JPH05244107A - Sdh frame constituting method for digital image signal - Google Patents

Abstract

PURPOSE:To normally reproduce an image even if a position of a row is varied at the time of transmission by constituting a frame by inserting a prescribed signal into a start position of a digital image signal of one unit. CONSTITUTION:A prescribed signal having a specific pattern is inserted into encoded data of an image signals. That is, in a state (a) that encoded data of a digital image signal is stored in an SDH frame (STM-4), a unique word UW of 4 bytes (32 bits) is positioned as a prescribed signal, in the head of a first row of the part of a 12-column portion in which information related to an image signal in the part in which the encoded data is stored and a sound signal are stored (b, c). As for this first row, since the 12-column portion is prepared, even if a four-row portion is used for the unique word UW, there is no problem in a fact that video sampling information fs is stored. Accordingly, even in the case transmission is executed by repeating by a multiplex repeating installation, the lead position of the encoded data of each one unit can surely be detected.

Description

Detailed Description of the Invention

[0001]

The present invention relates to B-ISDN (Broad Integrate).
More specifically, SDH (Synchronization) is related to transmission technology of digital image signals using d Services Digital Network).
ous Digital Huerarchy).

[0002]

2. Description of the Related Art In Japan, when transmitting and receiving a digital image signal using B-ISDN, which will be provided by NTT, it is necessary to configure a frame according to the SDH frame format.

FIG. 1 is a schematic diagram showing a basic configuration of a communication system when an image signal is transmitted using B-ISDN. Here, both image encoding devices 1 and 1 are connected by B-ISDN.

On the other hand, in the image coding apparatus 1, a digital image signal obtained by coding the image signal is transmitted from the transmitting apparatus 11 thereof.
The STM-1 frame having a transmission speed of about 150 Mb / s, which is the basis of SDH, is multiplexed to four, and the STM-4 frame having a transmission speed of about 600 Mb / s is sent to the nearest multiplex relay device 2. In this multiplex repeater 2, the signals of four STM-4 are multiplexed to about 2.4 Gb /
The signal s is transmitted to the multiplex relay device 2 closest to the image coding device 1 on the receiving side. In this multiplex relay device 2, 4
From about 2.4 Gb / s signals that are multiplexed STM-4 signals
One STM-4 signal of 600 Mb / s is separated and transmitted to the receiving device 12 of the image coding device 1 on the receiving side. Upon receiving this signal, the image encoding device 1 reproduces the image by extracting the encoded data from the STM-4 frame and decoding it.

By the way, in the SDH frame format, one row is made up of 270 columns of 9 columns (bytes) of section overhead and 261 columns of payload, and each such row is connected in series for 9 lines to form one frame. Make up. Figure 2 (a),
(b) and (c) are schematic diagrams showing a state in which encoded data of an image signal is configured in one SDH frame for transmitting a digital image signal. Since the example shown in FIG. 2 is the above-mentioned STM-4 frame, it is multiplexed four times.

FIG. 2 (a) is a schematic diagram showing an entire STM-4 frame, in which rows originally arranged in series are vertically arranged in parallel. Of the section overhead (SOH), A1, A2 ... Are frame signals for synchronizing the frames, and AU-PTR is a pointer that specifies the position of the payload. The first column of the payload is the path overhead (POH), and the next four columns are not used and are used for storing the coded data of the image signal from the sixth column next to the last column of the payload part. Row 25 is unused. Therefore, the encoded data is stored in column 231 of the payload portion of column 261.

FIG. 2B is a schematic diagram showing only the portion of FIG. 2A in which encoded data is stored. The portion where the encoded data is stored is further divided into 12 columns on the head side and the other portion where the encoded data of the actual image signal is stored. In the portion where the encoded data is actually stored, # 1, # 2, # 3, and # 4 each represent data for one column of each of the four multiplexed STM-4 signals.

Various information relating to the image signal and an audio signal accompanying the image signal are stored in the 12th column portion on the head side, and fs at the head of the first row is video sampling information.
(9 bits), and VL located in the second row is the video coded data length (2 bytes). The audio signal is stored in the third row and below. The important thing here is that if the sampling information fs, which is the sampling information of the encoded data stored in the frame, is not located in the first row of the frame, the encoding stored in the entire frame on the receiving side. It means that the data cannot be decrypted.

This is because the amount of information is small in the case of transmitting only the audio signal, so that the information is transmitted in units of lines in the frame, but the amount of data in the transmission of the digital image signal is large, so that it is not in units of lines. This is because fs indicating sampling information of the entire frame needs to be located in the first row of the frame because information is transmitted in frame units.

Incidentally, FIG. 2C is a schematic diagram showing a portion for 12 columns on the head side shown in FIG. 2B described above. First
In rows, fs is 9 bits, so the other 10 columns (bytes)
Minutes are unused.

[0011]

By the way, when the coded data of an image signal as described above is transmitted by the multiplex relay device 2 of the communication system shown in FIG. 1, these image coding devices 1 are framed. Since the signal multiplexing and demultiplexing are controlled and transmitted for each row, the fs position in the frame may move.

FIG. 3 is a schematic diagram showing such a state. FIG. 3 (a) is a schematic diagram showing the structure of one frame of the SMT-4 frame similar to that of FIG. 2 (a), but the encoded data of the image signal in the payload is stored for the reason described above. In this part, the fs that should originally be located in the first row of the frame is controlled by the multiplex relay device 2 so that fs is located in the other row, for example, in the third row as shown in FIG. 3 (b). It may be done. When such a frame in which fs is located in a row other than the first row is received by the receiving apparatus 12 of the image encoding apparatus 1, the sampling information originally supposed to be given by fs is not given, and thus the encoding is performed. There arises a problem that the data cannot be decrypted.

The change in the position of the row in the frame as described above does not usually occur, but may occur when the relay line is once disconnected and then restored in the communication system, for example.

The present invention has been made in view of the above circumstances, and even if the position of a row in a frame changes during transmission of coded data, the first row of the original frame is detected and a normal operation is performed. An object of the present invention is to provide an SDH frame configuration method capable of image reproduction.

[0015]

According to the SDH frame forming method of a digital image signal of the present invention, a predetermined signal having a specific pattern (hereinafter referred to as a unique word UW) is inserted into encoded data of the image signal.

The SDH of the digital image signal of the present invention
The frame configuration method uses a signal of a pattern in which "0" or "1" are consecutive as the unique word UW.

Further, SDH of the digital image signal of the present invention
The frame configuration method uses a signal of a pattern in which 16 "0" s or "1" s are consecutive as the unique word UW.

[0018]

According to the SDH frame forming method of the digital image signal of the present invention, the first position of the coded data is detected by detecting the unique word UW even when the position of the row in the frame is changed and transmitted. It becomes possible to detect.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments.

FIGS. 4 (a), 4 (b) and 4 (c) are schematic diagrams showing a method for constructing an SDH frame of a digital image signal according to the present invention.

FIG. 4 (a) is a schematic diagram showing a state in which coded data of a digital image signal is stored in an SDH frame (STM-4) similar to that shown in FIGS. 2 and 3 (a).

In the method of the present invention, the information on the image signal in the portion storing the encoded data shown in FIG. 4 (b) and the portion of the first row in the portion of 12 columns storing the audio signal are stored. A 4-byte (32-bit) unique word UW is located at the beginning as a predetermined signal. As shown in Fig. 4 (c), 12 columns are prepared for this first row, so even if 4 columns of them are used for the unique word UW, it is necessary to store fs. Has no problem.

FIG. 5 is a schematic diagram showing an example of the above-mentioned unique word UW. Here, "0s" having 16 consecutive bits are used as the unique word UW. By inserting such a unique word UW at the position shown in FIG. 4 (c) and transmitting it from the image encoding device on the transmitting side,
As shown in (b), even if a frame in which fs is located in a row other than the first row is received by the image encoding device on the receiving side, the unique word described above is received on the image encoding device on the receiving side.
By detecting the UW as the start position of the encoded data, the data of each subsequent line can be decoded as a series of image signals to reproduce the image.

FIG. 5B is a schematic diagram showing a unique word of another embodiment of the present invention. In this example, 16 consecutive "1" s are used as the unique word UW as the unique word UW. Also, the above 16-bit continuous ”
Needless to say, the signal is not limited to "0" or "1", and any pattern signal that does not appear in the coded data of the image signal can be used as the unique word UW of the present invention regardless of the number of bits.

[0025]

As described above in detail, according to the SDH frame forming method of the digital image signal of the present invention, the coded data of the image signal is transmitted by the multiple repeater according to the STM-4 frame of SDH by using ISDN. Even when the data is relayed and transmitted, it is possible to reliably detect the head position of each unit of encoded data on the receiving side. Therefore, the receiving side can always reproduce a normal image.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a basic configuration of a communication system when transmitting an image signal using ISDN.

FIG. 2 is a schematic diagram showing a state in which coded data of an image signal is configured in one SDH frame for transmitting a digital image signal.

FIG. 3 is a schematic diagram showing a state in which, when a digital image signal is transmitted, data that should originally be located in the first row of a frame is controlled by the multiplex relay device so that it is located in another row. ..

FIG. 4 is a schematic diagram showing a method of constructing an SDH frame of a digital image signal according to the present invention.

FIG. 5 is a schematic diagram showing an example of a unique word in the SDH frame construction method for a digital image signal according to the present invention.

[Explanation of symbols]

 UW unique word

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Claims (3)

[Claims] 1. A frame constructing method for transmitting a digital image signal according to the SDH frame format, wherein a predetermined signal (U
W) is inserted to form a frame, and an SDH frame forming method for a digital image signal. 2. The predetermined signal (UW) is "0" or "
2. The SDH frame construction method for a digital image signal according to claim 1, wherein the 1 "bit is a signal having a plurality of consecutive bits. 3. The predetermined signal (UW) is "0" or "
2. The SDH frame construction method for a digital image signal according to claim 1, wherein the 1 "bit is a signal having 16 or more consecutive bits.