JPH1013787A - Voice signal multiplexer system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To output a voice signal (a plurality of channels) in a continuous sound when a video signal of a plurality of channels is subject to frame switching. SOLUTION: Video signals V1-V4 are switched by a frame switcher 1 in the unit of frames, a H-sync separator section 2 separates a horizontal synchronizing signal from the video signal, a sampling pulse generating section 3 generates a sampling pulse based on the horizontal synchronizing signal and the pulse is given to voice data generating sections 4a-4d. Then audio signals A1-A4 are sampled at a sampling section 11 based on the pulse and the data are time base compressed by a time base compression section 12, a data hold section 13 holds the resulting data by 4H each, the audio data are sequentially switched by an audio switcher 5 in the order of 4a, 4b, 4c, 4d and the result is given to a multiplexer section 6, where data of each audio channel are multiplexed by 4H each for each horizontal blanking period of the video signal sequentially. In the case of reproducing the audio signal, multiplexed data are separated from the video signal and the audio signal of a channel is designated and extracted, the audio signal is expanded based on time base and the result is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to frame switching of video signals from a plurality of television cameras (hereinafter abbreviated as "cameras"), compression of audio signals from each camera on a time axis, and horizontal retrace period of video signals. The present invention relates to an audio signal multiplexing method for recording and reproducing each audio without interruption.

[0002]

2. Description of the Related Art When a plurality of surveillance cameras are installed, video signals from each camera are recorded together with audio signals, and are reproduced when an abnormality occurs, so that the situation of the abnormality can be confirmed.
In order to simplify the recording equipment, for example, there is a method in which a signal from each camera is switched and recorded in frame units by a frame switcher. In this case, even if the video is dropped, there is no problem in understanding the video content in many cases, but the audio signal is also switched at the same time, so the reproduced audio is interrupted and it is not clear what it is saying The problem arises.

[0003]

SUMMARY OF THE INVENTION In view of the foregoing, the present invention switches and records video signals from a plurality of cameras or the like in units of frames, samples audio signals from each of the cameras or the like, and sets a time axis. By compressing, all the audio channels are recorded without interruption, the audio channel is specified at the time of reproduction, and the reproduced audio signal is expanded on the time axis so that the audio of the channel can be reproduced without interruption. It is in.

[0004]

According to the present invention, in order to solve the above-mentioned problems, a video signal of a plurality of channels whose frames are synchronized is switched by a frame switcher. A sampling pulse generating unit for generating a sampling pulse, a plurality of sampling units for sampling audio signals of a plurality of channels with pulses from the sampling pulse generating unit, and a plurality of time axes for compressing data from the respective sampling units on a time axis basis. A compression unit, a plurality of data hold units respectively holding data from the time axis compression units, an audio switcher for switching data from each data hold unit in a required time interval and a required order, and data from the audio switcher Is the horizontal retrace period of the video signal from the frame switcher. A multiplexing unit for multiplexing at a required position, an audio channel selecting unit for selecting an audio channel multiplexed on the video signal, a pulse generating unit for generating a pulse based on a horizontal synchronization signal of the video signal, and a pulse generating unit An audio separating unit for separating audio data of a channel selected from the video signal from the multiplexing unit by a pulse, and a time axis extending unit for extending the audio data from the audio separating unit in the time axis. The present invention provides an audio signal multiplexing method for outputting audio data from a unit.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an audio signal multiplexing system according to the present invention, a frame switcher is used to switch video signals of a plurality of channels whose frames are synchronized, wherein a required sampling pulse based on a horizontal synchronization signal of the video signal is sampled. The audio signal of a plurality of channels generated by the pulse generation unit is sampled by the sampling unit with the pulse from the sampling pulse generation unit, and the data from each sampling unit is time-axis-compressed by the time-axis compression unit. The data from the compression unit is held in the data hold unit, and the data from each data hold unit is switched by the voice switcher in a required time interval and in a required order, and the data from the voice switcher is input to the multiplexing unit.
The video signal from the frame switcher is multiplexed at a required position in the horizontal retrace period, and the signal from the multiplexing unit is recorded in the image recording / reproducing device. The audio data multiplexed into the signal is separated, and the data of the audio channel selected by the audio channel selection unit is extended on the time axis by the time axis extension unit and output.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a voice signal multiplexing system according to the present invention. 1 and 2 are main block diagrams of an audio signal multiplexing system according to an embodiment of the present invention. FIG. 1 shows an audio multiplexing side, FIG. The cameras and audio signal sources are four channels of sound 1 to sound 4 output from each camera in pairs with movie 1 to movie 4.

In FIG. 1, reference numeral 1 denotes a frame switcher for sequentially switching video signals from four cameras, ie, images 1 to 4 in frame units. For example, the video signal and the video 1 to the video 4 are frame-synchronized by a common synchronization signal, and the frame switcher 1 uses the synchronization signal to switch the video signal in a frame unit (for example, a required frame number unit). . Reference numeral 2 denotes an H-sync separation unit that separates a horizontal synchronization signal (H-sync) from a video signal from the frame switcher 1. 3
Is a sampling pulse generator, which is output from the H-sync separator 2
A sampling pulse synchronized with H-sync is generated based on H-sync. 4a to 4d are audio data generation units, respectively.
Audio signals from microphones or the like attached to the four cameras are input, and sound 1 to sound 4 are respectively input. Each of the audio signals is sampled by a sampling unit 11 using a pulse from the sampling pulse generation unit 3, and sampling data is output. Is time-axis-compressed by the time-axis compression unit 12, is held for a required time by the data hold unit 13 (), and is output to the audio switcher 5. The audio switcher 5 switches and outputs the audio data from the audio data generators 4a to 4d in synchronization with the frame switcher 1 for each frame, for each required number of frames, or for each horizontal scanning period (1H). A multiplexing unit 6 multiplexes the audio data from the audio switcher 5 to a required position in the horizontal retrace period of the video signal from the frame switcher 1 ().

In FIG. 2, reference numeral 21 denotes an H-sync separation unit, which separates a horizontal synchronization signal (H-sync) from the video signal from the multiplexing unit 6. Reference numeral 22 denotes a pulse generation unit which generates a pulse for extracting audio data multiplexed on the video signal from the multiplexing unit 6. Reference numeral 23 denotes an audio separation unit which separates (extracts) audio data from the video signal from the multiplexing unit 6 with a pulse from the pulse generation unit 22. Reference numeral 24 denotes an audio channel selection unit for selecting any one of the sounds 1 to 4 according to the designation. 25 is the data memory,
The audio data selected by the audio channel selection unit 24 is recorded. Reference numeral 26 denotes a time axis extending unit which extends the time axis of the audio data read from the data memory 25. Reference numeral 27 denotes a filter which removes a high-frequency component of the data from the time axis extending unit 26.

Next, the operation of the audio signal multiplexing system according to the present invention will be described. “Eye 1” to “Eye 4” in FIG. 1 are, for example,
These are video signals from four cameras installed for monitoring, and “Sound 1” to “Sound 4” are audio signals output in pairs with “Screen 1” to “Screen 4”. Each video signal from the camera is switched by the frame switcher 1 on a frame basis (for example, on a frame basis), output via the multiplexing unit 6, and recorded on, for example, an image recording / reproducing apparatus (VTR).
This VTR is used, for example, for playing back when there is an abnormality in the monitoring area and confirming the state of the abnormality.

FIG. 3 is an operation explanatory diagram in the case where the data of the sound 1 to the sound 4 compressed on the time axis are sequentially multiplexed in each horizontal retrace period of the video signal. As an example. That is, the H-sync separation unit 2 separates the H-sync from the video signal from the frame switcher 1, and the sampling pulse generation unit 3 uses this H-sync as a reference.
A sampling pulse synchronized with H-sync is generated at the back porch phase of H-sync. In the figure, the sampling pulse has the same cycle as H-sync, that is, a repetition cycle of about 15 KHz in the case of the NTSC system.However, the present invention is not limited to this, and a higher repetition cycle can improve the sound quality. it can. The sampling pulse is input to the audio data generation unit 4a, applied to the sampling unit 11, samples a 1-channel audio signal, and outputs sampling data. This sampling data is sent to the time axis compression unit 12, and the time axis compression unit 12
Min (for the number of horizontal scanning periods equal to the number of audio channels)
To the audio data multiplexing period (H-
Compress the time axis so that it enters the sync back porch. The data hold unit 13 holds this data for a horizontal scanning period equal to the number of audio channels, that is, 4H, applies this data to the audio switcher 5, and outputs 4a → 4b → 4c → 4d → The video signals are sequentially switched every 1H, input to the multiplexing unit 6, and sequentially multiplexed in the audio channel order during the audio data multiplexing period of each horizontal retrace period of the video signal ().

In the above description, the data from the time axis compression unit 12 is held by the data hold unit 13 for 4H. However, an integer multiple of this is held, and the multiplexing unit 6 holds each horizontal signal of the video signal. 1ch, 1ch,..., 2ch, 2ch,.
The same audio channel, such as 3ch, 3ch,.

FIG. 4 is an operation explanatory diagram in the case of sequentially multiplexing data of sound 1 to sound 4 which have been time-axis-compressed for each audio channel for one vertical scanning period in each horizontal retrace period of a video signal. An example in which sound 1 (1 ch) is processed as in FIG. The difference from the operation of FIG. 3 is that the sampling data sampled by the sampling unit 11 is held by the time axis compression unit 12 for the period of the vertical scanning period equal to the number of audio channels, that is, 4 V, and this data ′ is Apply to switcher 5, 1V in order of 4a → 4b → 4c → 4d →
In this case, the signals are sequentially switched for each audio signal, input to the multiplexing unit 6, and sequentially multiplexed (') by 1 audio channel to 1V in the audio channel order during the audio data multiplexing period of each horizontal retrace period of the video signal. The other parts are the same as those in FIG. 3 and will not be described. Although the data hold unit 13 holds the data from the time axis compression unit 12 for 4 V, the data hold unit 13 holds an integer multiple of this data, and the multiplexing unit 6 stores one channel for each vertical scanning period of the video signal. 1ch, 2ch, 2ch, 3ch, 3ch
A plurality of the same audio channels such as ch,... may be successively multiplexed in each horizontal retrace period of each vertical scanning period.

The video signal from the multiplexer 6 is, for example, V
Input to TR and recorded. The signal reproduced by the VTR is
The video signal is switched for each required number of frames such as video 1 → video 2 → video 3 → video 4 →... The video from each camera is displayed in a frame-by-frame manner on a screen such as a monitor. Then, the audio is separated from the audio signal from the audio data multiplexing period of the video signal by the audio separation unit 23 by the pulse generated by the pulse generation unit 22 based on the H-sync separated from the video signal by the H-sync separation unit 21. Sampling, taking out the data of the channel (sound 1 etc.) designated by the audio channel selection unit 24, writing it to the data memory 25 once, reading it out, and expanding the time axis so as to return to the original audio frequency by the time axis expanding unit 26 Then, the filter 27 removes high-frequency components and the like and outputs the result. As a result, the sound of the specified channel is reproduced as a continuous sound instead of being dropped.
Note that the audio channel selection unit 24 includes the audio data generation units 4a to 4d.
In accordance with the data generation method (whether the audio channel is switched every 1H, every several Hs, every 1V, or every several V), it is set to take out the data from the audio separation unit 23.

In the above description, the case where the number of audio signals is four has been described, but when the number of audio channels is different from this, the compression ratio on the time axis is increased or decreased according to the number of audio channels.

[0015]

As described above, according to the audio signal multiplexing method according to the present invention, the video signals from a plurality of cameras are switched on a frame basis by the frame switcher, but the audio signals are sampled at an appropriate frequency. Since the time axis is compressed and multiple channels are sequentially switched and multiplexed during the horizontal retrace period of the video signal, the video data is extracted by extracting the data of the specified audio channel from the video signal and expanding the time axis. Although the sound is dropped, the sound can be reproduced as a continuous sound, and there is no problem that the sound cannot be recognized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main part of an audio signal multiplexing system according to an embodiment of the present invention on the audio multiplex side.

FIG. 2 is a block diagram of a main part on the audio separation side in one embodiment of the audio signal multiplexing system according to the present invention.

FIG. 3 is a conceptual diagram illustrating multiplexing of an audio signal.

FIG. 4 is a conceptual diagram illustrating multiplexing of an audio signal.

[Explanation of symbols]

 Reference Signs List 1 frame switcher 2, 21 H-sync (horizontal synchronization signal) separation unit 3 sampling pulse generation unit 4a to 4d audio data generation unit 5 audio switcher 6 multiplexing unit 11 sampling unit 12 time axis compression unit 13 data hold unit 22 pulse generation unit 23 Audio separation unit 24 Audio channel selection unit 26 Time axis expansion unit

Claims (8)

[Claims] 1. A method of switching video signals of a plurality of channels synchronized with a frame by a frame switcher.
A sampling pulse generator that generates a required sampling pulse based on the horizontal synchronization signal of the video signal,
A plurality of sampling units for respectively sampling audio signals of a plurality of channels with pulses from a sampling pulse generation unit, a plurality of time axis compression units for respectively compressing data from each sampling unit on a time axis, and a plurality of time axis compression units for each of the time axis compression units. A plurality of data holding units for holding data, an audio switcher for switching data from each data holding unit in a required time interval and a required order, and a horizontal return of data from the audio switcher to a video signal from the frame switcher. An audio signal multiplexing system comprising a multiplexing unit for multiplexing at a required position in a line period. 2. The time axis compressing section sets audio data for a horizontal scanning period equal to the number of audio channels from each sampling section to an audio data multiplexing period of a horizontal retrace period of a video signal. 2. The audio signal multiplexing method according to claim 1, wherein time axis compression is performed. 3. The data holding unit holds data from each of the time axis compression units, respectively, for a period of horizontal scanning equal to the number of audio channels, and a multiplexing unit via the audio switcher for each video signal. The audio signal multiplexing method according to claim 1 or 2, wherein the audio signals are sequentially multiplexed at required positions in the horizontal retrace period in the order of required audio channels by one audio channel. 4. The data hold unit holds data from each time axis compression unit for a period obtained by multiplying a required period by a required integer in a horizontal scanning period equal to the number of audio channels, and stores the data through the audio switcher. 3. The audio signal multiplexing method according to claim 1, wherein the multiplexing unit sequentially multiplexes the required audio channels at required positions in each horizontal retrace period of the video signal in order of one audio channel. 5. Each of the data holding units holds data from each of the time axis compression units, respectively, in a period of vertical scanning equal to the number of audio channels, and each of the video signals is transmitted by the multiplexing unit via the audio switcher. 3. The multiplexing method according to claim 1, further comprising multiplexing sequentially at a required position in a horizontal flyback period by a required one audio channel in each vertical scanning period.
The described audio signal multiplexing method. 6. The data hold unit holds data from each time axis compression unit for a period obtained by multiplying a vertical scanning cycle period equal to the number of audio channels by a required integer, and passes through the audio switcher. 3. The audio signal multiplexing method according to claim 1, wherein the multiplexing unit sequentially multiplexes the required audio channels in a required position in each horizontal retrace period of the video signal by one audio channel in each vertical scanning period. 7. An audio channel selector for selecting an audio channel multiplexed on the video signal, a pulse generator for generating a pulse based on a horizontal synchronizing signal of the video signal, and a pulse from the pulse generator. An audio separation unit that separates audio data of a channel selected from the video signal from the multiplexing unit, and a time axis extension unit that extends the time axis of the audio data from the audio separation unit, and audio data from the time axis extension unit 7. The audio signal multiplexing method according to claim 1, wherein said signal is output. 8. A signal from the multiplexing unit is recorded in an image recording / reproducing apparatus, and at the time of reproduction, the audio separating unit separates audio data multiplexed into a video signal by a pulse from a pulse generation unit, 8. The audio signal multiplexing method according to claim 7, wherein the data of the audio channel selected by said audio channel selector is time-expanded by said time-axis expander and output.