JPH10304379A - Image coding method and device, recording medium and image transmission method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply coding processing to a video signal so that a phase of a pull-down pattern is correctly detected and occurrence of unnatural motion between frames is prevented even in the case that no motion is in existence in an object image to detect the phase of the pull-down pattern. SOLUTION: An MPEG encoding controller 23 has a phase pattern detection process that detects disturbance of a phase pattern for pull-down conversion processing, and a phase pattern correction process that corrects disturbance of the phase pattern detected by the phase pattern detection process. In the case that disturbance of the phase pattern is detected in the phase pattern detection process, a bit share calculation section 22 executes a bit assignment calculation program (BIT- ASSING) where bit assignment is calculated after the phase is corrected by the phase pattern correction means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image encoding method and apparatus for encoding a video material subjected to a pull-down conversion process, a recording medium, and an image transmitting method.

[0002]

2. Description of the Related Art When video information is stored on a package medium such as a digital video disk (DVD) or a video CD, an encoding system for compressing and encoding the video information first requires an image of a material. The encoding difficulty (Difficulty) of the video information is measured, and based on the encoding difficulty, a bit allocation process is performed for each frame of each video information so as to be within the number of bytes given in the recording capacity of the package medium. The method of encoding is generally adopted. Hereinafter, this encoding method is referred to as a two-pass encoding method.

[0003] For example, FIG. 12 shows a specific example of a video encoding system for compressing and encoding video information by adopting the two-pass encoding method for the digital video disk.

In FIG. 12, a video encoding controller 10 for controlling video encoding is connected via a network 2 to a supervisor controller 1 for managing the entire system.

[0005] The supervisor controller 1 is a controller that executes a supervisor, which is a program for monitoring the operation of the entire system, particularly for efficiently controlling the operation of the programs constituting the operating system.
In this video encoding system, the entire DVD authoring system is managed, encoding conditions are given to each encoding system such as video, audio, subtitles, and menus, and a report of the encoding result is received.

For a specific example of this video encoding system, video encoding conditions are specified by, for example, a file named v.enc. Then, from the video encode controller 10, the encoded bit stream is converted to a RAID 16 (Redundant Arrays of Inexpensive Diode) in which a plurality of hard disk drives (HDDs) are connected in parallel to improve the recording capacity and transfer speed performance.
skes) and the data (vxxx.aui) required when the encoded bit stream is multiplexed with sub-pictures such as audio, subtitles, and menus. .

The video encoding controller 10 has a graphical user interface (Graphical User I).
nterfece: GUI) 11, a bit allocation calculation unit 12 storing a bit allocation calculation program (Bit_Assign) described later, and an MPEG encoding controller 13 for executing the bit allocation calculation processing program inside the bit allocation calculation unit 12. , Digital VTR controller 1
4 is provided.

The user can use the graphical user interface 11 to manage the above program of the bit allocation calculator 12 and three programs of the MPEG encoder controller 13. In addition, the DVTR controller 14 can be managed.

[0009] The MPEG encoding controller 13
The bit allocation calculation processing program in the bit allocation calculation unit 12 is executed, and the MPEG encoder 1
5 is controlled. In addition, the DVTR controller 14
It controls TR17. The DVTR 17 is connected to an MPEG encoder 15, and the MPEG encoder 15 is connected to a monitor 18 for displaying an encoded result. Further, the MPEG encoder 15 is also connected to the RAID 16 for recording an encoding result.

The MPEG encoder 15 removes the redundancy in the time direction by motion compensation prediction. Also,
The MPEG encoder 15 converts an intra-frame encoded image encoded only within a frame into an I-picture (Intra Code
d), an inter-frame forward prediction coded image coded by predicting the present from a past screen is coded by predicting the present from a P-picture (Predictive Coded), a picture in both past and future directions. A bidirectional predictive coded image is converted to a B-picture (Bidirectionaly Predictive Co
ded) to compress and encode the video information. Here, a group of pictures including one I-picture is always a GOP (Group of Pictures) as shown in FIG. In FIG. 13, the number N of frames of the GOP
Is 15, and the head of the GOP in the display order is the B picture next to the P or I picture before the I picture. G
The end of the OP is the first P picture before the next I picture.

The operation of the video encoding system will be described with reference to the flowchart of FIG. First, in step S1, an encoding condition v.enc such as a total bit amount or a maximum rate to be assigned to video via the network 2 is given from the supervisor controller 1,
The MPEG encoding controller 13 sets this encoding condition. Thereafter, in step S2, the MPEG encoder controller 13 measures the encoding difficulty (Difficulty) of the encoded material using the MPEG encoder 15. Here, the DC value of each pixel and the motion vector amount M
Also read E. Then, a file is created based on these measurement results.

The actual Difficulty is measured as follows. Video information serving as an encoding material is reproduced by a DVTR 17 from a digital video cassette which is a master tape. MPEG encoding controller 13
Measures the encoding difficulty of the video information reproduced by the DVTR 17 via the MPEG encoder 15. Here, the amount of generated bits is measured under the condition that the number of quantization steps is set to a fixed value at the time of encoding. The amount of generated bits is large in an image having many motions and large high frequency components, and the generated bit amount is small in a still image or an image having many flat portions. The magnitude of the generated bit amount is defined as the encoding difficulty.

Next, in step S3, based on the encoding conditions set in step S1, according to the magnitude of the encoding difficulty of each picture measured in step S2,
The MPEG encoding controller 13 executes a calculation program (BIT_ASSIGN) inside the bit allocation calculation unit 12,
The allocation calculation of the allocated bit amount (target amount: target) is performed.

Then, the user is made to judge whether or not to execute encoding using the result of the bit allocation calculation in step S3, based on the image quality of the local decoder output built in the MPEG encoder 15.

Actually, in step S4, the preview mode (Pr) in which an arbitrary processing range can be designated without outputting the bit stream based on the bit allocation to the RAID 16 is described.
eview), and the user checks the image quality.

If there is no problem with the image quality in the image quality evaluation in step S5, the process proceeds to step S6, where the MPEG encoder 1
5 is performed, but if there is a problem with the image quality, the process proceeds to step S8, where customizing work for image quality adjustment such as increasing the rate of the problematic portion or adjusting the filter level is performed. In step S9, a bit allocation recalculation is executed.

Thereafter, returning to step S4, the customized portion is previewed, the image quality is checked in step S5, and if all the portions are good, the process proceeds to step S6, where the entire encoder is executed by the MPEG encoder 15. In step S7, the bit stream that is the encoding result is a SCSI (Small Computer System Interface).
The data is directly written to RAID 16 via e).

After the encoding in step S6, the video encode controller 10 reports the above-described encoding result information to the supervisor controller 1 via the network.

In the flowchart of FIG. 14, the processing of each step except for step S2, step S4, and step S6 means off-line processing.

Hereinafter, in particular, the bit allocation calculation inside the bit allocation calculation unit 12 executed by the MPEG encoding controller 13 in step S3 will be described in detail with reference to FIG. First, the supervisor controller 1 specifies the total bit amount (QTY_BYTES) allocated to video from the disk capacity and the maximum bit rate (MAXRATE). On the other hand, the MPEG encoding controller 13 executes the bit allocation calculation program inside the bit allocation calculation unit 12 and sets the total bit number limited so as to be equal to or less than the maximum bit rate (MAXRATE).
(USB_BYTES), and the GOP header (GOP h
SUPER_BYTES, which is a target value of the total number of targets, is calculated from the value obtained by subtracting the number of bits (TOTAL_HEADER) required for the eader) and the total number of frames. And this SUPPLY
The amount of bits to be allocated to each picture (target amount: target) is distributed so as to be within the size of _BYTES. TARGET_BYTES sums the amount of bits allocated to all pictures
Then, the value obtained by subtracting TARGET_BYTES from SUPPLY_BYTES is the remainder in bit allocation (REMAIN_BYTES).

FIG. 16 is a flowchart showing the details of the bit allocation calculation process in step S3.

First, as described above in step S11,
The total bit amount (QTY_BYTES) sent from the supervisor controller 1 and the maximum bit rate (MAXRATE) are input. Next, the measurement file created in the measurement of the encoding difficulty (Difficulty) in step S2 in FIG. 14 is read as it is in step S12, and the respective images measured together with the measurement of the encoding difficulty are measured. In step S13, a point at which the scene changes is found from the DC value and the change amount of the parameter of the magnitude of the motion vector amount ME.

The detection / processing of the scene change in step S13 has been disclosed by the present applicant in Japanese Patent Application No. 8-274,094.
This is a process of detecting a scene change point according to the “video signal processing device” disclosed in the specification and the drawings.

This "video signal processing apparatus" detects the DC level of each frame of the video signal, and detects the scene change frame of the video signal from the error value obtained by approximating the DC level with a curve. , Clarify the scene change point. Then, at the point where the scene change is detected, the P picture is changed to the I picture to improve the image quality.

In step S13, chapter boundary processing is also performed. At the time of a chapter search in a DVD playback device, a jump is performed from an unspecified picture. Even in such a case, the position of the chapter must be set to GO to prevent disturbance of the playback image.
Change the picture type to be at the beginning of P,
Limit GOP length.

The above steps S12 and S1
As a result of the series of operations in Step 3, picture types (I, P,
When the change processing of the (B picture) is executed, the picture type at the time of measuring the encoding difficulty (Difficulty) is changed. Therefore, in steps S14 to S17, the value of the encoding difficulty corresponding to the changed picture type is determined. Interpolation / correction. In step S18 to step S20, a target for each picture is determined according to the encoding difficulty obtained by interpolation / correction of the encoding difficulty in steps S14 to S17 and the total number of bits (SUPPLY_BYTES). Calculate the number of bits.

Then, in step S21, after calculating the address for writing the bit stream of the encoding result in the RAID 16, the process proceeds to step S22 to create a control file for the encoder.

For example, as a specific example of the bit allocation calculation,
First, the bit amount is allocated to each GOP, and then each GOP is
It is assumed that bit allocation according to the encoding difficulty of each picture is performed within the above. Here, the bit allocation amount (GOP_TARGET) in GOP units at the time of encoding is allocated according to GOP_DIFF which is the sum of the encoding difficulty levels for each GOP.
FIG. 17 shows an example of a simplest function for converting the GOP_DIFF and the GOP_TARGET amount. In this example, the vertical axis Y is G
OP_TARGET, the horizontal axis X is GOP_DIFF, and an evaluation function of Y = AX + B is used.

First, the total number of bits USB_BYTES, which is limited so as to be equal to or less than the maximum bit rate, is changed to the total bit amount QTY_BYTES given by the supervisor controller 1.
Then, using the maximum bit rate MAXRATE, USB_BYTES = min (QTY_BYTES, MAXRATE × KT × total_frame_number) (1)

Here, in the case of NTSC, KT = 1/8 (bits) / 30
(Hz), 1/8 (bits) / 25 (Hz) for PAL. Also, total
_frame_number is the total number of frames of the material to encode,
min (s, t) is a function that selects the smaller of s, t.

The SUPPLY_BYTES is the number of bits TOT required for the header of the GOP from the USB_BYTES obtained by the above equation (1).
Subtract AL_HEADER and obtain as SUPPLY_BYTES = USB_BYTES-TOTAL_HEADER (2).

The encoding difficulty (Di) of all pictures
The total sum of (fficulty) is expressed as DIFFICULTY_SUM = Σdifficulty (3) in step S17.

Further, the minimum value of GOP_TARGET is determined by the following (4)
As in the equation, B = GOP_MINBYTES (4).

Then, in step S18, Σy = A × Σx + B × n is obtained.

Where Σy = SUPPLY_BYTES, Σx = DIF
FICULTY_SUM, n is the total number of GOPs.

Therefore, A = (SUPPLY_BYTES-B × n) / DIF
FICULTY_SUM. Then, the target amount for each GOP can be expressed as GOP_TARGET = A × GOP_DIFF + B (5) in step S19.

Thereafter, in step S20, bits are allocated in each GOP according to the encoding difficulty (Difficulty) of each picture. When the distribution of each picture in the GOP is proportional to the degree of difficulty of encoding, the target amount of each picture is obtained by the following equation (6).

Target (k) = GOP_TARGET × diffrculty (k) / GOP_DIFF (6) (1 ≦ k ≦ the number of pictures in GOP) Next, processing of a movie (film) material will be described. As shown in FIG. 18, a movie film is composed of 24 frames / sec. In order to convert this to 30 frames / sec of NTSC, a process of repeating the same field image periodically is performed. Here, this processing is referred to as 2/3 pull-down conversion processing.

The phase of the pull-down pattern is determined when converting the film material to the NTSC video material, and in many cases, the pattern is converted regularly.

One frame of a video is composed of two fields, of which the first field is the first field.
Is the top field (top_field) and the second field (2nd field) is the bottom field (bottom_field)
And A place where the same field image is repeated is called a repeat first field (repeat_first_field). In the case of such a movie material, if the position of the same field is known, the encoding efficiency can be increased by not encoding the field at the time of encoding.

In such a method of detecting a 2/3 pull-down pattern and automatically detecting a pull-down pattern in consideration of the pattern, when encoding, the current and one frame before
repeat_first_fie based on the difference between p_field and bottom_field
Examine the position of ld and detect the pull-down phase. There are the following four combinations based on the 2/3 pull-down pattern at the time of encoding.

0: bottom_field_first 1: bottom_field_first, repeat_first_field 2: top_field_first 3: top_field_first, repeat_first_field These are defined as a picture mode (p_mode).

Consider the relationship between the 2/3 pulldown pattern and the video frame number k from the beginning of one roll of video tape containing NTSC video material. Set the picture mode of k at the position containing the non-repeat top_field to p
_mode [k]. Then, as can be seen from FIG.
It can be seen that there is a frame number whose mode does not belong to 0 to 3. In this case, the value of p_mode is 4.

FIG. 19 is a state transition diagram of p_mode [k]. When the pull-down patterns are regularly continuous, the value of p_mode [k] is calculated as shown in the following equation (7).
As the frame number k increases, it increases by 1 in the remainder (mod 5) divided by 5.

P_mode [k + 1] = (p_mode [k] +1) mod 5 (7) When the pull-down pattern is disturbed, as shown in the following equation (8), p_mode is 0 or Only in case 2 can that value be repeated.

P_mode [k + 1] = (p_mode [k] +1) mod 5 (limited to a case where p_mode [k] is 0 or 2) (8) In a system employing a two-pass encoding method The pull-down pattern is automatically detected at the time of provisional encoding for measuring the encoding difficulty in step S2 in FIG. At this time, the bit distribution is calculated based on the measured pull-down pattern, and a control file is created. Then, at the time of the main encoding, the encoding is executed in accordance with the bit allocation described in the control file.

[0047]

By the way, in the above-mentioned automatic detection method of the pull-down pattern at the time of provisional encoding,
Since the pull-down pattern is detected based on the difference between the top_field and the bottom_field one frame before the current frame, if the target image is close to a still image, it may not be detected correctly.

For example, consider the first part of a movie. Initially, it starts with the title scene, but such video fades in from black, with the movie company logo, and fades out to black. It is difficult to detect an accurate phase due to the difference between the top_field and the bottom_field one frame before, as described above, in a portion with little movement such as fade-in / out to black, and there are many mistakes. .

In the case of starting from a scene with a lot of motion immediately after a portion with little motion, the image is processed with an erroneous pull-down pattern until the phase is locked to the correct phase. Sometimes it became natural.

The present invention has been made in view of the above-described circumstances. In detecting the phase of a pull-down pattern, the phase of the pull-down pattern can be correctly detected even when the target image has no motion. It is an object of the present invention to provide an image encoding method and apparatus capable of performing an encoding process so as to prevent an unnatural motion from occurring.

Further, the present invention has been made in view of the above-mentioned circumstances, and even when the target image does not move,
It is an object of the present invention to provide a recording medium for recording a video material coded so that the phase of a pull-down pattern is correctly detected and an unnatural movement between frames is prevented.

Further, the present invention has been made in view of the above-mentioned circumstances, and in detecting the phase of a pull-down pattern, the phase of the pull-down pattern can be correctly detected even when the target image has no motion. It is an object of the present invention to provide an image transmission method for transmitting an image subjected to an encoding process so as to prevent an unnatural motion between frames.

[0053]

According to the present invention, there is provided an image encoding method and apparatus, comprising:
Since the bit allocation is calculated after correcting the phase pattern, encoding can be performed with a phase that matches the pull-down pattern of the material.

Further, in order to solve the above-mentioned problem, the recording medium according to the present invention corrects the above-mentioned phase pattern when detecting the disturbance of the phase pattern in the pull-down conversion processing, and then calculates the bit allocation to obtain the code. Since encoded data obtained by encoding is recorded, it is possible to record a video encoded with a phase that matches the pull-down pattern of the material.

Further, in order to solve the above-mentioned problem, the image transmission method according to the present invention, when detecting a disturbance of the phase pattern of the pull-down conversion processing, corrects the above-mentioned phase pattern and then calculates the bit allocation. Since data is transmitted, it is possible to transmit a video encoded with a phase that matches the pull-down pattern of the material.

[0056]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an image coding method and apparatus according to the present invention will be described with reference to the drawings.

In this embodiment, for example, a video material recorded on a digital video cassette tape is used for a digital video disk (Digital Video Disk: DVD).
This is a video encoding system for encoding by employing a two-pass encoding method, and has a configuration as shown in FIG.

This video encoding system has basically the same configuration as the video encoding system shown in FIG. 12, but the processing in the MPEG encoding controller 23 inside the video encoding controller 20 is different. .

That is, the MPEG encoding controller 23 has a phase pattern detecting step of detecting a phase pattern disturbance in the pull-down conversion process, and a phase pattern correcting step of correcting the phase pattern disturbance detected by the phase pattern detecting step. When the phase pattern detecting step detects the disturbance of the phase pattern, the bit pattern is corrected by the phase pattern correcting means, and then a bit allocation calculation program (BIT_ASSING) for calculating the bit allocation is internally stored in the bit allocation calculation unit 22. Run with

The basic operation of the video encoding system shown in FIG. 1 according to the present embodiment can be described with reference to the flowchart in FIG. Particularly important in the present invention is the process of measuring the encoding difficulty in step S2.

The measurement of the encoding difficulty in step S2 is as follows.
It can be performed as follows. That is, the video information serving as the encoding material is reproduced by the DVTR 17 from the digital video cassette. The MPEG encoder controller 23 measures the encoding difficulty of the video information reproduced by the DVTR 17 via the MPEG encoder 25.

At this time, if the video material is 2 /
3 When the material requires pull-down conversion processing,
The MPEG encoder controller 23 controls the MPEG encoder 25 to automatically detect the 2/3 pull-down conversion process in the process of measuring the encoding difficulty.

More specifically, the to
repeat_first_fie based on the difference between p_field and bottom_field
Examine the position of ld and detect the pull-down phase. However, when the phase of the pull-down pattern is automatically detected, if the target image is a scene with very little motion such as a still image, the phase of the pull-down pattern may be erroneously detected.

Assuming that the pull-down pattern of the material is regular, the frame number k in which the transition of the pull-down pattern which can be detected in the phase pattern detecting step is disordered satisfies the following equation (9).

P_mode [k + 1] ≠ (p_mode [k] +1) mod 5 (9) From the phase relationship before and after the frame at the position where the pull-down pattern is disturbed, the phase pattern is corrected in the phase pattern correcting step. Fix it.

For example, FIG. 2 shows a specific example of a setting window via the GUI 21 when manually correcting a phase pattern. The user can specify the start and end timecode TS of the range to be corrected, including the out-of-phase position.
And TE. In the figure, the range in which pm_change is set to “1” is the range in which the modification is specified. The result of the customization parameter specification work is created as a file called weight.txt as shown in Table 1 below.

[0067]

[Table 1]

Here, ENCU_nb is the roll number of the video cassette to be encoded, Filter (denoted as Fil in Table 1) is the strength of the filter, and D_weight (D_w) is the weighting factor at the time of bit allocation. ing. Also, Scene_add
(S_add) is used when it is desired to manually change a P picture to an I picture at a scene change point or the like. Also,
mquant_level (Mq) is the selection of a processing mode in a frame in the case of a flat image in each picture (MQUANT ON / OF
F). Pm_change (pm_c) is a flag used when the user specifies modification. Here, the time information of the parameter change point is represented as a time code (Timecode).

This weight.txt file is read at the time of the bit redistribution calculation processing in step S9 of FIG. 14, and the predetermined processing is performed at a designated time position to correct the pull-down pattern and then perform the bit allocation. Become.

Here, the procedure of the phase correction processing of the actual pull-down pattern performed in the phase pattern correction step will be described. Specify the frame number range of the material to be encoded.
0 ≦ k ≦ kstop, and the value of the range to be modified (pm_change [k]) is
It is assumed that the frame number of 1 is kstart ≦ k ≦ kend. Also, the picture type (I, P, B picture) when encoding the frame with the frame number k is represented as p_type [k]. Since the frame whose p_mode [k] is 4 is not encoded, the picture type is not specified.

First, according to the flowchart shown in FIG.
The pull-down pattern is determined sequentially from the back to the front in time while the pull-down phase after the range to be corrected first and the phase of the range to be corrected are continuous, and the pull-down pattern before the range to be corrected next is determined. Ensure that connections to ranges adhere to state transition rules. Here, pstart indicates a picture mode in which connection is allowed.

More specifically, in a loop in which the value of k is reduced by one with respect to the values of k from kstop-1 to kstop-1 in steps S21 and S22, p_mode_org [k] = p_
mode [k], p_type_org [k] = p_type [k].

Next, in step S23, step S24, and step S25, k is kstop or pm_change [k] and pm_chang.
When e [k + 1] is 0, set cycle = p_mode [k].

On the other hand, in step S24, pm_change [k] is set to 1
In the case of, the cycle = (cycle + 4)% in step S26
5, Let p_mode [k] = cycle.

Next, pm_change [k] is set to 0 in step S23.
Not (p_mode [k] +1)% 5 == p_mode in step S29
If not [k + 1], the process proceeds to step S30, where p_mode [k]
Is 0 or 4, the process proceeds to step S34, and pstart = 0 is set. If p_mode [k] is not 0 or 4 in step S30, the process proceeds to step S31, and it is determined whether p_mode [k] is 1 or 2; if yes, the process proceeds to step S33 and psta
rt = 2. No in step S31, and p_mode [k] is 3
In step S32, the process proceeds to step S32, where pstart = 4.

The processing in each of the above steps is performed in step S
In a loop in which j is increased by 1 from 1 at 35, the process is repeated until the value of p_mode [k + j] becomes equal to pstart in step S36. Then, in step S37, p_mo
After setting de [k + j] = pstart, in step S38, pstart =
In the case of 4, after the process of j = 1, in step S39 pstart
After setting = 0, j is incremented and executed in step S40.

FIGS. 5 and 6 show specific examples of the procedure for correcting the pull-down pattern shown in FIG. FIGS. 5A and 6A show p_type_org [k] before pull-down pattern correction.
And p_mode_org [k]. Here, for example, FIG.
(A) of p_mode_org [k] is “2,2,2” and “0,0,0,0,0,
It is assumed that the user sets pm_change to “1” and manually sets pm_change to “1” as shown in FIG. 5B at a point including a continuous portion such as “0.” Then, the MPEGE encode controller 23 of the video encode controller 20.
Determines a pull-down pattern sequentially from the rear to the front in time while making the pull-down phase after the range to be corrected and the phase in the range to be corrected continuous. Next, as shown in FIG. 5C, the connection with the range before the range to be corrected follows the state transition rule shown in FIG. 19, that is, when the pull-down pattern is disturbed, the connection is permitted. As described above, the pull-down pattern is corrected from the front in the range where pm_change is “1” so that p_mode [k] is continuous at “0”.

In FIG. 6A, p_mode_org [k] is changed to “2,
When the user sets pm_change to “1” as shown in FIG. 6B and manually sets pm_change at a location including continuous portions such as “2, 2” and “0, 0”, the video encoding controller The MPEGE encoding controller 23 of 20 determines the pull-down pattern sequentially from the rear to the front in time while making the pull-down phase after the range to be corrected and the phase in the range to be corrected continuous. As shown in FIG. 6 (C),
P_mode so that the connection with the range before the range to be modified adheres to the rule of the state transition shown in FIG. 19, that is, as is permitted when the pull-down pattern is disturbed.
Set the pull-down pattern to pm so that [k] continues at "2"
_change is modified from the front in the range of “1”.

When the pull-down pattern is corrected in this way, the number and position where the value of p_mode becomes 4 before and after the correction are different. This means that the number and position of the frames to be coded change. Accordingly, it is necessary to correct the picture type after the correction of the pull-down pattern. This procedure will be described with reference to FIG.

FIG. 4 is a flow chart of the process from 1 to kstop.
This is a loop for increasing the value of k by one for the value of k.
After setting k = 1 and pshift = 0 in step S41, when it is determined in step S42 that p_mode [k] == p_mode_org [k], pshift = 0 in step S43 and step s4
In step 4, p_type [k] = p_type_org [k].

On the other hand, in step S42, p_mode [k]] p_m
If ode_org [k] and p_mode [k] is 4 in step S45, the process proceeds to step S46. This step S4
6, when p_mode_org [k] and p_mode_org [k + 1] have the same value and p_type_org [k] is a P picture or I picture,
Proceed to step S47, set pshift = 0, and p_type [k] =
Let p_type_org [k].

In step S46, p_mode_org [k] and p_m
If ode_org [k + 1] has the same value and p_type_org [k] is not a P picture or I picture, the process proceeds to step S48, where pshift = −1, and p_type [k] = p_type_org [k−1 ]
And

If p_mode [k] is not 4 in step S45, the process proceeds to step S51. When p_mode_org [k] is 4 in step S51, step S5
In 2, pshift is set to 0.

In step S53, p_mode [k] and p_mode [k + 1]
Are the same, the process proceeds to step S56, where p_type
[k] = P picture. Otherwise, step S
Proceeding to 54, p_type [k] = p_type_org [k-1].

In step S51, p_mode_org [k] is set to 4
If not, the process proceeds to step S55, where p_type [k] =
Let p_type_org [k + pshift].

FIGS. 7, 8, and 9 show specific examples in which the picture type is corrected after the pull-down correction using the flowchart in FIG.

Since the value obtained at the time of measuring the encoding difficulty is a value for the picture type before correction, the value of the encoding difficulty also needs to be corrected with the correction of the picture type. As a simple correction example, the following (10)
As shown in the equation, the closest to the frame that needs to be modified,
That is, the value of the encoding difficulty of the same picture type is used.

Difficulty [k] = difficulty [kk] (10) (kk satisfies p_type [k] == p_type_org [kk], the value closest to k) Next, the automatic correction method will be described. The difference between the automatic correction and the manual correction is that only the range to be corrected is automatically determined or the manual is specified, and the other steps are the same.

Since the probability of erroneously detecting the phase when automatically setting the pull-down phase at the time of measuring the encoding difficulty is sufficiently smaller than 50%, it is possible to examine the length of the section where the phase is discontinuous. The position where the correct phase detection is performed can be specified.

In the case of the measurement pattern as shown in FIG. 10, the section in which the phase is discontinuous corresponds to the picture mode p_mo.
In the section where de [k] shows the same value as the previous value, pd_mode = 1 at this time, and pd_mode = 0 at other parts, the number of frames at the part where pd_mode = 1 becomes Hz_count
The period from when the value becomes “2” to the position when the value becomes “3” is a section where the phase is discontinuous.

FIG. 11 is a flowchart. Here, the measured picture mode of the k-th frame counted from the start point of the material to be encoded is p_mode [k]. Also, consider a case where the initial phase of the pull-down pattern is measured in the range of 0 ≦ k ≦ kend.

First, in step S61, ps = 0, error_min =
kend + 1, and in step S62, k = 0, error [0] = error [1] =
0, Hz_count = 0.

In step S63, if k> 0, p_mod
A section in which e [k] and p_mode [k-1] have the same value is determined. If they are the same, pd_mode = 1 is set in step S64, and pd_mode = 0 in other parts as in step S65. Then, in step S66, the number of frames Hz_count of the portion where pd_mode = 1 is counted.

Next, steps S67 to S70
The pd_cycle of the k-th frame is generated with the default value of ps, and is compared with the measured picture mode p_mode [k]. If not, error [pd_mode] is counted up.

More specifically, the frame number is determined in step S67.
It is determined whether or not k is smaller than 5, and if the frame is the fourth frame, pd_cycle [ps] [k]!
= p_mode [k], and if the frame is the fifth or more, pd_cycle [ps] [k mod 5 + 5]! = p_mod in step S69
error [pd_mode] = err in step S70 after e [k]
or or [pd_mode + 1].

Here, the pull-down pattern when the material is converted from a film to a video by a frame is almost regularly performed in most cases. Therefore, it is assumed that the pull-down pattern of the material to be encoded is known in advance. Considering that a material is specified as a chapter at the beginning and must be encoded in a state where p_mode is "2", the initial pattern of the pull-down can be represented by seven patterns.

When these seven patterns are shown up to k = 10, Becomes

Next, assuming that k = k + 1 in step S71, the processing from step S63 to step S71 is repeated until k> kend in the determination in step S72.

Then, in step S73, the value of Hz_count is
If it is larger than kend / 2 + 1, the process proceeds to step S74, and Hz
It is determined that the material measured as _mode = 1 has not been subjected to pull-down processing. If the value of Hz_count is equal to or less than kend / 2 + 1, the process proceeds to step S75, and it is determined that the material measured with Hz_mode = 0 has been subjected to pull-down processing.

Then, the magnitude of the error with respect to ps is compared, and the smallest one is determined as the mode of the initial phase. That is, in step S76, error [Hz_mode] is set to error_min.
If it is smaller than error_min = error [Hz_min], pd_st
art = ps.

In step S78, ps is set to ps + 1, and in step S79, steps p62 to step S are performed until ps> 6.
The process up to 78 is repeated.

As described above, in the specific example of the video encoding system shown in FIG. 1, since the encoding can be performed manually or automatically with the phase that matches the pull-down pattern of the video material, the portion where the movement is awkward is eliminated. Thus, high image quality can be realized.

The above-mentioned D recording the video material encoded by the above-mentioned image transmission method and apparatus.
A recording medium such as a VD can reproduce a high-quality image without causing unnatural motion between frames because the phase of the pull-down pattern is correctly detected even when the target image has no motion. Have recorded.

Further, when transmitting the encoded video material by the above-described image transmission method, even if the target image does not move, the phase of the pull-down pattern is correctly detected, so that unnaturalness between frames is caused. A high-quality image can be transmitted without causing motion.

[0105]

According to the image encoding method and apparatus according to the present invention, the phase of a pull-down pattern can be correctly detected even when the target image has no motion. An encoding process can be performed so as to prevent an unnatural movement from occurring.

Further, according to the recording medium of the present invention, even when there is no motion in the target image, the phase of the pull-down pattern is correctly detected so that unnatural motion between frames is prevented. Encoded data that has been encoded can be recorded.

Further, according to the image transmission method of the present invention, even if there is no motion in the target image, the phase of the pull-down pattern can be correctly detected, and unnatural motion between frames can be prevented. , The encoded image can be transmitted.

[Brief description of the drawings]

FIG. 1 is a block diagram of a video encoding system as an embodiment of an image encoding method and apparatus according to the present invention.

FIG. 2 is a diagram showing a specific example of a setting window when performing manual correction.

FIG. 3 is a flowchart for explaining an actual pull-down pattern phase correction processing procedure performed in a phase pattern correction step.

FIG. 4 is a flowchart illustrating a picture type correction processing procedure performed on a picture type after a pull-down pattern has been corrected.

FIG. 5 is a timing chart for explaining a first specific example of the procedure for correcting the pull-down pattern shown in FIG. 3;

FIG. 6 is a timing chart for explaining a second specific example of the procedure of the pull-down pattern correction shown in FIG. 3;

FIG. 7 is a diagram for explaining a first specific example of the procedure of picture type correction shown in FIG. 4;

FIG. 8 is a diagram for explaining a second specific example of the procedure of the picture type correction shown in FIG. 4;

FIG. 9 is a diagram for describing a third specific example of the picture type correction procedure shown in FIG. 4;

FIG. 10 is a timing chart for explaining a method of automatically correcting a pull-down pattern.

FIG. 11 is a flowchart illustrating a method of automatically correcting a pull-down pattern.

FIG. 12 is a block diagram of a specific example of a conventional video encoding system employing a two-pass encoding system.

FIG. 13 is a diagram for explaining a GOP structure.

FIG. 14 is a flowchart for explaining the operation of the conventional video encoding system shown in FIG. 12;

FIG. 15 is a diagram illustrating a bit allocation calculation process performed by the conventional video encoding system.

FIG. 16 is a flowchart illustrating details of a bit allocation calculation process in step S3 shown in the flowchart of FIG. 14;

FIG. 17 is a diagram illustrating an evaluation function for bit allocation processing in GOP units.

FIG. 18 is a diagram illustrating a pull-down conversion process.

FIG. 19 is a state transition diagram of a picture mode.

[Explanation of symbols]

1 Supervisor controller, 20 video encoding controllers, 22 bit allocation calculator, 23M
PEG encoding controller, 25 MPEG encoder

Claims (8)

[Claims] 1. An image encoding method for encoding a video material subjected to a pull-down conversion process, wherein the phase pattern detection step detects a disturbance of a phase pattern of the pull-down conversion process, and the phase pattern detection step detects A phase pattern correcting step of correcting a phase pattern disturbance, wherein when the phase pattern detecting step detects the phase pattern disturbance, the phase is corrected in the phase pattern correcting step, and then the bit allocation is calculated. An image encoding method characterized by the following. 2. The method according to claim 1, wherein, when the phase pattern detecting step detects the disturbance of the phase pattern, the phase pattern correcting step corrects the phase pattern from a later point in time. Image coding method as described in the above. 3. The image encoding method according to claim 1, wherein said video material is encoded using an intra-frame encoded image, an inter-frame forward predictive encoded image, and a bidirectional predictive encoded image. . 4. An image encoding apparatus for encoding a video material to be subjected to a pull-down conversion process, wherein when the disturbance of the phase pattern of the pull-down conversion process is detected, the phase distribution is corrected and then the bit allocation is performed. An image coding apparatus comprising a control unit for calculating. 5. The image encoding apparatus according to claim 4, wherein said control means corrects the phase pattern from a temporally later point when detecting the disturbance of the phase pattern. 6. The image coding apparatus according to claim 4, wherein the video material is coded using an intra-frame coded image, an inter-frame forward prediction coded image, and a bidirectional prediction coded image. . 7. A recording medium for encoding and recording a video material subjected to a pull-down conversion process, wherein when a disturbance of a phase pattern in the pull-down conversion process is detected, the phase distribution is corrected and then bit allocation is performed. A recording medium characterized by recording calculated encoded data. 8. An image transmission method for encoding and transmitting a video material subjected to a pull-down conversion process, wherein when a disturbance of a phase pattern of the pull-down conversion process is detected, the phase distribution is corrected and then bit allocation is performed. An image transmission method, comprising transmitting calculated encoded data.