JP3094893B2 - Video encoding device - Google Patents

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 performing digital transmission and storage by reducing the amount of information by coding in digital television transmission systems, image storage / transmission systems, image databases, and the like. .

[0002]

2. Description of the Related Art There are a large number of digital image systems and applications for encoding image information, reducing the amount of information, and transmitting / accumulating the information. In recent years, in order to improve the encoded image quality, a method requiring complicated processing and a method requiring an enormous number of operations have been widely used. For example, in order to widely measure the properties of an image and to know and select an encoding mode or an encoding parameter that matches the properties, a search for all of a large number of candidate modes or candidate parameters is performed. .

[0003]

However, such a full search type process imposes a heavy load on the computing system. In particular, in encoding processing by software on platforms such as workstations and personal computers that have been developing in recent years, the processing time is significantly increased, and work efficiency is greatly impaired. Also, in the case of encoding processing by hardware, if a combination with other unique techniques for improving the encoding image quality is performed, the longer calculation of the basic processing part may shorten the processing time of other image quality improving techniques. This has to be shortened, which is a major constraint.

Accordingly, it is an object of the present invention to provide a moving picture coding apparatus capable of improving the processing speed while maintaining the image quality as compared with the conventional full search processing.

[0005]

According to the present invention, a plurality of coding modes or coding parameters prepared in advance are searched for, and an appropriate coding mode or coding parameter is selectively used to obtain a moving image. In an apparatus that performs an encoding process, a measuring unit that measures a past encoding process history, and a limiting unit that adaptively limits a search range of an encoding mode or an encoding parameter with reference to the measured encoding process history. Is provided.

[0006] In the moving picture coding process, the image properties which dynamically fluctuate according to the history of the coding state are predicted.
Since the encoding mode and the encoding parameters that match those are limited in advance and the search is performed within the limited encoding mode and the encoding parameters, the encoding processing time is reduced without further deterioration of the encoding image quality. High-speed encoding can be performed.

The measuring means includes a means for measuring a histogram of the magnitude of the motion vector in the past coding processing history, and the limiting means limits the motion vector search range according to the measured histogram. It is preferable to include a range limiting means.

It is preferable that the motion vector search range limiting means detects a range in which the ratio of the motion vectors defined by the threshold is included from the measured histogram, and sets the detected range as a motion vector search range.

It is preferable that the apparatus further comprises reset means for periodically resetting the motion vector search range to an initial value.

It is preferable that the apparatus further comprises reset means for adaptively resetting the motion vector search range according to the measured histogram. In one embodiment of the present invention, the reset means enlarges the motion vector search range from the measured histogram when the rate at which the size of the motion vector reaches the maximum value of the motion vector search range exceeds a threshold value. Means.

The measuring means includes means for measuring the utilization rate of at least one prediction mode in the past encoding processing history, and the limiting means searches for a prediction mode candidate in accordance with the measured utilization rate of the prediction mode. It is preferable to include a prediction mode limiting unit that limits

The prediction mode limiting means may include means for limiting the prediction mode to be searched to the I / P mode when the utilization rate of the B mode is smaller than a predetermined threshold, or the use of the B mode. When the rate is smaller than a predetermined first threshold, the utilization rate of the P mode is compared with a predetermined second threshold. When the utilization of the P mode is smaller than the second threshold, a prediction mode to be searched is determined. When the utilization rate of the P mode is equal to or more than the second threshold value, the prediction mode to be searched may be limited to the I / P mode.

Preferably, the apparatus further comprises reset means for periodically resetting the prediction mode candidates to be searched to initial values.

It is preferable that the apparatus further comprises reset means for adaptively resetting the prediction mode candidates to be searched in accordance with the measured histogram. In one embodiment of the present invention, the reset unit is a unit for resetting, in the measured histogram, a prediction mode candidate to be searched for when a magnitude of a motion vector having a predetermined coverage is smaller than a threshold, to an initial value. .

The measuring means includes means for measuring the utilization rate of the interlace-compatible processing structure mode in the past coding processing history, and the limiting means searches for the processing rate in accordance with the measured utilization rate of the processing structure mode. It is also preferable to include a processing structure limiting means for limiting the number of times.

The processing structure limiting means preferably includes means for limiting the processing structure to be searched to the field structure when the utilization rate of the field mode is larger than a predetermined threshold.

It is preferable that the apparatus further comprises reset means for periodically resetting the processing structure to be searched to the frame structure.

[0018]

FIG. 1 is a block diagram schematically showing an embodiment of a moving picture coding apparatus according to the present invention.

In FIG. 1, reference numeral 10 denotes an image pre-processing unit for creating a format corresponding to a prediction mode labeling and processing structure (frame structure or field structure) for input image data. The preprocessed image data is output to the motion compensation unit 11. The motion compensation unit 11
An appropriate motion vector is detected, an appropriate prediction mode and a processing structure are determined, and compensation is performed according to the motion vector to create an encoded input image. The created encoded input image is output to the signal compression unit 12. Signal compression unit 12
In the present embodiment, the DCT transform processing is first performed, then the quantization processing is performed, and then the encoded image is output by further performing variable length coding processing and the like. At this time, the encoding state,
Reference is made to the quantization parameter determined by the quantization control unit 13 according to the image properties and the like.

In FIG. 1, solid arrows indicate the flow of image data, and broken arrows indicate the flow of control signals. Image preprocessing unit 10 and motion compensation unit 1 described above
1, the signal compression unit 12 and the quantization control unit 13 are all well-known configurations in this field.

According to the present invention, a specially configured circuit, indicated at 14, is added to this known configuration. In other words, the encoding mode / parameter with high processing efficiency for receiving the encoding history from the image pre-processing unit 10 and the motion compensation unit 11 to speed up the encoding process is limited, and the result is referred to as the image pre-processing unit 10 and A circuit 14 for outputting to the motion compensator 11 is added. Hereinafter, the additional circuit 14 will be described in detail.

The encoding history measuring unit 15 receives the past encoding history up to the previous frame or the previous field and measures a numerical value such as a utilization rate necessary for processing efficiency. The encoding mode / parameter limiting unit 16 speeds up the encoding process without deteriorating the image quality based on the measurement value from the encoding history measuring unit 15 and the threshold value stored in the criterion value storage unit 17 in advance. The search range of the coding mode and / or the coding parameter for performing the search is adaptively limited. In the present embodiment, the encoding mode / parameter limiting unit 16 is reset to an initial value provided from an initial value storage unit 19 in response to a periodic reset signal provided from a frame clock unit 18.

FIG. 2 is a block diagram specifically showing an example of the additional circuit 14 in the embodiment of FIG.

As shown in FIG.
In the figure, a prediction mode utilization rate measurement unit 15a, a processing structure utilization rate measurement unit 15b, and a motion vector histogram creation unit 1
5c is present.

The prediction mode utilization rate measuring unit 15a transmits an image unit “macro block (for example, 16 × 1
6)), the utilization rate of the prediction mode (I / P / B) is measured. In the present embodiment, the utilization rates R _B and P of the B mode
The mode utilization rate R _P is measured. If the utilization rate of the I mode is R _I , then R _B + R _P + R _I = 100%.

The processing structure utilization rate measuring unit 15b measures the utilization rate of the processing structure mode (frame mode, field mode) in motion compensation. In the present embodiment, the utilization rate R _{Fi in the} field mode is measured. When the utilization rate of the frame mode is R _Fr , R _Fi + R _Fr = 100%
It is.

Motion vector histogram creating section 15c
Is a histogram S of the absolute value of the selected motion vector.
Create x (i) and Sy (j).

The coding mode / parameter limiting unit 16 includes a prediction mode limiting unit 16a, a processing structure limiting unit 16b, and a motion vector search range limiting unit 16c.

The prediction mode limiting unit 16a compares the magnitude of the threshold R _Bth and R _Pth from the prediction mode utilization utilization given from rate measuring unit 15a R _B and R _P as a criterion value storage unit 17, respectively The prediction mode is limited. That is, first compares the R _B and R _Bth, R _B <If R _Bth, B picture type contained a B-mode (I, a traversal of the P and B-mode, I / P / B-mode) by the image quality Since it is determined that the effect of improvement is small, the B mode is excluded from the selection candidates, and only prediction modes other than the B mode are set as the selection candidates as follows. That is, R _P and R _Pth are compared, and R _P <
In the case of R _Pth , a restriction is made to use only the I mode as the prediction mode. _Unless R _P <R _Pth , the I / P mode (the search for the I mode and the P mode,
(Also referred to as a picture type).

The B mode in MPEG2 is effective for improving the image quality, but the processing time is longer than that in the I mode or the P mode because the number of motion vector searches is increased. For this reason, when the utilization rate of the B mode is small such as when the motion of the image is large, the mode is switched to the I / P mode to speed up the processing. Further, when the utilization rate of the P mode is low, the prediction mode is limited to only the I mode, thereby further increasing the processing speed.

If R _B <R _{Bth is} not satisfied, the I / P / B mode (full search of I, P and B modes) is set as Init1.
Initialize to use.

The processing structure limiting section 16b compares the field mode utilization rate R _Fi from the processing structure utilization rate measuring section 15b with the threshold value R _Fith from the criterion value storage section 17 to limit the processing structure. I do. That is, R _Fi > R _Fith
If so, the frame (Fr) structure (Fi / Fr mode)
Therefore, it is determined that the effect of improving the image quality is small, and only the field mode having the field (Fi) structure is limited to the selection candidates.

When the use rate of the field mode is large, for example, when the motion of the image is large, the processing is speeded up by switching to the field mode of the field (Fi) structure. If R _Fi > R _{Fith is} not _satisfied , initialization is performed so that the frame structure (Fi / Fr mode) is used as Init2.

The motion vector search range restriction unit 16c compares the threshold value MV _th from the histogram Sx (i) and Sy (j) as a criterion value storage unit 17 from the motion vector histogram creation unit 15c, a motion vector Search range (MV
_Rangex, to include the motion vectors in the proportions specified in the threshold MV _th to _MV rangey) within the motion vector search range (MV _rangex, limiting the _MV rangey). As described above, when the motion of the image is small, the processing time is shortened without deteriorating the image quality by limiting the motion vector search range.

In the present embodiment, the encoding mode parameters limited as described above are reset to initial values by a periodic reset signal (every N frames) provided from the frame clock unit 18. This allows
Significant image quality deterioration due to excessive limitation is prevented.

FIGS. 3 and 4 show the additional circuit 14 described above.
The operation of the additional circuit 14 will be described in more detail with reference to these drawings.

As shown in FIG. 3, when the coding history is input from the image preprocessing unit 10 and the motion compensation unit 11, first, in step S1, the current frame is set in the coding mode.
It is determined whether it is time to switch parameters. If it is not the switching timing, the following step S
Steps S2 to S11 are executed.

First, in step S2, it is determined whether the current prediction mode is the B mode. If the mode is the B mode, the counter value B _count is incremented (step S3). If not in step B, step S
At 4, it is determined whether the current prediction mode is the P mode. In the P mode, the counter value P
_{The count} is incremented (step S5). If the mode is not the P mode, since the mode is the I mode, the counter value I
_{The count} is incremented (step S6).

Next, in step S7, it is determined whether the current processing structure is in the field mode. If the mode is the field mode, the counter value Fi _count is incremented (step S8). If the mode is not the field mode, since the mode is the frame mode, the counter value Fr _count is incremented (step S9).

Next, in step S10, the absolute value (| MVx |, | MVy |) of the selected motion vector is measured and set to (X, Y). In the next step S11, the counter values MVx (X) _count and MVy (Y) _count are incremented.

In the case of the switching timing, step S
1 to steps S12 to S14, the utilization rates R _B and R _P , the utilization rate R _Fi , and the motion vector histogram S
x (X) and Sy (Y) are calculated respectively.

The utilization ratio R _B and R _P is calculated by the following equation (step S12). R _B = B _count / (B _count + P _count + I _count ) ×
100 R _P = P _count / (B _count + P _count + I _count ) ×
100

The utilization rate R _Fi is calculated by the following equation (step S13). R _Fi = Fi _count / (Fi _count + Fr _count ) × 100

The motion vector histograms Sx (X) and Sy (Y) are calculated by the following equations (step S14).

(Equation 1)

Following the processing of steps S12 to S14,
The processes of steps S15 to S17 shown in FIG. 4 are respectively performed, and it is determined whether or not it is the timing of the reset signal periodically provided from the frame clock unit 18.

If it is determined in step S15 that it is the reset timing, the limitation of the prediction mode is initialized, and the I / P / B mode is used (step S20). If not reset timing is determined whether R _B <R _{Bt h} in step S18. Unless R _B <R _Bth, for use of B-mode is required, the process proceeds to step S20 I / P / B-mode (B-picture type). If the R _B <R _Bth,
Since the effect of the B mode is small, the I / P mode (P picture type) or the I mode is used.

That is, in step S19, R _P <R
Discriminated whether _Pth, if R _P <R _Pth, performs limited to use only I mode as a prediction mode (step S22). If R _P <R _{Pth is} not satisfied, the use of the I / P mode is limited (step S21). In step S23, the prediction mode thus limited is output. Accordingly, when the utilization rate of the B mode is lower than the threshold R _Bth , the prediction mode is limited to the I / P mode. Further, the utilization rate of the P mode is equal to the threshold R
_When it is lower than _Pth , the prediction mode is limited to only the I mode.

If it is determined in step S16 that it is the reset timing, the limitation of the processing structure is initialized, and
An Fr structure (Fi / Fr mode) is used (step S25). If it is not the reset timing, it is determined in step S24 whether or not R _Fi > R _Fith . If R _{Fi is} not _{greater than} R _Fith , the use of the Fr mode is necessary, and therefore the same step S2 as the initialization processing is performed.
Proceeding to No. 5, the structure becomes the Fr structure (Fi / Fr mode). R _Fi >
If it is R _Fith , it is determined that the effect of the frame (Fr) mode is small, and the processing is limited to only the Fi mode using the field (Fi) structure (step S26).
In step S27, the processing structure thus limited is output. As a result, when the selectivity of the Fi mode is higher than the threshold R _Fith , the processing structure is limited to the Fi structure (Fi mode only).

If it is determined in step S17 that it is the reset timing, the limitation of the motion vector search range is initialized, and MV _rangex = X _MAX , MV _rengey = Y _MAX
(Step S36). If not reset timing in step S28 and S31, the magnitude of the threshold MV _th from the histogram Sx (X) and Sy (Y) and the determination reference value storage unit 17 of the motion vectors are compared as follows, respectively. That is, in step S28, the MV
_th> Sx (i) and is determined whether Sx (i + 1) ≧ MV th, in step _{S31, MV th> Sy (j} ) and Sy (j + 1) ≧ MV
_th is determined.

MV_th> Sx (i) and Sx (i + 1) ≧ MV_thDena
If not (step S28), i is the maximum value X of X_MAX To
This i is incremented by one until it becomes equal,
The comparison is repeated (steps S29 and S30). i = X
_MAX If MV has been reached in step S36,
_rangex= X_MAX , MV_rangey= Y_MAX And initialize. M
V _th> Sx (i) and Sx (i + 1) ≧ MV_thIf (
Step S28), the x position of the search range in step S34
Mark component is MV_rangex= I + 1.

Similarly, MV _th > Sy (j) and Sy (j + 1) ≧ M
If not V _th (step S31), j is repeated comparison increments the j one by one until it is equal to the maximum value Y _MAX and Y (steps S32 and S33).
When j = Y _MAX , in step S36,
_{Initialize as} MV _rangex = X _MAX , MV _rangey = Y _MAX . If MV _th > Sy (j) and Sy (j + 1) ≧ MV _th (step S31), the y coordinate component of the search range is limited to MV _rangey = j + 1 in step S35. In step S37, the search range of the motion vector thus limited is output. As a result, the search range of the motion vector is limited to a range including the motion vector at a rate defined by the threshold value _MVth .

As described above, according to the present embodiment, it is possible to effectively limit and simplify the image encoding process while dynamically referring to the encoding state, and thus perform high-speed processing without deteriorating the encoded image quality. Becomes possible.

FIG. 5 is a flowchart showing the operation of the additional circuit in another embodiment of the moving picture coding apparatus of the present invention. The configuration and operation of other circuits in this embodiment are substantially the same as those in the previous embodiment described with reference to FIGS.

Step S1 of FIG. 3 in the previous embodiment
Following the processing of steps S2 to S14, step S15 shown in FIG.
1, S16, and S171 and S173 are executed.

In step S151, step S
It is determined whether the histogram Sx (i) of the motion vector calculated in step 14 is equal to or greater than a predetermined coverage R. Sx (i)
If <R, i is incremented (step S1
52) The determination in step S151 is performed again. It should be noted that i = 0 when proceeding from step S14 to step S151.
Has been reset to

[0056] When Sx (i) is predetermined inclusion rate R above, at step S153, i is determined whether or not less than the threshold MV _0. If i ≧ MV ₀ , it is determined that it is not the reset timing, and the process proceeds to step S18, where i
<In the case of MV ₀ proceeds to step S154.

In step S154, step S154
It is determined whether the histogram Sy (j) of the motion vector calculated in 14 is equal to or greater than a predetermined coverage R. Sy (j)
If <R, j is incremented (step S1
55) The determination in step S154 is performed again. Note that j = 0 when proceeding from step S14 to step S151.
Has been reset to

[0058] When Sy (j) is a predetermined inclusion ratio R above, at step S156, j is determined whether less than a threshold value MV _0. If j ≧ MV ₀ , it is determined that the timing is not the reset timing, and the process proceeds to step S 18, where j
<For MV ₀ limited prediction modes is determined that the reset timing is initialized, is adapted to use, I / P / B picture, mode (step S20).

As described above, steps S151 to S156 are performed.
When the magnitude of the motion vector of the predetermined inclusion rate R is smaller than the threshold value in the histogram, the prediction mode candidates to be searched are reset to the I / P / B full search mode. Generally, in an image having a large motion vector, the image properties change greatly and the effect of the B mode is small. However, in an image having a small motion vector, the effect of the B mode is conversely increased. I / P /
An adaptive reset is performed to reset B to full search mode. As a result, it is possible to prevent a reduction in processing speed due to unnecessary reset operations.

If it is not the reset timing, it is determined in step S18 whether R _B <R _Bth . If not R _B <R _Bth , it is necessary to use the B mode, so the process proceeds to step S20 and the I / P / B mode (B
Picture type). If R _B <R _Bth , the I / P mode (P picture type) or I mode is used because the effect of the B mode is small.

That is, in step S19, R _P <R
Discriminated whether _Pth, if R _P <R _Pth, performs limited to use only I mode as a prediction mode (step S22). If R _P <R _{Pth is} not satisfied, the use of the I / P mode is limited (step S21). In step S23, the prediction mode thus limited is output. Accordingly, when the utilization rate of the B mode is lower than the threshold R _Bth , the prediction mode is limited to the I / P mode. Further, the utilization rate of the P mode is equal to the threshold R
_When it is lower than _Pth , the prediction mode is limited to only the I mode.

In step S16, it is determined whether it is a periodic reset timing. If it is determined that it is the reset timing, the limitation of the processing structure is initialized, and the Fr structure (Fi / Fr mode) is used (step S25). If it is not the reset timing, it is determined in step S24 whether or not R _Fi > R _Fith . If R _{Fi is} not _{greater than} R _Fith , the use of the Fr mode is necessary. Therefore, the process proceeds to step S25 which is the same as the initialization processing, and the Fr structure (Fi / Fr mode) is obtained. R
_{If Fi} > _RFith , it is determined that the effect of the frame (Fr) prediction mode is small, and F by the field (Fi) structure is determined.
Limit the processing to only the i-mode (step S
26). In step S27, the processing structure thus limited is output. As a result, when the selectivity of the Fi mode is higher than the threshold R _Fith , the processing structure is limited to the Fi structure (Fi mode only).

[0063] The rate is the maximum value of the magnitude of the motion vector search range MV _Rangex of x-coordinate component of step S171 motion vector P (| _MV rangex |) is to determine whether it exceeds a threshold value P _0. P (| MV _rangex |) ≦ P ₀
In this case, it is determined that it is not the reset timing, and the process proceeds to step S28. If P (| MV _rangex |)> P ₀ , the x-coordinate component MV _rangex of the motion vector search range is enlarged by a predetermined amount ΔMVx in step S172, and the process proceeds to step S27. Output the component MV _rangex .

[0064] The rate is the maximum value of the magnitude of the motion vector search range MV _Rangey y coordinate component of the motion vector in step S173 P (| _MV rangey |) is to determine whether it exceeds a threshold value P _0. P (| MV _rangey |) ≦ P ₀
In the case of, it is determined that it is not the reset timing, and the process proceeds to step S31. If P (| MV _rangey |)> P ₀ , the y coordinate component MV _rangey of the motion vector search range is expanded by a predetermined amount ΔMVy in step S174, and the process proceeds to step S27, where the y coordinate of the expanded motion vector search range is increased. Output the component MV _rangey .

As described above, steps S171 to S174
, The rate P (| MV) at which the magnitude of the motion vector falls within the motion vector search range from the histogram
_{rangex |), P (| MV} rangey |) given these motion vector search range when a exceeds the threshold value P ₀ amount DerutaMVx,
Each is enlarged by ΔMVy. If the motion vector search range is not wide enough for the motion in the image, the probability of selecting a large motion vector increases. Therefore, only in such a case, an adaptive reset for expanding the motion vector search range by a predetermined amount is performed. As a result, it is possible to prevent a reduction in processing speed due to unnecessary reset operations.

[0066] If not reset timing in step S28 and S31, compared as magnitudes of following each of the threshold MV _th from the histogram Sx (X) and Sy (Y) and the determination reference value storage unit 17 of the motion vector Is done. That is, in step S28, MV _th > Sx (i) and Sx
It is determined whether (i + 1) ≧ MV _th . In step S31, it is determined whether MV _th > Sy (j) and Sy (j + 1) ≧ MV _th .

If MV _th > Sx (i) and Sx (i + 1) ≧ _MVth are not satisfied (step S28), this i is incremented by 1 until i becomes equal to the maximum value X _MAX of X, and the comparison is performed. Is repeated (steps S29 and S30). i = X
If it becomes _MAX , in step S36, MV
_rangex = X _MAX, initializes the _MV rangey = Y _MAX. M
If V _th > Sx (i) and Sx (i + 1) ≧ MV _th (step S28), the search range is set to MV in step S34.
_{Limit rangex} = i + 1.

Similarly, MV _th > Sy (j) and Sy (j + 1) ≧ M
If not V _th (step S31), j is repeated comparison increments the j one by one until it is equal to the maximum value Y _MAX and Y (steps S32 and S33).
When j = Y _MAX , in step S36,
_{Initialize as} MV _rangex = X _MAX , MV _rangey = Y _MAX . If MV _th > Sy (j) and Sy (j + 1) ≧ MV _th (step S31), the search range is limited to MV _rangey = j + 1 in step S35. In step S37, the search range of the motion vector thus limited is output. As a result, the search range of the motion vector is limited to a range including the motion vector at a rate defined by the threshold value _MVth .

As described above, according to the present embodiment, it is possible to effectively limit and simplify the image encoding process while dynamically referring to the encoding state, so that the high-speed processing can be performed without deteriorating the encoded image quality. Becomes possible. Moreover, it is possible to effectively prevent a significant deterioration in image quality due to excessive limitation and a reduction in processing speed due to unnecessary reset operation.

In the embodiment described above, the prediction mode, the processing structure mode, and the motion vector search range are all limited. However, the moving picture coding apparatus of the present invention employs any one or two of them. Obviously, it may be configured to make one limitation. In the above-described embodiment, when the utilization rate of the B mode is low, the prediction mode is set to the I / P
Mode or the I mode, but when the utilization rate of the B mode is low, the prediction mode is set to the I / P mode.
Obviously, the mode may be limited to only the mode.

The embodiments described above are merely examples of the present invention, and do not limit the present invention. The present invention can be embodied in other various modifications and alterations. Therefore, the scope of the present invention is defined only by the appended claims and their equivalents.

[0072]

As described above in detail, according to the present invention, a plurality of coding modes or coding parameters are searched for detecting image properties, and an appropriate coding mode or coding parameter is selectively selected. In a device that performs moving image encoding processing by using, a measuring unit that measures a past encoding processing history, and adaptively sets a search range of an encoding mode or an encoding parameter with reference to the measured encoding processing history. And limiting means for limiting to As described above, in the moving image encoding process, the image properties that dynamically fluctuate based on the history of the encoding state are predicted, and the encoding mode and the encoding parameters that match the prediction are limited in advance. Since the search is performed within the encoding parameters, the encoded image quality is not further deteriorated,
High-speed encoding with a reduced encoding processing time can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing an embodiment of a moving picture coding apparatus according to the present invention.

FIG. 2 is a block diagram specifically showing one example of an additional circuit in the embodiment of FIG. 1;

FIG. 3 is a flowchart showing the operation of the additional circuit of FIG. 2;

FIG. 4 is a flowchart showing the operation of the additional circuit of FIG. 2;

FIG. 5 is a flowchart illustrating an operation of an additional circuit in another embodiment of the moving picture encoding device of the present invention.

[Explanation of symbols]

 Reference Signs List 10 image preprocessing unit 11 motion compensation unit 12 signal compression unit 13 quantization control unit 14 additional circuit 15 encoding history measurement unit 15a prediction mode utilization ratio measurement unit 15b processing structure utilization ratio measurement unit 15c motion vector histogram creation unit 16 encoding Mode / parameter limitation unit 16a Prediction mode limitation unit 16b Processing structure limitation unit 16c Motion vector search range limitation unit 17 Judgment reference value storage unit 18 Frame clock unit 19 Initial value storage unit

Continuation of front page (56) References JP-A-3-24889 (JP, A) JP-A-6-78289 (JP, A) JP-A-6-62388 (JP, A) JP-A-6-326988 (JP) (A) Special table Hei 4-500423 (JP, A) (58) Fields surveyed (Int. Cl. ⁷ , DB name) H04N 1/41-1/419 H04N 5/91-5/956 H04N 7/24 -7/68

Claims (15)

(57) [Claims] 1. An apparatus that searches for a plurality of encoding modes or encoding parameters prepared in advance and performs a moving image encoding process by selectively using an appropriate encoding mode or encoding parameter. Measuring means for measuring an encoding process history; and limiting means for adaptively limiting a search range of the encoding mode or the encoding parameter with reference to the measured encoding process history. Video encoding device. 2. The apparatus according to claim 1, wherein said measuring means includes means for measuring a histogram of a magnitude of a motion vector in a past encoding process history, and said limiting means limits a search range of the motion vector according to the measured histogram. The apparatus according to claim 1, further comprising a motion vector search range limiting unit that performs motion vector search. 3. The motion vector search range limiting means,
3. The apparatus according to claim 2, further comprising means for detecting, from the measured histogram, a range including a motion vector at a rate defined by a threshold, and using the detected range as a search range of the motion vector. 4. The apparatus according to claim 2, further comprising reset means for periodically resetting the motion vector search range to an initial value. 5. The apparatus according to claim 2, further comprising reset means for adaptively resetting the motion vector search range according to the measured histogram. 6. The reset means expands the motion vector search range when the rate at which the size of the motion vector reaches the maximum value of the motion vector search range exceeds a threshold from the measured histogram. The apparatus of claim 5, wherein the apparatus is provided. 7. The measuring means includes means for measuring a utilization rate of at least one prediction mode in a past encoding process history, and the limiting means searches according to the measured utilization rate of the prediction mode. The apparatus according to any one of claims 1 to 6, further comprising prediction mode restriction means for restricting prediction mode candidates. 8. The prediction mode limiting means includes means for limiting the prediction mode to be searched to the I / P mode when the utilization rate of the B mode is smaller than a predetermined threshold value. An apparatus according to claim 7. 9. The prediction mode limiting unit compares the utilization rate of the P mode with a second predetermined threshold value when the utilization rate of the B mode is smaller than a predetermined first threshold value. When the usage rate is smaller than the second threshold, the prediction mode to be searched is limited to the I mode, and when the usage rate of the P mode is equal to or more than the second threshold, the prediction mode to be searched is limited to the I / P mode. The apparatus of claim 7, comprising means. 10. The apparatus according to claim 7, further comprising reset means for periodically resetting the search mode candidate to be searched to an initial value. 11. The apparatus according to claim 7, further comprising a reset unit that adaptively resets the prediction mode candidates to be searched according to the measured histogram. . 12. The method according to claim 12, wherein the reset unit is a unit that resets the prediction mode candidate to be searched to an initial value when a magnitude of a motion vector having a predetermined inclusion rate is smaller than a threshold value in the measured histogram. An apparatus according to claim 11, characterized in that: 13. The measuring means includes means for measuring a utilization rate of an interlaced processing structure mode in a past encoding processing history, and the limiting means according to the measured utilization rate of the processing structure mode. 13. The apparatus according to claim 1, further comprising processing structure limiting means for limiting a processing structure to be searched. 14. The processing structure limiting means according to claim 13, wherein said processing structure limiting means includes means for limiting a processing structure to be searched to a field structure when a utilization rate of a field mode is larger than a predetermined threshold value. The described device. 15. The apparatus according to claim 14, further comprising reset means for periodically resetting the search processing structure to a frame structure.