JPS6390953A - Multi-media communication equipment - Google Patents

Abstract

PURPOSE:To improve transmission quality by detecting an information quantity generated in each media, and varying respective encoding speed in the transmission capacity of one line portion in accordance with its generation quantity. CONSTITUTION:A system control part 11 always detects the information generation quantity of a moving picture, a still picture and a voice encoding signal, and in case it is smaller than a prescribed value, based on a result of detection of a voice level, it is regarded as silent, and a voice encoding/decoding device 10 is controlled so as to stop a voice encoding operation. Also, encoding/ decoding devices 8, 9 are controlled so that information of a curtailed portion of voice information can be allocated to moving picture and still picture media. On the other hand, in the receiving side, a signal from a transmission line is written temporarily in a buffer, separated into the moving picture, the still picture or the voice by a media discriminating bit being in the head of an information frame, and decoded by the respective encoding/decoding devices 8-10. In this case, each encoding/decoding device detects the information frame already, and in case each information does not exist, it is read out repeatedly, or in case of a voice, it is processed as silent.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical field to which the invention pertains The present invention relates to a multimedia communication device for conducting teleconferences and the like by combining various media such as moving images, still images, and audio.

(2) Prior art As a conventional communication method of this type, 1. For example, video and audio are each encoded by 1.464 Mb using separate encoding devices.
There is a method in which the data is encoded at a speed of 1.536 Mb/s, 64 kb/s, time division multiplexed at 1.536 Mb/s including a frame synchronization pattern, and transmitted (see [l]).

In this method, the encoding device for each media is fixed at the specific speed mentioned above.2For example, 64 kb/s is fixedly allocated as an audio signal even when no talking is being performed. Inefficient. In other words, each media such as video or audio is controlled to be encoded at a constant transmission speed.2 For example, even when conference participants are moving a lot and a lot of video information is tilted, the encoding speed is controlled to be constant for each media. Since the speed is suppressed to a constant value, there is a drawback that if the number of video frames is reduced by reducing the number of video frames, the resolution will deteriorate due to the reduction in the number of sampling pixels. This drawback becomes even more noticeable as the transmission speed becomes lower.

[1] Kuroda et al., “1.5 Mb/s interframe coding device for video conferencing,” Tsuken Jitsuho, 33. Fish 11, 1984゜(3) Purpose of the Invention In order to solve the drawbacks of the conventional system, the present invention provides information for each medium within the capacity of the transmission path given during one communication.
The purpose is to improve transmission quality by making it possible to change IT allocation using simple means, and the drawings will be described in detail below.

(4) Structure of the invention (4-1) Differences between the characteristics of the invention and the conventional technology The present invention has the following features:
In a multimedia communication device consisting of a combination of moving images, still images, audio encoded signals, etc., the amount of information generated in each medium during two communications is detected, and the transmission capacity of each medium is determined within the given transmission capacity. It is characterized by improving the quality of the two-picture signal by providing a function to change the signal. Therefore, what is 5 conventional technology?

The difference is that a function is added to detect the amount of information generated in each medium and control the respective encoding speeds to be changed within the transmission capacity of one line in accordance with the amount of information generated.

(4-2) Embodiment FIG. 1 shows an example of the configuration of a multimedia communication terminal according to the present invention, where l is a video camera, 2 is a video monitor,
3 is a camera for still images, 4 is a monitor for still images, 5 is a microphone for audio, 6 is a speaker, 7 is a keyboard for control, 8 is a video encoding/decoding device, 9 is a still image encoding/decoding device. A decoding device, 10 a voice encoding/decoding device, and 11 a system control unit.

12 is a transmission control unit, and 13 is a transmission line interface.

When using this terminal to communicate with the other party's terminal,
The video signal is extracted by the camera 1 or 3, and the audio signal is extracted by the microphone 5, and redundancy reduction coding is performed by the encoding/decoding device 8 or 9 and 10, respectively. ff1
The signals are multiplexed in the first section 12 and sent out to the transmission line via the interface 13. Here, when multiplexing is performed by the transmission control unit 12, a clock is extracted from the transmission path, synchronization is established between the terminals, and information of each medium is sent out for each information frame. That is, the system control unit 11 displays a moving image.

The amount of information generated in still images and audio encoded signals is constantly detected, and based on the audio level detection results, if the audio level is lower than a specified value, it is assumed to be silent and the audio encoding operation is stopped. In addition to controlling the decoding device 10, the encoding/decoding devices 8 and 9 are also controlled so that information for the reduction of audio information can be assigned to moving images and still image media.

On the other hand, on the receiving side, the signal from the transmission path is once written into a buffer, separated into moving images, still images, or audio by the media identification bit at the beginning of the information frame, and then sent to each encoding/decoding device 8, 9.10. It is decrypted with At this time, each encoding/decoding device outputs an information frame, and if there is no success, it is read out repeatedly, or in the case of audio, it is processed as silent. After this, monitor 2 or 4 respectively. It is output to the speaker 6. In the above explanation, moving images and audio are always transmitted, but still images are not always transmitted.

The keyboard 7 controls the start or end of communication.

FIG. 2(a) shows an example of the configuration of a video encoding/decoding device 8, and FIG. 2<b> shows an example of the configuration of ten audio encoding/decoding devices. In this FIG. 2(a), 21
is an A/D converter, 22 is a vector quantizer, 23 is a variable length encoder, 24 is a transmission buffer, 25 is a D/A converter,
26 is a quantization decoder, 27 is a variable length decoder, and 28 is a reception buffer. The analog signal from the camera is digitized by an A/D converter 21, quantized and encoded by a vector quantizer 22 and a variable length encoder 23, and then digitized by a buffer 2.
Sent on 4th. On the receiving side, the received signals are synchronized and temporarily stored in the bath sofa 28.

It is decoded and converted into the original analog signal. here.

The amount of generated video information is determined by detecting the amount of memory in the buffer 24, and this is communicated to the system control unit 11.

Further, the variable length encoder 23 changes the code assignment based on instructions from the system control unit 11, and in the case of a silent section, increases the number of frames or encodes with the normal number of pixels.

On the other hand, the audio system is shown in FIG. 2(b). In the figure,
29 is an A/D converter, 30 is a level detector, 31 is an AD
32 is a transmission buffer, 33 is a D/A converter, 34 is an ADPCM decoder, and 35 is a reception buffer. The audio signal from the microphone is digitized by an A/D converter tfA unit 29, and the level of the audio signal is detected by a 5-level detector 30 to determine whether there is a sound or no sound. This result is transmitted to the system control unit 11, and if there is no sound, the operation of the ADPCM encoder 31 is stopped. On the receiving side, after synchronization, the ADPCM decoder 34 decodes the
The D/A converter 33 converts it into the original analog signal.

The difference between this configuration and conventional methods is that when silence is detected, the audio encoding operation is stopped, and
The objective is to increase the transmission capacity by increasing the allocation of the video information amount by the amount that the audio information amount is reduced. Note that the same control as that for moving images is also possible for still image encoders, and is also applicable to data other than still images. In the above explanation.

Vector quantization was assumed as the video encoding method, but
Orthogonal transform encoding may be used, or a combination of these or other encoding methods may be used. Furthermore, the explanation has been made using speech/silence separation coding based on level detection as the audio coding method.

Other Method 2 For example, a method may be used in which feature parameters are extracted and the amount of encoded information is made variable by increasing or decreasing the number of parameters.

FIG. 3 shows an example of an information frame format in the one-line transfer system, which consists of one normal synchronization frame pattern bit followed by a bit for media identification and an information bit. By multiplexing and transmitting information for each media in units of information frames according to the amount of information generated, this former 7) eliminates error retransmission (and error correction codes) in accordance with the X series recommendations. It becomes possible to realize simple transmission using

In this way, the amount of information generated in each media such as moving images, still images, and audio is constantly detected.1 For example, in silent sections, the amount of information generated in each media is increased to the video signal. It becomes possible to transmit information, and it is possible to reduce deterioration in resolution due to frame dropping and pixel thinning. That is, when the amount of audio information generated is small, such as during a silent section, it is possible to increase the transmission capacity allocated to video and improve the quality.

(5) Detailed Description of the Invention As described above, the present invention has the advantage that when a voice call is not being made in a video conference or the like, a high-resolution screen of the other party can be seen and quality is improved. In addition, in the present invention, only the frame allocation is changed for each media on the frame format and the multiplexing method is changed, and the transmission procedure does not use a complicated procedure such as an HDLC procedure, but instead uses an error correction code such as an error correction code. Since it can be configured with a circuit similar to that of a car, it also has the advantage of being economically configurable with a small hardware scale.

[Brief explanation of the drawing]

FIG. 1 shows an example of the configuration of a multimedia terminal according to the present invention.
FIG. 2 shows an example of the configuration of a video and audio encoding/decoding device, and FIG. 3 shows an example of the information frame configuration. 1... Camera for video, 2... Monitor for video, 3
... Camera for still images, 4... Monitor for still images,
5...Mic for audio, 6...Speaker 17...
Keyboard, 8... Video encoding/decoding device, 9...
Still image encoding/decoding device, 10... Audio encoding/decoding device, 11... System control unit, 12... Transmission control unit, 13... Transmission line interface, 21... A/
D converter, 22... Vector quantizer, 23... Variable length encoder, 24... Transmission buffer 525... D/
A converter, 26... Quantization decoder, 27... Variable length decoder, 2nd... Reception buffer 729... A/D converter, 30... Level detector, 31...・ADPCM
Encoder, 32... Transmission buffer, 33... D/A converter, 34... ADPCM decoder, 35... Reception buffer. Barren light j; depending on

Claims (1)

[Claims] A multimedia communication device that mutually transmits and receives video signals from video and still image cameras using a combination of two or more media including at least video, still images, and audio. A means for compressing and encoding an audio signal from a microphone to a specified amount of encoded information; a means for compressing and encoding an audio signal from a microphone to a specified amount of encoded information; and the video/still image code. means for monitoring the amount of generated information of encoded signals and encoded audio signals and controlling the allocation of the moving images, still images and audio media in units of information frames; Means for multiplexing the capacity as a transmission signal at a constant speed and transmitting it to a transmission line; Means for identifying media in information frame units from the received signal and separating it into video, still image encoded signals and audio encoded signals; video encoded signal What is claimed is: 1. A multimedia communication device comprising: means for decoding and sending to a moving image and still image monitor; and means for decoding an audio encoded signal and sending to a microphone.