JP3210377B2 - Image / audio transmission device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image / sound transmission device, and more particularly to an image / sound transmission device which enters a thinned image signal and takes in the image signal.

[0002]

2. Description of the Related Art In a video conference apparatus, a remote monitoring apparatus, and the like, image signals and audio signals from a television camera, a microphone, or the like installed at one end are installed at the other end. To the TV monitor and speaker installed at the other end, and image and audio signals from the TV camera and microphone installed at the other end to the TV monitor and speaker installed at the other end. Exchanges and the like are performed.

[0003] In this type of image / audio transmission device, a still image transmission device using an analog telephone subscriber line is generally employed, and a detected image and a detected sound at one end are accurately transmitted to the other end. I am trying to do it. However, this still image transmission apparatus has a problem that it takes about 30 seconds to transmit one screen detected by a television camera or the like, during which time the situation of the photographing unit changes, thereby impairing the conference function and the monitoring function.

In order to solve this problem, an image / sound transmission apparatus using a high-speed transmission integrated service digital network (hereinafter referred to as an "ISDN network") nationwide has been used. It has become.

[0005] Even an image / audio transmission apparatus using this ISDN network cannot transmit in real time as compared with the transmission speed of a normal television image signal, and transmits a television image signal at a high speed with a reduced resolution (spatial frequency). I was trying to do it.

For example, one screen of a television camera is sampled at 768 × 480 for horizontal and vertical pixels, and
When an ISDN network with a high speed of 64 Kbps is used by quantizing with 8 bits per screen, it takes about 50 seconds to transmit the entire screen. Therefore, one of the TV cameras
The screen is thinned by halving the horizontal and vertical pixels by half.
When the quantization data was reduced to 4 × 240 and the quantized data was compressed to で by the predictive coding method (hereinafter referred to as “DPCM”), it was reduced to 短縮, which is about 6 seconds for transmitting one entire screen.

[0007] However, the image / audio transmission apparatus using the ISDN network has a problem that the transmission speed of an image or the like can be increased, but the resolution is reduced by half and the reproducibility of details is inferior.

Accordingly, the present invention is to provide an image / audio transmission apparatus which performs high-speed transmission of television images using an ISDN network or the like and does not reduce the resolution.

[0009]

According to the present invention, an image signal of a television camera at one end is transmitted to a television monitor at the other end through a thinning-out image transmission circuit, and an audio signal of an audio generation unit at one end is converted to an audio signal. In an image / audio transmission device configured to transmit to an audio receiving unit at the other end via a transmission circuit,
An audio detector for detecting an audioless state in which an audio signal is not transmitted to the audio transmission circuit; and an image insertion unit for causing the image signal of the television camera to enter the audio transmission circuit during the detection of the audioless state. And a video / audio transmission device characterized by providing the above.

[0010]

The image signal from the television camera at one end is transmitted to the television monitor at the other end via the thinning image transmission circuit.

[0011] Also, the audio signal of the audio generation unit at one end is transmitted to the audio reception unit at the other end via the audio transmission circuit.

When the audio signal of the audio transmission circuit becomes silent during transmission of the thinned image signal and audio signal, the silent state is detected, and the image signal of the television camera is transmitted during the detection period. The resolution of the decimated image signal is increased by infiltrating the circuit.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a video / audio transmission apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an outline of the image / audio transmission apparatus.

At one end A of the image / audio transmission device 10, a television camera 11 installed in a video conference hall is provided. A television monitor 12 is provided near the television camera 11 and receives an image signal transmitted from the other end B. In addition, a microphone 13 for detecting a voice signal and a speaker 14 for receiving a voice are provided in a video conference room.
And an operation unit 15 for controlling the television camera 11, the television monitor 12, and the like. These TV cameras 11,
The television monitor 12 and the like are connected to a transmission circuit device 16 having a basic interface of 2B + D.

The transmission circuit device 16 is connected to an integrated digital network (hereinafter, ISDN) via a line termination device (hereinafter, referred to as "DSU") 17. Where I
The SDN line uses a 2B or B basic interface.
A DSU 20 at the other end B is sequentially connected to this ISDN line, and a television camera 21, a television monitor 22, a microphone 23, a speaker 24, and an operation unit 25 similar to the one at the one end A are connected to the DSU 20. 2B
A transmission circuit device 26 having a + D basic interface is provided.

With this configuration, the television camera 1 at the end A is provided.
1, the transmission circuit device 16, the DSU 17, the ISDN network 18, the DSU 20
Are transmitted to the television monitor 22 and the speaker 24 at the other end B via the other end, and the image signal of the television camera 21 and the audio signal of the microphone 23 from the other end B are transmitted to the transmission circuit device 2
6, transmitted via the DSU 20, the ISDN network 18, and the DSU 17 to the television monitor 12 and the speaker 24 at one end A, and mutually exchange images and sounds for video conference and on-site monitoring.

FIG. 1 shows the transmission circuit devices 16, 26,
FIG. 3 is a block diagram specifically showing the transmission circuit device 16 in detail.

An upstream B1 for sending an image to the transmission circuit device 16
A 2B + D basic interface including a channel, a downlink B1 channel for receiving an image, an uplink B2 channel for transmitting an audio, a downlink B2 channel for receiving an audio, and a D channel for transmitting and receiving a control signal is provided.

In the upstream B1 channel, an amplifier 30 for amplifying an analog image signal detected by the television camera 11, an analog / digital converter 31 for converting an analog image signal into a PCM digital signal, and encoding the digital signal. An encoding unit 32, and a compression unit 33 for thinning out the encoded signal of the encoding unit 32 to 1/2 and performing processing such as compression to 1/2 by DCPM are sequentially connected. In the compression section 33, a transmission frame signal is formed by adding a line number to the thinned and compressed coded signal.
17 is transmitted to the television monitor 22.
Is to be projected on.

The encoding section 32 is connected to an encoded data section 35 for converting the encoded signal into data, and the encoded data of the image signal is transmitted to the signal switching section 50 of the upstream B2 channel.

In the downstream B1 channel, an amplifier 4 for receiving a digital decimated and compressed signal transmitted from the DSU 17
0, a decompression unit 41 for decompressing the decompressed signal, and a decompression unit 4 for decoding the decompressed image signal.
2. A digital / analog converter 43 for converting the decrypted signal into an image signal of an analog signal, and an amplifier 44 for amplifying the analog signal are sequentially connected so that the image of the other end B is displayed on the television monitor 13. Has become.

The decoding section 42 is connected to an encoded data section 45 for receiving encoded data, and receives the encoded data of the image signal transmitted from the signal switching section 60 for the downstream B2 channel.

The microphone 13 is provided for the up-link B2 channel.
An amplifier 51 for amplifying the analog audio signal detected by
An audio detector 53 that detects an audio signal and sends a control signal to the controller 52 when the audio signal is in a non-voice state. An analog audio signal from the audio detector 53 is converted into a digital signal, and an analog signal is encoded. / Digital conversion encoder 54, a digitally encoded signal and the upstream B
The signal switching unit 50, which receives an image signal from one channel and is switched and controlled by a control signal of the control unit 52, is connected to an amplifier 55 for amplifying a digitally encoded signal and an image signal of encoded data. The digitally coded signal and the image signal are transmitted to the speaker 24 at the other end B through the DSU 17 or the like.

An amplifier 61 amplifies the digital audio signal transmitted from the DSU 17 and the incoming video signal in the downstream B2 channel. The amplifier 61 detects the amplified audio signal and the incoming video signal and, if the video signal is input, a control unit. A code detector 63 for sending a control signal to 62;
The signal switching unit 60, which is switched under the control of the control unit 61 when an audio signal and an incoming image signal are received and an image signal is input, converts a digital audio signal into an analog signal and decodes the digital / analog signal. Encoding unit 64, amplifier 6 for amplifying an analog signal
5 are sequentially connected so that the audio signal at the other end B is transmitted to the speaker 14 at the other end A.

The D channel is connected to a line control unit 70 for receiving a dial signal or the like from the operation unit 15 for switching lines such as the B1 channel and the B2 channel.
And so on.

The transmission circuit device 26 is the transmission circuit device 1
6 is configured to receive image signals and audio signals from the television camera 11 and the like via the transmission circuit device 16 and to transmit image signals and audio signals from the television camera 21 and the like to the transmission circuit device 16. It has become.

Next, the operation of the image / sound transmission device having such a configuration will be described.

An image signal projected by the television camera 11 is transmitted to the DSU 17 through an amplifier 30, an analog / digital converter 31, an encoder 32, a thinning-out unit, a compression unit 33 to which compression and line numbers are added, and an amplifier 34. Is done.
The image signal transmitted to the DSU 17 is an ISDN network 18,
The compressed signal is transmitted to the transmission circuit device 26 via the DSU 20, expanded and displayed on the television monitor 22,
An image of one end A is projected on the other end B.

The audio signal detected by the microphone 13 is also transmitted to the DSU 17 via the amplifier 51, audio detector 53, analog / digital encoder 54, signal converter 50, and amplifier 55. The audio signal transmitted to the DSU 17 is transmitted to the transmission circuit device 26 via the ISDN 18 and the DSU 20, and is converted into audio by the speaker 24, and the audio at one end A is heard at the other end B.

During such a transmission, in a video conference or the like, an audio signal may be temporarily interrupted and a silent state may occur.
This silent state reaches about 50% during a conference in a long time, and the upstream B2 channel becomes a play channel in which no sound is transmitted.

The no-voice state that has become the idle channel is detected by the voice detection unit 53, and this detection signal is transmitted to the control unit 5
Sent to 2. When the control unit 52 receives the no-sound detection signal, it sends a control signal to the signal conversion unit 50 and switches from the analog / digital encoding unit 54 to the encoded data unit 34.

Thus, the upstream B2 channel is converted from the audio transmission circuit to the video transmission circuit, and the video signal of the upstream B1 channel is converted to the amplifier 55, the DSU 17, the ISDN network 18,
The signal is transmitted to the transmission circuit device 26 via the SU 20.

For this reason, the compression unit 33 of the upstream B1 channel
The image signal at the time of the non-speech state is introduced into the image signal decimated by the above via the uplink B2 channel, and the resolution is improved as compared with the decimated state.

A case will be described in which this pull-in operation is performed by the down-link B1 channel and down-link B2 channel of the transmission circuit device 16 with the image signal projected by the television camera 21 at the other end B and the audio signal detected by the microphone 23.

The image projected by the television camera 21 is transmitted to the upstream B1 channel of the transmission circuit device 26, the DSU 20, the IS
DN network 18, DSU 17, amplifier 40, expander 41, decoding section 42, analog / digital conversion section 43, amplifier 4
4 is displayed on the television monitor 12.

The audio signal detected by the microphone 23 is transmitted to the upstream B2 channel of the transmission circuit device 26 and the DSU.
20, ISDN 18, DSU 17, amplifier 61, code detector 63, signal converter 60, analog / digital code converter 64, and amplifier 65, and are taken out to speaker 14 as voice.

When the B2 channel code detecting section 63 detects an incoming image signal during transmission of the video or the like, the signal converter 60 is switched from the analog / digital encoding section 64 to the encoded data section 45, and the incoming image signal is transmitted. Is B1
It is sent to the coded data part 42 of the channel.

For this reason, the deciphering section 42 adds the decimated image signal and the incoming image signal, approaches the image signal before the decimated image signal is passed through the analog / digital conversion section 43. Is displayed on the television monitor 12.

As a result, the other end B
Can be accurately projected at high speed with high resolution to detail.

According to this thinned-out image transmission circuit device, when requesting a detailed image in a video conference, the sound of the audio transmission circuit may be temporarily cut off using a manual switch, and only the monitoring device may be used. In this case, a high-resolution image can be obtained by opening the switch of the audio transmission circuit.

In this embodiment, the DPCM is used for compressing and decompressing images. However, in a video conference or the like, a discrete cosine transform (DD) which can transmit several images per second is used.
CD) can be used. According to this discrete cosine transform method, in addition to being faster than the method of the present invention, in order to enhance the resolution, hierarchical coding processing is applied to the interface of the B1 channel and the B2 channel, and data transmission from a spreading system in which arithmetic coding is performed. For example, the resolution can be further increased by, for example, assigning to the.

[0043]

According to the present invention, the resolution of a received image can be minimized by effectively utilizing an audio signal channel in a non-speech state while maintaining a high image transmission speed. In addition, since an image signal which is thinned out by the image thinning means and is not transmitted by the image transmission channel is transmitted through the audio transmission channel by using the audio transmission channel in a non-audio state, the transmitted audio signal is limited. Audio is not degraded.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a transmission circuit device implemented in the present invention.

FIG. 2 is a block diagram showing an image / audio transmission device to which the transmission circuit device of FIG. 1 is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Image / audio transmission apparatus 11 Television camera 12 Television monitor 13 Microphone 14 Speaker 15 Operation part 16 Transmission circuit device 17 Line termination unit (DSU) 18 Integrated service digital network (ISDN network) 20 Line termination unit (DSU) 21 Television camera 22 TV monitor 23 Microphone 24 Speaker 25 Operation unit 26 Transmission circuit device 30 Amplifier 31 Analog / digital converter 32 Encoding unit 34 Encoded data unit 50 Signal switching unit 41 Decompression unit 42 Encoded data unit 43 Decryption unit 44 Digital / Analog converter 50 Signal switching unit 52 Control unit 53 Audio detection unit 54 Analog / digital conversion encoding unit 61 Control unit 62 Code detection unit 63 Signal switching unit 64 Analog / digital conversion encoding unit 70 Control circuit unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04M 11/00-11/10 H04N 7/10 H04N 7/14-7/173 H04N 7/20-7 / twenty two

Claims (1)

(57) [Claims] 1. A picture Den image signal of one end of the television camera
The image / audio transmitted to the television monitor at the other end via the transmitting means and the audio signal from the microphone at the one end to the audio receiving section at the other end via the audio transmitting means. In the transmission device, image encoding means for encoding the image signal of the television camera, image thinning means for thinning out the encoded image signal, an image transmission channel for transmitting the thinned image signal, and the microphone Audio transmission for transmitting audio signals
A channel, and a non-speech detection unit that detects whether or not a non-speech state in which a speech signal is not output from the microphone. If a non-speech state is detected by the non-speech detection unit , instead of the speech signal, The encoded image signal
The image is transmitted by being thinned out by the image thinning means.
The image signal not transmitted by the channel
Means for transmitting an image signal via a channel, and a thinned image transmitted via the image transmission channel.
The image signal has been transmitted via the audio transmission channel
An image to which an image signal is added and sent to the television monitor at the other end
An image / audio transmission device comprising: signal receiving means .