JP2000101440A - Coding/transmission method and device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a circuit scale, while enhancing the transmission efficiency when transmitting image compressed data or the like through a transmission line, including an inhibit code in compliance with the SMPTE Recommendations 125M or the like. SOLUTION: When dividing W bits in one word of data on a transmission line into a 1st block, consisting of (W-M) bits and a 2nd block consisting of M bits, (W-M)×N bits in input data in K bits are stored in a 1st area of a memory circuit 4 corresponding to the 1st block in N words, the remaining K-((W-M)×N) bits are converted into a conversion code consisting of N words in M bits by a conversion ROM 3 so as not to match the inhibit code in the unit of words when the converted code is matched with an optional code in the 1st block, the conversion code consisting of N words in M bits converted by the conversion ROM 3 is stored in a 2nd area of the memory circuit 4 corresponding to the 2nd block in N words, and data are outputted in the unit of words from the 1st and 2nd areas of the memory circuit 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for encoding arbitrary data and transmitting the encoded data over a transmission line defined by a specific transmission standard or by transmitting the data over a transmission line defined by a specific transmission standard. The present invention relates to an encoded transmission method and an encoded transmission device for recording on a medium.

[0002]

2. Description of the Related Art SMPTE recommendation 125M and the like are defined as digital transmission standards for video signals in a studio, and are widely used. Also, with the spread of digital compression video tape recorders and the like, proposals have been made in recent years to transmit or record compressed image information in accordance with the above-mentioned transmission standards.

[0003]

In the above transmission standard,
A special code such as EAV or SAV indicating a synchronization position of a video signal is defined, and valid video data (Active Video of SMPTE Recommendation 125M) is defined.
A prohibition code is set in the data in the range of) to distinguish it from the special code.

For example, in SMPTE recommendation 125M, 1
Of 0-bit data, 0 to 3 and 1020 to 1023
Is a prohibition code and is represented by 10 bits
Eight out of 024 levels are prohibited codes, and the remaining 10
Video signals are transmitted at 16 levels. Prohibition code is 1
Minimum and maximum of 4 in 0-bit dynamic range
This is a level, and when transmitting a video signal, it is possible to transmit the video signal without greatly deteriorating the image quality only by clipping the level of the prohibition code. Here, the 1016 level corresponds to about 9.99 bits of the code (log2 10
16 = 9.99).

However, when the compressed data is stored in the effective data portion of the video and transmitted, it is necessary to encode and transmit while avoiding the prohibition code, but the compressed data is usually a random code string having no redundancy. Therefore, it is difficult to reduce the dynamic range. Therefore,
Conventionally, it has been proposed that out of 10 bits, only the lower 9 bits are used as compressed data, and the most significant bit is obtained by inverting the most significant bit of the compressed data and transmitting the same.

In such a case, the upper two bits are always 0.
Since the value is 1 or 10, the prohibition code is not necessarily generated, but only 9 bits out of 9.99 bits of valid data are used, resulting in transmission loss. In order to effectively use the 1016 level of valid data, for example, even when transmitting 9.5 bits, 19 bits are converted to 20 bits.
It has to be converted to it, which is difficult to realize due to the circuit scale.

Accordingly, an object of the present invention is to provide a coded transmission method and a coded transmission device capable of performing efficient transmission while reducing the circuit scale.

[0008]

In order to solve this problem, the coded transmission method of the present invention uses W (W is an integer of 2 or more) bits as one word, and a prohibition code is set in word units. In the transmission path, any input data is set to N (N is 2) by using K (K is an integer of 2 or more) bits as a coding unit.
(K <N × W), and outputs the W bits in one word of the transmission path.
It is divided into a first section consisting of W-M bits and a second section consisting of M bits, and among the K-bit input data, (W-M
M) × N bits are allocated to a first section of N words, and the remaining K − ((W−M) × N) bits are combined with an arbitrary code of the first section, and a word unit prohibition code is used. Is converted to a conversion code composed of M bits and N words so as not to match with the above, and is then allocated to the second section of N words.

According to this method, K − ((W−M) ×
Since it is only necessary to convert (N) bits into a conversion code consisting of M bits and N words, transmission can be performed efficiently while reducing the circuit scale. Further, the encoded transmission apparatus of the present invention uses W (W is an integer of 2 or more) bits as one word and transmits arbitrary input data to K (K is 2 (K <N × W) is output after converting into N (N is an integer equal to or greater than 2) words using the above integer) bits as a coding unit, and includes a storage unit and a conversion unit. When W bits in one word of the path are divided into a first section consisting of WM bits and a second section consisting of M bits, (W−M) × N bits are stored in the first area of the storage means corresponding to the first section of N words, and the remaining K bits are stored.
Converting the ((W−M) × N) bits into a conversion code consisting of M bits and N words so that the conversion means does not match the prohibition code in word units when combined with an arbitrary code in the first section; The conversion code composed of M bits and N words converted by the conversion means is stored in the second area of the storage means corresponding to the second section of N words, and is converted from the first and second areas of the storage means in word units. It is characterized by outputting data.

[0010] According to this configuration, K-
Since it is only necessary to convert ((W−M) × N) bits into a conversion code composed of M bits and N words, transmission can be performed efficiently while reducing the circuit scale.

[0011]

Embodiments of the present invention will be described below. FIG. 1 shows a block diagram of an encoded transmission device according to an embodiment of the present invention. In FIG. 1, 1 is an input terminal for inputting compressed image data, 2 is a first memory circuit for temporarily storing compressed image data, and 3 is a conversion R for converting data.
OM, 4 is a second memory for storing the converted data,
Reference numeral 5 denotes a SAV / EAV addition circuit that encodes the converted data in the form of SMPTE recommendation 125M, 6 denotes a timing control circuit that controls the timing of each circuit, and 7 denotes an output terminal that outputs data.

The operation of the coded transmission apparatus configured as described above will be described below. SMPTE Recommendation 12
In 5M, one word is composed of 10 bits. In this embodiment, 39-bit input data is converted into 4 words (40 bits) and output. Also, one word is a first section composed of lower 6 bits out of 10 bits,
The processing is performed in the second section composed of the remaining upper 4 bits.

The compressed image data input from the input terminal 1 is first stored in the first memory circuit 2. Here, the compressed image data is divided into 39 bits as one unit (coding unit) in the input order. Then, one coding unit is composed of a first group of 24 bits corresponding to the first section of 4 words, and the remaining 15 bits corresponding to the second section of 4 words.
It is divided into a second group of it and output separately.

In the second memory circuit 4, one word is 10 words.
Writing and reading of the memory are performed in 4-word units (40 bits). Also, 40 bi for 4 words
In t, the first area 24 bits and the second area 16 bits
And split into This is shown in FIG. First memory circuit 2
The 24-bit data of the first group output from the first group is sequentially written into the first area 24 bits of the second memory circuit 4. The 15 bits of the second group output from the first memory circuit 2 are converted into 16 bits by the conversion ROM 3.
After being converted into data of t, the data is written to the second area 16 bits of the second memory circuit 4.

The details of the data conversion will be described below. SM
In the PTE recommendation 125M, 0 to 3 and 1020 to 1023 are set as prohibition codes for image portions. This is 000-003 and 3FC in hexadecimal
ＦＦ3FF. Here, considering the upper 4 bits, among 16 possible values of the number of 4 bits,
0 and 15 correspond to the prohibition code. That is, unless the value of the upper 4 bits is 0 or 15, even if the value of the lower 6 bits is arbitrary, it does not match the prohibition code. In this case, the value that can be taken by the data of the upper 4 bits, that is, the value that does not correspond to the prohibition code, has 14 levels.

On the other hand, since the second group has 15 bits, its level is 32768 (2 to the 15th power). Also, in the 16 bits of the second area for 4 words,
All values except for the prohibition code are 38416 (= 14 × 1
4 × 14 × 14). Here, 32768 <384
Since it is 16, the 15 bits of the second group can be converted into a value of 16 bits of the second area while avoiding the prohibition code.

Conversion is 15 bit input, 16 bit output
Therefore, it can be realized by using a conversion ROM 3 corresponding to 2 Mbits of addresses of 15 bits and data of 16 bits. The 16-bit data converted by the conversion ROM 3 is stored in the second area 16 bit of the second memory circuit 4.
Is written to.

From the second memory circuit 4, the effective image range (Active Video) of SMPTE recommendation 125M
Is read out in 10-bit units within one word, and then encoded by an encoding circuit.
The synchronization signal of E recommendation 125M is inserted and output from the output terminal. In this embodiment, the compressed data is converted,
Although only the encoding process to be transmitted is shown, the process on the decoding side can be easily realized by the reverse process of the above embodiment. In this case, the conversion ROM for converting data has an input address of 16 bits and output data of 15 bits, and the relationship between the address input and the output data is exactly reversed.

In this embodiment, the conversion is performed using the ROM (conversion means). However, the conversion may be performed by calculation using the calculation means. Further, although the first area is set to the lower bits and the second area is set to the upper bits, it is apparent that the same effect can be obtained even if the first area is assigned to an arbitrary location. In this embodiment, one word is 10 bi.
For the transmission path of t, the first area is set to the lower 6 bits and the second area is set to 4 bits. However, the present invention is not limited to this, and can be generalized as follows.

That is, W (W is an integer of 2 or more) bits is one word, and K (K is an integer of 2 or more) bits is added to arbitrary input data on a transmission line in which a prohibition code is set in word units. After converting into N (N is an integer of 2 or more) words as a coding unit (K <N × W), it is output, and is provided with a storage unit and a conversion unit. When W bits are divided into a first section made up of WM bits and a second section made up of M bits, of the K-bit input data, (W−M) × N bits are converted into N words of N words. When the remaining K-((W−M) × N) bits are stored in the first area of the storage means corresponding to the first section and matched with an arbitrary code of the first section by the conversion means. Convert to a conversion code consisting of M bits and N words so as not to match the prohibition code in word units. Then, a conversion code consisting of M bits and N words converted by the conversion means is stored in the second area of the storage means corresponding to the second section of N words, and the word is read from the first and second areas of the storage means. Output data in units. In the above, in order to convert to a conversion code consisting of M bits and N words so as not to match the prohibition code in word units when combined with an arbitrary code in the first section,
What is necessary is that (Equation 1) holds.

[0021]

(1) J ^N ≧ 2 ^L (L = K − ((W−M) × N))) That is, when there are J types (J <2 to the power of M) that do not correspond to the prohibition code in M bits , N words, the number of bits allocated to the second section is L (L = K − ((W−M) ×
N))), J, K, N, and M may be determined so that (J to the N power) is equal to or more than (2 to the L power).

As described above, according to this embodiment,
By dividing the 39-bit compressed image data into two types of regions and performing encoding, 4-bit 40-bit data that does not include the transmission line prohibition code of SMPTE recommendation 125M can be obtained. At this time, 9.75b per word
It will transmit the input data of it (= 39/40), and the efficiency is 97.5%. Even in this case, the conversion is 2
This can be realized with one Mbit ROM, and the circuit scale can be reduced.

As shown in FIG. 3, W (W is an integer of 2 or more) bits is one word, and an arbitrary transmission line is set on a transmission line in which a prohibition code is set in units of words, as shown in FIG. Is converted into N (N is an integer of 2 or more) words using K (K is an integer of 2 or more) bits as a coding unit (K <N × W), and is output. The W bits in one word of the path are divided into a first section consisting of WM bits and a second section consisting of M bits, and (W−M) × N bits of the K-bit input data are Allocated to the first section of N words, and the remaining K-((W-
M) × N) is converted into a conversion code composed of M bits and N words so that when the bits are combined with an arbitrary code in the first section so as not to match the prohibition code in word units, Will be distributed, and the effect will be
Since it is only necessary to convert K-((W−M) × N) bits into a conversion code consisting of M bits and N words, it is possible to perform efficient transmission while reducing the circuit scale. The symbol * in FIG. 3 means multiplication.

[0024]

According to the coded transmission method and coded transmission apparatus of the present invention, it is only necessary to convert K-((W-M) .times.N) bits into a conversion code consisting of M bits and N words. Efficient transmission can be performed while reducing the circuit scale.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an encoded transmission device according to the present invention.

FIG. 2 is a schematic diagram showing how data is stored in the coded transmission device of the present invention.

FIG. 3 is a schematic diagram for explaining an encoded transmission method according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 data input terminal 2 first memory circuit 3 code conversion ROM 4 second memory circuit 5 SAV / EAV addition circuit 6 timing control circuit 7 output circuit

Claims (6)

[Claims] 1. A method in which W (W is an integer of 2 or more) bits is one word, and K (K is an integer of 2 or more) bits is input to a transmission line in which a prohibition code is set in word units. This is a coded transmission method in which, as a coding unit, N (N is an integer of 2 or more) words is converted (K <N × W) and then output. Divided into a first section of M bits and a second section of M bits,
(W−M) × N bits of the K-bit input data are allocated to the first section of N words, and the remaining K−
N words after converting ((W−M) × N) bits into a conversion code consisting of M bits and N words so that when the bits are combined with an arbitrary code in the first section, the conversion code does not match the prohibition code in word units. And transmitting the encoded data to the second section. 2. When there are J types (J <2 to the power of M) of the M bits that do not correspond to the prohibition code, the number of bits allocated to the second section of N words is represented by L (L = K− ( (W−M) ×
2. The coded transmission method according to claim 1, wherein J, K, N, and M are determined such that (J N) is equal to or more than (2 L). 3. The encoding transmission method according to claim 1, wherein the transmission path is defined by a digital transmission standard for video signals, and the input data is image compression data. 4. W (W is an integer of 2 or more) bits is one word, and arbitrary input data is K (K is an integer of 2 or more) bits on a transmission line in which a prohibition code is set in word units. A coded transmission device that converts a coding unit into N (N is an integer of 2 or more) words (K <N × W) and outputs the converted word. The coding and transmission device includes a storage unit and a conversion unit. W in word
When the bits are divided into a first section composed of WM bits and a second section composed of M bits, (W−M) × N bits of the K-bit input data are divided into N words. The data is stored in a first area of the storage unit corresponding to the first section, and the remaining K − ((W−M) × N) bits are converted into an arbitrary code of the first section by the conversion unit. M so that it does not match the prohibition code in word units when
Is converted into a conversion code composed of N words of bits, and the conversion code composed of N words of M bits converted by the conversion means is converted to N
A second section of said storage means corresponding to said second section of words
Wherein the data is output in word units from the first and second areas of the storage means. 5. When there are J types (J <2 to the power of M) of values that do not correspond to a prohibition code in M bits, the number of bits allocated to the second section of N words is L (L = K− ( (W−M) ×
2. The coded transmission apparatus according to claim 1, wherein J, K, N, and M are determined so that (J) raised to the (N) th power is equal to or more than (2 L). 6. The coded transmission apparatus according to claim 1, wherein the transmission path is defined by a digital transmission standard for video signals, and the input data is image compression data.