JPH04127681A - Time code reader and video tape recorder using the same - Google Patents

Abstract

PURPOSE:To obtain sufficient edition accuracy and convenience even in a time code edition system combining low-priced VTR not equipped with the time code reader in the inside by setting one system of a time code as a main time code and the other system of a time code as a sub time code. CONSTITUTION:This device reads the two systems of time codes reproduced from a magnetic tape simultaneously with video signals and outside a VTR 2, the two kinds of time code signals to be reproduced from the VTR 2 are used. One time code designated by a user is interpolated by using the other time code regardless of whether absolute time is coincident for the both time codes or not so as to always obtain the continuous time codes. Thus, even in the time code edition system combining the low-priced VTR not equipped with time code readers 1 in the inside, the sufficient edition accuracy and convenience can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for reading time information recorded and reproduced using a video tape recorder (VTR) or the like.

[Conventional technology]

Conventionally, when recording absolute time information corresponding to the video signal called a time code on a magnetic tape along with a video signal in a VTR, there is a method of providing a recording track in the running direction of the tape and recording a linear time code (LTC), and a rotating head. A vertical period time code (V
There is a method to record ITC). FIG. 2 shows the recording patterns on these tapes. A video track 31 is formed on the magnetic tape 30 by a rotary head 35, and VITC is superimposed and recorded in a vertical period 37. Further, along the running direction of the tape, an LTC track 32, a linear audio track 33, and a control track 34 are formed by combination heads 36a, b, and c, and LTC, audio signals, and CTL signals are recorded, respectively. In this way these LTC and/or VI
By recording the TC on a tape in correspondence with the video signal, and using a time code playback device to play back and read the same at the same time as the video signal, the video signal recorded at any location can be randomly searched. is now possible.

However, like linear track audio, LTC can cause reading errors when the running speed is slow, and reading is often unreadable especially when operating a VTR through a pause state during tape editing. appears in

On the other hand, with VITC, there is no problem with reading it when driving at normal to low speeds, but FF/RE, which fast forwards and rewinds 7 times,
Reading becomes difficult when high-speed playback is performed, such as during W), and the normal limit is about 5 times the speed.

Conventionally, as a method for correcting the time code reading error due to the tape running condition described above, for example, as described in Japanese Patent Laid-Open No. 1-271987, a control signal (CTL) indicating the recording position of the video signal is used. ), and by adding and subtracting the CTL difference data to the LTC read in the past at the time when the LTC becomes unreadable, the LTC
There are some that perform TC interpolation.

[Problem to be solved by the invention]

However, the above-mentioned conventional time code reading device is built into a VTR, and is based on the premise that the CTL signal, which is an internal signal of the VTR, and a signal indicating the tape traveling direction can be used. This method is not necessarily suitable for constructing a general-purpose time code reading device. Therefore, a problem has arisen in that a time code editing system combined with an inexpensive VTR that does not have an internal time code reading device cannot provide sufficient editing precision and usability.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a device having a means for reading both VITC and LTC outside the VTR, a means for defining either VITC or LTC as a main time code and the other as a sub time code; A means for detecting that a reading error has occurred in the main and sub time codes, a means for calculating difference data between the main and sub time codes, and a means for detecting the occurrence of a reading error in the main time code. A means for interpolating the main time code using the calculated difference data is provided.

[Effect]

By defining main and sub from VITC and LTC, the user can select one as a reference even if the two do not match. The main read error detection means causes the device to enter an interpolation operation if the error is detected. The means for detecting a sub reading error causes the calculation of the difference data to stop when the error is detected. A continuous time code is then obtained by means of interpolating the main time code using the difference data.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. A time code reading device 1 and a VTR 2 are connected. V
When TR2 is in the playback state, as shown in FIG. 2, the video signal is on the magnetic tape, the VITC superimposed during the vertical blanking period of the video signal, and the LTC on the linear track along the running direction of the tape. is being recorded, the time code reading device 1 receives a video signal including VITC from the VTR 2 through the input terminal 3, and receives a video signal including VITC from the VTR 2 through the input terminal 4.
is supplied and performs time code reading processing.

The video signal containing VITC is sent to the VITC separation circuit 5, and the V which is superimposed on the vertical blanking period of the video signal is
TTC is separated. At this time, a vertical synchronization signal VD is also separated and generated, and is supplied to the signal processing unit (CPU) 13 as a signal that provides timing for processing to be described later.
The separated VITC is converted into a pulse signal having a desired level by a waveform shaping circuit 6 and sent to a VITC decoder 7. The VITC decoder 7 decodes the received pulse signal into VITC data representing hours: minutes, 2 seconds: frames, and sends it to the buffer memory 8.
A read error signal ERRl having a high level is supplied to the CPU 13.

The buffer memory 8 sequentially writes VITC data, and when a read command is received from the CPU 13, the written VITC data is taken into a register inside the CPU 13 via the data bus 12.

On the other hand, as in the case of VITC, LTC is also waveform-shaped by a waveform shaping circuit 9, and then decoded by an LTC decoder 10 into LTC data representing hours, minutes, seconds, and frames. LTC decoder 10 supplies read error signal ERR2 to CPU 13.

LTC data is written into buffer memory 11 and sent to CPU 13 via data bus 12.

The difference data memory 14 is the VIT calculated by the CPU 13.
A memory that stores differential data between C and LTC, and this data is referenced when interpolating the main time code.

The LTC/VITC encoder 15 converts the read time code data back into VITC and LTC pulse formats. LTC is output from the output terminal 21 and VITC is superimposed on the vertical period of the video signal by the adder circuit 17. After that, it is output from the output terminal J8. In addition, the display 16 displays the read time code data as follows:
Minutes and 2 seconds: Displayed in frames.

From the input terminal 19, selection signals V and T/L for selecting the main time code from VITC and LTC are sent to the CPU.
13. As a result, if the VITC and LTC recorded on the tape do not match, for example, a video signal containing VITC indicating a different absolute time is added or recorded to a tape on which LTC has been previously recorded. Even when the user is in a state where the time code is the main one specified by the user, it is possible to obtain time information corrected based on the time code specified as the main one.

Also, from input terminal 20, time code interpolation is 0N10.
A control signal COMP for FF is input to the CPU 13, so that it is possible to switch to a mode in which no correction is made even when the time code cannot be read.

Next, the processing procedure of this apparatus will be explained using the flowchart shown in FIG.

The CPU 13 determines which of VITC and LTC is set by the user as the main time code (
SL). The processing starts at the time when the vertical synchronization signal VD separated by the VITC separation circuit 5 is detected (
S2). Alternatively, the VD may be counted by a counter inside the CPU 13, and processing may be started at a cycle that is an integral multiple of the VD.

Next, the data decoded by the VITC decoder 7 and the LTC decoder 10 into a format representing hours 2 minutes 2 seconds:frame is written to the buffer memories 8 and 11, respectively (S
3) When writing to the buffer is completed, writing of new data is prohibited until a series of processes described below are completed (S4).

Next, check whether or not to perform time code interpolation (S5
), if interpolation is to be performed, the process proceeds to S6; if not, the process proceeds to S8, where the main time code data in the buffer is used as output data regardless of the presence or absence of an error. S6
Then, the state of the read error in the VITC decoder 7 and the LTC decoder IO is determined, and the processing is branched as follows. When the read error signal ERR1 is "H", that is, when there is an error in the main data, the process proceeds to S9, where the value obtained by adding the differential data read from the differential data memory 14 to the sub data is set as output data, and ERR2=
“When H11, that is, when there is an error in the sub data, proceed to S8, output the main data, and
, ERR2 are both "L", the process advances to S7 and the differential data is updated. In other words, the sub data is subtracted from the main data, and the result is stored in memory 1 as new difference data.
Write in 4. After that, the process advances to S8 and the main data is output.

After the output data is set for each case in this way, the data is transferred to the VITC/LTC encoder 15.
and is sent to the time code display 16 (SIO).

Finally, writing to the buffer memories 8 and 11 is permitted (Sll), and the process returns to the first step S1.

As described above, two types of time code signals are used outside the VTR, and one time code specified by the user can be used with the other time code, regardless of whether the two time codes match or not. This makes it possible to use an inexpensive VTR that does not have an internal time code reader.
It is possible to provide sufficient editing accuracy and usability even in a time code editing system that combines the following.

〔Effect of the invention〕

As explained above, two types of time code signals reproduced from the VTR are used outside the VTR, and one time code specified by the user is applied to the other time code, regardless of whether or not the absolute time of the two is the same. Since it is possible to always obtain a continuous time code by interpolating the time code, it has sufficient editing accuracy and ease of use even in a time code editing system that combines an inexpensive VTR that does not have an internal time code reader. can be provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a diagram showing recording tracks on a magnetic tape, and FIG. 3 is a block diagram showing one embodiment of the present invention.
3 is a flowchart showing a processing procedure in the illustrated embodiment. ■ ・・・・・・Time code reader 2 ・・・−・
・VTR 7...VITC decoder 10...LTC decoder 13...CPU 14...Difference data memory

Claims (1)

[Scope of Claims] 1. In an apparatus for reading two systems of time codes simultaneously reproduced from a magnetic tape as a video signal, means for detecting a time code reading error; means for setting one as the main time code and the other as the sub-time code, and a means for calculating data corresponding to the difference between the main and sub-time codes, and when an error is detected in reading the time code set as the main time code. A time code reading device characterized in that the time code is interpolated by adding data corresponding to the difference to the main time code data before an error is detected. 2. A video tape recorder comprising the time code reading device according to claim 1.