JP2004179695A - Recording method - Google Patents

Abstract

When connecting and recording two video data encoded in accordance with the MPEG-2 standard, an image of a connected portion is prevented from being disturbed as much as possible.
When a place where the second video data is connected is after an I picture or a P picture of the first video data, and a B picture following the I picture or the P picture exists, the second video data is connected. 2 is changed after the B picture, and the place where the second video data is connected is after the I picture or the P picture of the first video data. If there is no subsequent B picture, the place where the second video data is connected is changed after the I picture or P picture.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a recording method for connecting and recording first video data encoded according to the MPEG-2 standard and second video data encoded according to the MPEG-2 standard.
[0002]
[Prior art]
One of the standards for encoding digital video data is the MPEG-2 standard. The MPEG-2 standard is described in detail in "ISO / IEC 13818-2 International Standard MPEG-2 Video (Nov. 1994)".
[0003]
[Problems to be solved by the invention]
However, when two pieces of video data encoded according to the MPEG-2 standard are connected and recorded, if the place where the two pieces of video data are connected is within a GOP (Group of Pictures), the image of the connected portion may be disturbed. is there.
[0004]
Accordingly, it is an object of the present invention to minimize an image of a connected portion when two video data encoded according to the MPEG-2 standard are connected and recorded.
[0005]
[Means for Solving the Problems]
One of the recording methods in the present invention is a recording method for connecting and recording first video data encoded according to the MPEG-2 standard and second video data encoded according to the MPEG-2 standard, When the place where the second video data is connected is after the I picture or the P picture of the first video data, and there is a B picture following the I picture or the P picture, 2 is changed after the B picture, and the place where the second video data is connected is after the I picture or the P picture of the first video data, and the I picture Alternatively, if there is no B picture following the P picture, the place to connect the second video data is And changes after the picture or the P picture.
[0006]
One of the recording methods in the present invention is a recording method for connecting and recording first video data encoded according to the MPEG-2 standard and second video data encoded according to the MPEG-2 standard, When the place where the second video data is connected is in the middle of one track, the recording of the second video data is started from the track.
[0007]
One of the recording methods in the present invention is a recording method for connecting and recording first video data encoded according to the MPEG-2 standard and second video data encoded according to the MPEG-2 standard, When the place where the second video data is connected is in the middle of one track, the recording of the second video data is started from a track subsequent to the track.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
(First Embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
In the first embodiment, a recording method of connecting and recording second video data encoded according to the MPEG-2 standard after an I picture or a P picture of the first video data encoded according to the MPEG-2 standard Will be described. Note that the first video data is composed of B0, B1, I2, B3, B4, P5, B6, B7, P8, B9, B10, P11, B12, B13, and P14, and the second video data is B20, B21, I22, B23, B24, P25, B26, B27, P28, B29, B30, P31, B32, B33, P34. B indicates a B picture, I indicates an I picture, and P indicates a P picture.
[0009]
FIG. 1 is a diagram illustrating a case where second video data is connected after a P8 picture. The images are scheduled to be edited in the order of B6, B7, P8, B20, B21, and I22. In the first embodiment, since the image to be edited is a P picture, when rewriting the data on the medium, a B picture following the P8 picture is searched on the medium, and the point at which the B picture ends (that is, At the point when the I picture or P picture appears). In this example, since the B pictures following P8 are B6 and B7, images are connected in the order of I22, B20, B21, and P25 after B7. As a result, on the medium, the images are recorded in the order of P8, B6, B7, I22, B20, and B21, and the reproduced images are the images scheduled in the order of P5, B6, B7, P8, B20, B21, and I22.
[0010]
If there is no succeeding B picture, new video data is connected by using the time point at which the I picture or P picture as the connection destination ends (that is, the time point at which the next I picture or P picture appears) as a rewriting point. Just fine.
[0011]
FIG. 2 shows processing to be added when the medium on which the MPEG data is recorded is a magnetic tape in the first embodiment. In this example, it is assumed that the track pattern is created as shown in FIG. The rewrite point in this case is at track number 11. Therefore, first, as shown in FIG. 2, the original track data is once read. The track data includes the latter half of the data of B7 and the data of P11 following the latter. Of these, the data portion of B7 is set as the storage portion, and the data of B20, which will be additional recording data, is connected thereafter. This is used as re-recorded track data, and the entire track of track number 16 is rewritten again.
[0012]
As described above, according to the recording method in the first embodiment, when the second video data is connected after the I picture or the P picture of the first video data, the B picture following the I picture or the P picture is used. Since the second video data can be connected from the point after the picture, the disturbance of the image of the connected portion can be reduced as much as possible.
[0013]
Further, according to the recording method of the first embodiment, it is not necessary to re-encode the video data of the connected portion, so that the two video data can be connected with a small load.
[0014]
(Second embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.
In the second embodiment, a description will be given of a recording method in which a B picture of first video data encoded according to the MPEG-2 standard is connected to second video data encoded according to the MPEG-2 standard and then recorded. . Note that the first video data is composed of B0, B1, I2, B3, B4, P5, B6, B7, P8, B9, B10, P11, B12, B13, and P14, and the second video data is B20, B21, I22, B23, B24, P25, B26, B27, P28, B29, B30, P31, B32, B33, P34. B indicates a B picture, I indicates an I picture, and P indicates a P picture.
[0015]
FIG. 4 is a diagram illustrating a case where the second video data is connected after the B7 picture. Images are scheduled to be connected in order of B6, B7, B20, B21, and I22. In the first embodiment, since the image to be edited is a B picture, when rewriting the data on the media, the data from the B picture immediately after the preceding I picture or P picture to the B picture at the connection point is rewritten. Is temporarily stored. In this example, since the preceding I picture or P picture is a B6 or B7 picture, it is temporarily stored.
[0016]
With respect to the temporarily stored B picture, a portion subjected to backward prediction is converted. Conversion is performed on a macroblock basis. This is shown in FIG. That is, the macroblock data is examined to determine whether the prediction direction is forward prediction, backward prediction, or bidirectional prediction (step S1).
[0017]
In the case of forward prediction, no processing is performed, and processing proceeds to the next macroblock.
In the case of backward prediction, the referenced macroblock is read from the reference image (step S2), and the data is replaced as it is with the target macroblock data (step S3). That is, for a macroblock for which backward prediction has been performed, the entire macroblock is replaced.
[0018]
In the case of bidirectional prediction, the motion vector data for backward prediction is removed from the macroblock information of the macroblock (step S4), and the display of the prediction direction is changed to forward prediction (step S5). The DCT data of the macro block is left as it is. As a result, the macroblock subjected to bidirectional prediction is converted into a macroblock equivalent to the macroblock subjected to forward prediction by rewriting the macroblock information without changing the DCT data.
[0019]
After the conversion of all the temporarily stored macroblocks is completed, the temporarily stored data is written from the head of the preceding I picture or P picture on the medium, and then a new MPEG image is connected. In the example of FIG. 4, from the position where the P8 picture is recorded, the temporarily stored and converted B6 and B7 are overwritten, and subsequently, the writing is performed in the order of I22, B20 and B21. As a result, on the medium, P5, B3, B4, B6, B7, I22, B20, and B21 are recorded in this order, and as the reproduced image, images scheduled in the order of P5, B6, B7, B20, B21, and I22 are reproduced. .
[0020]
FIG. 8 shows a case where the conversion in units of macroblocks in the second embodiment is not performed. If the P8 data on the medium is erased by overwriting, B6 and B7 cannot be reproduced because the backward predicted image is lost.
[0021]
As described above, in the second embodiment, among the macroblocks of the B picture, the macroblock that has been performing the backward prediction and the bidirectional prediction is different from the data constituting the original B picture. However, the impact is minor.
[0022]
First, the case of a macroblock for which backward prediction has been performed will be described.
In the backward prediction, if the prediction value from the reference image is R and the error is e with respect to the encoding target data C, there is a relationship of C = R + e. Normally, this e is DCT-transformed and recorded in a macroblock. The fact that e is small increases the compression efficiency of predictive coding. Therefore, according to the conversion of the present embodiment, replacing with a macroblock of a reference image uses R instead of C, which has a relationship of R = C−e. A small value of e means that the difference between R and C is small. Even if R is used instead of C, the difference is small. That is, according to the present embodiment, when the macroblock for which the backward prediction has been performed is replaced with the macroblock of the reference image, the deterioration of the image is considered to be slight. However, since the compression efficiency deteriorates, the data amount is considered to increase.
[0023]
Next, a case of a macroblock for which both predictions have been performed will be described.
In the bidirectional prediction, forward prediction and backward prediction are respectively performed on the encoding target data C to obtain respective reference images, and the average value thereof is used as a reference image. Here, a prediction value from forward prediction is Rf, its error is ef, a prediction value from backward prediction is RB, and its error is eB. At this time, similarly, there is a relationship of C = Rf + ef and C = Rb + eb. Further, assuming that an error when bidirectional prediction is performed is ew, this has a relationship of C = (Rf + Rb) / 2 + ew. From this, there is a relationship of ew = 2 (ef + eb). At this time, assuming forward prediction as in the conversion in the second embodiment, decoding is performed using RBs instead of RBs, and the data to be decoded is Cnew = Rf + ew. The original C is decoded as data obtained by adding an error by Cnew-C = (Rf-Rb) / 2. That is, the image quality is deteriorated by the difference between the predicted value Rf and RB from the original reference image.
[0024]
It is not generally known which of Rf and RB is closer to C. For example, if Rf is an image far different from C compared to RB, if the conversion according to the second embodiment is performed and only forward prediction is handled, the obtained image will have a large error. . However, in this case, using only RBs means that the prediction error is smaller. That is, the use of backward prediction has a smaller prediction error and better compression efficiency. Therefore, when Rf is much different from C as compared to RB, bidirectional prediction is not applied.
[0025]
After all, when bidirectional prediction is applied, it is considered that Rf and RB are almost the same and close to C. Therefore, the error (Rf−Rb) / 2 when the conversion according to the second embodiment is performed is also: Somewhat small. Therefore, even if the conversion according to the second embodiment is performed on a macroblock on which bidirectional prediction has been performed, image quality degradation is minimal.
[0026]
As described above, since the conversion processing of the B picture in the second embodiment can be performed by replacing the entire macroblock or rewriting the macroblock information, the amount of calculation and the like can be reduced as compared with re-conversion of the entire image.
[0027]
FIGS. 6 and 7 are diagrams for explaining processing to be added when the medium on which the MPEG data is recorded is a magnetic tape. In this example, it is assumed that the track pattern is created as shown in FIG. The rewrite point in this case is at track number 8. Therefore, first, as shown in FIG. 6, a track skip marker is written at the head of the location where the data of P8 appears in the track of track number 8. From the beginning of the following track number 9, B6 and B7 temporarily stored and converted are written in the order of I22, B20 and B21 to be subsequently connected. As a result, in the example of the second embodiment, the created track pattern is as shown in FIG.
[0028]
The track skip marker is a group of data having a fixed length, and may be any data that can be identified from normal MPEG data. Specifically, a sync block having a specific ID or a gap data pattern can be used (refer to the consumer digital VTR standard). The track skip marker may be written while the data of P8 of this track appears, and need not be exactly between B4 and P8. When one track includes a plurality of picture data, it is sufficient that the data be on the first picture after the rewriting point.
[0029]
If a track skip marker appears when a track is reproduced, the picture data on which the marker is written is invalidated, and the MPEG data is defined as continuing from the beginning of the next track. Therefore, when reproducing the track number 8, the data portion of B4 in the first half is valid, but the P8 data portion in which the track skip marker appears is invalid. The data following the data of B4 is reproduced as starting from the beginning of the track number 9. As a result, the data recorded on this magnetic tape is equal to the data on the media shown in FIG.
[0030]
As described above, according to the recording method in the second embodiment, when the second video data is connected after the B picture of the first video data, the connected portion is immediately after the preceding I picture or P picture. Since the backward prediction of the B picture up to this can be converted, it is possible to minimize the disturbance of the image of the connected portion.
[0031]
Further, according to the recording method of the second embodiment, it is not necessary to re-encode the video data of the connected portion, so that the two video data can be connected with a small load.
[0032]
FIG. 9 is a diagram showing a configuration of a computer system for realizing the above embodiment of the recording method according to the present invention.
As shown in FIG. 9, the computer system 1200 includes a CPU 1201, a ROM 1202, a RAM 1203, a keyboard controller (KBC) 1205 of a keyboard (KB) 1209, and a CRT controller (CRT) 1210 as a display unit. A CRTC 1206, a disk controller (DKC) 1207 of a hard disk (HD) 1211 and a flexible disk (FD) 1212, and a network interface controller (NIC) 1208 for connection to a network 1220 are connected via a system bus 1204. The configuration is such that they are communicably connected to each other.
[0033]
The CPU 1201 comprehensively controls each component connected to the system bus 1204 by executing software stored in the ROM 1202 or the HD 1211 or software supplied from the FD 1212.
That is, the CPU 1201 reads out a processing program according to a predetermined processing sequence from the ROM 1202, the HD 1211, or the FD 1212 and executes the processing program, thereby performing control for realizing the operation in the present embodiment.
[0034]
The RAM 1203 functions as a main memory or a work area of the CPU 1201.
The KBC 1205 controls an instruction input from the KB 1209, a pointing device (not shown), or the like.
The CRTC 1206 controls display on the CRT 1210.
The DKC 1207 controls access to the HD 1211 and the FD 1212 that store a boot program, various applications, an editing file, a user file, a network management program, and a predetermined processing program in the present embodiment.
The NIC 1208 exchanges data bidirectionally with devices or systems on the network 1220.
[0035]
Further, an object of the present invention is to provide a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and a computer (or CPU or MPU) of the system or the apparatus to store the storage medium. Needless to say, this can also be achieved by reading and executing the program code stored in the program.
[0036]
In this case, the program code itself read from the storage medium realizes the function of the above-described embodiment, and the program code itself and the storage medium storing the program code constitute the present invention.
[0037]
As a storage medium for supplying the program code, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, and the like can be used.
[0038]
When the computer executes the readout program code, not only the functions of the above-described embodiments are realized, but also an OS (basic system or operating system) running on the computer based on the instruction of the program code. ) Performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.
[0039]
Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function is executed based on the instruction of the program code. It goes without saying that a CPU or the like provided in the expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.
[0040]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, when connecting and recording two video data encoded according to the MPEG-2 standard, the image of the connection part can be made as little as possible.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a positional relationship between pictures according to a first embodiment.
FIG. 2 is a diagram illustrating a configuration of a track according to the first embodiment.
FIG. 3 is a diagram illustrating a recording pattern according to the first embodiment.
FIG. 4 is a diagram illustrating a positional relationship between pictures according to the second embodiment.
FIG. 5 is a diagram illustrating macroblock conversion according to the second embodiment.
FIG. 6 is a diagram illustrating a configuration of a track according to the second embodiment.
FIG. 7 is a diagram illustrating a recording pattern according to a second embodiment.
FIG. 8 is a diagram illustrating an example in which macroblock conversion is not performed in the second embodiment.
FIG. 9 is a diagram showing a configuration of a computer system for realizing the first and second embodiments of the recording method according to the present invention.
[Explanation of symbols]
1200 Computer system 1201 CPU
1202 ROM
1203 RAM
1204 System bus 1205 KBC
1206 CRTC
1207 DKC
1208 NIC
1209 KB
1210 CRT
1211 HD
1212 FD
1220 Network

Claims (3)

A recording method for connecting and recording first video data encoded according to the MPEG-2 standard and second video data encoded according to the MPEG-2 standard,
When the place where the second video data is connected is after the I picture or the P picture of the first video data, and there is a B picture following the I picture or the P picture, Changing the place where the second video data is connected after the B picture;
If the place where the second video data is connected is after an I picture or a P picture of the first video data and there is no B picture following the I picture or the P picture, A recording method, wherein a place where the second video data is connected is changed after the I picture or the P picture. A recording method for connecting and recording first video data encoded according to the MPEG-2 standard and second video data encoded according to the MPEG-2 standard,
If the place where the second video data is connected is in the middle of one track, the recording of the second video data is started from the track. A recording method for connecting and recording first video data encoded according to the MPEG-2 standard and second video data encoded according to the MPEG-2 standard,
If the place where the second video data is connected is in the middle of one track, the recording of the second video data is started from a track subsequent to the track.

Images