JP2000023154A - Moving image encoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the encoded output of high image quality at all times by judging an encoding parameter for realizing optimum encoding in real time and switching encoded output data. SOLUTION: This encoder is provided with plural moving image encoding parts 1(2A), 2(2B) and 3(2C), an input part 10 for simultaneously inputting input moving images to the plural moving image encoding parts, a system control part 1 for independently setting the respectively different plural encoding parameters to the plural moving image encoding parts and parallelly encoding the input moving images and an encoded output data selection part 3 for selecting optional one from the encoded output data of the plural moving image encoding parts. The system control part 1 judges the encoding parameter for performing the encoding of high quality based on encoded results in the plural moving image encoding parts and controls the encoded output data selection part 3 so as to select the encoded output data at the time of performing the encoding by the encoding parameter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving picture coding apparatus for compressing and coding a moving picture.

[0002]

2. Description of the Related Art For example, a moving image is processed in real-time
In a moving picture coding apparatus that performs coding using the G2 coding method (ITU-T H.262), it is possible to set many coding parameters. FIG. 6 shows the configuration of a coded picture and the direction of motion compensation using a motion vector when the period M of an I picture or a P picture is 1, 2, or 3.

FIG. 7 is a diagram showing a general configuration of an MPEG2 encoding apparatus.
0, a motion vector compensator (MC) 101, a DCT transformer 102, a quantizer 103, and a variable length encoder 10
4, an inverse quantization unit 105, an inverse DCT transform unit 106,
It includes a local decode frame memory 107, a motion vector detection unit (ME) 108, and an encoding control unit 109.

[0004] By the way, when performing encoding in real time, there are parameters (for example, a motion compensation mode and a DCT mode) which can be automatically controlled in order to perform encoding with high image quality. There are also difficult coding parameters. For example, as shown in FIG. 6, as the value of M is larger, the distance between the screens of the I picture and the P picture becomes larger, and in the case of an input moving image with a large motion, the accuracy of the motion vector detection is reduced. In some cases, coding efficiency due to motion compensation may decrease. In such a case,
It is generally known that a coded picture configuration with a small value of M is more likely to obtain higher image quality.

[0005]

However, what kind of coded picture is actually suitable for realizing high quality coding for an image input in real time depends on the input image. For this reason, it is difficult to make a determination unless encoding is actually performed, and it is difficult to control this in real time with the configuration of a conventional encoding device. Therefore, conventionally, the operator has empirically determined the purpose of use and the properties of the input image signal, and has set the coding parameters before starting the coding.

In addition, in the motion vector detection (ME), when the calculation processing capability of the motion vector detection unit is constant, the motion vector detection accuracy and the motion vector detection range are limited by the processing capability, and the motion vector detection range is widened. If
The motion vector detection accuracy becomes coarse, and conversely, when the motion vector detection range is narrowed, the motion vector detection accuracy becomes fine. In the case of an encoding device that can control the motion vector detection range and the motion vector detection accuracy of the motion vector detection unit, the motion vector detection range is narrow if the motion of the input image is small when encoding in real time. Is generally considered better, but it is difficult to determine exactly what setting is appropriate without looking at the result of actual encoding.

The present invention has been made in view of such a problem, and an object thereof is to independently set a plurality of different coding parameters for a plurality of moving picture coding units. To perform encoding of the input video in parallel, determine the encoding parameters for realizing the optimal encoding in real time, and switch the encoded output data to be selected to always output a high-quality encoded output. It is an object of the present invention to provide a moving picture coding device that can be obtained.

[0008]

According to a first aspect of the present invention, there is provided a moving picture coding apparatus comprising: a plurality of moving picture coding units; An input unit for simultaneously inputting to an image encoding unit, and control for independently setting a plurality of different encoding parameters for the plurality of video encoding units and encoding the input video in parallel Unit, the control unit determines an encoding parameter to perform high-quality encoding based on the encoding result in the plurality of video encoding units, and performs encoding with the encoding parameter. Control is performed so as to select the encoded output data at the time of execution.

The video encoding apparatus according to a second aspect of the present invention is the video encoding apparatus according to the first aspect, wherein the video encoding apparatus is based on the MPEG2 encoding system, Sets the period of the intra-frame coded image (I picture) or the inter-frame forward prediction coded image (P picture) as an encoding parameter independently for the plurality of video encoding units.

A video encoding apparatus according to a third aspect of the present invention is the video encoding apparatus according to the second aspect, wherein the intra-frame encoded image ( I picture) has the same period, and the plurality of moving picture coding units have the same coding delay.

In a fourth aspect of the present invention, in the moving picture coding apparatus according to the first invention, the moving picture coding apparatus is based on an MPEG2 coding method. Using the SNR of the coded image as data representing the image quality of the resulting coded image, the control unit sets a coding parameter with which the SNR increases in the cycle of the intra-frame coded image (I picture) to a high quality. It is determined that the parameter is an encoding parameter for encoding.

Further, a moving picture coding apparatus according to a fifth aspect of the present invention is the moving picture coding apparatus according to the first invention, wherein the moving picture coding apparatus uses an MPEG2 coding method. The controller uses the average quantization scale of the intra-frame coded image (I-picture) of the coded image as data representing the image quality of the image, and the control unit determines the intra-frame coded image (I-picture) at a period of the intra-frame coded image (I-picture). It is determined that the coding parameter that reduces the average quantization scale of the coded image (I picture) is a coding parameter for performing high-quality coding.

[0013] Further, a moving picture coding apparatus according to a sixth invention is the moving picture coding apparatus according to the first invention, wherein the moving picture coding apparatus is based on the MPEG2 coding system. The motion vector detection range and the detection accuracy are controlled as the coding parameters of the moving image coding unit.

The video encoding apparatus according to a seventh aspect of the present invention is the video encoding apparatus according to the sixth aspect, wherein the data representing the image quality of the encoded image obtained as the encoding result is inter-picture data. Using the motion compensation error, the control unit determines that the encoding parameter in which the motion compensation error is small is an encoding parameter for performing high-quality encoding.

Further, the video encoding apparatus according to an eighth aspect of the present invention is the video encoding apparatus according to the first aspect, wherein the encoded output data selection section switches the encoded output data. It has.

Further, according to a ninth aspect of the present invention, in the moving image encoding apparatus according to the first aspect, the control unit is determined to be an encoding parameter for performing high quality encoding. The coding parameter is set in a specific one of the plurality of video coding units to perform coding, and the coding of the specific one video coding unit is performed. Select output data.

That is, in the moving picture coding apparatus of the present invention, a plurality of different coding parameters are independently set for a plurality of moving picture coding units, and the input moving picture is coded in parallel. In addition, the encoding parameter for performing high-quality encoding is determined based on the encoding result at this time, and encoded output data when encoding is performed with the encoding parameter is selected. By determining the encoding parameters for realizing the optimal encoding in real time and switching the encoded output data to be selected, it is possible to always obtain an encoded output with high image quality.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the outline of an embodiment of the present invention will be described. In the present embodiment, a plurality of moving picture coding units are prepared, and a plurality of different coding parameters are set independently for the plurality of moving picture coding units, and are controlled in parallel by the control of the system control unit. To encode the input moving image. Then, data representing the image quality after encoding calculated by each moving image encoding unit is output to the system control unit. The system control unit evaluates data representing the image quality after encoding from each of the moving image encoding units and determines an optimal encoding parameter for each certain period, and determines a code corresponding to the optimal encoding parameter. The encoded output data selection unit is controlled so as to select the encoded output data.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of the first embodiment of the present invention. A plurality of moving image encoding units 1 (2) connected to an input terminal (input unit) 10 and operating in parallel.
A), 2 (2B), 3 (2C), and a selector for selecting arbitrary output data from the encoded output data of the plurality of video encoding units 1 (2A), 2 (2B), 3 (2C). And an operation of the encoded data output selecting unit 3 having the following, and a plurality of moving image encoding units 1 (2A), 2 (2B), and 3 (2C):
And a system controller 1 for controlling the operation of the encoded data output selector 3.

In the present embodiment, an MPEG2 encoding system is used as a moving image encoding system. The different encoding parameters set in the encoding units operating in parallel use the period (M) of the intra-frame encoded image (I picture) or the inter-frame forward prediction encoded image (P picture). The SNR (Signal to Noise Ratio) of the encoded image is used as data representing the image quality of the encoded image, and switching is performed in GOP (Group of Picture) units.

The system control unit 1 sets coding parameters for the moving picture coding units 1 (2A), 2 (2B), and 3 (2C) operating in parallel. Video encoding unit 1 (2A)
Is the period (M) of the intra-frame coded image (I picture) or the inter-frame forward prediction coded image (P picture)
Is set to 3 and encoding is performed. The video encoding unit 2 (2B) encodes the intra-frame encoded image (I picture)
Alternatively, it is set so that the encoding is performed with the period (M) of the inter-frame forward prediction encoded image (P picture) being set to 2. The moving picture coding unit 3 (2C) sets the coding so that the cycle (M) of the intra-coded picture (I picture) or the inter-frame forward prediction coded picture (P picture) is set to 3. . Further, the system control unit 1 determines the selection of the output of the video encoding unit in the initial state, controls the encoded data output selection unit 3, and outputs the encoded video data in the initial state to the output terminal 11. Is output.

The moving image signal input from the input terminal 10 is
Video encoding units 1 (2A) and 2 (2
B), 3 (2C). FIG. 2 is a block diagram showing the configuration of each of the video encoding units 1 (2A), 2 (2B), and 3 (2C) in FIG. 1. The SNR calculation unit 32 is added to the configuration of FIG. I have. The encoding control unit 21 performs encoding control according to the control from the system control unit 1. For example, the encoding control unit of the moving image encoding unit 1 (2A) calculates M =
The control is performed so as to perform the encoding in Step 3. Video encoding unit 2
The encoding control unit (2B) performs control so as to perform encoding at M = 2. The encoding control unit of the video encoding unit 3 (2C) performs control such that encoding is performed with M = 1.

The moving image signal input to the input terminal 40 is
It is input to the input order rearranging section 23 and the motion vector detecting section (ME) 24. Input order sorting unit 23
In accordance with the control of the encoding control unit 21, the input images are rearranged according to the value of M, and the moving image signals rearranged in the encoding order are converted into motion vector compensating units (MC) 25 and SN
Output to the R calculator 32. At this time, the moving image encoding unit 1
(2A), rearrangement is performed so that the encoding delays in the video encoding unit 2 (2B) and the video encoding unit 3 (2C) are the same. FIG. 6 shows the timing at this time.

In the motion vector detecting section (ME) 24, M
, The detection of the motion vector necessary for encoding is performed by the input moving image signal and the local decode frame memory 31.
And outputs it to the motion vector compensator (MC) 25. The motion vector compensator (MC) 25 performs motion compensation between the moving picture signal in the input encoding order and the local decode signal output from the local decode frame memory 31, and the DCT converter 2
6 outputs a motion compensation error signal. The DCT transform unit 26 performs a DCT transform on the motion compensation error signal and outputs it to the quantization unit 27.

The quantization section 27 quantizes the DCT-transformed motion compensation error signal under the control of the coding section control section 21 and outputs the quantized signal to the variable length coding section 28 and the inverse quantization section 29. I do. The variable length coding unit 28 performs variable length coding under the control of the coding unit control unit 21 and outputs coded data to an output terminal 41. In the inverse quantization unit 29, the input quantized signal is inversely quantized, and the inverse DCT transform unit 3
Output to 0. The inverse DCT transform unit 30 performs an inverse DCT transform on the input inverse quantized signal and outputs the result to the local decode frame memory 31.

In the local decode frame memory 31, the inverse DC signal inputted under the control of the
A local decode signal is generated from the T signal and stored in the local decode frame memory 31, and the necessary local decode signal is converted to a motion vector detector (ME) 2
4. Motion vector compensator (MC) 25, SNR calculator 3
Output to 2. The SNR calculation unit 32 calculates the SNR in units of frames for the video signals in the coding order input from the input order rearranging unit 23 using the local decode signal output from the local decode frame memory 31, and the coding control unit 21. Encoding control unit 2 of moving image encoding units 1 (2A), 2 (2B), and 3 (2C)
1 outputs the SNR of each frame to the system control unit 1 as data representing the image quality of encoded data.

The system control unit 1 includes a moving image encoding unit 1
From the SNRs of the frame units input from (2A), 2 (2B), and 3 (2C), the video encoding units 1 (2A), 2 (2A)
The SNRs for one GOP period of (2B) and 3 (2C) are calculated, and the moving picture coding unit that achieves the best SNR is determined. The system control unit 1 selects a moving image encoding unit that outputs encoded data for the next 1 GOP period by controlling the encoded data output selection unit 3 based on the determination result at this time, and achieves high image quality. The obtained encoded data is output to an output terminal 11
Output to

FIG. 3 is a diagram showing the operation of the encoded data output selector 3. Which moving picture coding unit realizes high quality coding is performed every time one GOP coding is completed. In the initial state, the encoded data 1 of the video encoding unit 1 (2A)
The encoded output data selection unit 3 is controlled such that _GOP (0) is selected and output. At the timing when the encoding of GOP (0) is completed, it is determined which moving image encoding unit has good encoding performance, and encoded data output in the next GOP (1) period is selected. In FIG. 3, at the end of GOP (0) encoding, the encoding parameters of the moving image encoding unit 2 (2B) are determined to realize high image quality, so the next G
2_GOP (1) as output encoded data of OP (1)
Is selected and output.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a block diagram showing the configuration of the second embodiment of the present invention. This embodiment does not have the encoded data output selection unit, and is configured so that the encoded data of the video encoding unit 1 (2A) is always output to the encoded data output terminal 11. The system control unit 1 determines which coding parameter is better from the data representing the image quality corresponding to the coded data output from the moving picture coding units 1 (2A), 2 (2B), and 3 (2C). By using an encoding parameter for realizing high image quality as an encoding parameter of the moving image encoding unit 1, encoded data for realizing high image quality is always output to the encoded data output terminal 11.

FIG. 5 shows a state of switching the encoding parameters. The system control unit 1 includes a moving image encoding unit 1 (2
A), 2 (2B), and 3 (2C) are set with the encoding parameters in the initial state, and encoding of GOP (0) is started. G
During the encoding period of OP (0), the video encoding unit 1 (2
The encoded data encoded by the encoding parameter PARA_1 set in A) is output. At the end of GOP (0) coding, it is determined which moving picture coding unit has good coding performance, and the coding to be set in the moving picture coding unit 1 (2A) in the next GOP (1) period Determine and set parameters.

In the embodiment shown in FIG. 5, the moving picture coding unit 2
It is determined that the coding parameter PARA_2 of (2B) realizes good coding performance, and the moving image coding unit 1 (2A)
Is set as an encoding parameter for GOP (1), and the encoding parameter PARA_1 previously used in the moving image encoding unit 1 (2A) is
GOP set as an encoding parameter of (2B)
The encoding of (1) is performed. As described above, by performing encoding by switching the encoding parameter according to the input moving image, it is possible to always output encoded data realizing high image quality.

[0032]

According to the present invention, a plurality of moving picture coding units are independently set with a plurality of different coding parameters to perform coding of an input moving picture in parallel, thereby achieving an optimum To provide a moving picture coding apparatus capable of always determining a coding parameter for realizing coding and switching coding output data to be selected, so that a high quality coding output can be obtained. Can be.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a video encoding device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a detailed configuration of each video encoding unit in FIG. 1;

FIG. 3 is a diagram illustrating a state of switching output encoded data according to the first embodiment of the present invention.

FIG. 4 is a block diagram illustrating a configuration of a video encoding device according to a second embodiment of the present invention.

FIG. 5 is a diagram showing how output encoded data is switched by switching encoding parameters in a second embodiment of the present invention.

FIG. 6 is a diagram for explaining a difference in a coded picture configuration in the MPEG2 coding method.

FIG. 7 is a general block diagram of an MPEG2 encoding method.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C059 KK26 LA09 MA00 MA05 MA23 MC11 MC31 MC38 ME01 NN03 NN28 PP05 PP06 TA17 TA63 TB03 TC03 TD05 UA02 UA33 UA38

Claims (9)

[Claims] A plurality of moving image encoding units; an input unit for simultaneously inputting an input moving image to the plurality of moving image encoding units; and a plurality of different moving image encoding units. A control unit configured to independently set a plurality of coding parameters and perform coding of the input moving image in parallel, wherein the control unit calculates a coding result in the plurality of moving image coding units. Video coding, wherein a coding parameter for performing high-quality coding is determined based on the coding parameter, and control is performed so as to select coded output data when coding is performed with the coding parameter. apparatus. 2. The moving picture coding apparatus according to the MPEG2 coding system, wherein the control unit sets an intra-frame coded picture (I picture) or an inter-frame forward prediction coded picture (I-picture) as a coding parameter. 2. The moving picture coding apparatus according to claim 1, wherein a period of the P picture is set independently for the plurality of moving picture coding units. 3. A cycle of an intra-frame coded picture (I picture) set in the plurality of moving picture coding units is the same, and coding delays of the plurality of moving picture coding units are the same. 3. The moving picture coding apparatus according to claim 2, wherein: 4. The moving picture coding apparatus according to the MPEG2 coding method, wherein the data of the coded picture as data representing the quality of the coded picture obtained as the coding result is S
Using the NR, the control unit controls the intra-frame coded image (I
The moving picture coding apparatus according to claim 1, wherein the coding parameter that increases the SNR in a cycle of (picture) is determined to be a coding parameter for performing high-quality coding. 5. The moving picture coding apparatus according to the MPEG2 coding system, wherein data representing the image quality of the coded picture is an intra-frame coded picture (I
Using the average quantization scale of the intra-frame coded image (I-picture), the control unit increases the encoding parameter at which the average quantization scale of the intra-frame coded image (I-picture) decreases in the cycle of the intra-frame coded image (I-picture). The moving picture coding apparatus according to claim 1, wherein the moving picture coding apparatus determines that the parameter is a coding parameter for performing quality coding. 6. The video encoding apparatus according to the MPEG2 encoding system, wherein a motion vector detection range and a detection accuracy are controlled as encoding parameters of the plurality of video encoding units. The moving picture coding apparatus according to claim 1. 7. A motion compensation error between pictures is used as data representing the image quality of an encoded image obtained as a result of the encoding, and the control unit determines an encoding parameter with which the motion compensation error is small as a high-quality code. The moving picture coding apparatus according to claim 6, wherein the moving picture coding apparatus determines that the coding parameter is a coding parameter for performing coding. 8. The moving picture coding apparatus according to claim 1, further comprising a selector for switching coded output data of said plurality of moving picture coding units. 9. The moving image coding apparatus according to claim 1, wherein the control unit converts the coding parameter determined to be a coding parameter for performing high-quality coding into a specific one of the plurality of moving image coding units. 2. The moving picture coding apparatus according to claim 1, wherein the coding unit is set to perform the coding, and the coded output data of the specific one moving picture coding unit is selected.