JP2000083254A - Moving picture coding method and moving picture decoding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a moving picture coding method and a moving picture decoding method where scrambling and compression coding are properly applied to a video image that is subjected to 3:2 pull-down in a DVD or a digital broadcast and the copyright is protected and viewing can be limited. SOLUTION: In the case of receiving a video image that is subjected to 3:2 pull-down, a redundant field eliminating section 103, a scramble section 107, and a compression coding section 109 conduct elimination of a redundant field, scrambling and compression coding in this order. Furthermore, a watermark information embedding section 108 embeds information relating to a scramble key to the video image as electronic watermark information between the scrambling and the compression coding process. Thus, a correct video image is restored even from a 3:2 pull-down video image, and scrambling and compression coding are conducted without deteriorating a coding efficiency and reproduction or copying by methods other than the normal method is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a moving picture coding method for coding a moving picture signal and a moving picture decoding method for decoding coded moving picture data.
The present invention relates to a moving image encoding method and a moving image decoding method including scramble / descramble suitable for copyright protection and parental control in digital broadcasting and the like.

[0002]

2. Description of the Related Art Moving picture coding techniques for transmitting and storing a larger amount of video signals with a smaller amount of data include, for example, M
PEG2 video standard (ISO / IEC13818-2)
Is being put to practical use as represented by

In the MPEG2 video standard, one screen is divided into a plurality of blocks of 8 pixels × 8 pixels, and each block is subjected to DCT (discrete cosine transform) to obtain a DC.
It is based on quantizing the T coefficient and performing variable length coding. Also, by using the motion compensation inter-picture prediction together, the coding efficiency is enhanced by utilizing the correlation of the images in the time direction.

[0004] With this moving picture coding technique such as MPEG2, high quality digital video has become familiar. For example, MPEG2 has already been applied to DVDs and digital broadcasting. Also, its application is expanding to higher-speed and higher-resolution video such as HDTV. Generally, digital images have high image quality.
There is no deterioration due to duplication, and compatibility with computers and networks is good.

[0005] However, if anyone can easily make high-quality copies for many generations without deterioration, the problem of illegal copying arises, and copyright protection is required. Also, in the case of pay broadcasting or the like, it is necessary to restrict viewing in accordance with charging. For example, a mechanism is required such as 1) cannot copy illegally, 2) cannot reproduce illegally copied data, 2) cannot reproduce with an unauthorized reproducing device, and 4) cannot reproduce without paying the user.

[0006] To achieve this, an encryption or scramble technique is used. On the encoding side, scrambling is performed using the key data, and on the decoding side, descrambling is performed using the key data that has been properly obtained or restored. If there is no legitimate key data on the decryption side, descrambling cannot be performed and normal video cannot be viewed.

[0007] In analog broadcasting, viewing restriction by such scrambling has already been performed. For digital video, for example, in current DVDs, a method of scrambling compression-encoded data is used. The outline of this method is described in the Technical Report of the Institute of Image Information and Television Engineers, Vol. 21, No. 31 pp. 15 to 19, "DVD Copyright Protection System" (May 1997).

[0008] This DVD scrambling method is based on the idea that video data is compressed and encoded and then scrambled. On the other hand, a method of scrambling video data and then compressing and encoding is considered. For example, Japanese Patent Application Laid-Open No. Hei 10-13828 describes such an example.

The basic configuration in this case is that on the encoding side, input video is scrambled based on the generated key data and then compression-encoded, and at this time, the key data is separately multiplexed. . On the other hand, on the decryption side, after performing compression / decryption (decompression), descrambling is performed using the separated and decrypted key data.

In this case, since the compression coding is performed after scrambling, the scrambling algorithm is used so that the coding efficiency of the compression coding is not reduced by the scrambling process and the picture quality after decoding is not deteriorated. Needless to say, you need to choose.

By the way, a movie must be included in the video source. When converting a movie to a video signal, a 3: 2 pulldown technique is used. The 3: 2 pulldown refers to converting a film image of 24 frames / second into an interlaced image of 60 (or 59.94) fields / second. FIG. 7 shows this 3: 2 pull-down state. The 3: 2 pull-down is realized by repeating the image of the immediately preceding field of the same polarity in a cycle of once every five fields. In the range of FIG. 7, fields 5 and 10 are repetitive fields, and the image of field 3 is repeated in field 5 and the image of field 8 is repeated in field 10.

When compressing and coding a 3: 2 pull-down video, if the 3: 2 pull-down pattern is detected and the repetition field is deleted in advance before coding, the amount of image to be coded is reduced. Will be reduced.

FIG. 8 is a diagram showing an example of a method for detecting an original 3: 2 pull-down pattern from a 3: 2 pull-down video. Basically, it suffices to detect the coincidence of each field image with the field image one frame before, and within the range of FIG.
And the field 10 matches the field 8, respectively. Otherwise (except for special cases such as still images)
No match is found. Therefore, it can be seen that fields 5 and 10 are repeated fields,
The 3: 2 pull-down structure can be restored. That is, if the frame of the original film is expressed as a picture, the fields 1 to 12 and the pictures 1 to 5 as shown in FIG.
Is required.

In the conversion from a motion picture film to an interlaced video, not only a case where a repetitive field in which a field of the same polarity just before one frame is repeated as shown in FIG. 7 is inserted, but also one frame immediately before and one frame immediately after In some cases, a mixed field obtained by mixing images of fields having the same polarity is inserted. (For example, in FIG. 7, the image of field 5 is generated by mixing the image of field 3 and the image of field 7.) Therefore, in this specification, a repeated field or a mixed field is collectively referred to as a redundant field. I will call it. In addition, when a mixed field is inserted, it cannot be strictly called 3: 2 pull-down, but in this specification, it is referred to as 3: 2 pull-down including that case.

[0015] Even if the input video is 3: 2 pull-down, there is no particular problem in the case of scrambling after compression encoding as in the aforementioned DVD scrambling method. However, in the case where the input video is scrambled and then compression-encoded, conventionally, there is no appropriate method of scrambling the 3: 2 pull-down input video. Even if an attempt is made to scramble and descramble a 3: 2 pull-down image in the same manner as a normal image, for example, when a redundant field is deleted, information necessary for descrambling is deleted and a correct image cannot be restored. There is also a problem that the 3: 2 pull-down pattern cannot be correctly detected due to the influence of the scrambling process, and the coding efficiency is reduced.

[0016]

As described above, conventionally, there is no appropriate method for scrambling a 3: 2 pull-down video and then compressing and encoding the video. For example,
When the redundant field is deleted, information originally required during descrambling is deleted, so that a correct video cannot be restored, or a 3: 2 pull-down pattern cannot be correctly detected due to the influence of the scramble processing, thereby lowering the coding efficiency. , There was a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a moving picture coding method and a moving picture coding method capable of appropriately performing scramble and compression coding even on a 3: 2 pull-down video. It is an object to provide a decoding method.

[0018]

In order to solve the above-mentioned problems, the present invention provides a moving picture coding method for coding a moving picture signal, in which a 3: 2 pull-down picture is inputted. A first step of removing a redundant field, a second step of scrambling the video, and a third step of compression-encoding the video.
, The second step, and the third step are processed in this order.

As a result, even when a 3: 2 pull-down image is input, the image can be correctly restored, the coding efficiency does not decrease, and the possibility that the image data after descrambling is illegally copied is reduced. Thus, it is possible to realize scramble and compression coding.

The moving picture coding method may further include a fourth step of embedding the information on the scramble key in the second step in the video as digital watermark information, wherein the fourth step is the second step. It is preferable that the processing is performed after the step and before the third step.

Thus, the scramble key data can be transmitted safely and reliably without using a dedicated transmission path. The present invention also provides a moving picture decoding method for decoding a coded moving picture data and outputting a moving picture signal. A second step of descrambling the compressed and decoded video, and a third step of inserting a redundant field into the compressed and decoded video, wherein the first step is performed by the second step and The processing is performed before the third step.

As a result, even when a 3: 2 pull-down image is reproduced, the image can be correctly restored, the encoding efficiency does not decrease, and the possibility that the image data after descrambling is illegally copied is reduced. , Compression decoding and descrambling can be realized.

In the above moving picture decoding method, the method further comprises a fourth step of extracting information on a descrambling key in the second step from the video as digital watermark information, wherein the fourth step is performed by the fourth step. It is preferable that the processing is performed after the first step and before the second step. As a result, the key required for descrambling can be safely and reliably restored without using a dedicated transmission path.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) First, a moving picture coding method according to the present invention
A first embodiment to which a moving image decoding method is applied will be described.

FIG. 1 is a schematic block diagram of a moving picture coding apparatus according to the first embodiment of the present invention. 1 includes an original image input terminal 101, a 3: 2 pulldown detection unit 102, a redundant field exclusion unit 103, a prefilter unit 104, a scene change detection unit 105, and a key generation unit 1.
06, scramble unit 107, watermark information embedding unit 1
08, a compression encoding unit 109, a multiplexing unit 110, and a bit stream output terminal 111.

The original image input from the original image input terminal 101 has the 3: 2 pull-down pattern detected by the 3: 2 pull-down detecting section 102 by, for example, the method described with reference to FIG. Pulldown information 114
Is supplied to the redundant field elimination unit 103 and the compression encoding unit 109. Next, the redundant field elimination unit 103 excludes the above-described redundant field based on the 3: 2 pull-down information 114. Subsequently, the pre-filter unit 1
04, the scene change detection unit 105 removes noise or high frequency components by filtering,
And a scene change is detected. The scrambler 107 scrambles the video data as it is. At this time, the key data 112 generated by the key generator 106 is used as a scramble key. In addition, scramble on / off in scramble section 107 is switched according to scramble on / off information 113.

The watermark information embedding unit 108 embeds the key data 112 generated from the key generating unit in the case of scramble on in the video as electronic watermark information in accordance with the scramble on / off information 113. further,
In the compression encoding unit 109, compression encoding is performed by, for example, the MPEG2 method. The coded data multiplexed with the scramble on / off information 113 by the multiplexing unit 110 is output from the bit stream output terminal 111 and transmitted or stored. It should be noted that the scramble on / off information 113 and the 3: 2 pull-down information 114 are also supplied to the compression encoding unit 109, and are used for controlling the encoding. At the same time, the 3: 2 pull-down information 114 uses the syntax of the compression encoding. It is described as

Hereinafter, each part of FIG. 1 will be described in more detail. The 3: 2 pull-down detection unit 102 detects 3: 2 pull-down as described with reference to FIG.
If the 3: 2 pulldown pattern is known, 3: 2
The pull-down detection unit 102 can be omitted. In this case, the 3: 2 pulldown information 114 may be separately input from the outside.

In the redundant field elimination unit 103, 3: 2
The redundant fields (fields 5 and 10 in the example of FIG. 8) of the pull-down are excluded, but the exclusion here may be physically deleting them from the processing memory, or May be added as a flag indicating that there is no need to process. The redundant field elimination unit 103 also performs conversion from a field image to a picture (frame) image at the same time. This conversion may be a physical conversion,
Only some flags may be added.

In the pre-filter unit 104, for example, a two-dimensional filter for cutting high-frequency components in an oblique direction of an image is used to remove noise and high-frequency components. At this time, when 3: 2 pull-down data is input, it is desirable in terms of image quality to use a filter in a picture (frame) after removing redundant fields. However, it is also possible to simply use an in-field filter. Note that a time-direction filter may be used as the pre-filter.

The scene change detecting section 105 detects a scene change by utilizing the correlation of the images in the time direction and the like, and compresses the scene change detecting information (not shown) into the compression encoding section 109.
To supply. This scene change detection information is
It is used for setting the P / picture type and controlling the code amount. That is, GOP is added to the point where a scene change is detected.
Or increase the code amount distribution to the image immediately after the point where the scene change is detected.

The pre-filter unit 104 and the scene change detection unit 105 have optional functions for high-quality encoding, and are not necessarily essential components.

The scramble in the scramble section 107 converts the video itself so that it becomes difficult to view the scrambled video. As described above, since the scrambling is performed before the compression encoding,
A method should be selected that does not reduce the coding efficiency as much as possible. Specifically, for example, there are methods of exchanging slices, exchanging macroblocks, and converting pixel values. Further, these conversions may be performed only for a specific picture type.

In particular, the scramble here is desirably a complete conversion within the field. If a conversion that is not completed within a field, for example, data exchange or conversion within a frame, is performed, the frame must be treated as a single unit. The degree of freedom of the process is reduced. Also, for example, as in slow playback / still playback on DVD,
A disadvantage also arises when data must be reproduced on a field-by-field basis.

It is desirable that exactly the same scrambling be performed on two field images constituting a picture. As a result, even when 3: 2 pull-down video is input, both fields of the frame image are scrambled in the same manner, so that encoding in the frame mode after scrambling does not lower the encoding efficiency.

The watermark information embedding unit 108 embeds the key data 112 necessary for descrambling as digital watermark information in the scrambled video. If the scramble key and the descramble key are different, the descramble key is embedded.

Digital watermarking, also called data hiding or digital watermarking, is a technique for embedding additional information in an image in a form invisible to the user. For details, see, for example, Nikkei Electronics 1997
No. 24 February, no. 683, p. 99-124. The embedded additional information is not deleted by compression encoding or filtering, and it is difficult to illegally extract or falsify it. In the present embodiment, since the key data 112 is embedded as the digital watermark information, the possibility that the key data is illegally extracted is reduced, and it is not necessary to transmit the scrambled key data through another path.

The compression encoder 109 switches between two modes based on the scramble on / off information 113, a mode corresponding to the presence of scramble and a mode corresponding to the absence of scramble. What is switched here is the content of the encoding process and the parameters. Specifically, for example, the selection criteria of a macroblock type of MPEG2, a motion vector search range, and the like.

In MPEG2, motion-compensated inter-picture prediction is performed. For each macroblock, intra-coding for coding in a picture, forward prediction coding, backward prediction coding, bidirectional prediction (interpolation) are performed. ) Coding is performed while adaptively selecting coding. For example, in the case of scramble-on, the selection criterion is changed so that intra coding is easily selected. This is because the correlation between screens in the time direction may be slightly lower depending on the scrambling algorithm.

When a scrambling method involving the movement of pixels is employed, the search range of the motion vector may be expanded when scrambling is on. Furthermore, when the compression encoding unit 109 originally has a built-in pre-filter unit and scene change detection unit, these functions are turned off when the scramble is on.

The scramble-on /
The multiplexing of the off information 113 may be multiplexed in the data, or may be separately transmitted or stored. FIG. 2 is a schematic configuration diagram of the video decoding device according to the first embodiment of the present invention. 2 includes a bit stream input terminal 201, a separating unit 202, a compression decoding unit 203, a watermark information extracting unit 204, a descrambling unit 205, a post filter unit 206, a redundant field inserting unit 207, and a reproduced image output terminal. 208.

The bit stream input from the bit stream input terminal 201 is firstly separated by the demultiplexer 202 into the scramble-on / multiplex signal multiplexed by the multiplexer 110 in FIG.
The off information 210 is separated and supplied to the compression / decoding unit 203, the watermark information extraction unit 204, the descramble unit 205, and the post filter unit 206. Next, the compression / decoding unit 203
Performs, for example, MPEG2 decoding (expansion). Also,
The 3: 2 pull-down information 211 described as the compression encoding syntax is separated, and the redundant field insertion unit 2
07. Subsequently, in the watermark information extraction unit 204, according to the scramble on / off information 210,
In the case of scramble-on, key data 209 is extracted from the video as digital watermark information. Descramble part 2
At 05, descrambling is performed using the key data 209 as a descrambling key. At this time, the descrambling is switched on / off according to the scramble on / off information 210. The post-filter unit 206 performs filtering for image quality adjustment. At this time, characteristics are switched according to the scramble on / off information 210. In the redundant field insertion unit 207,
A redundant field is inserted based on the 3: 2 pull-down information 211, and a reproduced image is output from the reproduced image output terminal 208.

Hereinafter, each part of FIG. 2 will be described in more detail. The scramble on / off information 210 is supplied to the compression / decoding section 203. Based on the scramble on / off information 210, two modes are switched between a mode corresponding to the presence of scrambling and a mode corresponding to the absence of scrambling. Here, what is switched is the contents of decoding processing and parameters. For example, in the case of scramble-on, the post-filter originally included in the compression / decoding unit 203 is turned off (or its characteristics are changed).

The watermark information extracting unit 204 extracts the watermark information embedded by the watermark information embedding unit 108 in FIG. 1 and restores key data 209 necessary for descrambling. This cannot be performed without a proper decryption device, and it is difficult for a person who does not know the extraction algorithm and parameters to extract the key data illegally.

The descrambling in the descrambling unit 205 is an inverse conversion of the scramble in the scramble unit 107 in FIG. If the scramble is a conversion completed in the field, the descrambling is naturally a conversion completed in the field. Also, if the scrambling for the two fields constituting the picture on the encoding side is exactly the same, the descrambling for the two fields constituting the picture on the decoding side will also be identical.

The post-filter unit 206 is provided for image quality adjustment, for example, for edge enhancement and coding distortion removal, and its characteristics are switched according to the scramble on / off information 210.

The post filter section 206 has an optional function for reproducing high quality images, and is not an essential component. The feature of the present invention lies particularly in the order of each processing. Generally, it is reasonable to perform the processing in the order shown in FIGS. 1 and 2, but it is also possible to perform the processing in any other order. Again, there are some constraints or desirable order. The same applies to processing by software.

First, the processing procedure on the encoding side is as follows: (1) If the 3: 2 pull-down detection unit 102 is present, it is positioned before the redundant field exclusion unit 103 and before the scramble unit 107. .
This is because the redundant field to be excluded becomes unknown unless the 3: 2 pull-down is detected. If 3: 2 pull-down detection is performed after scrambling, a 3: 2 pull-down pattern may be erroneously detected due to the effect of scrambling. (2) The redundant field elimination unit 103 includes the compression encoding unit 1
It is positioned before 09. By performing compression encoding after excluding the redundant field, the amount of images to be encoded can be reduced, and the encoded image quality can be improved. Further, the redundant field elimination unit 103 includes the scramble unit 1
It is desirable to be located at a stage before 07. In that case, the amount of scramble calculation processing is small. (3) If the pre-filter unit 104 is present, it is positioned before the scramble unit 107. In addition, it is desirable to be located after the redundant field elimination unit 103. Applying a pre-filter after scrambling may adversely affect image quality. You can also apply in-frame filtering to movie sources by removing redundant fields and applying a prefilter,
High-quality filtering becomes possible. (4) When the scene change detection unit 105 exists,
It is positioned before the scramble unit 107. If scene change detection is performed after scrambling, a scene change point may be erroneously detected. (5) The scramble unit 107 is located before the compression encoding unit 109. By performing scrambling and then compression-encoding, it is possible to minimize the portion where the unscrambled video or video data exists on the decoding side, and reduce the possibility of unauthorized duplication. (6) When the watermark information embedding unit 108 exists,
It is located downstream of the scramble unit 107 and upstream of the compression encoding unit 109. By embedding the key data after scrambling, it is possible to extract the key data before descrambling on the decryption side. Further, since the watermark information is embedded in the state of a video, it is necessary to embed the watermark information before compression encoding.

Next, regarding the processing procedure on the decoding side: (1) The descrambling unit 205 is located after the compression decoding unit 203. By performing descrambling after compression decoding, the location where the descrambled data exists can be minimized, and the possibility of unauthorized duplication can be reduced. (2) The redundant field insertion unit 207 includes the compression decoding unit 20
It is located after 3. That is, since compression coding can be performed after excluding redundant fields on the coding side, the amount of images to be coded is reduced, and the quality of coded images can be improved. Also, redundant field insertion unit 2
07 is desirably located after the descrambling unit 205. In that case, the amount of descrambling operation is small. (3) If the watermark information extraction unit 204 is present, the watermark information extraction unit 204 is located after the compression
It is positioned earlier than 05. Thus, key data can be extracted before descrambling. Further, since the watermark information is extracted in the state of a video, it needs to be extracted after compression decoding. (4) If the post filter unit 206 exists, the post filter unit 206 is located downstream of the descrambling unit 205. If a post filter is applied before descrambling, image quality may be adversely affected.

As described above, according to the present embodiment, (1) the redundant field is correctly excluded, scrambled / compressed and encoded, and compressed and decoded before the redundant field is inserted. High and the amount of processing calculation is small. In addition, since the data is scrambled, compression encoded, compressed and decoded, and then descrambled, the location of unscrambled video or video data at the time of decoding can be minimized, reducing the possibility of unauthorized duplication. can do. (2) The key data required for descrambling is embedded in the video as watermark information after scrambling and before compression encoding, and extracted from the video after compression and decoding and before descrambling. , And it is difficult to extract key data illegally. Further, there is no need to provide a transmission path dedicated to key data. (3) The content and parameters of compression encoding are switched according to the presence or absence of scrambling, and the content and parameters of compression decoding are switched according to the presence or absence of scrambling, so that the effect of scrambling on encoding efficiency and image quality is minimized. can do. (4) Since the scramble is a conversion completed within the field, the degree of freedom of processing on the encoding side or the decoding side is large. (5) Since the scramble is performed after detecting the 3: 2 pull-down pattern, there is no erroneous detection of the 3: 2 pull-down pattern. (6) Since scrambling is performed after detecting a pre-filter / scene change, there is no adverse effect on image quality due to scrambling and erroneous detection of a scene change. In addition, since the post filter is applied after descrambling, there is no adverse effect on the image quality.

(Second Embodiment) Next, a second embodiment to which the moving picture coding method and the moving picture decoding method of the present invention are applied will be described.

FIG. 3 is a schematic block diagram of a moving picture coding apparatus according to the second embodiment of the present invention. The moving picture coding apparatus of FIG. 3 is different from the moving picture coding apparatus of FIG. 1 in that the watermark information embedding section 108 of FIG. 1 is omitted, and the multiplexing section 110 of FIG. The points are different, and the other points are the same as those of the moving picture coding apparatus of FIG.

That is, the key data 112 generated by the key generating unit 106 is not embedded in the video as digital watermark information as in the first embodiment,
At 01, it is multiplexed with the encoded moving image data together with the scramble on / off information 113. Here, the key data 112 is multiplexed in a place where general users cannot access, for example, a physical layer or a header portion.

FIG. 4 is a schematic block diagram of a moving picture decoding apparatus according to the second embodiment of the present invention. The moving picture decoding apparatus of FIG. 4 does not include the watermark information extracting unit 204 and the separating unit 202 differs from the moving picture decoding apparatus of FIG.
1 and the other points are the same as those of the moving picture decoding apparatus of FIG.

That is, the key data 209 used in the descrambling unit 205 is not extracted from the video as digital watermark information as in the first embodiment, but cannot be accessed by a general user in the separating unit 401. Separated from location, eg physical layer or header part.

In the second embodiment, the key data 112
Are multiplexed in places where general users cannot access.
That is, even if only the part that can be accessed by the user using the normal duplication method is copied, the key data cannot be copied. Therefore, the copied video cannot be descrambled and reproduced. Therefore, unauthorized copying can be prevented.

Further, in this embodiment, embedding / extraction of information into a video by a digital watermark is not used at all, so that the processing is simplified as compared with the first embodiment.
Therefore, the present embodiment is suitable for a case where scrambling and descrambling of a video is more simply performed.

(Third Embodiment) Next, a third embodiment to which the moving picture coding method and the moving picture decoding method of the present invention are applied will be described.

FIG. 5 is a schematic block diagram of a moving picture coding apparatus according to the third embodiment of the present invention. 5 includes an original image input terminal 101, a scramble unit 501, an encode unit 502, and a bit stream output terminal 111. Further, the scramble unit 501 includes the 3: 2 pull-down detection unit 10
2, a redundant field excluding unit 103, a key generating unit 106, a scrambling unit 107, a watermark information embedding unit 503, and a redundant field inserting unit 504. Also,
The encoding unit 502 includes a 3: 2 pulldown detection unit 505, a selection unit 506, a redundant field exclusion unit 507,
A pre-filter unit 508, a scene change detection unit 509,
It comprises a compression encoding unit 510.

The functions of the respective processing units are basically the same as those in the first embodiment, and the same parts as those in FIG. 1 are denoted by the same reference numerals or the same names, and description thereof is omitted. Compared to the first embodiment, first, the pre-filter unit 104 and the scene change detection unit 105, which are provided at the preceding stage of the scramble unit 107 in FIG. 1, are omitted (there may be provided).

In the watermark information embedding unit 503,
Not only the key data 112 but also the scramble on / off information 113 and the 3: 2 pull-down information 114 are embedded in the video as watermark information. That is, there is no need to use a dedicated transmission path or storage location for transmitting such information.

The redundant field insertion unit 504 converts the output format of the scramble unit 501 into the encode unit 5
02 (approximately 60 fields /
Second), and is not necessarily required, for example, when encoding by software.

In the selection section 506, based on the scramble on / off information 113, the 3: 2 pull-down information 114 input from the scramble unit 501 and the 3: 2 pull-down information 511 supplied from the 3: 2 pull-down detection section 505. Is selected and the 3: 2 pull-down information 512 is output. That is, when the scramble is off, the 3: 2 pull-down information 511 detected by the 3: 2 pull-down detection unit 505 is selected, and when the scramble is on, the 3: 2 pull-down information 114 detected in the scramble unit 501 is selected. You. In the latter case, the 3: 2 pulldown information 511, which is the detection result of the 3: 2 pulldown detection unit 505, is ignored.

The pre-filter unit 508 and the scene change detection unit 509 are controlled based on scramble on / off information. That is, in the case of scramble on, pre-filtering and scene change detection are performed on already scrambled video, so that these functions are turned off or characteristics are changed (for example, scene change detection is performed). Is changed).

FIG. 6 is a schematic block diagram of a moving picture decoding apparatus according to the third embodiment of the present invention. The moving picture decoding device in FIG. 6 includes a bit stream input terminal 201, a decoding unit 601, a descrambling unit 602, and a reproduced image output terminal 208. Further, the decoding unit 601 includes a compression decoding section 603 and a redundant field insertion section 604. The descrambling unit 602 includes a watermark information extracting unit 605 and a descrambling unit 606.

The function of each processing unit is basically the same as that of the first embodiment, and the same parts as those in FIG. 2 are denoted by the same reference numerals or the same names, and description thereof is omitted. The compression decoding unit 603 outputs the 3: 2 pull-down information 604 described as the syntax of the compression encoding, and the redundant field insertion unit 604 inserts a redundant field based on this. That is, the output of the decode unit 601 is a video signal in which the scramble is still generated and a redundant field is inserted.

The watermark information extraction unit 605 extracts the scramble on / off information 210, the key data 209, and the 3: 2 pull-down information 607 from the video and supplies them to the descramble unit 606.

In the descrambling section 606, when the scramble is on, the key data 209 is used and the 3: 2 pull-down information 607 is also referred to in consideration of the fact that the redundant field has already been inserted. I do. That is, for example, the same descrambling as one frame before is performed for the redundant field.

One of the features of this embodiment is that an external scramble unit 501 and descramble unit 602 are connected to a conventional encode unit 502 and decode unit 601 which do not support scramble / descrambling. With the scramble function
That is, a descrambling function can be realized.

The encoding unit 502 is a compression encoding unit in a broad sense, and is capable of performing a conventional compression encoding operation (which does not support scrambling). First, when the scramble on / off information 113 indicates scramble off, the encoding operation as in the related art is performed. That is,
After detecting the 3: 2 pull-down pattern by the 3: 2 pull-down detection unit 505, the redundant field is excluded by the redundant field elimination unit 507, the pre-filter unit 508 and the scene change detection unit 509 are operated as usual, and the compression code is used. Compression section 510 performs compression encoding. On the other hand, in the case of scramble-on, the content and parameters of the encoding process in the encoding unit 502 (compression encoding unit in a broad sense) are changed. Specifically, the detection result of the 3: 2 pull-down detection unit 505 originally incorporated is ignored, and the pre-filter unit 508 and the scene change detection unit 509 are turned off or the characteristics are changed. In addition, compression coding section 510 changes, for example, the selection criteria of the macroblock type. By connecting the scramble unit 501 externally to the encode unit 502, a scramble function can be added.

The decoding unit 601 is a compression decoding section in a broad sense, and performs a conventional compression decoding operation (same as when descrambling is not performed) regardless of whether scramble is on or off. In the case of scramble-on, the output from the decode unit 601 remains scrambled, so that normal viewing cannot be performed, and illegal copying is impossible. Also, by connecting the descrambling unit 602 externally, a descrambling function can be added, and normal video can be viewed.

In the present embodiment, all information (key data, scramble on / off information, 3: 2 pull-down information) necessary for descrambling is embedded in the video as watermark information. There is no need to newly provide a transmission path, and the conventional encoding unit and decoding unit can be used as they are.

In the present embodiment, when a redundant field is inserted by the redundant field insertion unit 504, 3:
By adopting an insertion method that allows the 2: 2 pull-down detection unit 505 to correctly detect the 3: 2 pull-down pattern again, it is not necessary to send the 3: 2 pull-down information 114 from the scramble unit 501 to the encode unit 502 separately. In this case, the encoding unit 502
Within, 3: 3 from the 3: 2 pull-down detector 505 always
2 pull-down information 511 is used.

(Fourth Embodiment) Next, a fourth embodiment of the moving picture coding method and the moving picture decoding method of the present invention will be described.

The present embodiment can be applied even if it is not necessarily related to 3: 2 pull-down, or if it is not related to embedding of information by a digital watermark. According to the present embodiment, in a moving image encoding method for compressing and encoding a moving image having a frame structure composed of two fields, a first step of scrambling a video, and a video after the first step are performed. Including a second step of compression encoding, the scrambling in the first step is a complete conversion in each field and the same conversion in two fields constituting each frame. Things.

That is, the moving picture coding method according to the present embodiment includes the following two steps. Step 1: Scramble the input video.

The scramble conversion rule is completed in each field. The scramble conversion rule is the same for the two fields that make up each frame.

Step 2: Compress and encode the scrambled video and output coded moving image data. However,
When coding 3: 2 pulldown video, redundant fields are excluded before step 1.

The moving picture decoding method according to the present embodiment is a moving picture decoding method for decoding coded moving picture data to obtain a moving picture having a frame structure composed of two fields. A first step of compressing and decoding the data, and a second step of descrambling the compressed and decoded video after the second step,
The descrambling in the second step is characterized in that it is a complete conversion in each field and the same conversion is performed in two fields constituting each frame.

That is, the moving picture decoding method according to the present embodiment includes the following two steps. Step 1: Compress and decode input coded video data. Step 2: descramble the compressed and decoded video and output a reproduced video.

The descrambling conversion rule is completed in each field. -The descrambling conversion rule configures each frame 2
Identical in two fields.

However, when decoding 3: 2 pull-down video, a redundant field is inserted after step 2. In MPEG2, a frame prediction (Frame-ba) is set as a motion compensation prediction mode in a macroblock encoding mode when encoding a video having a frame structure.
sed prediction and field prediction (F
field-based prediction). The DCT mode includes a frame DCT and a field DCT. In general, when coding interlaced video, when motion is large, field prediction or field DCT is often more suitable in terms of coding efficiency. On the other hand, when there is no motion or the motion is small, frame prediction or frame DCT is often more suitable in terms of coding efficiency. In the actual compression encoding step, encoding is performed while adaptively selecting the prediction mode and the DCT mode for each macroblock. In the field prediction, the number of motion vectors to be transmitted is larger than that in the frame prediction. Therefore, when there is no large difference in prediction error between the field prediction and the frame prediction, it is better to use the frame prediction.

However, if different scrambling is performed on the two fields forming one frame, even if the frame DCT or the macroblock whose frame prediction is suitable for the original (before scrambling), the frame DCT after the scrambling is obtained. In the case of frame prediction, since the code amount is greatly increased, the field DCT or the field prediction, which was originally not very suitable, must be selected, and the coding efficiency is reduced.

On the other hand, if the same scrambling is performed on the two fields forming one frame, the frame DCT before the scrambling or the macroblock for which the frame prediction is appropriate before the scrambling will be used even after the scrambling.
And frame prediction are easily selected, and the coding efficiency does not decrease.

In view of the above, when scrambling is performed before compression coding, the same scrambling should be performed on two fields constituting one frame.
In the case of 3: 2 pull-down video, as shown in FIG. 7, since the film video was originally 24 frames per second, a picture (original film 1 frame) formed by removing the redundant field is encoded. In this case, coding by frame DCT / frame prediction provides very high coding efficiency.
Therefore, in such a case, the frame DCT is forcibly applied.
-It is appropriate to encode by frame prediction.

However, if different scrambling is performed on two fields constituting one picture after the redundant field is deleted, the original (before scrambling) is performed.
Although the macroblock is suitable for the frame DCT or the frame prediction, the code amount is significantly increased in the frame DCT or the frame prediction after scrambling. Even if field DCT or field prediction, which was originally not very suitable, is selected, the coding efficiency is reduced.

On the other hand, if the same scrambling is performed on the two fields constituting one picture after removing the redundant field, if the coding is performed by the frame DCT or the frame prediction even after the scrambling, the coding efficiency is the same as before the scrambling. Is very good.

In view of the above, when scramble is performed on a 3: 2 pull-down video after redundant field deletion before compression encoding, the same scramble should be performed on two fields constituting one picture. It is.

If the scramble conversion rule is completed in each field and is the same in the two fields constituting each frame (each picture), the inverse scramble conversion rule is also included in each field. And the two fields constituting each frame (each picture) are identical.

As described above, according to the fourth embodiment,
It is possible to provide a moving picture coding method and a moving picture decoding method capable of obtaining a scrambling effect without lowering the coding efficiency of compression coding.

(Modification) The present invention is not limited to the above-described first to fourth embodiments, but may be, for example, the following (1) to (5).
Various modifications and applications are possible as exemplified in FIG. (1) In the above embodiments, MPEG2 is assumed as the basic compression encoding method, but other compression methods may be used. (2) The original image to be transmitted may be a normal resolution or an HDTV. Various applications other than DVD and digital broadcasting are also possible. (3) The key data for descrambling need not be embedded as watermark information or multiplexed, but may be embedded in a proper decryption device in advance or transmitted separately. (4) In the third embodiment, the watermark information embedding unit 503 embeds 3: 2 pull-down information 114 as watermark information in a video, and
In 5, the 3: 2 pull-down information 607 is extracted from the video. This technique is useful even if used alone without necessarily being combined with a scrambling technique or a compression encoding technique. That is, the 3: 2 pull-down information can be reliably transmitted in a format accompanying the video without using a special transmission path or storage location for the 3: 2 pull-down information. This 3: 2 pull-down information is transmitted by analog transmission
It will not be lost even if it goes through compression / decompression processing and filtering processing. (5) The procedure described in each embodiment can be implemented by software, and the same effect can be obtained by introducing a computer program including the procedure into a computer through a recording medium.

[0092]

As described above, according to the present invention,
It is possible to provide a moving picture coding method and a moving picture decoding method capable of appropriately performing scramble and compression coding on a 3: 2 pull-down video.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a moving picture coding apparatus according to a first embodiment to which a moving picture coding method and a moving picture decoding method of the present invention are applied.

FIG. 2 is a block diagram showing a schematic configuration of a video decoding device according to the first embodiment.

FIG. 3 is a block diagram showing a schematic configuration of a moving picture coding apparatus according to a second embodiment to which the moving picture coding method and the moving picture decoding method of the present invention are applied.

FIG. 4 is a block diagram showing a schematic configuration of a video decoding device according to the second embodiment.

FIG. 5 is a block diagram showing a schematic configuration of a moving picture coding apparatus according to a third embodiment to which the moving picture coding method and the moving picture decoding method of the present invention are applied.

FIG. 6 is a block diagram showing a schematic configuration of a video decoding device according to the third embodiment.

FIG. 7 is an explanatory diagram of 3: 2 pull-down.

FIG. 8 is a diagram showing an example of a 3: 2 pull-down pattern detection method.

[Explanation of symbols]

 Reference Signs List 101 Original image input terminal 102 3: 2 pulldown detection unit 103 Redundant field elimination unit 104 Prefilter unit 105 Scene change detection unit 106 Key generation unit 107 Scramble unit 108 Watermark information embedding unit 109 Compression encoding unit 110 Multiplexing unit 111 Bit stream output Terminal 112 Key data 113 Scramble on / off information 114 3: 2 pull-down information 201 Bit stream input terminal 202 Separation unit 203 Compression decoding unit 204 Watermark information extraction unit 205 Descramble unit 206 Post filter unit 207 Redundant field insertion unit 208 Playback image output Terminal 209 Key data 210 Scramble on / off information 211 3: 2 pull-down information 301 Multiplexer 401 Demultiplexer 501 Scramble unit 502 Encode unit 503 watermark information embedding section 504 redundant field inserting section 505 3: 2 pull-down detecting section 506 selecting section 507 redundant field excluding section 508 pre-filter section 509 scene change detecting section 510 compression encoding section 511 3: 2 pull-down information 512 3: 2 pull-down Information 601 Decoding unit 602 Descramble unit 603 Compression decoding unit 604 Redundant field insertion unit 605 Watermark information extraction unit 606 Descramble unit 607 3: 2 pulldown information

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H04N 7/08 H04N 7/08 Z 5C063 7/081 7/167 Z 5C064 7/167 F term (reference) 5C021 YC08 ZA02 5C024 DA07 HA02 5C052 GB06 GC05 5C053 FA13 FA20 FA22 GB21 5C059 KK43 MA00 PP04 PP11 RB09 RC35 SS02 SS13 UA02 UA05 5C063 AB03 AB05 AC01 AC10 CA05 CA34 5C064 CA14 CB01 CC04

Claims (12)

[Claims] 1. A video encoding method for compressing and encoding a video signal, comprising: a first step of removing a redundant field from a video when a 3: 2 pull-down video is input; It comprises a second step of scrambling and a third step of compression-encoding a video, wherein the first, second, and third steps are processed in this order. Video encoding method. 2. The method according to claim 2, further comprising a fourth step of embedding information on the scramble key in the second step as digital watermark information in the video, wherein the fourth step is performed after the second step and in the fourth step. The moving picture coding method according to claim 1, wherein the processing is performed before the third step. 3. The compression coding in the third step has a first mode corresponding to the presence of scrambling and a second mode corresponding to the absence of scrambling, wherein the first mode and the second mode are different from each other. 2. The moving picture coding method according to claim 1, wherein the coding processing contents or parameters are different from each other. 4. The moving picture coding method according to claim 1, wherein the scrambling in the second step is a complete conversion in the picture of each field. 5. The method according to claim 1, further comprising a fifth step of embedding information regarding the redundant field excluded in the first step in the video as digital watermark information, wherein the fifth step is performed before the third step. The moving picture coding method according to claim 1, wherein the moving picture coding is performed. 6. A moving picture coding method for compressing and coding a moving picture having a frame structure composed of two fields, comprising: a first step of scrambling a video; and a scrambling by the first step. After the processing, a second step of compression-encoding the video, wherein the scrambling in the first step is a complete conversion in each field, and the same conversion is performed in two fields constituting each frame. A moving image encoding method. 7. A moving picture decoding method for decoding coded moving picture data, comprising: a first step of compressing and decoding coded moving picture data when a 3: 2 pull-down video is reproduced; A second step of descrambling the compressed image, and a third step of inserting a redundant field into the compressed and decoded image, wherein the first step is the second step and the third step A moving picture decoding method characterized in that the moving picture is decoded before the moving picture is decoded. 8. A method according to claim 2, further comprising the step of extracting information on the descrambling key in the second step from the video as digital watermark information, wherein the fourth step is performed after the first step. The moving picture decoding method according to claim 7, wherein the processing is performed before the second step. 9. The compression decoding in the first step has a first mode corresponding to the presence of scrambling and a second mode corresponding to the absence of scrambling, wherein the first mode and the second mode are decoding. 8. The moving picture decoding method according to claim 7, wherein the processing contents or parameters of the moving image are different from each other. 10. The moving picture decoding method according to claim 7, wherein the descrambling in the second step is a complete conversion in an image of each field. 11. A fifth step of extracting information on a redundant field to be inserted in the third step from a video as digital watermark information, wherein the fifth step is performed after the first step. 8. The moving picture decoding method according to claim 7, wherein the processing is performed before the third step. 12. A moving picture decoding method for decoding a coded moving picture data to obtain a moving picture having a frame structure composed of two fields, wherein a first method for compressing and decoding the coded moving picture data is provided. And a second step of descrambling the video after the decoding process in the first step, wherein the descrambling in the second step is a complete conversion in each field, and A moving image decoding method characterized in that the same conversion is performed in the two fields constituting (i).