JPH1066068A - Video data compressor and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a video image with high quality by applying compression coding to video data nearly in real time. SOLUTION: An encoder control section 22 calculates a statistic variable such as intra-AC denoting complicatedness of a pattern of a video image, and a motion detector 14 calculates a motion predict error (ME residual error) respectively. A host computer 20 indicates a complicated pattern based on the statistic variable and the ME residual error, approximates real difficulty data Dj corresponding to the data amount after compression coding and calculates object data amount Tj denoting a data amount after compression. A quantization circuit 168 quantizes a j-th picture based on a quantization value Qj adjusted by a quantization control circuit 180 based on the object data amount Tj and calculates its mean value. The host computer 20 calculates a global complexity of a TM 5 of the MPEG based on the mean value of the quantization value Qj and a data amount of the j-th picture after the compression to update proportional coefficients εI, ε<p> , εB used for approximating the real difficulty data Dj .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video data compression apparatus for compressing and encoding non-compressed video data and a method thereof.

[0002]

2. Description of the Related Art Uncompressed digital video data is stored in a moving picture (MPEG) format.
I-picture (intra c
oded picture), B picture (bi-directionaly coded
picture) and P-picture (predictive coded pict
ure), compression encoded in GOP (group of pictures) units, and a magneto-optical disk (MO disk;
When recording on a recording medium such as an o-optical disc, the data amount (bit amount) of the compressed video data after compression encoding is
It is necessary to keep the quality of the video after decompression decoding high, while keeping it below the recording capacity of the recording medium or below the transmission capacity of the communication line.

For this purpose, first, non-compressed video data is preliminarily compression-encoded and the data amount after compression-encoding is estimated (first pass). Next, the compression rate is adjusted based on the estimated data amount. Then, compression encoding is performed so that the data amount after the compression encoding becomes equal to or less than the recording capacity of the recording medium (second pass).
(Hereinafter, such a compression encoding method is also referred to as “two-pass encoding”).

However, if compression encoding is performed by two-pass encoding, it is necessary to perform the same compression encoding process twice on the same non-compressed video data, which takes time. Further, since the final compressed video data cannot be calculated by one compression coding process, the captured video data cannot be directly compression-coded and recorded in real time (real time).

[0005] The present invention has been made in view of the above-mentioned problems of the prior art.
It is an object of the present invention to provide a video data compression device and a video data compression device capable of compressing and encoding audio / video data to a predetermined data amount or less. Further, the present invention can compress and encode video data almost in real time.
It is an object of the present invention to provide a video data compression device and a method thereof capable of obtaining a high quality video after decompression decoding. Further, the present invention provides a video data compression device and a video data compression method capable of performing a compression encoding process by estimating a data amount after compression encoding and adjusting a compression ratio without using two-pass encoding. With the goal.

[0006]

In order to achieve the above object, a video data compression apparatus according to the present invention calculates index data for calculating the complexity of uncompressed video data of a moving picture for each picture. Means, performing a predetermined calculation process of multiplying the calculated index data by a predetermined coefficient, difficulty data calculation means for calculating difficulty data corresponding to the data amount after compression, based on the calculated difficulty data, A target value calculating means for calculating a target value of a data amount of the uncompressed video data after compression for each picture; and a picture data of the uncompressed video data, the compressed data amount is calculated by a predetermined compression method. A compression unit configured to generate compressed video data by compressing to the target value, and updating the predetermined coefficient based on a data amount of the generated compressed video data. And a that coefficient update means.

Preferably, the compression means converts the uncompressed video data into a plurality of types of pictures (I picture,
P picture and B picture or a combination thereof) in a predetermined order, and the index data calculating means calculates an ME residual as the index data of the picture compressed into the P picture and the B picture. Then, flatness, intra AC data, activity, or a combination thereof is calculated as the index data of the picture compressed into the I picture.

Preferably, the compression means includes a compression processing means for performing a predetermined compression processing on the uncompressed video data, and a video data which has been subjected to the predetermined compression processing, and A quantizing means for quantizing with a value to generate the compressed video data; and a quantizing value adjusting / setting means for sequentially adjusting the quantized value based on the calculated target value and setting the quantized value in the quantizing means. The coefficient update unit has an average value of the quantization values set in the quantization unit of the compression unit, a data amount of the generated compressed video data, and the calculated index data. The predetermined coefficient is updated based on the predetermined coefficient.

[0009] Preferably, the coefficient updating means includes a global complexity based on an average value of the quantization values set in the quantization means of the compression means and a data amount of the generated compressed video data. And a coefficient calculating means for calculating the predetermined coefficient based on the calculated global complexity and the index data.

Preferably, the coefficient calculating means divides the global complexity of a picture which becomes an I picture after compression by the generated flatness, intra AC or activity to obtain the predetermined coefficient for the I picture. The predetermined coefficient for the P picture and the predetermined coefficient for the B picture are calculated by dividing the global complexity of a picture that becomes a P picture or a B picture after compression by the generated ME residual. .

Preferably, the coefficient calculating means adds or subtracts a predetermined offset value to or from the global complexity, and divides the result by the generated flatness, intra AC or activity to obtain an I picture picture. Is calculated, and the global complexity of a picture that becomes a P picture or a B picture after compression is divided by the generated ME residual,
The predetermined coefficient for the P picture and the predetermined coefficient for the B picture are calculated.

A video data compression device according to the present invention compresses and encodes non-compressed video data to generate compressed video data having a data amount suitable for the storage capacity of a recording medium or the transmission capacity of a transmission path.

In the video data compression device according to the present invention, the index data calculation means generates index data (statistical quantity) indicating the complexity (difficulty) of each picture of the video data. As index data of a picture which becomes an I picture after compression, for example, flatness (flatness) newly defined as a value indicating the flatness of a picture, D
Intra A newly defined as the sum of the variances with the video data for each DCT block as the processing unit of the CT processing
C and TM5 [test model 5; known as a compression algorithm of the MPEG system; ISO / IEC JTC / SC29 / WG
11 / NO400 (Apr. 1993)], an activity for calculating a quantization value (MQUANT) of a macroblock.
ity) is used. As index data of a picture that becomes a P picture or a B picture after compression,
The prediction error amount of motion prediction (ME residual) is used.

The difficulty data calculating means uses a calculated coefficient data having a strong correlation with the difficulty data to multiply the index data by a predetermined coefficient and weight the index data to perform a predetermined arithmetic processing, for example, a linear function. Approximation by
Difficulty data indicating the complexity (difficulty) of the picture is calculated.
Conventionally, this difficulty data has been obtained by, for example, preliminary compressing and encoding uncompressed video data to actually generate compressed video data and counting the data amount of the compressed video data. By approximating the difficulty data, the encoder for calculating the difficulty data becomes unnecessary, and the processing time required for the preliminary compression encoding becomes unnecessary.

The target value calculating means allocates a large amount of data to a picture having a complicated pattern and a small amount of data to a picture having a flat pattern based on the calculated difficulty data so as to allocate a small amount of data to the picture having a flat pattern. Calculate the target value of the data amount. By calculating the target value in this way, the data amount after compression is adapted to the recording capacity of the recording medium while keeping the quality of the compressed video high.

The compression means is, for example, an MPEG system.
After compression, multiple types of pictures (I picture,
(Combination of P picture and B picture) in a predetermined order. The compression processing means performs a predetermined compression process on the non-compressed video data, for example, a process of rearranging pictures of the non-compressed video data into an order suitable for encoding, and a discrete cosine transform (DCT) process.

The quantization means quantizes the video data which has been subjected to DCT or the like with a quantization value set from the outside to generate compressed video data. In the MPEG system, the quantized video data is further subjected to variable-length coding to be compressed video data. The quantization adjustment / setting unit adjusts the quantization value every moment based on the calculated target value, and sets the quantization value in the quantization unit. As described above, the quantization value is adjusted and set to the quantization means, and the quantization means performs the quantization process based on the set quantization value, so that the data amount of the compressed video data is substantially equal to the target value. Become.

The coefficient updating means is, for example, the compression means is 1
Each time one picture is compressed, the quantization adjustment / setting means of the compression means multiplies the average value of the quantization values set in the quantization means by the data amount of the compressed video data. A numerical value called “city” is calculated, and this global complexity is divided by index data (flatness, intra AC, activity and ME residual) calculated by the index data calculating means, and a weighting coefficient used for approximation of difficulty data Is calculated, and the weighting coefficient used for the arithmetic processing is updated. By updating the weighting coefficient, it is possible to always use the optimum weighting coefficient for the picture of the video data, and it is possible to approximate the difficulty data with high accuracy using the index data.

The video data compression method according to the present invention calculates index data indicating the complexity of uncompressed video data of a moving image for each picture, and multiplies the calculated index data by a predetermined coefficient. Performing arithmetic processing, calculating difficulty data corresponding to the data amount after compression, based on the calculated difficulty data, calculating a target value of the data amount of the uncompressed video data after compression for each picture, Each picture of the uncompressed video data is compressed by a predetermined compression method so that the data amount after compression becomes the calculated target value to generate compressed video data, and based on the data amount of the generated compressed video data. Then, the predetermined coefficient is updated.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment Hereinafter, a first embodiment of the present invention will be described. By compression encoding video data such as the MPEG method, when compression encoding video data with a high degree of difficulty, such as a pattern with many high frequency components or a pattern with a lot of motion, distortion due to compression is likely to occur. Become. For this reason, it is necessary to compress and encode video data having a high degree of difficulty at a low compression ratio. For compressed video data obtained by compressing and encoding data having a high degree of difficulty, a compressed image of video data having a pattern having a low level of difficulty is obtained. It is necessary to allocate a larger amount of target data than data.

As described above, in order to adaptively allocate a target data amount to the degree of difficulty of video data, the two-pass encoding method shown as a conventional technique is effective. However, the two-pass encoding method is not suitable for real-time compression encoding. The simplified two-pass encoding method shown as the first embodiment has been made to solve the problem of the two-pass encoding method, and the compressed video data obtained by preliminary compression-encoding the non-compressed video data The difficulty level of the uncompressed video data is calculated from the difficulty level data, and the FI level is calculated based on the difficulty level calculated by the preliminary compression encoding.
The compression rate of the uncompressed video data delayed by a predetermined time by the FO memory or the like can be adaptively controlled.

FIG. 1 is a diagram showing a configuration of a video data compression device 1 according to the present invention. As shown in FIG. 1, the video data compression apparatus 1 includes a compression encoding unit 10 and a host computer 20. The compression encoding unit 10 includes an encoder control unit 12, a motion estimator 14,
Simple 2-pass processing unit 16, second encoder (encoder) 1
8, and the simple two-pass processing unit 16 includes a FIFO memory 160 and a first encoder 162. The video data compression device 1 uses these components to generate uncompressed video data VI input from external devices (not shown) such as an editing device and a video tape recorder device.
For N, the above-described simple two-pass encoding is realized.

In the video data compression device 1, a host computer 20 controls the operation of each component of the video data compression device 1. Also, the host computer 20
The data amount of the compressed video data generated by the encoder 162 of the simple two-pass processing unit 16 preliminarily compression-encoding the non-compressed video data VIN, the value of the DC component (DC component) of the DCT-processed video data, and the DC component The power value of the (AC component) is received via the control signal C16, and the difficulty of the picture of the compressed video data is calculated based on the received values. Further, the host computer 20 based on the calculated difficulty, assigned to each picture of the target amount of data T _j of the compressed video data encoder 18 is generated via a control signal C18, the quantization circuit 166 of the encoder 18 (FIG. 3 ), And the compression rate of the encoder 18 is adaptively controlled on a picture basis.

The encoder control unit 12 determines whether or not there is a picture of the uncompressed video data VIN by the host computer 20.
And performs a pre-process for compression encoding for each picture of the uncompressed video data VIN. That is, the encoder control unit 12 rearranges the input non-compressed video data in the order of encoding, performs picture / field conversion, and performs 3: 2 pull-down processing (movie processing) when the non-compressed video data VIN is video data of a movie. Of the 24 frames / sec video data into 30 frames / sec video data, and removes the redundancy before the compression encoding.
The FIF of the simple 2-pass processing unit 16 is used as the video data S12.
Output to the O memory 160 and the encoder 162. The motion detector 14 detects a motion vector of the uncompressed video data, and outputs the motion vector to the encoder control unit 12 and the encoders 162 and 18.

In the simple 2-pass processing unit 16, the FIFO
The memory 160 converts the video data S12 input from the encoder control unit 12 into, for example, uncompressed video data VIN
Is delayed by the time of L (L is an integer) picture input, and is output to the encoder 18 as delayed video data S16.

FIG. 2 shows a simplified two-pass processing unit 1 shown in FIG.
6 is a diagram illustrating a configuration of a sixth encoder 162. FIG. The encoder 162 includes, for example, as shown in FIG.
4. DCT circuit 166, quantization circuit (Q) 168, variable length coding circuit (VLC) 170, inverse quantization circuit (IQ)
172, inverse DCT (IDCT) circuit 174, addition circuit 1
Is a general video data compression encoder composed of the video data S12 and the motion compensation circuit 178. The input video data S12 is compression-coded by the MPEG method or the like, and the amount of compressed video data for each picture is determined. Output to the host computer 20.

The addition circuit 164 subtracts the output data of the addition circuit 176 from the video data S12,
6 is output. The DCT circuit 166 includes the addition circuit 1
For example, the video data input from 64 is converted to 16 pixels ×
Discrete cosine transform (D
CT), converts the data in the time domain into the data in the frequency domain, and outputs the data to the quantization circuit 168. Further, the DCT circuit 166 controls the DCT of the video data after the DCT.
The value of the component and the power value of the AC component are output to the host computer 20.

The quantization circuit 168 converts the frequency domain data input from the DCT circuit 166 into a fixed quantization value Q
And the variable length coding circuit 17 as quantized data.
0 and output to the inverse quantization circuit 172. The variable-length coding circuit 170 performs variable-length coding on the quantized data input from the quantization circuit 168, and converts the amount of compressed video data obtained as a result of the variable-length coding into a control signal C
16 to the host computer 20. The inverse quantization circuit 172 inversely quantizes the quantized data input from the variable length encoding circuit 168, and outputs the inversely quantized data to the inverse DCT circuit 174.

The inverse DCT circuit 174 includes the inverse quantization circuit 17
Inverse DCT processing is performed on the inversely quantized data input from 2 and output to the adding circuit 176. Addition circuit 1
76 is the output data of the motion compensation circuit 178 and the inverse DC
The output data of the T circuit 174 is added and output to the addition circuit 164 and the motion compensation circuit 178. The motion compensation circuit 178 performs a motion compensation process on the output data of the addition circuit 176 based on the motion vector input from the motion detector 14, and outputs the result to the addition circuit 176.

FIG. 3 is a diagram showing a configuration of the encoder 18 shown in FIG. As shown in FIG.
Has a configuration in which a quantization control circuit 180 is added to the encoder 162 shown in FIG. The encoder 18
With these components, based on the target amount of data T _j set from the host computer 20, the motion compensation process to the L picture delayed by the delayed video data S16 by the FIFO memory 160, DCT processing, quantization processing and The variable-length encoding processing is performed to generate compressed video data VOUT in the MPEG format or the like, and output the same to an external device (not shown).

In the encoder 18, the quantization control circuit 180 sequentially monitors the data amount of the compressed video data VOUT output from the variable length quantization circuit 170, and finally monitors the amount of compressed video data VOUT from the j-th picture of the delayed video data S16. data amount of the compressed video data generated is, so as to approach the target amount of data T _j set from the host computer 20,
The quantization value Q _j to be set in the quantization circuit 168 is sequentially adjusted. The variable-length quantization circuit 170 outputs the compressed video data VOUT to the outside, and also outputs the delayed video data S1
6 is output to the host computer 20 via the control signal C18, the actual data amount _Sj of the compressed video data VOUT obtained by compression-encoding 6.

Hereinafter, a simplified two-pass encoding operation of the video data compression apparatus 1 according to the first embodiment will be described. FIGS. 4A to 4C are diagrams illustrating the operation of the simple two-pass encoding of the video data compression device 1 according to the first embodiment. The encoder control unit 12 controls the video data compression device 1
4A, the encoder control unit 12 performs preprocessing such as rearranging the pictures in the encoding order, and as shown in FIG. 4A, the FIFO memory 160 and the encoder 162. Note that the encoder control unit 12
, The order of picture encoding shown in FIG. 4 and the like differs from the order of display after decompression decoding.

The FIFO memory 160 delays each picture of the input video data S12 by L pictures and outputs the delayed picture to the encoder 18. Encoder 16
Reference numeral 2 denotes a data amount of compression-encoded data obtained by compression-encoding a picture of the input video data S12 in a preliminary and sequential manner, and compression-encoding a j-th (j is an integer) picture; And outputs the DC component value and AC component power value of the video data to the host computer 20.

For example, the delay input to the encoder 18
The video data S16 is stored in the L memory by the FIFO memory 160.
As shown in FIG. 4 (B),
As described above, the encoder 18 determines the j-th
(J is an integer) picture (picture of FIG. 4B)
-A), the encoder 162
Are L-pins from the j-th picture of the video data S12.
The (j + L) -th picture ahead of the kuture (FIG. 4
This means that picture b) of (B) is compression-encoded.
You. Therefore, the encoder 18 transmits the delayed video data S16.
When starting the compression encoding of the j-th picture,
The encoder 162 is configured to j-th to
(J + L-1) -th picture (range of FIG. 4B)
c) the compression encoding has been completed and these pictures
Difficulty data D after compression encoding_j, D _{j + 1}, D_{j + 2},
…, D_{j + L-1}Is already calculated by the host computer 20.
Has been issued.

The host computer 20 calculates the following equation (1)
As a result, the encoder 18 sets the j-th
A target data amount T _j to be allocated to the compressed video data obtained by compression-coding the third picture is calculated, and the calculated target data amount T _j is set in the quantization control circuit 180.

[0036]

(Equation 1)

Where D _j is the video data S
12 is the actual difficulty data of the 12 th picture,
R ′ _j is the average of the target data amount that can be allocated to the j-th to (j + L−1) -th pictures of the video data S12 and S16, and the initial value of R ′ _j (R ′
₁ ) is a target data amount that can be allocated to each picture of the compressed video data on average, and is expressed by the following equation (2). Each time the encoder 18 generates one picture of the compressed video data, Updated as shown.

[0038]

(Equation 2)

[0039]

(Equation 3)

It should be noted that the numerical bit rate (Bit rat
e) is based on the transmission capacity of the communication line and the recording capacity of the recording medium.
Data amount per second (bit amount)
The picture rate (Picture rate) is
Number of pictures per second (30 pictures / sec.
(NTSC), 25 sheets / second (PAL))
_{j + L}Is a picture determined according to the picture type
Shows the average amount of data per group. DC of encoder 18
The T circuit 166 is configured to output the delayed video data S16
DCT processing is performed on the j-th picture, and a quantization circuit 168
Output to The quantization circuit 168 is a DCT circuit 1
Frequency domain of the j-th picture input from
Of the target data amount T by the quantization control circuit 180._j
Quantized value Q adjusted based on_jQuantized by
Output to the variable length coding circuit 170 as encoded data.
You. The variable length coding circuit 170
Variable quantized data of the input j-th picture
After long encoding, the target data amount T_jData volume close to
And outputs the compressed video data VOUT.

Similarly, as shown in FIG. 4B, when the encoder 18 compresses and encodes the (j + 1) -th picture (the picture a 'in FIG. 4C) of the delayed video data S16. , The encoder 162 completes the compression encoding of the (j + 1) -th to (j + L) -th pictures (range c ′ in FIG. 4C) of the video data S12,
The actual difficulty data D _{j + 1} , D _{j + 2} , D of these pictures
_{j + 3} ,..., D _{j + L} have already been calculated by the host computer 20.

The host computer 20 uses the following equation (1).
The encoder 18 determines the (j + 1) th of the delayed video data S16.
A target data amount T _{j + 1} to be allocated to compressed video data obtained by compression-encoding the third picture is calculated and set in the quantization control circuit 180 of the encoder 18.

The encoder 18 is connected to the host computer 2
From 0, the (j + 1) -th picture is compression-encoded based on the _scale data amount _Tj set in the quantization control circuit 180, and compressed video data VOUT having a data size close to the target data size _{Tj + 1} is generated. And output. In the same manner, the video data compression device 1 similarly converts the k-th picture of the delayed video data S16 into a quantized value Q _k (k = j + 2,
j + 3,...) are changed for each picture, and are sequentially compression-encoded and output as compressed video data VOUT.

As described above, according to the video data compression apparatus 1 shown in the first embodiment, the degree of difficulty of the pattern of the non-compressed video data VIN is calculated in a short time, and the compression ratio according to the calculated degree of difficulty is calculated. Thus, the non-compressed video data VIN can be adaptively compression-encoded. That is, according to the video data compression apparatus 1 shown in the first embodiment, unlike the two-pass encoding method, the non-compressed video data VI
N based on the degree of difficulty of the picture
IN can be compression-encoded, and can be applied to applications requiring real-time performance such as live broadcasting. In addition to the data multiplexing apparatus 1 according to the present invention, the data multiplexing apparatus 1 according to the present invention uses the data amount of the compressed video data compressed and encoded by the encoder 162 as difficulty data as it is, Various configurations can be adopted, such as simplification.

Second Embodiment According to the simple two-pass encoding method shown in the first embodiment, it is possible to perform compression encoding processing on non-compressed video data adaptively in real time according to the difficulty of a picture. . However, when the simple two-pass encoding method shown in the first embodiment is used, when strict real-time performance is required, the delay time of the FIFO memory 160 cannot be increased, and a truly appropriate calculation is difficult for the target data amount T _j, the quality of the image obtained compressed video data VOUT to expansion decoding is likely to decrease.

In the second embodiment, the processing content of the host computer 20 is changed by using the video data compression apparatus 1 (FIG. 1) shown in the first embodiment, and the delay time of the FIFO memory 160 is increased. In order to obtain an appropriate value of the target data amount _Tj without performing the above processing, the j-th picture to the L-th picture of the uncompressed video data and the j-th picture of the compressed video data obtained by preliminary compression encoding are used. (J + L
-1) Actual difficulty data D _{j to} D _{j + L-1 of the first} picture
From the (j + L) -th picture to the (j + L + B) -th picture (B is an integer) of the compressed video data, the difficulty data (prediction difficulty data) D _{j + L to} D _{j + L + B} are calculated. Difficulty data D _{j to} D _{j + L-1} (actual difficulty data) and difficulty data D ′ obtained by prediction
_{Based on j + L to} D ′ _{j + L + B} , the target data amount T is more appropriate than the simple two-pass encoding method shown in the first embodiment.
_The compression encoding method (simple prediction 2
The path encoding method will be described.

First, the simplified predictive two-pass encoding method described in the second embodiment will be conceptually described. Simple prediction 2
In the path encoding method, the picture becomes gradually more difficult, that is, the picture of the non-compressed video data, in which the high frequency components after the DCT processing in the compression encoding gradually increase and the movement becomes faster, becomes more difficult. On the contrary, it is assumed that the pattern of the uncompressed video data, in which the pattern gradually becomes difficult (simplifies), can be predicted to be further simplified.

That is, in the predictive simple two-pass encoding method, the host computer 20 uses the
If the picture is expected to become more difficult,
In preparation for a picture with a more difficult picture, the target data amount to be allocated to the picture currently being compression-encoded is saved, and conversely, if the picture is expected to become simpler, the compression will be performed at that point. The compression rate of the encoder 18 is controlled so as to increase the target data amount allocated to the picture being coded.

Further, a conceptual description of the simple predictive two-pass encoding method will be continued. Video data generally has high correlation in the time direction and the spatial direction, and compression coding of video data is performed by focusing on these correlations and removing redundancy. The high correlation in the time direction means that the difficulty level of the picture of the current uncompressed video data is close to the difficulty level of the picture of the subsequent uncompressed video data. In addition, the tendency of the increase and decrease of the difficulty level up to the present time often continues thereafter.

As a specific example, the non-compressed video data of the case where the camera starts rotating slowly in the horizontal direction from the stationary state and finally rotates at a constant rotation speed while photographing a stationary object. Think about the design. At first, since the camera is in a stopped state, a still image is captured, and the difficulty of the picture is reduced. Next, assuming that the rotation speed becomes constant after one to two seconds from starting to rotate the camera, the difficulty of the picture tends to increase from one to two seconds after starting to rotate the camera. When this state is viewed from the video data compression device 1 side, several GOPs
During the generation of the compressed video data, the pattern of the input non-compressed video data tends to be more difficult.

Therefore, in the case shown in this specific example, when the difficulty of the pattern of the non-compressed video data shows a tendency to increase, it is predicted that the difficulty of the pattern after that shows a tendency to increase. Reasonable. The simple predictive two-pass encoding method described below positively utilizes the temporal correlation of the difficulty and the increasing / decreasing tendency of the difficulty to apply the first embodiment to each picture of the compressed video data. Simple 2 shown
It is intended to allocate a more appropriate target data amount than in the path encoding method.

The operation of predictive simple two-pass encoding of the video data compression device 1 according to the second embodiment will be described below. FIGS. 5A to 5C are diagrams illustrating the operation of the predictive simple two-pass encoding of the video data compression device 1 according to the second embodiment. As in the first embodiment, the encoder control unit 12 performs pre-processing such as rearranging pictures in the encoding order by the encoder control unit 12 on the uncompressed video data VIN input to the video data compression device 1. And the video data S12 as shown in FIG.
Is output to the FIFO memory 160 and the encoder 162.

As in the first embodiment, the FIFO memory 160 delays each picture of the input video data S12 by L pictures, and
Output to As in the first embodiment, the encoder 162 preliminary compresses and encodes the picture of the input video data S12 sequentially, and compresses and encodes the j-th (j is an integer) picture. Data amount of compression encoded data, D of video data after DCT processing
The value of the C component and the power value of the AC component are output to the host computer 20. The host computer 20
Based on these values input from the encoder 162, sequentially, to calculate the real difficulty data D _j.

For example, since the delayed video data S16 input to the encoder 18 is delayed by L pictures by the FIFO memory 160, as shown in FIG. j
When the third picture (picture a in FIG. 5B) is compression-encoded, the encoder 162 performs L-pictures from the j-th picture of the video data S12 in the same manner as in the first embodiment. This means that the preceding (j + L) -th picture (picture b in FIG. 5B) has been compression-encoded.

Therefore, when the encoder 18 starts compression encoding of the j-th picture of the delayed video data S16, the encoder 162 sets the (j) -th picture of the video data S12.
-A) -th to (j + L-1) -th pictures (FIG. 5)
(B), where FIG. 5 shows the case where A = 0), completes the compression encoding, the data amount of these pictures after compression encoding, and the D of the video data after DCT processing.
The value of the C component and the power value of the AC component are output to the host computer 20. Host computer 20
_Are based on these values input from the encoder 162, based on the difficulty data (actual difficulty data, range d in FIG. 5B) D _jA , D _{j-A + 1} ,..., D _j , D _{j + 1} , D _{j + 2} ,
.., D _{j + L−1} has already been calculated. Note that A is an integer, and may be either positive or negative.

The host computer 20 stores actual difficulty data
D_jA, D_{j-a + 1}, ..., D_j, D_{j + 1}, D_{j + 2}, ..., D
_{j + L-1}(J + L) -th video data S12 based on
After compression coding of the (j + L + B) -th picture
Difficulty data (predicted difficulty data, range e in FIG. 5B)
D '_{j + L}, D '_{j + L + 1}, D '_{j + L + 2}, ..., D '_{j + L + B}To
And predicts the delayed video data S16 according to Equation 4 shown below.
Target data amount T after compression encoding of the j-th picture
_jIs calculated. Accordingly, the j-th delay video data S16
Target data amount T after compression coding of eye picture_jIs calculated
To include actual difficulty data and predicted difficulty data
(A + L + B + 1) picture in the range c in FIG.
-Difficulty data will be used. The forecast difficulty
Data D _j’Is, for example, actual difficulty data D_jBy linear approximation
And extrapolating the straight line obtained by approximation
It can be calculated.

[0057]

(Equation 4)

Note that each symbol in Equation 4 is the same as each symbol in Equation 1.
The same. Encoder 18 is the same as in the first embodiment.
And the quantization control circuit 18 by the host computer 20.
Target data amount T set to 0_jBased on the goal date
Volume T_jProduces compressed video data VOUT with a data amount close to
And output. Further, the host computer 20
As in the operation shown in FIG. 5B, the delayed video data S1
6 (j + 1) -th picture (picture in FIG. 5C)
(Char + '), the (j +
L + 1) th picture (picture in FIG. 5C)
b ') The actual difficulty data D in the range d' in FIG.
_{j-A + 1}, D_{j-A + 2}, ..., D_j, D_{j + 1}, D_{j + 2}, ..., D
_{j + L}, And the prediction difficulty data shown in a range e ′ in FIG.
Data, D '_{j + L + 1}, D '_{j + L + 2}, D '_{j + L + 3}, ..., D '
_{j + L + B + 1}In other words, the actual difficulty shown in the range c 'in FIG.
Delay video data based on the
After compression encoding of the (j + 1) th picture in S16
Target data amount T_{j + 1}Is calculated. The encoder 18
Scale data amount T calculated by the host computer 20_{j + 1}
(J + 1) -th of the delayed video data S16 based on
Is compressed and coded, and the target data amount T_{j + 1}Close to
A large amount of compressed encoded data VOUT is generated. What
Note that the prediction simple 2-pass engine of the above video data compression apparatus 1
The code operation is the (j + 1) th of the delayed video data S16.
The same applies to eye pictures.

Hereinafter, the operation of the video data compression apparatus 1 according to the second embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing the operation of the video data compression device 1 (FIG. 1) in the second embodiment. FIG.
As shown in step 102, in step 102 (S102),
The host computer 20 converts the numerical values j and R ′ ₁ used in Expression 1 and the like into j = − (L−1), R ′ ₁ = (Bit rate
× (L + B)) / Picture rate

In step 104 (S104), the host computer 20 determines whether or not the numerical value j is larger than 0. If the value j is larger than 0, the process proceeds to S106, and if it is smaller, the process proceeds to S110. In step 106 (S106), the encoder 162
Compresses and encodes the (j + L) -th picture of the video data S12 to generate actual difficulty data D _{j + L.}

In step 108 (S108), the host computer 20 increments the numerical value j (j = j + 1). In step 110 (S110), the host computer 20 transmits the delayed video data S16
It is determined whether the j-th picture exists.
If the j-th picture exists, the process proceeds to S112; otherwise, the compression encoding process ends.

In step 112 (S112), the host computer 20 determines whether or not the numerical value j is larger than the numerical value A. When the numerical value j is larger than the numerical value A, the process proceeds to S114, and when the numerical value j is smaller, the process proceeds to S116. In step 114 (S114), the host computer 20 _executes the actual difficulty data D _{jA to} D _{j + L-1.}
, The predicted difficulty level data D ′ _{j + L to} D ′ _{j + L + B} are calculated. At step 116 (S116), the host computer 20 is the real difficulty data _{D 1 ~D j + L-1} ,
The prediction difficulty data D ′ _{j + L to} D ′ _{j + L + B} are calculated.

In step 118 (S118), the host computer 20 calculates the target data amount T
_j is calculated and set in the quantization control circuit 180 of the encoder 18. Further, the encoder 18 compression-encodes the j-th picture of the delayed video data S16 based on the target data amount T _j set in the quantization control circuit 180, and compresses the compressed picture actually obtained from the j-th picture. The data amount _Sj of the video data is output to the host computer 20. In step 120 (S120), the host computer 20 stores the data amount _Sj from the encoder 18, and further stores the data amount _Sj of the video data S12.
L) Output the actual difficulty data D _{j + L} of the picture.

In step 122 (S122), the encoder 18 outputs the compressed video data VOUT obtained by compression-coding the j-th of the delayed video data S16 to the outside. In step 124 (S124), the host computer 20 calculates the numerical value F _{j + L} used in Expression 3 according to the picture type. Step 12
6 (S126), the host computer 20
The operation shown in Equation 3 (R ′ _{j + 1} = R ′ _j −S _j + F _{j + L} )
I do.

As described above, according to the predictive simple two-pass encoding by the video data compression apparatus 1 shown in the second embodiment, the degree of difficulty of the pattern of the uncompressed video data VIN is calculated in a short time. The uncompressed video data VIN can be adaptively compression-encoded by further using the degree of difficulty predicted based on the degree of difficulty, and a more appropriate target data amount can be set for each picture of the compressed image data as compared with the simple two-pass encoding method. Can be assigned to Therefore, when the compressed video data is expanded and decoded by the predictive simple two-pass encoding method, a higher quality video can be obtained as compared with the case where the compressed video data is expanded and decoded by the simple two-pass encoding method.

Third Embodiment Hereinafter, a third embodiment of the present invention will be described. The simple two-pass encoding method shown in the first embodiment and the second
The prediction simple two-pass encoding method shown in the embodiment of
This is an excellent method that can compress and encode input non-compressed video data only by giving a delay of about 1 GOP (for example, 0.5 seconds) to generate compressed video data of an appropriate data amount. .

However, these methods require two encoders. In general, an encoder that compresses and encodes video data requires large-scale hardware, is very expensive even if integrated, and is large in size. Therefore, these methods require two encoders.
This necessitates a reduction in cost, size, and power saving of a device that realizes these methods. The shorter the time delay required for the compression encoding is, the better. However, the processing for calculating the actual difficulty data D _j and the prediction difficulty data D _j ′ and the preliminary compression encoding itself require processing time for several pictures. Since it is necessary, these processes themselves cause a hindrance to shortening of the time delay.

The third embodiment has been made in order to solve such a problem, and uses only one encoder, and is as appropriate as the simple two-pass encoding method and the predictive simple two-pass encoding method. It is an object of the present invention to provide a video data compression method that can generate compressed video data of a data amount and has a shorter time delay required for processing.

FIG. 7 is a diagram showing an outline of the configuration of a video data compression device 2 according to the present invention in the third embodiment. FIG. 8 is a diagram showing a detailed configuration of the compression encoding unit 24 of the video data compression device 2 shown in FIG. FIG.
8 and FIG. 8, the components of the video data compression device 2 are the same as those of the video data compression device 1 (FIGS. 1 and 2) described in the first embodiment and the second embodiment. Are denoted by the same reference numerals.

As shown in FIG. 7, the video data compression device 2
Replaces the compression encoding unit 10 of the video data compression device 1 (FIGS. 1 and 2) with a compression encoding unit 24 obtained by removing the encoder 162 from the compression encoding unit 10,
Is replaced by the encoder control unit 22, and the buffer memory (buf
fer) 182 is adopted. As shown in FIG.
The compression encoding unit 24 includes a video rearrangement circuit 220, a scan conversion / macroblock conversion circuit 222, and a statistic calculation circuit 224. Other components of the compression encoding unit 24 are the same as those of the compression encoding unit 10. Is adopted.

Similarly to the encoder control unit 12, the encoder control unit 22 notifies the host computer 20 of the presence or absence of a picture of the uncompressed video data VIN. Is performed. In the encoder control unit 22,
The video rearrangement circuit 220 rearranges the input uncompressed video data in the order of encoding.

Scan conversion / macroblock circuit 222
Performs picture / field conversion, and performs 3: 2 pull-down processing or the like when the uncompressed video data VIN is movie video data. The statistic calculation circuit 224 processes statistics such as flatness and intra AC from a picture which is processed by the video rearrangement circuit 220 and the scan conversion / macroblock conversion circuit 222 and is compression-coded into an I picture. Calculate the amount.

The video data compression apparatus 2 uses these components to calculate the statistics (flatness, flatness, etc.) of the uncompressed video data.
Intra-AC) and the prediction error amount of motion prediction (ME residual) are used instead of the difficulty of the picture of the uncompressed video data VIN, and adaptively set the target similarly to the video data compression device 1 (FIGS. 1 and 2). By calculating the data amount _Tj and performing high-precision feedforward control, the non-compressed video data VIN is compression-encoded into compressed video data having an appropriate data amount. In the video data compression device 2, the target data amount _Tj is determined by the motion detector 14 and the statistic calculation circuit 224 of the encoder control unit 22 based on the index data detected in advance. The compression coding method in the data compression device 2 is
Forward rate control (FFRC; feed f
oward rate control).

The ME residual is defined as the sum of absolute values or the sum of squares of the difference between the picture to be compressed and the video data of the reference picture. It is calculated from the following picture, and expresses the speed of movement of the video and the complexity of the picture, and has a correlation with the degree of difficulty and the data amount after compression, like the flatness.

Since the I picture is compression-coded without referring to other pictures, the ME residual cannot be obtained, and flatness and intra AC are used as parameters replacing the ME residual. The flatness is a parameter newly defined as an index indicating the spatial flatness of an image to realize the image data compression device 2, and indicates the complexity of the image. It has a correlation with the difficulty (degree of difficulty) and the amount of data after compression. Intra AC is a video data compression device 2
Is a parameter newly defined as the sum of variances with video data for each DCT block in the DCT processing unit in the MPEG system, and indicates the complexity of the video as well as the flatness. Has a correlation with the difficulty of the picture and the amount of data after compression.

Hereinafter, the ME residual, flatness, and intra AC will be described. First embodiment and second embodiment
In simplified two pass encoding scheme and prediction simplified two pass encoding system explained in the embodiment, the real difficulty data D _j indicates the difficulty of the pattern of the image, the target amount of data T _j is calculated based on the real difficulty data D _j Is done.

[0077] In addition, the data quantity of the compressed video data encoder 18 generates, in order to approach the value indicated by the target amount of data T _j, control of the quantization value Q _j in the quantization circuit 168 (FIG. 2, FIG. 8) Is performed. Thus, obtained without compression encoding video data, the real difficulty data D _j similarly to the picture of the video data complexity parameters appropriate indicating the (difficulty), quantization in the quantization circuit 168 of the encoder 18 If it can be obtained before the processing, the encoder 162
(FIG. 1) can be omitted, and the object of shortening the processing delay time can be achieved. ME residual, flatness and intra AC is because it has a strong correlation with the real difficulty data D _j, it is suitable to achieve this purpose.

[0078] treated compression coding with reference to the relationship between another picture of the ME residual and the real difficulty data D _j, when generating a P picture and B-picture, the motion detector 14 becomes compressed Picture (input picture)
Is searched for a macroblock in which the sum of absolute values or the sum of squares of the difference value between the macroblock of interest and the referenced picture (reference picture) is minimized, and a motion vector is obtained. As described above, the ME residual is defined as a value obtained by summing the absolute sum or the square sum of the minimum difference value of each macroblock when calculating a motion vector for the entire picture.

FIG. 9 shows the video data compression devices 1 and 2
ME residual and actual difficulty data when generating P-pictures
TA D_jIt is a figure which shows the correlation with. FIG.
When generating B pictures by the data compression devices 1 and 2
ME residual and actual difficulty data D_jFigure showing the correlation with
is there. 9 and 10, the actual difficulty data
TA D_jThe encoder 18 uses a fixed quantization value
The amount of compressed video data obtained by compression encoding
(Hereinafter the same in FIGS. 12 and 13)
9 and 10 show the standard images standardized by CCIR.
Statue [cheer (cheer leaders), mobile (mobile and calen
der), tennis (table tennis), diva (diva with nois
e)] and other images (resort) in MPEG2
ME residual obtained by compression encoding using the formula and actual difficulties
Degree data D_j10 is a graph showing the relationship with FIG.
In FIG. 10, the vertical axis (difficulty) of the graph is the actual difficulty level.
Data D_j, And the horizontal axis (me resid) indicates the ME residual. Figure
As can be seen with reference to FIG. 9 and FIG.
Difficulty data D_jHas a very strong correlation with Follow
The picture that becomes a P picture or B picture after compression.
Kucha's actual difficulty data D_jInstead, the ME residual is
Target data amount T _jCan be used to generate

[0080] Flatness and relationship diagram 11 of the real difficulty data D _j is a diagram showing a calculation method of flatness. As shown in FIG. 11, the flatness first divides each DCT block, which is a unit of DCT processing in the MPEG system, into small blocks of 2 pixels × 2 pixels.
Data (pixel value) of diagonal pixels in these small blocks
, The difference value is compared with a predetermined threshold value, and the total number of small blocks in which the difference value is smaller than the threshold value is calculated for each picture. Note that the value of the flatness becomes smaller as the picture pattern of the video is more spatially complicated, and becomes larger when the picture is flat.

[0081] Figure 12 is a video data compression apparatus 1 is a diagram showing the correlation between the flatness and the real difficulty data D _j when generating an I picture. FIG.
9A and 9B actually convert the standard image standardized by CCIR and other images into MPEG2
Is a graph showing the relationship between the flatness obtained when compression coding the real difficulty data D _j by method 1
In 2, the vertical axis of the graph (DIFFICULTY) indicates the real difficulty data D _j, the horizontal axis (flatness) indicates the flatness. As shown in FIG. 12, it to the flatness and the real difficulty data D _j, there is a strong negative correlation, the real difficulty data D _j can be approximated by a method such as substituting flatness to a linear function I understand.

[0082] Relationship intra AC between intra AC and the real difficulty data D _j, for each DCT block, and each pixel value pixels in a DCT block, the absolute value of the difference between the average value of pixel values in the DCT block It is calculated as a sum. That is, the intra AC can be obtained by the following Expression 5.

[0083]

(Equation 5)

[0084] Figure 13 is a video data compression apparatus 1 is a diagram showing the correlation between the intra AC and the real difficulty data D _j when generating an I picture. Note that FIG.
9A and 9B actually convert the standard image standardized by CCIR and other images into MPEG2
Intra AC obtained when compression encoding is performed by the system
Is a graph showing the relationship between the real difficulty data D _j, 1
In 3, the vertical axis of the graph (DIFFICULTY) indicates the real difficulty data D _j, the horizontal axis (intra AC) indicates the flatness. As shown in FIG. 13, there is a strong positive correlation between the intra AC and the actual difficulty data D _j , and the actual difficulty data D _j can be approximated by a method such as substituting the intra AC into a linear function. I understand.

[0085] As described so far, it can be seen the real difficulty data D _j can be approximated by a linear function or the like by the indicator data (statistical amount). Therefore, the actual difficulty data D _{j for} each picture type can be calculated as shown below.

The actual difficulty data D _j is approximated by the ME residual by the following equation 6 for the P picture and by the following equation 7 for the B picture. As for the I-picture, the real difficulty data D _j by the same approximate expression to Equation 6 can be approximated by determining flatness and intra AC or Izu thereof.

[0087]

(Equation 6)

[0088]

(Equation 7)

Further, in the simplified two-pass encoding method shown in the first embodiment, the target data amount T _j is calculated by substituting the actual difficulty data D _j obtained by these approximations into the equation (1). You. Alternatively, in the prediction simple two-pass encoding method shown in the second embodiment,
Predicted difficulty data D _j ′ is calculated from the actual difficulty data D _j obtained by these approximations, and the target data amount T _j is calculated by substituting the actual difficulty data D _j and the predicted difficulty data D _j ′ into Equation 4. Is done.

In the following, the actual difficulty data D _j is approximated by the ME residual, flatness and intra AC, and non-compressed video data is compression-encoded by the simple two-pass encoding method. The operation will be described. In the encoder control unit 22, the video rearranging circuit 220
Rearranges the pictures in the encoding order of the uncompressed video data VIN, and the scan conversion / macroblocking circuit 222
After performing picture-field conversion and the like, the statistic calculation circuit 224 performs the arithmetic processing shown in FIG.
Calculate statistics such as flatness and intra AC.

The motion detector 14 calculates the P picture and the B picture
A motion vector is generated for a picture to be compression-encoded into a picture, and an ME residual is calculated. FI
The FO memory 160 delays the input video data by L pictures.

The host computer 20 includes the motion detector 1
4 is applied to the ME residual generated by Equation 4 to approximate the actual difficulty data D _j , and the same arithmetic processing as Equations 6 and 7 is performed to obtain the flatness and intra to approximate the real difficulty data D _j by the AC. Further, the host computer 20, the real difficulty data D _j approximated into equation 1 to calculate the target amount of data T _j, set the target amount of data T _j calculated for the quantization control circuit 180 of the encoder 18.

[0093] The DCT circuit 166 of the encoder 18 performs DCT processing on the j-th picture of the delayed video data. The quantization circuit 168 converts the frequency domain data of the j-th picture input from the DCT circuit 166 into
Quantized by the quantization value Q _j of the quantization control circuit 180 is adjusted based on the target amount of data T _j. Variable-length coding circuit 170, and variable length coding the j-th picture of the quantized data inputted from the quantization circuit 168, substantially, it generates the compressed video data VOUT of the data amount close to the target amount of data T _j Then, the data is output to the outside via the buffer memory 182.

In the TM5 method or the like known as an MPEG compression algorithm, a statistic called activity shown in Expression 8 below is used to calculate a quantization value (MQUANT) of a macroblock. Activity, as well as the flatness and intra AC, because it has a strong correlation with the real difficulty data D _j, using the activity instead of these parameters, approximating the real difficulty data D _j, to perform compression coding The video data compression device 2 may be configured as follows.

[0095]

(Equation 8)

The operation of the video data compression apparatus 2 has been described above by taking the simple two-pass encoding shown in the first embodiment as an example. It goes without saying that it can be performed. Further, the same modification as that of the video data compression apparatus 1 shown in the first and second embodiments can be made to the video data compression apparatus 2 shown in the third embodiment. .

Fourth Embodiment Hereinafter, a fourth embodiment of the present invention will be described. In the FFRC method shown in the third embodiment, statistically obtained index data (statistics), that is, ME residual, flatness, intra AC, and activity are represented by linear functions such as Equations 6 and 7. by substituting in approximating the real difficulty data D _j. To these index data and the difficulty data D _j, 9, 10, as shown in FIGS. 12 and 13, has a strong correlation, depending picture of the video data, a slight error from the linear function Occurs.

The processing of the video data compression device 2 in the fourth embodiment is performed to solve such a problem, and is shown in Expressions 6 and 7 according to the picture data of the video data. The weighting coefficients a _p , a _B, etc. are adaptively adjusted every moment, so that the actual difficulty data D _j can be approximated with the index data with higher accuracy in the third embodiment, and higher quality compression can be achieved. It has been improved to be able to generate video data.

Hereinafter, an outline of the processing of the video data compression apparatus 2 in the fourth embodiment will be described. Each time the encoder 18 of the video data compression device 2 (FIG. 8) completes the compression encoding for one picture, the host computer 20 knows the data amount of the generated compressed video data for one picture, and , The average value of the quantized values Q _j during the compression encoding, and the global complexity described below. Global complexity, in TM5 of MPEG, as the data amount and a value obtained by multiplying the quantization value Q _j of the compressed video data is defined as shown in Equation 9-1 to Equation 9-3 below, the pattern of the image Show the complexity of.

[0100]

(Equation 9)

In the formulas 9-1 to 9-3,
S _i, S _b, S _p are each an amount of data of I picture, B picture and P picture, Q _i,
Q _b, Q _p is I-picture, respectively, represents the average value of the quantization value Q _j in generating the B-picture and _{P-picture, X i, X b, X} p are each I picture,
The global complexity of B picture and P picture is shown. The global complexity shown in Expressions 9-1 to 9-3 does not always match the actual difficulty data D _j , but unless the average value of the quantized values Q _j is extremely large or small, the actual complexity data D _j is used. It almost matches _j .

Here, assuming that index data of I picture, P picture and B picture, for example, intra AC (other parameters are possible) and ME residual are in a proportional relationship with global complexity, these index data And the global complexity, ε ^I , ε ^P , and ε ^B can be calculated by the following equations 10-1 to 10-3.

[0103]

(Equation 10)

The actual difficulty data D for each picture type
_j is calculated by using the proportional coefficients ε ^I , ε ^P , and ε ^B calculated by Equations 10-1 to 10-3.
It is calculated as shown in FIG.

[0105]

[Equation 11]

When the host computer 20 determines that
As shown in Equation 10-3, the proportional coefficients ε ^I , ε ^P , ε ^B
The encoder 18 is optimized by calculating each time the one compressed coded pictures, by determining the value of the real difficulty data D _j of each picture type by Equation 11-1 Equation 11-3, the video data regardless of pattern, it is possible to the real difficulty data D _j by the index data, always optimally approximated.

The host computer 20 performs the arithmetic processing shown in Expression 1 on the actual difficulty data D _j approximated as shown in Expressions 10 and 11, and obtains the target data amount T _j
Is calculated. It should be noted that, as in MPEG TM5,
For values determined based on the real difficulty data D _j, intentionally, when changing the value of the target amount of data T _j to be actually calculated at a fixed ratio, the equation below 12-1 formula 12- 3, the target data amount _Tj can be calculated.

[0108]

(Equation 12)

In all the denominators of the equations (12-1) to (12-3), DI _{, P, and B} are the Ls buffered in the FIFO memory 160 before being input to the encoder 18.
The actual difficulty data D _j approximated by the index data generated from the uncompressed video data for the picture,
_j indicates the average value of the amount of data that can be allocated to the L pictures after the j-th picture.

The operation of the video data compression device 2 according to the fourth embodiment will be described below with reference to FIG. FIG.
4 is a video data compression device 2 according to the fourth embodiment.
FIG. 9 is a diagram showing the compression encoding operation of FIG. As in the third embodiment, the encoder control unit 22 rearranges the pictures in the encoding order of the uncompressed video data VIN, performs picture / field conversion and the like, and performs the (j + L) -th compression compression encoding on the I picture. Statistics such as flatness and intra AC are calculated from the picture (FIG. 14A).

The motion detector 14 includes the first to third embodiments.
As in the embodiment, a motion vector is generated for the (j + L) th picture to be compression-encoded into a P picture and a B picture, and an ME residual is calculated (FIG. 14A). The FIFO memory 160 delays the input video data by L pictures, as in the first to third embodiments. The host computer 20 performs the computation processing shown in Equation 11-1 and 11-2 approximates the real difficulty data D _j with respect to the ME residual by the motion detector 14 generates, as shown in Equation 11-3 After performing the arithmetic processing, the actual difficulty data D _j
(FIG. 14b). Further, the host computer 20 calculates the approximate actual difficulty data D _j by the formula 1 or the formula 1
Substituted into 2-1～12-3 calculates the target amount of data T _j, set to the quantization control circuit 180 of the encoder 18 (FIG. 14c).

The DCT circuit 166 of the encoder 18 performs DCT processing on the j-th picture of the delayed video data, as in the first to third embodiments. Quantization circuit 168, the data of the j-th picture of the frequency domain inputted from the DCT circuit 166 is quantized by the quantization value Q _j of the quantization control circuit 180 is adjusted based on the target amount of data T _j together, the average value of the quantization values Q _j used for compression coding of the j-th picture, and outputs to the host computer 20. The variable length encoding circuit 170 includes the first to third embodiments.
As in the embodiment, the variable-length coding the j-th picture of the quantized data inputted from the quantization circuit 168, substantially, generates the compressed video data VOUT of the data amount close to the target amount of data T _j And the buffer memory 18
Output via 2.

When the encoder 18 completes the compression encoding of the j-th picture, the host computer 20
Is based on the average value of the quantization value Q _j for the j-th picture input from the quantization control circuit 180 and the data amount of the j-th picture compressed and coded.
The global complexity is calculated as shown in Expressions 9-1 to 9-3 (FIG. 14D). Further, the host computer 20 updates the proportional coefficients ε ^I , ε ^P , and ε ^{B based} on the calculated global complexity as shown in Equations 10-1 to 10-3 (FIG. 14E). The updated proportional coefficients [epsilon] ^I , [epsilon] ^P , and [epsilon] ^B are reflected in the conversion equations (Equation 11-1 to Equation 11-3) in the compression encoding of the next picture.

Referring to FIG. 15, the processing contents of host computer 20 in the fourth embodiment will be further described. FIG. 15 is a diagram showing the processing contents of the host computer 20 (FIG. 8) of the video data compression device 2 in the fourth embodiment. As shown in FIG.
In (S300), the host computer 20 takes in index data (statistics) such as the (j + L) th ME residual or intra AC from the encoder control unit 22 or the motion detector 14.

In step 302 (S302), the host computer 20 determines to which picture type the (j + 1) th picture is compression-encoded. If the (j + 1) th picture is compression-coded into an I picture, the process proceeds to S304. If the j + 1th picture is compression-coded into a P picture, the process proceeds to S306. Is S308
Proceed to processing.

Step 304 (S304), Step 3
06 (S306) and step 308 (S308), the host computer 20 determines the expression 11-
By 1 expression 11-3 approximates the real difficulty data D _j. In step 310 (S310), the host computer 20 using real difficulty data D _j approximated by the equation 1 or equation 12-1 formula 12-3, the target data amount T
Calculate _j . In step 312 (S312),
The encoder 18 compression-codes the j-th picture.

In step 314 (S 314), the host computer 20 determines the data amount of the j-th picture compressed by the encoder 18 and the quantization value Q _j set in the quantization circuit 168 by the quantization control circuit 180. From the average value, the global complexity X _i , X _b ,
X _p [X (I, B, P)] is calculated.

In step 316 (S316), the host computer 20 determines which picture type the (j + 1) th picture is compression-coded. If the (j + 1) th picture is compression-coded into an I-picture, the process proceeds to S318; if it is compressed into a P-picture, the process proceeds to S320; if it is compressed into a B-picture, Is S320
Proceed to processing. Step 318 (S318), Step 320 (S320) and Step 322 (S322)
In each case, the host computer 20 has the formula
The proportional coefficients ε ^I , ε ^P , and ε ^B are updated by −1 to Equation 10-3. In step 324 (S324), the host computer 20 increments the numerical value j.

Note that, as described in the third embodiment, an example
For example, as shown in Expression 13 below, the actual difficulty data D_jWhen,
Proportional coefficient ε^I, Ε^P, Ε^BAnd the product of index data
Offset between (δ^P) May be present. This
In such a case, as shown in Equation 14 below,
Complexity X_i, X_b, X_pOffset value from
δ ^I, Δ^B, Δ^PDivide the value obtained by subtracting by the index data
The proportional coefficient ε^I, Ε^P, Ε^BCalculating
Can be. Also, the video data pressure shown in the fourth embodiment
The operation of the compression device 2 is also described in the third embodiment and the like.
Modifications similar to those are possible.

As described above, according to the operation of the video data compression device 2 in the fourth embodiment, the same effect as the operation of the video data compression device 2 shown in the third embodiment can be obtained. also it can be calculated more accurately target amount of data T _j than in the third embodiment, as a result, it is possible to improve the quality of the compressed video data.

[0121]

As described above, according to the video data compression apparatus and method according to the present invention, audio / video data is compression-coded to a predetermined data amount or less without using two-pass encoding. Can be. Further, according to the video data compression apparatus and method thereof according to the present invention, video data can be compression-encoded substantially in real time, and high-quality video can be obtained after decompression decoding. Further, according to the video data compression apparatus and the method thereof according to the present invention, the compression rate can be adjusted by estimating the data amount after compression and encoding, and the compression and encoding processing can be performed without using two-pass encoding. .

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a video data compression device according to the present invention.

FIG. 2 is a diagram illustrating a configuration of an encoder of a simple two-pass processing unit illustrated in FIG. 1;

FIG. 3 is a diagram illustrating a configuration of an encoder illustrated in FIG. 1;

FIGS. 4A to 4C are diagrams illustrating an operation of a simple two-pass encoding of the video data compression device according to the first embodiment.

FIGS. 5A to 5C are diagrams illustrating an operation of a predictive simple two-pass encoding of the video data compression device according to the second embodiment.

FIG. 6 is a flowchart showing the operation of the video data compression device (FIG. 1) in the second embodiment.

FIG. 7 is a diagram illustrating an outline of a configuration of a video data compression device according to the present invention in a third embodiment.

8 is a diagram illustrating a detailed configuration of a compression encoding unit of the video data compression device illustrated in FIG. 7;

The video data compression apparatus shown in FIG. 9 1 and 7, is a diagram showing the correlation between the ME residual and the real difficulty data D _j when generating a P picture.

The video data compression apparatus shown in FIG. 10 to FIG. 1 and FIG. 7 is a diagram showing the correlation between the ME residual and the real difficulty data D _j when generating a B picture.

FIG. 11 is a diagram illustrating a method of calculating flatness.

The video data compression apparatus shown in FIG. 12 to FIG. 1 and FIG. 7 is a diagram showing the correlation between the flatness and the real difficulty data D _j when generating an I picture.

The video data compression apparatus in FIG. 13 FIG. 1 and FIG. 7 is a diagram showing the correlation between the flatness and the real difficulty data D _j when generating an I picture.

FIG. 14 is a diagram illustrating a compression encoding operation of the video data compression device (FIG. 8) according to the fourth embodiment.

FIG. 15 is a diagram illustrating processing contents of a host computer (FIG. 8) of the video data compression device 2 according to the fourth embodiment.

[Explanation of symbols]

1, 2, ... video data compression device, 10 ... compression encoder, 1
2, 22 ... encoder control unit, 14 ... motion detector, 16
... Simple two-pass processing unit, 160 ... FIFO memory, 16
2, 18 encoder, 164 addition circuit, 166 D
CT circuit, 168 quantization circuit, 170 variable length encoding circuit, 172 inverse quantization circuit, 174 inverse DCT circuit,
176: an addition circuit, 178: a motion compensation circuit, 180: a quantization control circuit, 182: a buffer memory, 20: a host computer.

Claims (12)

[Claims] 1. An index data calculating means for calculating index data for indicating the complexity of uncompressed video data of a moving picture for each picture; and performing a predetermined arithmetic processing for multiplying the calculated index data by a predetermined coefficient; Difficulty data calculation means for calculating difficulty data corresponding to the data amount after compression; and a target value for calculating a target value of the data amount of the uncompressed video data after compression based on the calculated difficulty data for each picture. Calculating means; and compressing means for compressing each of the pictures of the uncompressed video data by a predetermined compression method so that the data amount after compression becomes the calculated target value, thereby generating compressed video data. A video data compression device comprising: a coefficient updating unit that updates the predetermined coefficient based on a data amount of the compressed video data. 2. The compression means compresses the uncompressed video data into a picture type sequence including a plurality of types of pictures (I picture, P picture, B picture or a combination thereof) in a predetermined order, The index data calculating means calculates an ME residual as the index data of the picture compressed into the P picture and the B picture, and calculates flatness, intra AC as the index data of the picture compressed into the I picture.
The video data compression device according to claim 1, wherein the video data compression device calculates data and activity or a combination thereof. 3. The compression means comprises: a compression processing means for performing a predetermined compression processing on the uncompressed video data; Quantizing means for quantizing to generate the compressed video data; and, based on the calculated target value,
And a quantization value adjustment / setting means for adjusting and setting the quantization value in the quantization means. The coefficient updating means includes: an average value of the quantization values set in the quantization means of the compression means; The video data compression device according to claim 2, wherein the predetermined coefficient is updated based on the data amount of the compressed video data and the calculated index data. 4. The coefficient updating means calculates global complexity based on an average value of the quantization values set in the quantization means of the compression means and a data amount of the generated compressed video data. The video data compression device according to claim 3, further comprising: a global complexity calculating unit that performs the calculation; and a coefficient calculating unit that calculates the predetermined coefficient based on the calculated global complexity and the index data. 5. The coefficient calculating means calculates a global complexity of a picture which becomes an I picture after compression,
The predetermined coefficient for the I picture is calculated by dividing by the generated flatness, intra AC or activity, and the global complexity of a picture that becomes a P picture or a B picture after compression is calculated by the generated ME residual. The video data compression device according to claim 4, wherein the predetermined coefficient for a P picture and the predetermined coefficient for a B picture are calculated by dividing. 6. The flatness and intra AC generated by adding or subtracting a predetermined offset value to or from the global complexity.
Alternatively, the predetermined coefficient for the I picture is calculated by dividing by an activity, and after the compression, the P picture or the B picture is calculated.
6. The video data compression according to claim 5, wherein the predetermined coefficient for a P picture and the predetermined coefficient for a B picture are calculated by dividing a global complexity of a picture to be a picture by the generated ME residual. apparatus. 7. A method for calculating index data for indicating the complexity of uncompressed video data of a moving picture for each picture, performing a predetermined calculation process for multiplying the calculated index data by a predetermined coefficient, and compressing the data amount. Calculating the target data amount of the uncompressed video data after compression based on the calculated difficulty data, for each picture. A compression method for generating compressed video data by compressing the data amount after compression to the calculated target value according to the compression method, and updating the predetermined coefficient based on the data amount of the generated compressed video data. Data compression method. 8. A method of compressing the uncompressed video data into a picture type sequence including a plurality of types of pictures (I picture, P picture and B picture or a combination thereof) in a predetermined order, 8. The video according to claim 7, wherein an ME residual is calculated as the index data of the picture to be compressed, and flatness, intra AC data and activity or a combination thereof are calculated as the index data of the picture to be compressed into an I picture. Data compression method. 9. A predetermined compression process is performed on the uncompressed video data, and the video data that has been subjected to the predetermined compression process is quantized by a quantization value set from outside to generate the compressed video data And, based on the calculated target value, the quantized value is sequentially
9. The predetermined coefficient is updated based on an average value of the quantized values to be adjusted and set, a data amount of the generated compressed video data, and the calculated index data. 2. The video data compression method according to 1. 10. A global complexity is calculated based on an average value of the quantization values to be adjusted and set, and a data amount of the generated compressed video data, and the calculated global complexity and the index data are calculated. 10. The predetermined coefficient is calculated based on the predetermined coefficient.
2. The video data compression method according to 1. 11. The predetermined complexity for an I picture is calculated by dividing the global complexity of a picture that becomes an I picture after compression by the generated flatness, intra AC or activity, and calculates a P picture or a compressed picture after compression. The global complexity of a picture that becomes a B picture is divided by the generated ME residual to obtain the predetermined coefficient for the P picture and B
The video data compression method according to claim 10, wherein the predetermined coefficient for a picture is calculated. 12. A predetermined offset value is added to or subtracted from the global complexity, divided by the generated flatness, intra AC or activity to calculate the predetermined coefficient for an I picture, and after compression, 12. The predetermined coefficient for a P picture and the predetermined coefficient for a B picture are calculated by dividing a global complexity of a picture to be a P picture or a B picture by the generated ME residual.
2. The video data compression method according to 1.