JPS59138168A - Device for correcting automatically phase of sound - Google Patents

Abstract

PURPOSE:To compensate automatically a phase difference between a video signal and a sound signal by controlling the amount of delay of the sound signal at a variable delay circuit in response to a delay of the video signal in a frame synchronizer of a digital video device. CONSTITUTION:A switching timing pulse of a video switching device is inputted to a terminal (c) and a write inhibition pulse and a write start pulse extracted from the frame synchronizer (FS) are inputted respectively to terminals d1, d2. The switching timing pulse is applied to a pulse shaping circuit 11 so as to shape the pulse width to a degree including both the write inhibition and start pulses by using the front edge of the pulse. On the other hand, pulses incoming from the terminals d1, d2 are applied respectively to AND circuits 12, 13 and ANDed with a switching timing pulse, and a pulse representing the delay time of the video signal is formed by a pulse shaping circuit 14 and becomes a control signal of a sound signal variable delay device at an interface circuit 5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic audio phase correction device that automatically adjusts the phase difference (time difference) between a video signal and an audio signal in a television broadcasting station.

In recent years, the use of digital video equipment has rapidly increased in television broadcasting stations, and in particular, frame synchronizers (hereinafter referred to as FS), which have a synchronization conversion function, have the effect of greatly improving synchronization processing within broadcasting stations. The number of devices introduced is increasing as they become smaller and cheaper. but,
Introducing FS into the video signal system caused a phase difference (time difference) between the video signal and the audio signal.

This FS has a frame memory of that name,
Writing to this frame memory is performed by synchronizing input signals, and reading is performed by reference synchronization within the own station. Since these synchronizations are asynchronous to each other, the output video signal of the FS is input due to the phase relationship. There is a delay of about 0 to about 1 frame (33 m5ec) with respect to the video signal. On the other hand, since there is no equipment that causes such a delay in the path of the audio signal accompanying the video signal that needs to pass through the FS, the audio signal is in a phase-advanced (time-advanced) state with respect to the video signal. Become.

The permissible limits for the phase difference (time difference) between the video signal and the audio signal vary depending on the content of the program, but according to subjective evaluation experiments, the advance of the audio signal relative to the video signal is approximately 1 frame (33 m5ec) behind. is approximately 3 frames (medium 100 m8ec).

In this way, each time the video signal passes through one FS, it
This causes a delay of 33m5, but since many FSs have been introduced into in-office systems, even within one's own station there are multiple FSs.
Also, in the case of local stations, there are many times when they receive and broadcast programs sent from the parent station, and at that time, the FS on the parent station side is also connected in cascade, and the video signal and audio The phase difference (time difference) between signals has become a problem. but,
In the conventional FS, there were few cases where compensation was implemented because it was difficult to find an appropriate compensation method.

An object of the present invention is to solve such problems and to provide an automatic mourning audio phase correction device that can automatically compensate for the phase difference (time difference) between a video signal and an audio signal within its own station. .

The automatic audio phase correction device of the present invention combines the switching timing pulse of a video switching device that switches a plurality of video signals in television broadcasting, the write inhibit pulse and the write start pulse obtained from the synchronization conversion device of the video signal, and K. a logic circuit that generates a delay control signal from the start point of the pulse to the start point of the write start pulse; the delay amount is controlled in accordance with each video signal by the delay control signal of this logic circuit; and an audio signal variable delay circuit to which the output of the audio switcher for switching the audio signals is supplied.

The principle of FS is, for example, published in the magazine ``Broadcasting Technology'' in April 1978.
This FS is detailed on pages 82 to 92 of the monthly issue.
has a built-in write-protection control circuit. This circuit stops writing to the memory at the moment when the input video signal being supplied to %FS is suddenly switched from the signal that was being input to an asynchronous video signal. , wait for the beginning of the frame of the new video signal that has been switched, generate a write start pulse (write clear pulse), return the memory address to address 0, and then start writing again.As a result, the Fs output video signal is disturbed. do not have(
It has a function that allows synchronization. Therefore, the output video signal of the FS is delayed by the time from the moment when the input video signal to the FS is switched until a new write start pulse is obtained. This delay amount is 0 to approximately 33 m88e in the case of FS with frame sled,
For FS with field memory, O ~ approximately 16.5 m8
It becomes eC.

In the present invention, an audio signal delay device that can vary the amount of delay is provided in the audio signal system, and the amount of delay is determined by a control signal corresponding to the amount of video signal delay generated from the write inhibit pulse and write start pulse extracted from the FS. The control automatically corrects the phase difference (time difference) that occurs between the video signal and the audio signal.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a block diagram of a conventional video/audio switching device, which is commonly used in television broadcasting stations and is called a remote switcher. This device includes a video system consisting of a video switcher 1 that switches a plurality of video inputs, an FS3 that synchronizes the output of the video switcher 1, and an audio system that switches each audio signal attached to these video inputs together with the video switcher 1. It consists of an audio system consisting of a switch 2. In the figure, the asynchronous video signal a, which is not synchronized with the internal synchronization signal, is switched by the video switching device 1, and is supplied to the subsequent FS 3, where it is converted into a video signal synchronized with the internal synchronization signal, and the output signal is is output as On the other hand, the asynchronous video signal a1
~a Audio signal a? ~a'□ is audio switching device 2
, and here generally linked with the video switching device 1 (video signal a1 and accompanying audio signals a'1, a2 and a
'2, .

Video signals al and a2 output from the video switching device 1
...a, are asynchronous with each other and not synchronized with the local synchronization signal, so in order to synchronize with the local synchronization signal in FS3 as mentioned above, it is necessary to delay the video signal, so the video output This produces a phase difference (time difference) of approximately 0 to 33 mB compared to the audio output b'.

FIG. 2 is a block diagram of a remote switcher including an embodiment of the present invention. In the figure, an audio signal variable delay device 4 and a logic circuit 5 are added to the conventional configuration.

That is, the processing of the video signals a□ to an is the same as the conventional one. On the other hand, the audio signals a'1 to a'a are switched by the audio switching device 2, then passed through the audio signal variable delay device 4, subjected to phase adjustment, and outputted as the output signal b'. The delay amount of this audio signal variable delay device 4 is controlled by the output of the logic circuit 5, and a digital delay device or the like having a terminal that can remotely control the delay amount can be used. This logic circuit 5 receives the video switching timing pulse C taken out from the video switching device 1 and the write inhibit pulse and write start pulse d taken out from the FS 3, generates a signal corresponding to the amount of delay of the video signal, and outputs the signal. The audio signal is supplied as a control signal to the remote control terminal of the variable delay device 4.

FIG. 3 is a block diagram showing an example of the configuration of the logic circuit 5 in FIG. 2, and FIG.

In Fig. 3, the switching timing pulse (Fig. 4 (A)) of the video switching device 1 is applied to the terminal C, and the write inhibit pulse (Fig. 4 (0)) taken from the FS is applied to the terminals d1 and d2. and a write start pulse (fourth drawing) are respectively input.As the switching timing pulse of the video switching device 1 to be added to this terminal C, the switching timing information (usually a pulse) given to the switching device can also be output from the switching device. It is also possible to use pulsed tally information (usually a hasdata signal).

This input pulse is applied to the next-stage pulse shaping circuit 11, and the pulse width is changed using the leading edge of the input pulse to a pulse width that can include the leading edges of both the write inhibit pulse and the write start pulse. Create C' (Fig. 4 @)
. On the other hand, the write inhibit pulse and the write start pulse input from the terminal d is taken and supplied to the pulse shaping circuit 14. These AND gate circuits 12 and 13 are used to set the audio delay amount only when the input of the FS3 is switched, and even if the input signal to the FS is not switched, this can occur due to disturbances in the waveform of the input signal. This is to prevent the delay amount of the audio delay device 4 from changing when write is prohibited.

In the pulse shaping circuit 14, a pulse d' is generated, with the leading edge of the pulse entering from the terminal d being the leading edge and the leading edge of the pulse entering from the terminal d2 being the trailing edge (fourth drawing). The width of this d' pulse is a signal indicating the delay time of the video signal.

Further, the interface circuit 5 is a conversion circuit for applying a control signal e to the delay amount control remote control terminal of the audio signal variable delay device 4 using a pulse d' indicating the delay time of the video signal.

If the audio signal variable delay device 4 does not have a circuit for holding the control signal e, the interface circuit 5 is naturally provided with a control signal holding circuit, and the control signal of this holding circuit is reset every time a switching timing pulse arrives. I have to do it.

As explained above, when the video signal system in a television broadcasting station has an element that delays the video signal, such as a synchronization conversion device, the present invention provides an audio signal variable delay device in one audio signal system, and synchronizes the video signal system. Generating an audio delay control signal corresponding to the amount of delay of the video signal using a write inhibit pulse and a write start pulse taken out from the conversion device and a switching timing pulse of a video signal switch placed upstream of the synchronous conversion device; By configuring this to be controlled by adding it to the remote control terminal of the audio signal variable delay device, it is possible to automatically and accurately match the phase of the audio signal to the phase of the video signal, which was previously considered difficult to solve. I can do it.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional video/audio switching device (remote switcher), FIG. 2 is a block diagram of a video/audio switching device including an embodiment of the present invention, and FIG. 3 is a block diagram of the logic circuit shown in FIG. 2. , FIG. 4(4) to (2) are operation waveform diagrams of FIG. 2. In the figure, 1... video switcher, 2...
. . . Audio switching device, 3 . . .-FS (video signal synchronous conversion device), 4 . 14...Pulse shaping circuit, 12.13...AND circuit, 1
5...Interface circuit, LL1-a,...
......Video signal input, a;~aI...Audio signal input, b...Video output, b/...
・Audio output, C...Switching timing pulse, d
. . . Write start pulse, e . . . Delay control signal. Kotobuki Ime 4゜mine 2 Fig.

Claims (1)

[Claims] A write start pulse is generated from the start point of the pulse by a switching timing pulse of a video switcher that switches a plurality of video signals in television broadcasting, and a write inhibit pulse and a write start pulse obtained from a synchronous conversion device for the video signal. a logic circuit that generates a delay control signal at the starting point; the delay control signal of this logic circuit controls the amount of delay corresponding to each video signal, and supplies the output of an audio switcher that switches between a plurality of audio signals; An audio phase automatic correction device including an audio signal variable delay circuit.