JPS5930368A - Sound synchronizing device - Google Patents

Abstract

PURPOSE:To correct accurately a time shift between a video signal and a sound signal, without being subject to the deterioration in the characteristic, by delaying the sound signal after converting once into a digital signal and synchronizing the sound signal and the video signal. CONSTITUTION:A synchronizing signal is separated at a synchronizing signal separating circuit 1 from an input video signal and a synchronized clock signal is outputted from the 1st clock generator 2. The clock signal is applied to an A/D converter 7 inputting the input sound signal, and a write/readout control circuit 3, and after the sound signal is converted into a quantizing signal at the converter 7, the signal is applied to a storage device 4 and an overtake and outrun control circuit 10. Further, the 2nd clock in synchronizing with the synchronizing signal of the own station is generated from the 2nd clock generator 5 and applied to a D/A converter 8 and the control circuit 3. Further, the sound signal read out from the storage device 4 is analog-converted at the converter 8, allowing to correct accurately the time shift between an outputted sound signal from an LPF9 and the video signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has a method for correcting a time difference between a video signal and an audio signal that occurs when using a video synchronization coupling device that synchronizes a video signal arriving from the outside with a synchronization signal of its own station. This invention relates to an audio synchronization device.

Generally, a television broadcasting station receives video signals sent from other stations and video signals from relay sites, mixes these video signals with a video signal produced within the station, and sends out the video signal for its own station. In this case, it is necessary to synchronize the input video signal from the outside with the synchronization signal of the local station.

In the past, various types of synchronization devices have been developed and implemented, but in recent years, with the advancement of digital technology, video signals from the outside are first converted into digital signals and then stored in a storage device. A so-called video synchronization coupling device has been developed and put into practical use, in which the stored video signal is synchronized with the synchronization signal of its own station.

In addition, by using this video synchronization coupling device, it is easy to combine video signals of different systems, and
Recently, not only key stations and local TV broadcasting stations, but also broadcast vehicles dispatched to relay sites are being equipped with such equipment, and efficient operation is being achieved by making full use of a large number of television cameras.

However, this type of device has the problem of misalignment as described above.

On the other hand, since the audio signal sent together with the video signal is sent out without passing through such a video synchronous coupling device, there is a gap between the video signal sent through the video synchronous coupling device and the audio signal sent directly. causing a time lag,
This phenomenon occurs in that the audio signal is sent out before the video signal.

By the way, since a storage device that stores video signals usually stores video signals in units of one frame, the video signals sent from other stations and the video signals obtained through the video synchronization coupling device Therefore, there is a time difference of up to 33 frames between the video signal and the audio signal obtained through this device.
This results in a time lag of m5.

Normally, a time lag of this degree does not have a significant effect on audiovisual performance, but as this type of device is widely adopted, the phase advance of the audio signal relative to the video signal increases each time it passes through this device. Therefore, it is conceivable that the number of frames may reach several frames.

Therefore, even the viewers who receive such broadcast waves will be able to sense the discrepancy between the image and the sound.
There is a risk of causing discomfort to viewers.

Therefore, in order to correct the discrepancy between the audio signal and the video signal, the audio signal that arrives together with the video signal is passed through an analog variable delay circuit whose delay time can be variably controlled. There is also a device in which the delay time of the delay circuit is controlled based on the phase difference between the framing pulse extracted from the externally input video signal and the synchronization signal within the local station by converting it into a DC voltage. being developed.

However, if you try to obtain a delay amount of up to 33m5 by passing an audio signal through such an analog delay circuit, deterioration in characteristics is unavoidable. There was also the problem that the device itself became complicated, such as the need to provide a special force detector to determine the phase difference between the two.

The present invention has been made in view of the above circumstances, and is capable of accurately correcting the time difference between a video signal and an audio signal that occurs when a video synchronization coupling device is used. -H Since the signal is converted into a digital signal and then delayed, the characteristics deteriorate.

5- Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings.

1 in the figure is a synchronization signal separation circuit that separates a synchronization signal from a video signal arriving from the outside, and this synchronization signal separation circuit 1
The synchronization signal separated by the first clock generator 2
supplied to

The first clock generator 2 generates a clock signal that is an integer multiple of the synchronization signal, in this embodiment, three times the horizontal synchronization signal 15, 75KH2, that is, 47, 25KH2, and has a built-in address counter, By counting , the address signal necessary for writing is supplied to the storage device 4 via the write and continuation control circuit 3.

On the other hand, 5 is a second clock generator, which receives the synchronization signal of its own station and generates a horizontal synchronization signal 15.5 which is an integer multiple of this synchronization signal, in this embodiment, similar to the first clock generator 2.
? It generates a clock signal of three times 5KH2, that is, 47.25KH2, and also has a built-in address counter, and by counting this clock signal, the address signal necessary for reading is stored via the write and read control circuit 3. Device 4
We are trying to supply it to

Incidentally, the input audio signal is supplied to the A/O converter 7 via the low-pass filter 6.

This A/D converter 7 converts the audio signal into a clock signal output from the first clock generator 2, for example.
It converts to a quantized signal with 6 bits as one unit.
The quantized signals converted by the A/D converter 7 are sequentially written into the storage device 4 based on the clock signal and address signal output from the first clock generator 2.

The quantized signals written in the storage device 4 are sequentially read out based on the clock signal and address signal output from the second clock generator 5 and supplied to the D/A converter.

This D/A converter 8 converts the audio signal that has been converted into a quantized signal and stored into an analog audio signal according to the clock signal output from the second clock generator 5. The audio signal restored by the device 8 is output to the audio line via a low-pass filter 9.

Reference numeral 10 in the figure is a catch-up/overtake control circuit for dealing with a case where a catch-up occurs between the address being written to the storage device 4 and the address being read from the memory device 4.

The control circuit 10 includes an address comparison circuit that compares the write address generated by the first clock generator 2 and the read address generated by the second clock generator 5;
Monitors the audio signal input through the A/D converter and determines whether the audio signal continues for a certain period of time, for example, 33 m5, without causing any unnatural feeling even if the audio signal becomes discontinuous. It is equipped with an audio level monitoring circuit. First, when the read address catches up with the write address, a control signal is output to the write and read control circuit 3, and the write address is temporarily set one address before the read address. to hold.

To return to the forced state, the input audio level is monitored by the audio level monitoring circuit, and when the state that does not give any unnatural feeling continues for 33 m5 or more, a control signal is output to the write and read control circuit 3. .

Next, even when the address being read has caught up with the address being written, a control signal is output to the write and read control circuit 3 to temporarily hold the read address at address 1 of the write address.

Returning to a forced state is done in the same way as returning to a forced state.

By performing such an operation, the problem caused by the discontinuity of the sound can be eliminated even if the phenomenon of displacement and displacement occurs between the write address and the read address.

The waning audio signal is written to the storage device 4 according to a clock signal synchronized with this video signal, and
Since the audio signal written to the station is read out according to a clock signal synchronized with the synchronization signal of the own station, the time difference that occurs between the input audio signal and the output audio signal, that is, the output audio signal with respect to the input audio signal. It is possible to match the delay of the output video signal with respect to the input video signal that occurs when the video signal is passed through the video synchronization coupling device.

Therefore, it is possible to accurately correct the time lag between the video signal and the audio signal, which occurs when the video signal and audio signal are passed through a conventional video synchronous coupling device, and it is possible to eliminate any audiovisual unnaturalness caused by the discrepancy between the video and audio. It is something.

In particular, even when a large number of video synchronization coupling devices are interposed between the program production site and the transmitting station, it is possible to install the audio synchronization device based on the present invention in each video synchronization coupling device. , it is possible to eliminate the time lag between the video signal and the audio signal over the entire system.

Furthermore, since the analog delay circuit used in conventional devices of this type is not used at all, and the delay effect is performed after converting it into a digital signal, there is a risk of deterioration in characteristics. In addition, the synchronization signal supplied to the first clock generator 2 is separated from the video signal arriving from the outside, and the second
The synchronization signal supplied to the clock generator 5 of the station is that of the own station. In other words, this device can delay the audio signal to match the delay of the video signal by simply supplying the external video signal and the synchronization signal of the local station, so unlike conventional devices of this type, the device can delay the audio signal from the outside. There is no need to provide a special detector for determining the phase difference between the video signal and the synchronization signal within the local station, and the circuit configuration is simplified and can be manufactured at low cost.

According to the present invention, as shown in FIG. It is possible to provide an audio synchronization device that does not cause deterioration in characteristics, has a simple configuration, and can be manufactured at low cost.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. 2...first clock generator 4...Storage device 5...Second clock generator 7...A/D converter 8...D/A converter

Claims (1)

[Claims] A first clock generator outputs a clock signal synchronized with the input synchronization signal, a second clock generator outputs a clock signal synchronized with the local synchronization signal, and the first clock generator outputs the input audio signal. an A/D converter that converts the quantized signal into a quantized signal according to a clock signal;
A D/D converter writes the quantized signal converted by the D converter in accordance with the clock signal output from the first clock generator, and converts the written quantized signal into a second quantized signal into an analog audio signal. An audio synchronization device comprising: an A converter.