Television – Two-way video and voice communication – User positioning
Reexamination Certificate
1997-10-30
2001-03-06
Nguyen, Duc (Department: 2643)
Television
Two-way video and voice communication
User positioning
C714S746000
Reexamination Certificate
active
06198499
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a radio-communication video terminal device such as a TV-telephone by real-time transmission of video (with moving picture) and sound signals over radio channels having a low transmission performance particularly.
Owing to miniaturization of apparatuses advanced by the semiconductor technology development and an advance of video coding-decoding techniques, real-time transmission of video signals, which required the use of a cable line of high-transmission quality such as ISDN (Integrated Services Digital Network), has been possible to conduct over radio channels having a low transmission rate.
There's an exemplified structure of a radio-communication video terminal device utilizing a radio transmission channel. The radio-communication video terminal device comprises an antenna portion for transmitting and receiving radio signals, a RF (radio-frequency converting circuit) portion for converting a high-frequency-band signal received from the antenna portion into a signal in a frequency-band of a base-band and converting a base-band signal into a high-frequency-band signal, a RF-I/F (radio-frequency and intermediate frequency) portion for extracting digital video and digital voice signals from the signal in a frequency-band of a base-band from the RF portion and multiplexing and converting digital video and digital audio signals into signals in a frequency-band of a base-band, a video-transmission adapter portion for correcting an error in a signal from the RF-I/F portion or adding an error-correcting code to video frame data to be transmitted, a video codec portion for decoding video frame data from the video transmission adapter portion or coding a video signal, a monitor portion for displaying a video signal from the video codec portion, a video camera portion for inputting a video signal into the video codec portion, a voice codec portion for decoding voice signal from the RF-I/F portion or coding a voice signal, a speaker portion for reproducing a voice signal from the voice codec portion and a microphone portion for inputting a voice signal into the voice codec portion.
There's an exemplified structure of the prior art video-transmission adapter portion, which comprises an error-correction frame disassembling portion for correcting an error in a video signal outputted from the RF-I/F portion and an error-correction frame generating portion for generating an error-correction frame by adding an error-correction code to video frame data outputted from the video codec portion.
There's a data format to be used in the error-correction frame disassembling portion. The data format applies to data outputted from the RF-I/F portion to the error-correction frame disassembling portion and data outputted from the error-correction frame disassembling portion to the video codec portion.
There's a data format to be used in the error-correction frame generating portion. The data format applies to data outputted from the video codec portion to the error-correction frame generating portion and data outputted from the error-correction frame generating portion to the RF-I/F portion.
The operation of the radio-communication video terminal device using the video-transmission adapter portion will be described below.
At the receiving side, a high-frequency band signal received through the antenna portion is converted by the RF portion to a signal in a frequency-band of a base-band which is then divided into video data and voice data by the RF-I/F portion. The separated video data is input to the video transmission adapter in which the input data is subjected to error-correction by the error-correction frame disassembling portion and from which only video frame data is outputted to the video codec portion. The video codec portion decodes the input video frame data and outputs the decoded video signal to the monitor. On the other hand, the voice data outputted from the RF-I/F portion enters into the voice codec portion by which it is decoded and outputted as a voice signal to the speaker portion.
At a transmitting side, a video signal through the camera is input to the video codec portion in which the input signal is encoded and outputted as the encoded video frame data to the video transmission adapter. The error-correction frame generating portion generates error-correction frame data by adding an error correction code to the encoded video frame data and outputs the error-correction frame-data to the RF-I/F portion. On the other hand, a voice signal outputted from the microphone is encoded by the voice codec portion and then outputted to the RF-I/F portion. The RF-I/F portion multiplexes the encoded video data and voice data, converts the multiplexed data into a signal in a frequency-band of a base-band and outputs it to the RF portion which in turn converts the received signal into a high-frequency band signal and outputs the converted ted signal to the antenna portion.
The above-described prior art radio-communication video terminal device using radio transmission channels may receive erroneous video data that may be displayed with faults since the received data may contain not only correctable random errors but burst errors that are hardly corrected.
SUMMARY OF THE INVENTION
The present invention was made to provide a radio-communication video terminal device which is capable of displaying non-fault video in synchronization with voice signal.
A radio-communication video terminal device according to the present invention has an video transmission adapter which is composed of transmission video frame disassembling means for correcting a transmission error of video data, detecting an error in the corrected video data and extracting video frame data containing no error, transmission video frame generating means for generating a video frame to be transmitted by providing video-frame data with an error-correction code and a control signal for controlling other terminal with which the device will communicate, and video control means for instructing extraction of errorless video-frame data from the received video data and for controlling the video data according to the control signal.
The transmission video-frame disassembling portion is also composed of error-correcting means for executing error-correction, packet disassembling means for detecting an error and outputting only video-frame data and data selecting means for extracting only errorless video-frame data.
The transmission video-frame generating portion is composed of means for generating intraframe-coded data from interframe-coded data, data change-over means for changing over from the intraframe-coded data to the interframe-coded data and vice versa, packet assembling means for assembling a packet composed of video-frame data, a control signal for controlling the other terminal to be communicated and an error detection code for detecting an error, error-correction frame generating means for generating a frame composed of an error-correction code for correcting a transmission error, a synchronization signal and packet data.
In the above-mentioned radio-communication video terminal device, the video transmission adapter performs the error-detecting operation on the error-corrected video data to output errorless video-frame data that can be reproduced with no fault other to be communicated. In case if the data should contain an error, the device can require other terminal to be communicated intraframe-coding data, thus enabling the receiving terminal to quickly restore normal reproduction of video signals in synchronization with voice signals.
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Eng George
Nguyen Duc
Sharp Kabushiki Kaisha
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