JPS62171232A - Data compressing and stretching device - Google Patents

Abstract

PURPOSE:To efficiently attain recording or reproduction by providing a compressor compressing an inputted 2-byte length byte data into a 1-byte short-byte data and a stretcher converting the separator data separated by a reader into the data into the compressor and reproducing the result thereby minimizing the data compression. CONSTITUTION:The compressor 1 converts a signal into an expression data yk of a form shown in figure (b) or (c) and a byte length signal representing the data length of the data is outputted from a line sk together with the data converted and outputted. A recorder 2 packs a data of 1 state as shown in figure (c) among data outputted from the compressor 1 into the data shown in figure (d). Then the separator data is added and recorded in a recording medium 3 as the compressed data zj. At reproduction, the data compressed by a reader 4 is read. Then all numerical data yk outputted from the reader 4 based on the byte length signal sk by the expander 5 is expressed as the numeric data Xk of the 2-byte expression to reproduce the data before data compression.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention records a large amount of data by fully compressing the data without changing the information content represented by the data, and by fully decompressing the compressed data. The present invention relates to a data compression/expansion device for reproduction, and particularly to a data compression/expansion device capable of compressing input data into a minimum area and recording or reproducing it on a recording medium.

[Conventional technology]

If a large amount of data (obtained from image signals or measurement data, etc.) is to be recorded on a recording medium as is without data compression, a huge recording medium is required. Therefore, when compressing data such as 9-image signals, when the compressed data is played back and displayed as a video, the video is a video based on the data before data compression! In other words, the data is transformed and compressed to the extent that there is no significant difference when viewed by humans compared to the original image. In addition to these conventional data compression methods, a method for compressing data without compromising the information contained in the data is to add a flag to each piece of data that indicates the length of the effective number of bits. Alternatively, the flags of each of these data are collected as management data in a management table separately from the above data, and are collectively recorded at an address other than the data recording address on the recording medium.

Here, regarding the case of recording the length of the effective bit number of data, that is, the length of the recording area of each data, a data compression method when each data is composed of 12 bits will be described below.

(Axis in Figure 2) is a 12-bit digital signal output from a general A/D converter (analog-digital converter),
FIG. 2 is a bit configuration diagram showing a bit pattern of so-called 1 data. In the figure, CA) shows the bit numbers 0 to 15, and (B) is the data content in which "1" or "0" of the data shown in binary is expressed. In this figure, bit number A 0 to 7 are "1", and bit number A is 8 to 1
The case where o is l'-oJ is shown.

Here, bit number A 0 to 0 as shown in FIG. 2 (al)
7 is "1" and other bits, i.e. bit number A 8~
In the case of data where 15 is "0", this data is originally 1
It can be represented by data within a byte area.

Therefore, for each piece of data sequentially output from the A/D converter, it is determined whether the data can be represented within a 1-byte area or whether a 2-byte area is required. The data is recorded in the management table (status table) according to the above-mentioned 1-byte area, and the data that falls within the 1-byte area is recorded as 1-byte data. In this way, data that can be represented in only a 1-byte area can actually be recorded with half the amount of data, making effective data compression possible. Also, by reproducing compressed data based on the data in the management table mentioned above, that is, whether it is 1-byte data or 2-byte data, it is possible to reproduce the same 2-byte data as before data compression. Data can be easily reproduced.

In this way, conventional data compression compresses and records data that can be expressed in 1 byte out of 2 bytes of data (t-1 byte data), and also records data that can be expressed in 1 byte (recording). Recording was performed using a management table that indicates whether the data is 2-byte data (data with a short recording area) or 2-byte data (data with a long recording area).

[Problem that the invention seeks to solve]

However, in the conventional data compression/decompression device that compresses data as described above, the amount of data such as a management table showing the length of the recording area of each data may become enormous, and the storage medium of that data There is a problem in that it takes a long time to write or read data, resulting in many user complaints.

This invention was made to solve the above-mentioned problems, and it does not use any management table showing the length of the recording area of each data, and it minimizes the information content shown by each data without changing it. The object of the present invention is to obtain a data compression/expansion device that can efficiently record or reproduce data by compressing the data.

[Means to solve all problems]

The data compression/decompression device according to the present invention is capable of handling data that can be expressed in one byte out of the input two-byte long byte data. , a compressor that compresses it into 1-byte short (item) data, and data with a bit structure that is never inputted among the above-mentioned 2-byte or 1-byte short data as separator data that is continuously input from the compressor. A recorder that adds data to a switching point between byte data and 2-byte data and records it on a recording medium, a reader that reads compressed data from the recording medium and separates it into separator data and normal data, and the separator data. and an decompressor that reproduces each data by converting it into data input to the compressor.

[Effect]

The data compression/decompression device of the present invention compresses 2-byte data that can be expressed by 1 byte among the 2-byte data input to the compressor into 1 byte, and determines whether the data is long byte or short. A byte length signal indicating whether the data is a byte is output, and the recorder inserts the separator data at the switching point between consecutive 1-byte data and 2-byte data based on the byte length signal, compresses the data, and records it on the recording medium. , or reader/
Since the decompressor reproduces the data that is exactly the same as the data input to the compressor, that is, the data before compression, there is no need to use a management table that indicates the byte length of each data, and the information content of the input data can be changed. Data can be compressed and expanded without changing anything.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. In Figure 1, (1) is a compressor that inputs 12-bit data from, for example, an A/D converter (not shown) and compresses the data, and (2) is a compressor that compresses the data from the compressor (1). A recorder + (3) that adds separator data and controls recording is a recording medium for recording each of the above data, and (4) reads compressed data recorded on this recording medium (3), and among the data, Separator A reader that separates data.

(5) is a decompressor that decompresses the compressed data from the reader (4) into uncompressed data. Further, in the figure, is an integer starting from 1, and indicates the time of the digital data xk after 12-bit A/D conversion in the A/D converter. Yk is numerical data expressed in 1 or 2 bytes.

Sk is a status signal (byte length signal) indicating the length of the numerical data. Furthermore, zj is compressed data,
j indicates the order. Zj is compressed data, and zj
= zz (same data). Yk is 1 byte or 2
Numerical data expressed in bytes.

Sk is a state signal + Yk = yk, Sk =
sk (each with the same data). Xki This is the same numerical data as before data compression expressed in 2 bytes.

Here, the bit structure of data to be compressed or expanded will be explained. Numerical data usually expressed in 12 bits is expressed in a 2-byte area as shown in Figure 2 (at), and bit numbers 12 to 15 of bit number A are expressed as shown in Figure 2 (at).
The th bit is always "0". Further, the 1st bit in FIG. 2(a) is a sign bit. For example, if this sign bit is "0", it indicates "positive", and if it is "1", it indicates "negative". This sign bit t-1
When expanded to the 5th bit and expressed as shown in FIG. 2(b), 9 this data becomes numerical data expressed in 2 bytes. If the numerical value of this data is y, then this y is.

−(2-1)≦y≦2-1 It is an integer in the range expressed by (Equation 1). Do not do this within the range of the numerical value of y.

-(2-1)≦y≦2-1...The numerical values in the range expressed by (2nd formula) are actually expressed by data in a 1-byte area, as shown in Figure 2 (c). It is possible to express This state is called 1 state.

In addition, numerical values outside the numerical range shown in the second formula above are
Figure (It is possible to store two-state data in 2 bytes like dl.

Here, separator data for separating numerical data expressed in one state and numerical data expressed in two states on continuous data will be described. First, in the bit pattern of one state.

Although an 8-bit bit pattern of 10000000J can be expressed in one byte, it is numerical data (invalid numerical data) that is not within the range of the second equation above.

Therefore, this bit pattern is used as separator data for one state. Next, in the two-state bit pattern, a numerical value such as y=2 or y=215+2 is a numerical value outside the range exceeding the range of the first equation, and in the case of this embodiment, is not included in the input data. Therefore, this Y=
2 is used as separator data indicating the end of continuous two-state data.

After data compression or separator data is set as described above, data processing is performed as follows. First, all initial data will be written in 2-byte format. That is, until 1-state numerical data is input, the recorded data is processed as 2-byte data.

Then, when the 1-state data is input, separator data indicating the end of the 2-state data described above is inserted, and the ft-1 state data input after that is recorded. Then, when data of one state is consecutive and data of two states is inputted first, separator data indicating the end of the one state described above is inserted, and the data of the two states are subsequently recorded. In this way, after the 1-byte continuous data input, separator data indicating the end of the numerical data expressed in 1 byte is added, and after the 2-byte continuous data, the numerical value expressed in 2 bytes is added. Data is processed continuously while adding separator data indicating the end of data. The last data is always written in two states, and 2 +2 is added to the end as an end mark. The transition diagram in Figure 3 shows the transition of data processing in the above, and the transition diagram shown in Figure 2 is a star). Processing is performed to transition from the B state shown in the figure to the 1st state and 2nd state to reach the final E state.

Here, the above-mentioned data processing will be explained with reference to the first block diagram. First, it is assumed that determination of the range of the second expression or determination of separator data is achieved by simple bit operations.

Here, in FIG. 1, the compressor (1) is
b) Convert to expression data yk in the format of ttake(c).

Along with the converted and output data, a signal (byte length signal) indicating the data length of the data, that is, whether it is long byte (2 bytes) data or short byte (1 byte) data (byte length signal) 'i Sk Output from. Of the data output from the compressor (1) in the recorder (21),
Figure 2 (the data for one state shown in cl) is shown in the same figure (
Fill in the data shown in dl. Then, separator data is added in response to changes in the byte length signal Sk output from the number recorder (2) and recorded on the recording medium (3) as compressed data Zj.

During playback, the reader (4) reads out the data compressed as described above, separates the separator data from the data, and outputs numerical data Yk expressed in 1-byte or 2-byte representation and the byte length of that data. Outputs a byte length signal Sk i indicating the byte length. And an extender (
5), all the numerical data ykt output from the reader (4) are expressed as numerical data Xk in 2-byte representation based on the byte length signal Sk, and the data before data compression is reproduced.

In addition! In the above example, compressed short byte data (1 byte data) is explained as 8 bit data, and the ratio is even shorter as 4 bit short byte data, and each input data is compressed as 3 long and short data. Of course you can do it like this.

〔Effect of the invention〕

As described above, according to the present invention, data that can be expressed in short bytes among long byte data is compressed into short bytes, and separator data is inserted at the byte length switching point of continuous data of long bytes and short bytes. Since the data is inserted into the recording medium and recorded or reproduced, there is no need to use management table data, which is a huge amount of data that indicates the length of the recording area of each data as in the past.

The time required to write or read the management table data to a recording medium is significantly reduced, and the uncompressed data can be compressed and decompressed without any loss of information contained in each data. This has the effect of providing a data compression/decompression device that can be processed.

[Brief explanation of drawings]

Figure 1 is a configuration diagram showing a data compression/decompression device according to an embodiment of the present invention. Figures 2 (at to (d) are bit configuration diagrams showing the bit configuration of data before and after data compression in Figure 1. Figure 3 is a transition diagram showing the state transition during data recording or reproduction in Figure 1. In the figure, (1) is a compressor, (2) is a recorder, and (3) is a recording medium. (4) is a reader, and (5) is an expander. Note that the same symbols in the mouth indicate the same or equivalent parts.

Claims (3)

[Claims] (1) Continuously input data each consisting of long bytes with a predetermined number of bits, and convert data that can be expressed with a shorter number of bits than the predetermined number of bits to short byte data. A compressor that compresses the compressed data and outputs the compressed data together with a byte length signal indicating the short byte or long byte, and a bit configuration of the data indicated by the plurality of bits that is not input to the compressor. A recorder that adds long byte or short byte data as respective separator data to a switching point between continuous long byte data and short byte data based on the above-mentioned byte length signal, and writes these data continuously on a recording medium. , a reader that reads compressed data from the recording medium, creates a byte length signal for each data by separating separator data from the continuous data, and outputs each data along with the byte length signal; and the reader and an expander that converts all the data input from the reader into long byte data and returns it by converting short byte data to long byte data based on the byte length signal from. Stretcher. (2) The data according to claim 1, wherein each input data of the compressor is long byte data consisting of 2 bytes, and compresses this data into 1 byte short byte data. Compressor and expander. (3) The compressor inputs long byte data indicating a numerical value, and the recorder adds numerical data that is invalid as a numerical value to the switching point of each long and short byte data as separator data for each long and short byte. A data compression/expansion device according to claim 1 or 2, characterized in that: