JPH10164593A - Image encoder and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To markedly reduce the capacity of a memory required for rearranging image data before conversion at the time of converting picture data in a frame unit compressed within a frame to inter-frame compressed data such as MPEG compressed data. SOLUTION: This device is provided with an image-rearranging part 11, rearranging in-frame compressed data 21 in an order of capability for compressing according to the MPEG image compressing algorithm, a DVC- decoding system 12 decode-extending rearranged in-frame compressed data in the frame unit to convert to a base-band signal 22, and an MPEG encoding system 13 MPEG-compressing decoded image data. Then image data are rearranged, while keeping its compressed state before extending the in-frame compressed data. Thereby, the capacity of a memory 14 for rearranging images is markedly reduced (to about 1/5, e.g.), compared with a system rearranging image data after extending.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image encoding apparatus for generating compressed data between frames or MPEG data of an image, and more particularly to a technique for converting compressed data within a frame into compressed data between frames or MPEG compressed data. About.

[0002]

2. Description of the Related Art The standard of a home digital VTR (DVC: Digital Video Cassette) has been established, and several types of devices have already been commercialized. On the other hand CD
The development of digital video discs (DVDs) for recording video on discs of a size and corresponding devices is also proceeding at a rapid pace.

[0003] Both are consumer devices, and are expected to be used as products of different genres at least for the time being. That is, the former (DVC) is for an individual to leave some image information as a record, and the latter (DVD)
Will be mainly used for enjoying software such as movies.

[0004] By the way, a DVC recorded image is converted to, for example, a DV.
D is used as the source of D title.
When additionally recording a VC recording image on a DVD, it is necessary to convert the DVC data format to a DVD (MPEG) data format.

[0005] However, such conversion operation requires DVC.
There is a difference in the data compression method between DVD and DVD. That is, DVC adopts the intra-frame compression method, and DVD adopts the MPEG compression method. Therefore, in order to convert the DVC data format to the DVD (MPEG) data format, it is necessary to return the DVC image data to a baseband signal before inputting it to the MPEG encoding device.

That is, as shown in FIG. 4, an intra-frame compressed image data 41 input from a DVC is
After decoding by the C decoding system 42 and returning to the baseband signal 43, the MPEG encoding system 44 rearranges the image data in frame units in the order for performing the MPEG compression, and then performs the MPEG compression to the MPEG data. The stream 45 is generated.

Here, in order to rearrange the image data in the frame unit after the DVC decoding in the order for performing the MPEG compression, a memory for temporarily storing data for several images is required. Since the expanded image data is stored in this memory, the capacity of the image memory inside the MPEG encoding system 44 becomes very large, which causes an increase in the cost of the entire encoding apparatus. .

[0008]

In order to convert the intra-frame compressed data recorded on the DVC or the like into inter-frame compressed data such as MPEG compressed data, it is necessary to convert the frame-compressed data into a frame-based image. A relatively large-capacity memory for rearranging data in the order for performing inter-frame compression is required, which causes a problem of increasing costs.

The present invention has been made to solve such a problem. In converting image data in a frame unit which has been compressed within a frame into inter-frame compressed data such as MPEG compressed data, the image data before conversion is arranged. It is an object of the present invention to provide an image encoding device and an image encoding method that can significantly reduce the capacity of a memory required for replacement.

[0010]

In order to achieve the above object, an image coding apparatus according to the present invention, as shown in FIG. Rearranging means 2 for rearranging in the order for compression; decoding means (intra-frame compressed data decoding system) 4 for expanding compressed data 1 in a frame rearranged by the rearranging means 2; Encoding means (interframe compressed data encoding system) 5 for compressing image data between frames.

Here, as the encoding means (inter-frame compressed data encoding system), it is possible to apply an entire encoding system in which the order of frames is rearranged at the time of encoding, such as an MPEG encoding system. Can be.

In the present invention, for example, compressed data in a frame, which is image data read from a DVC or the like, is input,
After rearranging the image data in the state of the intra-frame compressed data, the intra-frame compressed data is decoded and converted into a baseband signal, and inter-frame compression is performed. By doing so, the capacity of the memory 3 used as a work area for rearranging image data can be significantly reduced as compared with the conventional method of rearranging image data after decoding and decompression.

When the input image data is in units of fields, the input image data may be divided into frames and rearranged in units of frames.

Further, according to the present invention, as set forth in claim 3, the encoding means rearranges the image data decoded by the decoding means in the order before the rearrangement by the rearranging means, and externally outputs the result. It is configured to output.
As a result, an image before MPEG encoding can be displayed at the time of editing or the like, and the workability of image editing and the like can be improved.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows the compressed data in the frame as MP
FIG. 2 is a block diagram illustrating a configuration of an MPEG image encoding device that encodes EG compressed data.

As shown in FIG. 1, the image encoding apparatus 1
0 is an image rearrangement unit 11, a DVC decoding system 12, an MPE
It comprises a G encoding system 13.

As described above, the image rearranging unit 11
The intra-frame compressed data 21 which is image data read from a VC or the like is rearranged in an order in which compression is possible according to an MPEG image compression algorithm (an image compression method including a combination of inter-frame compression and intra-frame compression). .

The DVC decoding system 12 includes a depacking unit 12
1. Variable length decoding (VLD) unit 122, inverse quantization (IQ)
A compression unit 123, an IDCT operation unit 124, and a deshuffling unit 125. The compressed data in a frame unit rearranged by the image rearrangement unit 11 is decoded and decompressed through the above units, and the baseband signal 22 is converted to an MPEG.
Output to the encoding system 13.

The MPEG encoding system 13 includes a pre-processing unit 13
1, DCT operation section 132, quantization (Q) section 133, variable length coding (VLC) section 134, inverse quantization (IQ) section 13
5. IDCT operation unit 136, motion vector detection (ME)
Unit 137, memory 138 for motion vector detection, reordering unit 139 for reordering image data, motion compensation (MC) unit 140, memory 141 for motion compensation, subtractor 142, adder for motion compensation 143, a buffer 144 for storing encoded data, and a rate control unit 145 for controlling the quantization rate.

Next, the operation of the MPEG image encoding apparatus will be described.

The intra-frame compressed digital image data 21 output from the DVC or the like is input to the image encoding device 10 via a digital interface (not shown).

In the image coding apparatus 10, first, the image rearranging section 11 rearranges the input intra-frame compressed data 21 in frame units according to a predetermined rule. This rearrangement method is basically the same as the rearrangement method of the input image performed in the input stage of the general MPEG encoding device.

That is, the images are B0, B1, I2, B
3, B4, P5, $ 6, B7, $ 8, B9, $ 10, $
.. Are input in the order of 11, B12, B13,...,...
B0, B1, $ 5, B3, B4, $ 8, B6, B7, P
11, B9, B10, # 14, B12, B13,...

When such image data is rearranged, a memory 14 for a predetermined image for temporarily storing image data is required. In the present embodiment, the image data rearrangement operation is performed in a compressed state before the in-frame compressed data is decompressed. Is significantly reduced (for example, to about 1/5).

The compressed data in the frame rearranged by the image rearranging section 11 is subjected to de-backing, variable length decoding (VLD), and inverse quantization (I
Q), an IDCT operation, and a process of deshuffling, which are decoded to become a baseband signal.
Is input to

The MPEG encoding system 13 firstly operates the preprocessing unit 1
At 31, the input image data, which is a baseband signal, from which high-frequency components have been removed is output to a subtractor 142, a motion vector detection (ME) unit 137, and a re-ordering unit 139.

At the time of encoding an I picture, the data obtained by subtracting zero from the input image by the subtractor 142 is output to the DCT operation unit 13.
2 and thereafter, the output data (DCT coefficient) of the DCT operation unit 132 is quantized and variable-length coded sequentially to obtain MPEG compressed data.

Also, when encoding a P picture or a B picture, the DC
The subtractor 14 subtracts the difference between the reference image and the input image obtained through T operation, quantization, inverse quantization, inverse DCT operation, motion compensation, and the like.
Determined in 2. The output of the subtractor 142 is input to the DCT operation unit 132, and thereafter, the output data (DCT coefficient) of the DCT operation unit 132 is quantized and variable-length-encoded sequentially to obtain MPEG compressed data. .

On the other hand, the re-ordering unit 139 includes the pre-processing unit 1
The image data in units of frames input from 31 is rearranged in the order before input to the image encoding apparatus 10, that is, in the order of the frames of the in-frame compressed data output from the DVC or the like. Output to
Thus, an image before MPEG encoding can be monitored at the time of editing or the like.

In order to rearrange the image data, a memory for a predetermined image is required as in the case of the rearrangement, but the memory is a memory 138 for detecting a motion vector.
It is not enough to add new memory.

Here, the outline of the reordering operation of the image data will be described with reference to FIG.

FIG. 3 shows the output order of the image data from the pre-processing unit 131, the image data in the two frame memories M1 and M2 in the memory 138, and 9 is a table showing a relationship of an output order of image data from a rearranging unit 139.

The output order of the image data from the preprocessing unit 131 is the same as the output order of the in-frame compressed data from the image rearranging unit 11 described above. Each time the I-picture or P-picture image data is output from the pre-processing unit 131, the image data is stored in the two frame memories M1 and M2 used for motion vector detection. The first "?" In the frame memory M1 is I before $ 0.
Or it is a P picture.

The re-arrangement unit 139 outputs the I-picture or P-picture image data from the pre-processing unit 131, and updates the contents of either one of the frame memories each time.
Image data already stored in the other frame memory is read out and inserted between B pictures output from the preprocessing unit 131, thereby rearranging the image data in the original order.

As described above, according to the image encoding apparatus of the present embodiment, the MPEG encoding is performed on the intra-frame compressed data before decoding.
By rearranging the image data for compression, the capacity of the memory 14 for image rearrangement can be significantly reduced as compared with the conventional method of rearranging the image data after decoding. It is possible to reduce the scale and cost.

Further, by adding the image data reordering section 139, an image before MPEG encoding can be displayed at the time of editing or the like, and the workability of image editing and the like can be improved.

[0038]

As described above, according to the present invention, the intra-frame compressed image data is compressed by the MPE.
A conventional method for rearranging decompressed image data by performing the operation of rearranging image data when converting into inter-frame compressed data such as G-compressed data in the compressed state before the intra-frame compressed data is expanded. As compared with the above, the capacity of the memory for image rearrangement can be significantly reduced, and the circuit scale and cost can be reduced.

Further, the image data decoded by the decoding means is rearranged again in the order before the rearrangement by the rearranging means, and the result is outputted to the outside.
An image before PEG encoding can be displayed at the time of editing or the like, and the workability of image editing and the like can be improved.

[Brief description of the drawings]

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

FIG. 2 is a block diagram illustrating a configuration of an MPEG image encoding apparatus according to an embodiment of the present invention.

FIG. 3 is a view for explaining a reordering operation of image data in the MPEG image encoding device of FIG. 2;

FIG. 4 is a block diagram showing a configuration of a conventional image encoding apparatus that generates inter-frame compressed data from intra-frame compressed data.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... In-frame compressed data 2 ... Rearrangement means 3 ... Memory 4 ... In-frame compressed data decoding system 5 ... Inter-frame compressed data 10 ... Image encoding device 11 ... Image rearranging unit 12 ... DVC decoding system 13 MPEG coding system 21 Compressed data in frame 22 Baseband signal 139 Reordering unit

Claims (5)

[Claims] 1. A reordering means for inputting image data of a frame unit which has been compressed in a frame and rearranging the image data in an order for inter-frame compression, and decoding for expanding the compressed data in the frame rearranged by the rearranging means. And an encoding means for inter-frame compression of the image data expanded by the decoding means. 2. A reordering means for inputting image data of a frame unit compressed in a frame and rearranging the image data in an order for MPEG compression, and a decoding means for expanding the intraframe compressed data rearranged by the rearranging means. MPEG image data decompressed by the decoding means
An image encoding apparatus, comprising: encoding means for performing compression. 3. The image encoding apparatus according to claim 1, wherein the encoding unit rearranges the image data expanded by the decoding unit in an order before the image data is rearranged by the rearranging unit. Image recoding means, which comprises a re-ordering means for externally outputting. 4. After inputting image data in a frame unit which has been compressed in a frame and rearranging it in the order for inter-frame compression, the rearranged image compressed data is decompressed.
An image encoding method characterized in that decompressed image data is compressed between frames. 5. After inputting frame-compressed image data in a frame unit and rearranging it in the order for MPEG compression, the rearranged image compression data is decompressed, and the decompressed image data is MPEG-compressed. Image encoding method.