JPH02108279A - Dubbing system for digital vtr - Google Patents

Abstract

PURPOSE:To improve the picture quality of dubbing by bypassing TCI decoding and D/A conversion (reproducing side) circuits, and A/D conversion and TCI encoding (recording side) circuits and dubbing with a signal system having the smallest deterioration. CONSTITUTION:After a signal recorded in a first tape 1 is reproduced by a video head 2 for reproduction, it is amplified up to a suitable level by a reproducing amplifier 3. Next, the reproducing demodulation is executed by a reproducing demodulating circuit 4, the error correcting/decoding is executed by an error correcting and decoding circuit 5 and an optimum demodulating digital signal is obtained. The reproducing digital signal is added through an output delaying circuit for dubbing for timing adjustment and a buffer amplifier 6 to a recording side VTR 11. At VTR 11, the signal is added through a buffer amplifier 15 to an error correcting and encoding circuit 16. It receives recording modulation 17, is amplified and recorded to a video tape 20 for dubbing. The tape travelling of the tape 20 and the rotation of a video head 19, after a digital demodulating signal from the circuit 5 is inputted to a TCI decoding circuit 7 and a D/A converter 8, are servo-controlled by the signal obtained by synchronization and separation.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a dubbing method for digital VTRs, and in particular, for use in commercial and broadcasting stations, it is possible to use digital VTRs in post-production, companies, broadcasting stations, etc. with less deterioration in image quality. The present invention relates to a method suitable for performing dubbing operations.

(Prior art) In normal dubbing, the first VTII output signal (Y,
Usually, CW and C- are added to the input terminal of the second VTR (recording side) for dubbing.

[Problems to be Solved by the Invention] However, in such a normal dubbing method, the signal passes through a circuit system that deteriorates image quality and sound quality, such as TCI decoding, D/^ conversion, A/D conversion, and TCI encoding processing. Therefore, there was a drawback that the original performance of the digital VTR could not be demonstrated.

Therefore, an object of the present invention is to reproduce signals digitally recorded on a first tape on a first digital VTR while suppressing signal deterioration as much as possible (ideally zero target). An object of the present invention is to provide a dubbing method that enables recording on a second tape.

[Means to solve the problem]

In order to achieve such an object, the present invention provides a reproduction side VTR.
A digital signal before D/A conversion and TCI decoding is obtained from the video signal from , and the signal is used as a digital signal of the recording side VTR, and the TCI decoded and D/A converted video signal is further synchronously divided and sent to the recording side. This is a servo synchronization signal for a VTR, and digital dubbing is performed using two types of signals.

[For production]

According to the present invention, the reproduced signal of the first VTR is converted into a human input signal of the second VTR as a digital signal, and a separately provided synchronization signal is used for synchronized operation of both VTRs. The goal is high image quality.

High-quality dubbing becomes possible.

In other words, the second VTR should reproduce and demodulate the digital signal reproduced by the first VTR and at the same time perform error correction and decoding to interpolate missing signals such as dropouts and restore the original signal as much as possible. In order to use the signal source as a signal source, the present invention bypasses the TCI decoding/D/A conversion (playback side) and A/D conversion/TCI encoding (recording side) circuits, and records using the signal system with the least deterioration. (Dubbing) enables dubbing with high image quality and high sound quality that is exactly the same as the parent tape (first tape).

Here's the first one. In order to synchronize the second deck (VTR), the synchronization signal is separated from the analog signal reproduced and demodulated or D/A converted by the first deck, and the second deck (VTR)
This is used as a synchronization signal for the VTR's servo signal.

Note that even if the servo synchronization control signal has some waveform distortion and waveform rounding, it will not interfere with the synchronous operation.

Therefore, in the dubbing system to which the present invention is applied, it is possible to record high-quality signals on the second tape that are almost the same as those on the first tape (parent tape).

〔Example〕

Hereinafter, the present invention will be described in detail based on Examples.

FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, 1 is the master tape (parent tape),
This tape is the source of dubbing.

Reference numeral 2 denotes a playback head that electromagnetically converts the information recorded on the tape 1 and outputs the converted information.

Reference numeral 3 denotes an amplifier that amplifies the reproduction output of the reproduction head 2 to an appropriate level, and has flat characteristics over a very wide band.

4 is a circuit for reproducing and demodulating the reproduced digital signal (No. 8).

5 is a circuit for error correction and decoding of the reproduced digital signal.

6 is a delay and buffer circuit for appropriately outputting the digital signal to be dubbed.

7 is a TCI decoding circuit for returning the digital signal reproduced and restored by the reproduction demodulation 4 and the error correction/decoding circuit 5 to Y, CW, and CN.

8 are Y, Cw, CN restored by the TCI decoding circuit 7
It is a D-converter that converts the digital signal back into the original analog signal.

Next, the configuration of the recording system VTIII will be explained.

12 is a servo circuit for operating in synchronization with the first VTR l0.

13 is Y (luminance signal), CW (wideband color signal),
This is a circuit that converts three analog signals of Cs (narrowband color signals) into digital signals.

14 is a TCI encoding circuit that performs time-base compression processing on the signal digitized by the ^/D converter 13 and converts it into a single digital signal.

15 is a buffer amplifier that functions as an input section for dubbing signals.

16 is an error correction/encoding circuit for digital recording signals.

17 is a recording modulation circuit for modulating the error-corrected and encoded signal.

18 is a recording amplifier and equalizer circuit for supplying the required recording current.

19 is a recording head, and 20 is a video tape to be dubbed.

Next, the operation of this embodiment will be explained.

The signal recorded on the tape 1 is reproduced by a video head 2, and then amplified by a reproduction amplifier 3 to an appropriate level. Next, the reproduction demodulation circuit 4 performs error correction and
The decoding circuit 5 performs error correction and decoding to obtain an optimal demodulated digital signal. This reproduced digital signal passes through a delay/buffer circuit 6 for timing adjustment and is applied to the recording side VTR.

In the recording side VTR, a signal is applied to an error correction/encoding circuit via a buffer amplifier 15. Thereafter, it undergoes recording modulation (17), is further amplified to an appropriate recording current value (18), and is recorded on a video tape zO by the video head 19.

The tape running of the tape 20 and the cylinder rotation of the video head 19 are servo-controlled by control signals input to the servo circuit 12 . Here, the servo control signal is obtained by inputting the digital demodulated signal obtained by the error correction/decoding circuit 5 to the TCI decoding circuit and the D/A converter 8, and the resulting Y (lli degrees). The signal is obtained by applying the signal to the synchronization separation circuit 9.

〔Effect of the invention〕

By implementing the present invention, the following special effects can be obtained.

■First. Connect the second VTR to the analog signal terminals (Y, Cw,
Since the digital signals are mutually combined without using (:N), digital-to-digital dubbing is possible, and there is no deterioration in image or sound quality.

■The wiring between the dubbing devices is now two-wire rather than three-wire, and at the same time, one wire is a control wire, so a wire with poor frequency characteristics is sufficient and costs are reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a dubbing system embodying the present invention. First tape (master tape), playback video head, playback amplifier and equalizer, playback demodulation circuit, error correction and decoding circuit, dubbing signal output delay circuit and buffer amplifier, TCI decoding circuit, D/A converter , synchronization signal generation circuit for dubbing, first VTR (playback side VTR), second VTIl (recording side VT11), recording side VT
R servo circuit, A/D converter, TCI encoding circuit, buffer 7 amplifier, error correction/encoding circuit, recording modulation circuit, recording amplifier and equalizer, recording video head, dubbing tape.

Claims (1)

[Claims] 1) Obtain a digital signal before D/A conversion and TCI decoding as a video signal from the playback VTR, use this signal as a digital signal input to the recording VTR, and synchronously separate the TCI decoded and D/A converted video signal. A dubbing method for a digital VTR, characterized in that the above two types of signals are used as a servo synchronization signal for a recording side VTR, and digital dubbing is performed using the two types of signals.