FR2719137A1 - Varying text content file transmission method - Google Patents

Abstract

The file transmission method involves encoding the file being transmitted with marker sequences indicating the nature of the following part of the data stream. The marker sequences include indication of the type of compression used for the large component of the file.The receiver reads the incoming data stream and invokes the appropriate decompression program when a marker indicating arrival of a compressed stream is detected. The appropriate program is read from the marker. The decompressed signals are transformed to an RGB video signal, or to an audio signal in a form suited to input to an amplifier.

Description

TRANSMISSION METHOD AND DEVICE
FILES COMPRISING A FOLDER TYPE
VOLUME AND W SECOND TYPE INFORMATION
VOLUME INFORMATION MATTERED
The present invention relates to a file transmission method comprising at least a first type of low volume information, such as alphanumeric or semi-graphic characters, and a second type of large volume information such as images, sound. or downloadable computer programs.

 Such methods are used for the transmission of texts and graphics of low definition, in particular according to videotex standards, by servers connectable by terminals such as MINITEL (registered trademark).

 It is known in the state of the art to transfer such files between a server center coding the signals relating to the two types of information and terminals connectable to the server via the telephone network, or specialized networks. However, the speed of telephone networks are relatively low, and are not compatible with the transfer of files representing large volumes of data, for example high definition images or high definition sound having a large bandwidth.

 For example, the French TELETEL network is limited to 1,200 baud in reception, according to the V23 standard. The transfer of a small image, for example of 320 * 240 pixels, representing 250 KB, or 2 million characters, will require a transfer time of 37 minutes, taking into account the service signals added to the characters specific to the image. transmitted image.

 On the switched network, the speed is significantly higher and can reach 19,200 baud for non-professional use, which reduces the transmission time to just under 2 minutes, which remains relatively long for conversational use of this file transfer type.

 It is clear that this transfer mode would hardly be compatible with a file transfer corresponding to larger images, or even to color images, representing a significantly greater volume, and with even longer transmission times.

Specialized peripherals have also been proposed in the state of the art. For example, French patent FR2620543 describes a device comprising:
- an interconnection bus
- a management and calculation unit connected to this bus
- a read only memory, connected to the bus, containing the software for receiving, memorizing and / or viewing the images received from the telematic network
- a random access memory connected to this bus
- a video memory connected to this bus to process and store the digital image information received from the bus
- a network interface, of the peripheral with the telematic network, interface also connected to the bus in order to allow the exchange of information between the network and the management and calculation unit and occasionally the entry in the RAM of specific software additional
a video interface receiving on its input digital image information from the video memory and outputting, on at least one output, video signals to at least one display module
- and a logical unit for controlling the operations of the peripheral, connected to the bus and to the video memory.

 This document discloses the production of specialized equipment, making it possible to view images on an integrated screen. The process implemented makes it possible to transmit images within time limits limited by the admissible bit rates by the network, and therefore results in the access times mentioned above.

 The object of the present invention is to provide a method of transferring information of different types, overcoming these drawbacks by allowing connection to the server by an inexpensive terminal using the networks known to the general public, while authorizing a transfer. accelerated information of large volume, and the exploitation of this information on a non-specialized device, for example a standard microcomputer, a television set, or a high-fidelity channel if necessary.

 The object of the invention is also to propose a method retaining compatibility with a connection by terminals of the state of the art.

 To this end, the invention relates more particularly to a method characterized in that the signals of the second type are compressed. The method consists in coding the file to be transmitted in the form of sequences consisting of service signals announcing the type of the following information, information of the first or second type. The signal sequence further includes signals defining the type of compression used.

Advantageously, the file transmission method according to the invention comprises a step of compressing large volume information of fractal type or
JPEG.

 According to a particular implementation mode, the compression of the large volume information is carried out according to at least two different compression modes, for example fractal FIF or JPEG-JPG.

 The invention also relates to a method of operating files consisting in transforming, in a mode suitable for being viewed on a display screen, the signals corresponding to the low volume information received, characterized in that it comprises a step activated by detecting the signal announcing the signals corresponding to the information of large volume, said step consisting in decompressing the information according to the compression mode indicated by the service signals relating to the compression mode employed, and transforming them into a signal suitable for being used by a means adapted to the type of information considered.

 According to a first variant, the decompressed signals are transformed into an RGB video signal suitable for being viewed on a television screen.

 According to a second variant, the decompressed signals are transformed into an audio signal suitable for being transmitted to an amplification stage.

 Advantageously, the method comprises a step of sending a control signal to the server center triggering the transmission by the server center of a sequence of signals comprising a service signal announcing high volume information, followed by a signal indicating the type of compression used, the terminal comprising means for interrupting the interpretation of low volume signals and for memorizing the information transmitted by the server after the detection of said service signals, the method consisting in decompressing said stored signals and transforming them into a video signal suitable for viewing on a screen.

 Preferably, the information of the first type is coded to videotex standards, in that the service signals announcing the information of large volume comprising a sequence "PRO2" capable of causing the passage of the videotex terminal in pipe mode ".

 The invention also relates to a device constituted by a circuit comprising an input socket suitable for being connected to the peri-computer socket of a videotex terminal, and an output socket suitable for being connected to the video input socket d '' a television set and / or a video recorder, the circuit comprising a memory for the storage of information coming from the videotex terminal, a computer for decompressing the signals coming from the videotex terminal, and a second memory for storing the corresponding program at least one decompression algorithm and a video processor delivering a video signal to the output jack.

Preferably, the device according to the invention furthermore comprises means for identifying the type of decompression mode and for activating the stored program.
The invention will be better understood on reading the description which follows, referring to the appended figures, where:
- Figure 1 shows a block diagram of a network for implementing the method according to the invention;
- Figure 2 shows the block diagram of an exemplary embodiment of a device according to the invention.

The network comprises a server center (1) to which terminals (2, 3) are connected, either via the switched telephone network or via a specialized network.
The terminals can be constituted by microcomputers (2) on which is installed a program for connection and exploitation of information, either by dedicated terminals (3) of the MINITEL type (registered trademark) provided with a peri socket. IT connected to a television set (4) via a Jan connection device (5). . The television set is advantageously connected to a video recorder (6) for recording images and text information.

 The server encodes the information according to a data transmission protocol corresponding for example essentially to the European standard "ETSI 300177". According to this standard, the signals consist of a succession of signal sequences relating to the information transmitted and to service signals.

 The information corresponding to alphanumeric or semi-graphic characters is coded and transmitted in asynchronous mode, for example in the form of a group of 10 binary elements comprising 7 useful information bits and 3 control bits. The first bit is a synchronization bit or start bit, and the next two bits the useful bits formed by a parity bit allowing self-checking of the useful bits, and a stop bit.

 The graphic information corresponding to a pixel by pixel coding of the image, followed by compression according to algorithms, preferably fractal or JPEG algorithms. The sequences of graphic information are preceded by a series of service bits forcing the passage into "by-pass" or "pipe" mode of the terminal, which then behaves transparently with respect to the peri-computer socket. By way of example, the sequences corresponding to the graphic information are preceded by a series of bits corresponding to the word FFD8, used to trigger the interface so that said interface ensures the storage in its buffer memory of the signals coming from the peri-computer socket , and followed by Lne series of bits corresponding to the word FFD9 indicating the end of the image data. During this step, the interpretation of signals by MINITEL is inhibited by a PRO2 sequence sent by the server before the image sequence.

 The method according to the invention consists in inserting, in addition, between the series of start bits of the image sequence and said image sequence a series of control bits specifying the compression mode implemented.

 Figure 2 shows the block diagram of a connection box between a MINITEL terminal and a television set.

 The box is connected to the computer peri-terminal socket.

 Information from d-MINITEL when it is activated in bypass mode is stored in a buffer memory (7). A microprocessor (8) performs the decompression operations according to one of the algorithms whose programs are stored in a memory (9). The decompressed images are stored in a second buffer memory (13) then transmitted to a video processor (il) connected to a video memory (12).

 The video processor (11) is connected to a television set via the scart socket.

The use of the process is as follows:
- The user connects to the server center using his MINITEL terminal
- it evolves in the service in the usual way, in the hierarchy of videotex pages
- when the user wishes to view an image accompanying a videotex page, he sends an appropriate command to the server. The host center sends in response a sequence of signals consisting first of all of a primer consisting of a part of the bits forcing the passage of the
MINITEL in "bypass" mode, followed by the sequence specific to the compression mode implemented for the image which will follow, for example in "JPEG" or "FIF". This sequence determines the corresponding program to be loaded into the microprocessor. The signal sequence then includes the compressed image file, terminated by a sequence of service signals reactivating the videotex function of the
MINITEL.

The compressed image sequence is then transmitted to the user by the telephone line according to the "ETSI 300-177" standard, the MINITEL being content to transmit the signals to the peri-computer socket to which the interface device is connected. The screen of
MINITEL displays the last videotex page during the decompression of the image by the interface device, and the display on the screen of the television set connected to said box.

 The signals from the MINITEL computer socket are stored in the buffer memory (7) before being processed by the microprocessor (8) in which the appropriate decompression program is loaded. The image is decompressed sequentially in real time. The decompressed data blocks are stored in a second memory buffer (13). At the same time, the microprocessor (8) orders the video processor (11) the sequential conversion of the decompressed digital image in blocks.

 The video processor (11) reads the data in the buffer memory (13) and transcodes the digital image so as to generate an RGB video signal directly usable by the television set. It transmits the image to the television in successive bands in the case of the JPEG compression standard (sequential display), or in a single block in the case of a fractal decompression. The current dimension of the transmitted images being of the order of 320 * 240, the device proceeds before displaying the image on the television set, to the resizing of the image transmitted by the host center. Without this function, the displayed image would use only a relatively small part of the surface of the TV screen. So, just before displaying said image in successive bands, the vicéo processor resizes the image so that it occupies at least two thirds of the television screen, regardless of the size of said screen.

The television then displays in color the digital image transmitted by the telematics server
A video recorder output (14) provided on the interface box allows the connection of a video recorder for recording the image or other computer data.

 The image is visible on the TV screen until a new image is ordered, the videotex functions can then be used again via the MINITEL.

 The method according to the invention can also be implemented on a single terminal, emulated by a computer program generating two distinct display zones, one simulating the screen and videotex command icons, and the other corresponding to the viewing of the video image by the television.

 The invention is described in the foregoing by way of nonlimiting example. It is understood that a person skilled in the art will be able to carry out different variants of the method and different forms of the device for implementing the method without going beyond the ambit of the invention.

 In particular, the device may include means for storing computer data which may be programs, or films digitized according to the MPEG (Moving JPEG) standard on magnetic tape of a video recorder or an audio tape recorder. These data are recorded by means of said devices in compressed or decompressed form.

Claims (10)

 1 - Method for transmitting files comprising at least a first type of low volume information, such as text, and a second type of large volume information such as images, sound or computer programs, signals of the second type being compressed, the method consisting in coding the file to be transmitted in the form of sequences consisting of service signals announcing the type of the following information, of information of the first or of the second type, characterized in that the signal sequence further comprises signals defining the type of compression used.  2 - A method of transmitting files according to claim 1 characterized in that the compression of the information of large volume is a compression of fractal or JPEG type.  3 - A method of transmitting files according to one of claims 1 or 2 characterized in that the information of the large volume information is produced according to at least two different compression modes.  4 - Method for operating files transmitted according to a method according to any one of claims 1 to 3 consisting in transforming the signals corresponding to the low volume information received in a mode suitable for being displayed on a display screen, characterized in that it comprises a step activated by the detection of the signal announcing the signals corresponding to the information of large volume, said step consisting in decompressing the information according to the compression mode indicated by the service signals relating to the compression mode employed, and in transform them into a signal suitable for being exploited by a means adapted to the type of information considered;  5 - Process for using files transmitted according to a process according to claim 4, characterized in that the decompressed signals are transformed into an RGB video signal suitable for being viewed on a television screen.  6 - A method of operating files transmitted according to a method according to claim 4, characterized in that the decompressed signals are transformed into an audio signal suitable for being transmitted to an amplification stage.  7 - operating method according to claim 4 characterized in that it comprises a step of sending a control signal to the server center triggering the transmission by the server center of a sequence of signals comprising a service signal announcing high volume information, for example a sequence PRO2, said sequence inhibiting the videotex mode of the terminal, followed by a header to the ETSI standard, and by a signal indicating the type of compression used, the terminal comprising means for interrupting the interpretation of low volume signals and memorizing the information transmitted by the server after the detection of said service signals, the method consisting in decompressing said stored signals and transforming them into a video signal suitable for being viewed on a display screen such than a television or microcomputer.  8 - Operating method according to claim 7 characterized in that the information of the first type is conducted to videotex standards, in that the service signals announcing the information of large volume comprising a sequence "PRO2" capable of causing the passage of videotex terminal in "hose" mode.  9 - Device for the implementation of the operating method according to claim 4 characterized in that it is constituted by a circuit comprising an own input socket to be connected to the perinformatic socket of a videotex terminal, and a output socket suitable for being connected to the video input socket of a television set and / or a video recorder, the circuit comprising a memory (7) for storing information coming from the videotex terminal, a computer (8 ) for decompressing signals from the videotex terminal, and a second memory for storing the program corresponding to at least one decompression algorithm and a video processor (11) resize the image and deliver a video signal to the output socket.  10 - Device according to claim 9 characterized in that it further comprises means for identifying the type of decompression mode and activating the stored program.