPTE time code character which precedes it.
The U. S . Patent No . 4 ,189, 756 pro~oses ~he apparatus which will sol~e the above defectsO In this apparatus, ~3~
since the number of ~'0"s irl the time code of one word is selected as an even number, the continuation of time codes is good under an~ conditions.
~owever, since the number is necessary to be an even number, there occurs such a defect that its circuit construction becomes complicated.
OBJECTS OF THE INVENTION
_ Therefore, it is an object of the present invention to record SMPTE time codes in a manner which overcomes the aforenoted problems heretofore present in the prior art.
Another object of this invention is to provide improved SMPTE
time code generating apparatus wherein the phase at the beginning of an SMPTE time code character always is compatible with the phase at the end of a preceding SMPTE time code character, even if these two characters are not generated in succession.
~ further object of this invention is to provide an improved SMPTE time code generator in which the phase relation at the beginning and end of each character remains constant regardless of the contents of that character.
In a broader aspect thereof, it is an aclditional object of this invention to provide apparatus for generating bi-phase coded characters - 20 having a constant phase relation, such as the same phase relation, at the beginning and end of each coded character regardless of the number of bi -phas e " 1 " s and " 0 " s incl uded therein .
Yet ano-ther object of this invention is to provide improved SMPTE time code generating apparatus which generates SMPTE time code characters which are particularly useful in assemble edit operations of a video tape.
Various other objects, advantages and features of the present invention will become readily apparent from the ensuing detailed description, and the novel features will be particularly pointed out in the appended claims. -In accorc1ance with this in~ention, there is provided a recording time cocle signal generating apparatus having a time code data signal generating circuit and a time code signal forming circuit which is supplied with the time code data signal from the time code data signal gene-rating circuit and produces a recording time code signal including bi~phase code signals, in which the recording time code signal is corresponded to an information signal and recorded continuously on a recording medium per word unit. In this case, it is soformed that even if the recording time code signal of word unit which consists of bi phase code signals is connected in a desired number and then recorded on the recording medium, there is produced no discontinuity at the connection point of the time code signals .
BRIEF DESCRIPTION OF THE DRAWINGS
The following description, given by way of example, will best be understood in conjunction with the accompanying drawings in which;
Fig. 1 is a block diagram of editing apparatus according to this invention which can be used in, for example, an assemble edit operation;
Fig. 2 is a partial block, partial logic diagram showing a practical example of a part Or Fig. 1; and Figs. 3A to 3F are waveform diagrams which are useful in understanding the operation of the example shown in Fig. 2.
DESCRIPTION F THE PREFERRED EMBODIMENT
An electronic edition apparatus in which the present invention is incorporated will be firstly described with re-ierence to Fig. 1. In the figure, pro~ided is an electronic editing VTR 5 which has provided with, for example, a pair of recording and reproducing rotary magnetic heads and a pair of rotary erasing magnetic heads on a tape guide drum (not shown), and also provided is a VTR ~ which serves to reproduce a video signal as an information signal from a magnetic tape which is not edited. In the VTR ~, the video signal reproduced from the magnetic 3~
tape is selected and then fed to the VTR 5 which then records the applied video signal on a new magnetic tape ;n an edited state. In this case, separate time code signals (such as the above SMPTE time code signals) are recorded on the respective magnetic tapes in V t`Rs ~ and 5.
One dot chain line block 6 in Fig. 1 designates an electronic editing apparatus which includes a recording time code signal generating apparatus 3. This time code signal generating apparatus 3 produces a time code signal to be recorded on the magnetic tape in the electronic editing VTR 5 and hence is formed of a time code data signal generator 12 and a time code signal forming circuit 11 which is supplied with a time code data signal from the time code data signal generator 12 and produces a recording time coc3e signal consisting of bi-phase coded s;gnals.
The recording time code signal from the tirne cocle signal forming circuit 11 is fed through an output terminal 1~ to the VTR 5 and recorded therein on a cue track or audio track of a magnetic tape as a recording medium per word unit in correspondence with the respective frames of a video signal as an information signal.
The electronic editing apparatus 6 further including VTR
control circuits 7 and 8 corresponding to the VTR ' s ~ and 5, which are connected to VTR ' s 4 and 5 through control huses, respectively, and time code reading-out circuits 9 and 10, which read out the time codes contained in the time code signals reproduced from VTR ' s ~ and 5 and which control circuits 9 and 10 are connected through data buses to a system control circuit 13, respectively. The time code data signal generator 12 is also connected to the system control circuit 13 through - a control bus.
The recording time code signal generating apparatus 3 will be described with reference to Fig. 2. As described above, this recording time code signal generating apparatus 3 is formed of the time code data signal generator 12 and the time code signal forming 3~
circuit 11. Especially, in the time code signal forming circuit 11, provided is means 15 which detects the polarity of a specific bit signal of a fixed binary Yalue or bit in the recording time code signal of word unit ( bi-phase code signals) and change the fixed binary bit in accordance with the detected po]arity.
The time code data signal generator 12 produces at its one output term;nal 12a time code data signal T~ of a binary code correspond-ing to the above ~MYTE time code, as shown in Fig. 3D, and at its other output terminals 12d and 12c first and second clock signals CL1 and CL2 as shown in Figs. 3A and 3B, respectively. The clock signals CL1 and CL2 are such clock signals which serve to provide a time code signal TC consisting of bi~phase code signals as shown in Fig. 3E.
The clock signal CL1 is so selected that its frequency is twice as that of the clock signal CL2 and the falling-down of, clock signal CL2 is in synchronism with the falling-down of clock signal CL1, and the time code data signal TD shown in Fig. 3D is so formed that its bit signal is syn-chronized with one period of clock signal CL2. Each period of clock signal CL2 i.e. each bit of time code data signal TD is marked with numbers of Tn-3, Tn-2, ---- Tn+~ as shown in Fig. 3.
Although the changing means 15 is formed of AND-circuits 19, 20 and an invertsr 18 in the example of Fig. 2, at first, this means 15 is not considered in the following description. The time code data signal TD and çlock signal CL2 are fed to an OR~circuit 16, and the output therefrom is fed commonly to J-and K-input terminals of a JK~flip~
-flop circuit 17 which is also supplied at its CK (clock)-input terminal with clock signal CL1 after being phase-inverted. Thus, the flip~flop circuit 17 produces at its Q-output terminal i.e. output terminal 1~ a time code signal TC consisting of bi~phase code signals as shown in Fig. 3E. This time code signal TC is provided by making the time code data signal TD as a bi-phase coded signal . In the case where the abo~e ~3~
changing means 15 is not provided, when the time code data signals TD shown in F;gs. 3D and 3D' are bi-phase-coded, there will occur such a case that a time code signal TC ' is produced as shown ;n Fig. 3F
which is inversed itl polarity as compar0d with the time code signal TC
shown in Fig. 3E~ (in the figure only bits of Tn_3 to Tn_1 are shown)~
To avoid this clefect, the above changing means 15 is provided to change the phase of time code signal TC ' to be in phase with the time code signal TC of word unit at its specific bit signals or respective bit signals after the bit signals of the Tn bit sigrnal in this example. To this end, a strobe signal ST (refer to Fig. 3C), which has a time width correspond-ing to the period of the specific bit signal whose binary bit is fixed to, for example, "0" such as an empty bit of the SMPTE time cocle signal for a user, is derived fi~om an output terminal 12b of time code data signal generator 12 once per the time code signal of one word. Thls strobe signal ST is fed after being inversed in phase by inverter 18 to the AND-circuit 19 and fed, as ;t is, to the other AND-circuit 20. The output from AND-circuit 19J which is supplied with the time code data signal TD as set forth above, is fed to OR-circuit 160 The AND-circuit 20 is also supplied with the output at the Q-output terminal of the JK-flip--flop circuit 17, and the output from the AND-circuit 20 is fed to OR-circuit 16 .
If the above strobe signal ST is produced at, for example, the Tn bit in the empty bits Tn_1 to Tn+2 for the user wherein the binary bits are "0", when the output in the former half period in the Tn bit of JK-flip-flop circuit 17 is in low level as shown in Fig. 3E, the output in -the ]atter half period is made in the same low level, while when the level in the former half period is high as shown in Fig. 3F~ the level in the latter half period is changed into the low level. Thus, in Fig.
3F the binary bit "0" is changed into "1 " in the Tn bit~ Accordingly, as shown in Figs~ 3E and 3F, after arrows indicating the boundary 3~
between the Tn and Tn-~1 bits, the time code signals TC and TC' become same in polarity and hence the respective bit signals of the time code signals TC and TC ' after the Tn ~1 bit become same in polarity.
As a result, since the polarity of the bit signal of the t;me code signal of one word at its end is fixed, the continuous time code signals of one word are recorded on the magnetic tape with a continuous recording pat-tern.
Next, the manner to carry out the electronic editing operation will be described. A video signal which is not edited is recorded on the magnetic tape of VTl~ 4 together with aninherent time code signal.
The editing VTR 5 selects the reproduced video signal from VTR 4 and records the same on the magnetic tape together with a ne~,v time code signal. In the case that the video signal of N frames reproduced from the magnetic tape of VTR ~ at a certain portion is recordecl on the mag-netic tape of VTR 5 as one cut, the video signals having frames more than N frames by several frames (several m sec. to several 10 m sec) are recorded together with an inherent time code signal and the video signals of M frames of another one cut from the VTR 4 are recorded in superimposed on the excessive portion of the former one cut video signals i~e. erasing the excessive portion together with inherent time code signal so as to make the junction between the video signal and time code signal smooth .
Meanwhile, in the recording time code signal geneIating apparatus 3, the time code signal is automatically delivered to the output ~5 terminal l4 in accordance with the constant travelling speed of the magnetic tape in the VTR 5, but the time code data signal generator 12 can be preset by the time code data signal ïrom the time code reading out circuit 10.
~ccordingly9 the recorcding of the video signal at the second cut in VTR
5 is carried out in the following manner. That is, the VTR 5 is rewound to reproduce the video signal of the first one cut and the recording of the S~
video signal of the second one cut from VTR ~ is initiated at the time when the video signal Or N frames is reproduced completely. In this case, the video signals more than M frames by several frames are also recorded. Meanwhile, during time period in which the video signal Or one cut is reproduced, the time code signal, which is recorded in corres-pondence with the video signal of one cut, is reproduced and then read out by the time code reading out circuit 10, and the termination oî the video signal of N frames is detected by the read-out time code signal. Then, the time code data signal from the time code reading out circuit 10 at that time is fed to the time code data signal generator 12 to preset the same, and ~hereafter the time code signal corresponding to the video signal at-the second cut is recorded continuously on the magnetic tape~
~s the above information signal, an audio signal of PCM and so on could be used in addition to the video signal of a television signal, and as the recording medium, a magnetic medium such as a magnetic disc, magnetic drum or the like and a recording medium of an optical system, pressure sensitive system and so on can be used in addition to the mag-netic tape.
Further, it is of no need that the change of the binary bit of the specific bit signal in the time code signal consisting Or bi-phase coded signals is limited from "0" to "1 " but the change could be carried out from "1 " to "0".
According to the present invention described as above, a signal generating apparatus is provided by which even if the time code signal of word unit consisting of bi phase coded signals is recorded on the recording medium continuously in a desired number, the recording time coded signal of word unit consisting of the bi-phase coded signals with no discontinuity at the junction point between adjacent time coded signa]s can be produced. ~ccordingly, if such time coded signal is recorded on the recording medium per word unit in correspondence 3~
with the track unit, f;eld unit or frame unit of the information signal, the assemble edition of the info:rma-tion signal at the track unit9 field unit or ïrame unit thereof can be easily carried out.
It will be apparent that many modirications and variations could be effected by one skilled in the art without departing ïrom the spirits or scope of the novel concepts oï tlle present invention.
This invention relates to appiaratus for generatillg coded characters and, more particularly, to such apparatus wherein a bi-phase coded character is generated ha~ing a constant relation between the phases at the beginning and end of each coded chiaracter regardless of the number o~ "1 " s and "0" s included in that character.
In accordance witn a specific aspect of this invention, an SMPTE time code character is generated having ~ level transition at the start thereof which is of the sanrle phase, or polarity, as the leveI transition at the end thereot.
With the advent of lrideo recording alld playback devices9 such as the ~ideo tape recorder (VTR~9 ~arious situations may arise wh~rein a recorded medium, such as recorded video tape, should be edited such that a certain iniormation thereon is replac0d by other, desired infor-~ ~ mation, or that a certialn additional information is recorded immediately *~1 2 :~L13~
, following a previously recorded segment. The former editing ope-ration is known as an insert edit whereinJ for example, one or more frames of video signals which are recorded on one video tape are replaced by an equal number of l~rames of video signals which has been recorded on another video tape. The latter edit operation is known as an assemble edit where-in one of more frames of video signals which had been recorded on another video tape are transferred, or re~recorded, onto the main video tapeJ
whereby an entire program may be "assembled".
As may be appreciated, in order to carry out an insert edit or an assemble edit operationJ that is, an operation wherein video signals which had been recorded on a secondary tape are transferredJ or re-recorded, onto a primary tape J two separate VrrR ' s are needed for controlling the respective playback and recording operations of the seconclary and primary tapes. The secondary VTR must be operated to ascertain those frames containing the video information which must be transferred to the primary tape and the primary VTR must be controlled so as to ascertain the precise location on the primary tape at which the secondary information is to be recorded. FurthermoreJ both VTR ' s must be operated in synchronism with each other.
In order to facilitate such editing operationsJ and particularly, to identify the specific frames of video signals which are to be edited, a standardi~ed code has been de~eloped, known as the SMPTE time code~
This SMPTE time code is a serial code formed of a predetermined number of binary bits which are recorded as phase-modulated, or bi-phase signals.
In accordance with the present standardJ the SMPTE time code cvntains eighty bi-phase bits which representJ in BCD format~ an inclication of the time at which each frame of ~ideo signals is recorded, a frame count and optional binary word information. This time code also includes a sixteen bit synchroni~ing word and a number of so called binary groups which may be used either for future information or as the user of the video , . .~. . . . . :
tape so desires. A more complete description of this ~MPTE
time code is described in "Standardization for Time and ~ontrol Code for Video Tape and Audio Recorders" by E~ K. Dahlin, I)ecember 1970, Journal of the S~IPTE, Volurnne 79~ page 1086. Another proposal for a standardized time code for viàeo recording is the EBU time code .
In the bi-phase representation of binary bits, the beginning of each bit period is marked by a level transition, either a positive transition ïrom a lower to a higher level or a negative transitionO
A binary "1 " is represented by yet another level transition during the bit period, while a binary "0" is represented by the absence of any additional bit transitions throughout the bit period. In recording the SMPTE time code on a video tape~ the bi-phase signals are record-ed in seriatum along a longitudinal edge of the tape such that the begin-ning of an SMPTE character starts at the beginning of the frame of video signals and ends at the end of that frame of signals. Thus, the end of one SMPTE character is coincident with the beginning of the next following SMPTE character,. Accordingly, it is important that the phase of the beginning of an SMPTE character, that is, the direction of the level transition at the start of the SMPTE character, be con-sistent, or compatible, with the phase at the end of the preceding SMPTE
character. This means that if the preceding SMPIE character ends with a negative-going transition, the next following SMPTE character should start with a negative-going transition.
In the insert edit operation wherein video signals which had been recorded on the primary tape are replaced by ~ideo si~nals which are played back from the secondary tape, that is, the secondary video signals are "insertec~" between two existing segments on the primary tape, the SMPTE time code characters which had been recorded for the particular segment on the primary tape which is being replaced ~ l n~rmally remain on the primary tape. Thus, in the insert edit opera tion, there is no change in the recorded SMPTE characters and, there-fore, there is no problem in making sure that the phase at the end of a preceding SMPTE character is compatible with the phase at the begin-ning of the next following SMPTE character. However, in the assemble edit operation, a new SMPTE time code is recorded together with the new video signals which are recorded from the secondary video tape~ Since the new SMPTE time code characters are not recorded during the same operation that the preceding SMPTE time code charac-ters were recorded! it is possible `that tlle phase at the beginning oî
a new character may not be compatible with the phase at the end of the preceding, previously recorded character. It has been thought that this problem can be solved by, for examplel reading the next-to last SMPTE time code character which is recorded on the primary tape just prior to the assemble edit location thereon and then interpolate the information represented by the read character such that the content of ;-the last character can be ascertained, and thus the phase at the end of that last character will be known. Once this phase is known, the new SMPTE time code characters can be generated so as to be compatible therewith. However, this assumes that the last few frames of the previously recorded video signals on the primary tape has been recorded in successionO Thus, the frame count contained in the last character will be one greater than the frame count included in the preceding charac-ter, and so on. This technique is not successful if successive frames of video signals are assembled on a frame-by-frame basis, such as for assembling an animat0d video picture. In that event, the content of the last-recorded SMPTE time code character will not merely be one frame greater than the SMPTE time code character which precedes it.
The U. S . Patent No . 4 ,189, 756 pro~oses ~he apparatus which will sol~e the above defectsO In this apparatus, ~3~
since the number of ~'0"s irl the time code of one word is selected as an even number, the continuation of time codes is good under an~ conditions.
~owever, since the number is necessary to be an even number, there occurs such a defect that its circuit construction becomes complicated.
OBJECTS OF THE INVENTION
_ Therefore, it is an object of the present invention to record SMPTE time codes in a manner which overcomes the aforenoted problems heretofore present in the prior art.
Another object of this invention is to provide improved SMPTE
time code generating apparatus wherein the phase at the beginning of an SMPTE time code character always is compatible with the phase at the end of a preceding SMPTE time code character, even if these two characters are not generated in succession.
~ further object of this invention is to provide an improved SMPTE time code generator in which the phase relation at the beginning and end of each character remains constant regardless of the contents of that character.
In a broader aspect thereof, it is an aclditional object of this invention to provide apparatus for generating bi-phase coded characters - 20 having a constant phase relation, such as the same phase relation, at the beginning and end of each coded character regardless of the number of bi -phas e " 1 " s and " 0 " s incl uded therein .
Yet ano-ther object of this invention is to provide improved SMPTE time code generating apparatus which generates SMPTE time code characters which are particularly useful in assemble edit operations of a video tape.
Various other objects, advantages and features of the present invention will become readily apparent from the ensuing detailed description, and the novel features will be particularly pointed out in the appended claims. -In accorc1ance with this in~ention, there is provided a recording time cocle signal generating apparatus having a time code data signal generating circuit and a time code signal forming circuit which is supplied with the time code data signal from the time code data signal gene-rating circuit and produces a recording time code signal including bi~phase code signals, in which the recording time code signal is corresponded to an information signal and recorded continuously on a recording medium per word unit. In this case, it is soformed that even if the recording time code signal of word unit which consists of bi phase code signals is connected in a desired number and then recorded on the recording medium, there is produced no discontinuity at the connection point of the time code signals .
BRIEF DESCRIPTION OF THE DRAWINGS
The following description, given by way of example, will best be understood in conjunction with the accompanying drawings in which;
Fig. 1 is a block diagram of editing apparatus according to this invention which can be used in, for example, an assemble edit operation;
Fig. 2 is a partial block, partial logic diagram showing a practical example of a part Or Fig. 1; and Figs. 3A to 3F are waveform diagrams which are useful in understanding the operation of the example shown in Fig. 2.
DESCRIPTION F THE PREFERRED EMBODIMENT
An electronic edition apparatus in which the present invention is incorporated will be firstly described with re-ierence to Fig. 1. In the figure, pro~ided is an electronic editing VTR 5 which has provided with, for example, a pair of recording and reproducing rotary magnetic heads and a pair of rotary erasing magnetic heads on a tape guide drum (not shown), and also provided is a VTR ~ which serves to reproduce a video signal as an information signal from a magnetic tape which is not edited. In the VTR ~, the video signal reproduced from the magnetic 3~
tape is selected and then fed to the VTR 5 which then records the applied video signal on a new magnetic tape ;n an edited state. In this case, separate time code signals (such as the above SMPTE time code signals) are recorded on the respective magnetic tapes in V t`Rs ~ and 5.
One dot chain line block 6 in Fig. 1 designates an electronic editing apparatus which includes a recording time code signal generating apparatus 3. This time code signal generating apparatus 3 produces a time code signal to be recorded on the magnetic tape in the electronic editing VTR 5 and hence is formed of a time code data signal generator 12 and a time code signal forming circuit 11 which is supplied with a time code data signal from the time code data signal generator 12 and produces a recording time coc3e signal consisting of bi-phase coded s;gnals.
The recording time code signal from the tirne cocle signal forming circuit 11 is fed through an output terminal 1~ to the VTR 5 and recorded therein on a cue track or audio track of a magnetic tape as a recording medium per word unit in correspondence with the respective frames of a video signal as an information signal.
The electronic editing apparatus 6 further including VTR
control circuits 7 and 8 corresponding to the VTR ' s ~ and 5, which are connected to VTR ' s 4 and 5 through control huses, respectively, and time code reading-out circuits 9 and 10, which read out the time codes contained in the time code signals reproduced from VTR ' s ~ and 5 and which control circuits 9 and 10 are connected through data buses to a system control circuit 13, respectively. The time code data signal generator 12 is also connected to the system control circuit 13 through - a control bus.
The recording time code signal generating apparatus 3 will be described with reference to Fig. 2. As described above, this recording time code signal generating apparatus 3 is formed of the time code data signal generator 12 and the time code signal forming 3~
circuit 11. Especially, in the time code signal forming circuit 11, provided is means 15 which detects the polarity of a specific bit signal of a fixed binary Yalue or bit in the recording time code signal of word unit ( bi-phase code signals) and change the fixed binary bit in accordance with the detected po]arity.
The time code data signal generator 12 produces at its one output term;nal 12a time code data signal T~ of a binary code correspond-ing to the above ~MYTE time code, as shown in Fig. 3D, and at its other output terminals 12d and 12c first and second clock signals CL1 and CL2 as shown in Figs. 3A and 3B, respectively. The clock signals CL1 and CL2 are such clock signals which serve to provide a time code signal TC consisting of bi~phase code signals as shown in Fig. 3E.
The clock signal CL1 is so selected that its frequency is twice as that of the clock signal CL2 and the falling-down of, clock signal CL2 is in synchronism with the falling-down of clock signal CL1, and the time code data signal TD shown in Fig. 3D is so formed that its bit signal is syn-chronized with one period of clock signal CL2. Each period of clock signal CL2 i.e. each bit of time code data signal TD is marked with numbers of Tn-3, Tn-2, ---- Tn+~ as shown in Fig. 3.
Although the changing means 15 is formed of AND-circuits 19, 20 and an invertsr 18 in the example of Fig. 2, at first, this means 15 is not considered in the following description. The time code data signal TD and çlock signal CL2 are fed to an OR~circuit 16, and the output therefrom is fed commonly to J-and K-input terminals of a JK~flip~
-flop circuit 17 which is also supplied at its CK (clock)-input terminal with clock signal CL1 after being phase-inverted. Thus, the flip~flop circuit 17 produces at its Q-output terminal i.e. output terminal 1~ a time code signal TC consisting of bi~phase code signals as shown in Fig. 3E. This time code signal TC is provided by making the time code data signal TD as a bi-phase coded signal . In the case where the abo~e ~3~
changing means 15 is not provided, when the time code data signals TD shown in F;gs. 3D and 3D' are bi-phase-coded, there will occur such a case that a time code signal TC ' is produced as shown ;n Fig. 3F
which is inversed itl polarity as compar0d with the time code signal TC
shown in Fig. 3E~ (in the figure only bits of Tn_3 to Tn_1 are shown)~
To avoid this clefect, the above changing means 15 is provided to change the phase of time code signal TC ' to be in phase with the time code signal TC of word unit at its specific bit signals or respective bit signals after the bit signals of the Tn bit sigrnal in this example. To this end, a strobe signal ST (refer to Fig. 3C), which has a time width correspond-ing to the period of the specific bit signal whose binary bit is fixed to, for example, "0" such as an empty bit of the SMPTE time cocle signal for a user, is derived fi~om an output terminal 12b of time code data signal generator 12 once per the time code signal of one word. Thls strobe signal ST is fed after being inversed in phase by inverter 18 to the AND-circuit 19 and fed, as ;t is, to the other AND-circuit 20. The output from AND-circuit 19J which is supplied with the time code data signal TD as set forth above, is fed to OR-circuit 160 The AND-circuit 20 is also supplied with the output at the Q-output terminal of the JK-flip--flop circuit 17, and the output from the AND-circuit 20 is fed to OR-circuit 16 .
If the above strobe signal ST is produced at, for example, the Tn bit in the empty bits Tn_1 to Tn+2 for the user wherein the binary bits are "0", when the output in the former half period in the Tn bit of JK-flip-flop circuit 17 is in low level as shown in Fig. 3E, the output in -the ]atter half period is made in the same low level, while when the level in the former half period is high as shown in Fig. 3F~ the level in the latter half period is changed into the low level. Thus, in Fig.
3F the binary bit "0" is changed into "1 " in the Tn bit~ Accordingly, as shown in Figs~ 3E and 3F, after arrows indicating the boundary 3~
between the Tn and Tn-~1 bits, the time code signals TC and TC' become same in polarity and hence the respective bit signals of the time code signals TC and TC ' after the Tn ~1 bit become same in polarity.
As a result, since the polarity of the bit signal of the t;me code signal of one word at its end is fixed, the continuous time code signals of one word are recorded on the magnetic tape with a continuous recording pat-tern.
Next, the manner to carry out the electronic editing operation will be described. A video signal which is not edited is recorded on the magnetic tape of VTl~ 4 together with aninherent time code signal.
The editing VTR 5 selects the reproduced video signal from VTR 4 and records the same on the magnetic tape together with a ne~,v time code signal. In the case that the video signal of N frames reproduced from the magnetic tape of VTR ~ at a certain portion is recordecl on the mag-netic tape of VTR 5 as one cut, the video signals having frames more than N frames by several frames (several m sec. to several 10 m sec) are recorded together with an inherent time code signal and the video signals of M frames of another one cut from the VTR 4 are recorded in superimposed on the excessive portion of the former one cut video signals i~e. erasing the excessive portion together with inherent time code signal so as to make the junction between the video signal and time code signal smooth .
Meanwhile, in the recording time code signal geneIating apparatus 3, the time code signal is automatically delivered to the output ~5 terminal l4 in accordance with the constant travelling speed of the magnetic tape in the VTR 5, but the time code data signal generator 12 can be preset by the time code data signal ïrom the time code reading out circuit 10.
~ccordingly9 the recorcding of the video signal at the second cut in VTR
5 is carried out in the following manner. That is, the VTR 5 is rewound to reproduce the video signal of the first one cut and the recording of the S~
video signal of the second one cut from VTR ~ is initiated at the time when the video signal Or N frames is reproduced completely. In this case, the video signals more than M frames by several frames are also recorded. Meanwhile, during time period in which the video signal Or one cut is reproduced, the time code signal, which is recorded in corres-pondence with the video signal of one cut, is reproduced and then read out by the time code reading out circuit 10, and the termination oî the video signal of N frames is detected by the read-out time code signal. Then, the time code data signal from the time code reading out circuit 10 at that time is fed to the time code data signal generator 12 to preset the same, and ~hereafter the time code signal corresponding to the video signal at-the second cut is recorded continuously on the magnetic tape~
~s the above information signal, an audio signal of PCM and so on could be used in addition to the video signal of a television signal, and as the recording medium, a magnetic medium such as a magnetic disc, magnetic drum or the like and a recording medium of an optical system, pressure sensitive system and so on can be used in addition to the mag-netic tape.
Further, it is of no need that the change of the binary bit of the specific bit signal in the time code signal consisting Or bi-phase coded signals is limited from "0" to "1 " but the change could be carried out from "1 " to "0".
According to the present invention described as above, a signal generating apparatus is provided by which even if the time code signal of word unit consisting of bi phase coded signals is recorded on the recording medium continuously in a desired number, the recording time coded signal of word unit consisting of the bi-phase coded signals with no discontinuity at the junction point between adjacent time coded signa]s can be produced. ~ccordingly, if such time coded signal is recorded on the recording medium per word unit in correspondence 3~
with the track unit, f;eld unit or frame unit of the information signal, the assemble edition of the info:rma-tion signal at the track unit9 field unit or ïrame unit thereof can be easily carried out.
It will be apparent that many modirications and variations could be effected by one skilled in the art without departing ïrom the spirits or scope of the novel concepts oï tlle present invention.
Claims (3)
1. An apparatus for generating a recording time code signal comprising;
a) a time code data signal generator;
b) a time code signal forming circuit which is supplied with a time code data signal from said time code data signal generator and produces a recording time code signal consisting of bi-phase coded signals, said recording time code signal being corresponded to an information signal and then recorded on a recording medium con-tinuously at word unit; and c) means provided in said time code signal forming circuit for discriminating the polarity of a specific bit signal of a fixed binary bit in said recording time code signal of word unit and for changing said fixed binary bit in accordance with polarity of the specific bit signal, whereby said recording time code signal of word unit has a constant polarity of bit signals after the above specific bit signal.
a) a time code data signal generator;
b) a time code signal forming circuit which is supplied with a time code data signal from said time code data signal generator and produces a recording time code signal consisting of bi-phase coded signals, said recording time code signal being corresponded to an information signal and then recorded on a recording medium con-tinuously at word unit; and c) means provided in said time code signal forming circuit for discriminating the polarity of a specific bit signal of a fixed binary bit in said recording time code signal of word unit and for changing said fixed binary bit in accordance with polarity of the specific bit signal, whereby said recording time code signal of word unit has a constant polarity of bit signals after the above specific bit signal.
2. An apparatus for generating a recording time code signal according to claim 1 further including mean for presetting said time code data signal generator in accordance with a given time code.
3. An apparatus for generating a recording time code signal as claimed in claim 1, wherein said means includes a detector for detecting a level at the beginning of said fixed binary bit to discriminate the polarity of said specific bit signal.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP53046934A JPS6019075B2 (en) | 1978-04-20 | 1978-04-20 | Recording time code signal generator |
| JP46934/78 | 1978-04-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1135840A true CA1135840A (en) | 1982-11-16 |
Family
ID=12761138
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000325717A Expired CA1135840A (en) | 1978-04-20 | 1979-04-18 | Apparatus for generating time code signals |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS6019075B2 (en) |
| AT (1) | AT380609B (en) |
| AU (1) | AU522543B2 (en) |
| CA (1) | CA1135840A (en) |
| DE (1) | DE2916074A1 (en) |
| FR (1) | FR2423819B1 (en) |
| GB (1) | GB2020516B (en) |
| NL (1) | NL7903078A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4340916A (en) * | 1980-04-11 | 1982-07-20 | Sony Corporation | Apparatus and method for detecting discontinuities in time code addresses |
| JPS57123578A (en) * | 1981-01-22 | 1982-08-02 | Sony Corp | Error correcting circuit for drive data |
| JPH03171460A (en) * | 1989-11-30 | 1991-07-24 | Sony Magnescale Inc | Method and device for magnetic recording |
| GB2249656B (en) * | 1990-11-12 | 1994-09-28 | Daewoo Electronics Co Ltd | A multi-deck video cassette recorder system |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE757737A (en) * | 1969-10-27 | 1971-04-01 | Ampex | NEW MODE OF INFORMATION RECORDING |
| US3681524A (en) * | 1970-06-16 | 1972-08-01 | Columbia Broadcasting Syst Inc | Multiple frequency time code generator and reader |
| US3795903A (en) * | 1972-09-29 | 1974-03-05 | Ibm | Modified phase encoding |
| JPS5949754B2 (en) * | 1976-07-31 | 1984-12-04 | ソニー株式会社 | tape editing machine |
| JPS5466111A (en) * | 1977-11-05 | 1979-05-28 | Sony Corp | Time code write system |
-
1978
- 1978-04-20 JP JP53046934A patent/JPS6019075B2/en not_active Expired
-
1979
- 1979-04-18 CA CA000325717A patent/CA1135840A/en not_active Expired
- 1979-04-19 NL NL7903078A patent/NL7903078A/en not_active Application Discontinuation
- 1979-04-20 AU AU46294/79A patent/AU522543B2/en not_active Ceased
- 1979-04-20 AT AT300879A patent/AT380609B/en not_active IP Right Cessation
- 1979-04-20 DE DE19792916074 patent/DE2916074A1/en active Granted
- 1979-04-20 GB GB7913748A patent/GB2020516B/en not_active Expired
- 1979-04-20 FR FR7910115A patent/FR2423819B1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| ATA300879A (en) | 1985-10-15 |
| NL7903078A (en) | 1979-10-23 |
| DE2916074A1 (en) | 1979-10-31 |
| AT380609B (en) | 1986-06-25 |
| DE2916074C2 (en) | 1988-03-03 |
| AU522543B2 (en) | 1982-06-10 |
| AU4629479A (en) | 1979-10-25 |
| FR2423819B1 (en) | 1986-07-18 |
| GB2020516A (en) | 1979-11-14 |
| GB2020516B (en) | 1982-06-30 |
| JPS6019075B2 (en) | 1985-05-14 |
| FR2423819A1 (en) | 1979-11-16 |
| JPS54139511A (en) | 1979-10-30 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4167759A (en) | Apparatus for inserting an address signal in a frame of the vertical blanking period of a television signal | |
| US4189756A (en) | Apparatus for generating bi-phase coded characters | |
| KR950014377B1 (en) | Helical scan device | |
| US4799111A (en) | Video signal recording and/or reproducing apparatus with a function for re-recording a search control-index signal | |
| EP0630023B1 (en) | Recording and reproducing apparatus | |
| US4329719A (en) | Apparatus for generating time code signals | |
| EP0209151B1 (en) | Apparatus for recording and/or reproducing an information signal | |
| CA1135840A (en) | Apparatus for generating time code signals | |
| US5287224A (en) | Apparatus for recording a video signal having programs and control data | |
| US4232347A (en) | Video tape control time code reading | |
| EP0259962B1 (en) | Method and apparatus for extracting binary signals included in vertical blanking intervals of video signals | |
| US4807057A (en) | Data recording apparatus | |
| US4996607A (en) | Audio signal recording apparatus | |
| US4300171A (en) | Magnetic recording medium direction sensing | |
| US5016119A (en) | Video signal reproducing apparatus with two modes of keeping track of address | |
| US5227926A (en) | Duplicator system manageable of life of mother tape | |
| US4348698A (en) | Magnetic devices for changing video recordings | |
| EP0736869B1 (en) | Method and apparatus for recording digital signals | |
| EP0279885A1 (en) | Video signal reproducing apparatus | |
| KR0158439B1 (en) | Process and device for copying magnetic tapes | |
| US6766105B1 (en) | Digital VTR | |
| US6188834B1 (en) | Device and method for recording and reproducing image information | |
| US5644446A (en) | Rotary-head digital reproducing/recording method and apparatus with block address-based area signal generation | |
| US5434715A (en) | Process and device for copying magnetic tapes containing both program material and control data | |
| EP0159111B1 (en) | Method and apparatus for storing/retrieving digital data on video tape |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |