JP2000175139A - Video editing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video editing device that can efficiently copy only video audio data of a desirably designated part in a short time. SOLUTION: In the case that a file desired to be copied is selected among a plurality of files recorded on a removable optical disk 109 that is loaded to an optical disk drive 110 of a nonlinear edit device 120 and a controller 119 designates a copy start frame position and a copy end frame position in the selected file, a CPU 114 stores the file name, the start frame position and the end frame position to a memory 113 in cross reference with each other, reads video audio data in a copy range designated by the stored start frame position and end frame position from the removable optical disk 109 via a SCSI control section 111, write the read video audio data to the memory 113 and on a hard disk(HDD) 115 as a new file.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video editing apparatus for recording and editing a video signal, and more particularly to a video editing apparatus for recording and editing only desired video and audio data among video and audio data recorded on a removable disk. And a video editing device that efficiently copies the data to a hard disk or a removable disk.

[0002]

2. Description of the Related Art Conventionally, copying of video and audio signals recorded on a video tape and production of professional video have been performed using a VTR and a non-linear editing machine. in this case,
In order to edit a video / audio signal recorded on a video tape by a non-linear editor, the video tape is reproduced by a VTR, and the reproduced video / audio signal is captured, that is, captured by the non-linear editor. In such editing of a video / audio signal, since there are generally a plurality of locations to be captured from a video tape, a plurality of ranges to be captured are specified first, and then these ranges are automatically captured. Such a method is called batch capture.

[0003] Such a batch capture method will be described with reference to FIGS. 6 to 8. FIG. 6 is a block diagram showing the configuration of a conventional video editing apparatus that performs batch capture. FIG. 7 is a table showing data when the video editing apparatus shown in FIG. 6 captures data. FIG. 5 is a flowchart showing the operation of the device.

[0006] The conventional video editing apparatus shown in FIG.
1, a nonlinear editing machine 2 and a controller 3. The nonlinear editing machine 2 includes a VTR control section 4, a video / audio input section 5, a compression section 6, a CPU 7, a memory 8, a bus 9, an interface (I / F) section 10, It comprises a SCSI controller 11 and a hard disk (HDD) 12.

The operation will be described with reference to a flowchart shown in FIG. First, when capturing with the non-linear editing machine 2, the user plays back the video tape of the VTR 1 and searches for a point at which the capture starts and a point at which the capture ends (step S18). When the user inputs a start point and an end point using the controller 3, the CPU 7 stores the time code in the memory 8 (step S19).

[0006] By repeating steps S18 and S19, the entire capture range is changed to the non-linear editing machine 2
(Step S20). As a result, data as shown in FIG. 7 is stored in the memory 8. In FIG. 7, N capture ranges are stored.
13 is the time code of the first start point, 14 is the time code of the first end point, 15 is the time code of the Nth start point, and 16 is the time code of the Nth end point.

Next, the nonlinear editing machine 2 automatically captures a range of N places. First, the VTR is searched for to the time code of the first start point shown in FIG. 7 (step S21). The cueing is executed by the CPU 7 sending a command from the VTR control unit 4 to the VTR 1.

Next, a pre-roll for rewinding the video tape for several seconds is performed, and the reproduction of the VTR is started (step S22). Pre-roll and playback start are performed by the CPU 7
This is executed by sending a command from the R control unit 4 to the VTR 1.

The CPU 7 reads out the time code being reproduced through the VTR control section 4, and starts capturing when the time code at the start point is reached (step S23). When the capture is started, the video / audio signal output from the VTR 1 is converted into a video / audio signal. The data is sent to the compression unit 6 via the input unit 5 and is compressed. The CPU 7 reads the compressed data into the memory 8 via the bus 9 and records the data on the hard disk 12 via the SCSI controller 11.

The CPU 7 continues to read the time code being reproduced, and stops capturing when the end time code is reached (step S24). Steps S21 to S24 are repeated for N locations shown in FIG. 7, and when all N locations have been captured, the process ends (steps S25 and S24).
26).

[0011]

As described above, conventionally, in the work of capturing a video / audio signal recorded on a video tape with a non-linear editing machine, it takes time to search for the video tape by a VTR, and In addition, since it takes time for the output signal to stabilize after the start of reproduction of the VTR, a work called pre-roll for rewinding and reproducing a few seconds before the position to be actually captured is required. And it is inefficient.

The present invention has been made in view of the above,
An object of the present invention is to provide a video editing apparatus capable of efficiently copying only video and audio data of a desired designated portion in a short time.

[0013]

According to a first aspect of the present invention, there is provided a disk drive for inserting a removable disk, and a hard disk.
A video editing apparatus for copying video / audio data recorded on a removable disk inserted into the disk drive to the hard disk, wherein a video / audio data file to be copied is designated among files recorded on the disk. File designating means, start frame position designating means for designating a frame position to be a copy start point in the video / audio data file designated by the file designating means, and video / audio data designated by the file designating means. An end frame position designating unit for designating a frame position to be a copy end point in the file; a file name designated by the file designating unit; and a file name designated by the start frame position designating unit and the end frame position designating unit. The start and end frame positions Copy range storage means for correspondingly storing the data, and data reading means for reading, from the removable disk, video and audio data of a copy range specified by a start frame position and an end frame position stored in the copy range storage means. And data writing means for writing the video / audio data read by the data reading means as a new file to the hard disk.

According to the first aspect of the present invention, in the video / audio data file designated to be copied, a frame position as a start point and an end point of the copy is designated, and the file name and the start frame position are designated. And the end frame position are stored correspondingly, the video / audio data in the copy range specified by the start frame position and the end frame position is read from the removable disk, and the read video / audio data is written to the hard disk as a new file. This eliminates the time required for cueing and pre-rolling as in the related art, thereby improving efficiency. In addition, since only necessary portions are specified and copied, the storage capacity of the disk can be used effectively.

[0015] The present invention described in claim 2 provides the present invention in claim 1.
In the invention described, the removable disk has compressed and recorded video and audio data by intra coding,
The gist of the present invention is to further include a decompression output means for decompressing the video and audio data recorded in the removable disk by compressing the data by intra coding and outputting the decompressed and restored video and audio data.

According to the second aspect of the present invention, the removable disk has the video and audio data compressed and recorded by intra coding, and the video and audio data compressed and recorded by the intra coding on this disk. Since the data is decompressed, restored, and output, a part to be copied can be accurately specified while viewing the output video / audio data.

Further, the present invention according to claim 3 provides the invention according to claim 1.
In the invention described in the above, the removable disk records video and audio data in a compressed form by the MPEG system, and the start frame position specifying means and the end frame position specifying means store the specified start frame position and end frame position. The encoded data of each frame at the position is GO
Determining means for determining whether or not the frame is at the boundary of P;
If it is determined that it is not the boundary of the OP, the start frame position is changed to the position of the boundary of the GOP. If it is determined that the encoded data of the frame at the end frame position is not the boundary of the GOP, the end frame position is changed. The gist of the present invention is to have a changing means for changing to a GOP boundary.

According to the third aspect of the present invention, the removable disk has the video and audio data compressed and recorded by the MPEG system, and the encoded data of the frame at the start frame position designated to be copied is the GOP. If it is not a boundary, the start frame position is changed to the position of the boundary of the GOP. If the encoded data of the frame at the end frame position is not the boundary of the GOP, the end frame position is changed to the boundary of the GOP. Necessary portions can be copied without omission even with video / audio data using a suitable inter-frame compression.

According to a fourth aspect of the present invention, there is provided at least two disk drives into which a removable disk is inserted, and the video / audio data recorded on the removable disk inserted into one disk drive is replaced with the other. A video editing device for copying to a removable disk inserted in a disk drive of the present invention, wherein a file specifying means for specifying a video / audio data file to be copied among files recorded on the one disk, and the file Start frame position designating means for designating a frame position to be a copy start point in the video / audio data file designated by the designating means, and copy end point in the video / audio data file designated by the file designating means End frame position specifying means for specifying a frame position to be A copy range storage unit that stores the specified file name, the start frame position and the end frame position respectively designated by the start frame position designation unit and the end frame position designation unit, and a copy range storage unit. Data reading means for reading from the one disk the video and audio data in the copy range specified by the stored start frame position and end frame position, and transferring the video and audio data read by the data reading means to the other disk. The gist of the invention is to have data writing means for writing as a file.

According to the fourth aspect of the present invention, in the video / audio data file designated to be copied, a frame position to be a start point and an end point of the copy is designated, and these file names and start frame positions are designated. And the end frame position are stored in a corresponding manner, and the video / audio data in the copy range specified by the start frame position and the end frame position is read out from one of the removable disks, and the read video / audio data is read out from the other removable disk. As a new file is written to a compact disk, the time required for cueing and pre-rolling is not required as in the past, which can improve efficiency.In addition, since only necessary parts are specified and copied, the storage capacity of the disk is reduced. Can be used effectively.

The present invention according to claim 5 provides the present invention according to claim 4.
In the invention described in the above, the one removable disk has video and audio data compressed and recorded by intra coding, and the video recorded by the one removable disk compressed by intra coding. Decompress audio data,
The gist of the present invention is to further include a decompression output unit for outputting the decompressed and restored video and audio data.

According to the fifth aspect of the present invention, one of the removable disks records the video and audio data in a compressed manner by intra coding, and the video and audio data compressed and recorded in the disk by the intra coding. Since the data is decompressed, restored, and output, the part to be copied can be properly specified while viewing the output video / audio data.

Further, the present invention described in claim 6 provides the invention according to claim 4.
In the invention described in the above, the one of the removable disks records video and audio data by compressing the data in an MPEG format, and each of the start frame position designating means and the end frame position designating means stores the designated start frame. Determining means for determining whether or not the coded data of each frame at the position and the end frame position is at the boundary of the GOP; as a result of the determination, it is determined that the coded data of the frame at the start frame position is not at the boundary of the GOP; In this case, the start frame position is changed to the position of the boundary of the GOP, and the encoded data of the frame at the end frame position is changed to the GOP.
And a change unit for changing the end frame position to a GOP boundary when it is determined that the end frame position is not the boundary of the GOP.

According to the sixth aspect of the present invention, one of the removable disks records the video and audio data in a compressed manner by the MPEG system, and the encoded data of the frame at the start frame position designated to be copied is stored in the removable disk. If it is not the boundary of the GOP, the start frame position is changed to the position of the boundary of the GOP,
Also, the encoded data of the frame at the end frame position is GO
If it is not the boundary of P, the end frame position is changed to the boundary of GOP, so that even video and audio data using inter-frame compression such as the MPEG system can be copied without omission.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a video editing device according to an embodiment of the present invention. The video editing apparatus according to the present embodiment uses a removable disk such as an optical disk as a recording medium, and outputs a desired specified video / audio signal to be copied among the video / audio signals recorded on the removable disk. A video recorder 101 for copying an input video / audio signal to an optical disk 109, and a desired video / audio signal desired to be copied among the video / audio signals recorded on the optical disk 109.
DD) 115, and a controller 119 for designating a position to be copied and the like.

The video recorder 101 includes a video / audio signal input unit 102, a JPEG compression unit 103, a memory 104,
It comprises a PU 105, a bus 106, a SCSI control unit 107, and an optical disk drive 108. The non-linear editing machine 120 includes the optical disc drive 1
10, SCSI controller 111, bus 112, memory 11
3, CPU 114, hard disk (HDD) 115,
It comprises a JPEG decompression unit 116, a video / audio signal output unit 117, and an interface (I / F) unit 118.

In this embodiment, the optical disk 109
Are compressed by the JPEG compression unit 103 of the video recorder 101 according to the JPEG system, that is, the intra-system, and are recorded.

Next, the operation of the video editing apparatus thus configured will be described. First, a procedure for recording a video / audio signal on an optical disc will be described. The optical disk 109 is inserted into the optical disk drive 108 of the video recorder 101.
Insert and format the computer file for writing. When recording is started, the input video / audio signal is compressed by the compression unit 103 via the video / audio signal input unit 102. In this embodiment, the compression unit 103
Uses the JPEG system, and the video signal is compressed by intra coding which is processed independently for each frame. The CPU 105 stores the compressed data in the memory 10
4 and the optical disk 109 inserted into the optical disk drive 108 via the SCSI control unit 107
Write to as a file. When recording is performed a plurality of times, a plurality of files are written to the optical disc 109.

Next, a procedure for capturing the video and audio data written on the optical disk 109 to the hard disk 115 of the nonlinear editing machine 120 will be described. First, the optical disk 109 is inserted into the optical disk drive 110 of the nonlinear editing machine 120.

The user selects a file to be captured from a plurality of files recorded on the optical disk 109, and determines a start point and an end point of the capture in the files (step S128). If you want to play the file to determine the start and end points,
The reproduction is instructed to the non-linear editing machine 120 via 19. When the reproduction is instructed, the CPU 114 reads the data of the file on the optical disk 109 inserted into the optical disk drive 110 via the SCSI control unit 111 and the bus 112 and stores the data in the memory 113. Next, this data is transferred to the JPEG decompression unit 116 to restore it to a video / audio signal, and output from the video / audio signal output unit 117. In this way, the user can view the reproduced video and audio signals.

When the user specifies a file name, a start point, and an end point using the controller 119, the CPU 114
Stores the file name, the frame number of the start point, and the frame number of the end point in the memory 113 (step S12).
9).

By repeating steps S128 and S129, the entire capture range is stored in the memory 113 of the nonlinear editing machine 120 (step S13).
0). In this way, data as shown in FIG. 2 is stored in the memory 113. In FIG. 2, N capture ranges are shown, 121 is the first file name,
122 is the frame number of the first start point, 123 is the frame number of the first end point, 124 is the N-th file name, 125 is the frame number of the N-th start point, and 126 is the frame of the N-th end point Number.

Once the range to be captured is determined,
The non-linear editor 120 shifts to the step of automatically capturing these. First, the CPU 114 reads the data in the first written range of the table of FIG.
Writing to the memory 113 (step S131).

Next, the CPU 114 writes the data written in the memory 113 as a new file on the hard disk 115 via the SCSI controller 111 (step S132). As described above, in the present embodiment,
Unlike the conventional technology using a VTR, no time is required for cueing the tape or for pre-rolling. Also, compared to the method of copying the entire file, only the necessary part of the file is copied,
Storage capacity can be used efficiently.

Steps S131 to S132 are repeated N times. When N locations stored in the table of FIG. 2 can be captured as files on the hard disk 115,
The process ends (steps S133 and S134).

Next, a video editing apparatus according to another embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a block diagram showing the configuration of the video editing device of the present embodiment, and FIG. 5 is a flowchart showing the operation of the video editing device shown in FIG. It should be noted that the video editing apparatus of this embodiment is different from the video editing apparatus shown in FIG. 1 in that the JPEG compression section 103 and the JPEG decompression section 116 are replaced with the MPEG compression section 203 and the MPEG decompression section 216, respectively.
The only difference is the use of, and the other configurations and operations are the same. That is, in the present embodiment, the video / audio signal recorded on the optical disc 109 is
One MPEG compression unit 203 compresses and records the data by the MPEG method.

The operation of the video editing apparatus shown in FIG. 4 will be described with reference to the flowchart shown in FIG. First, a procedure for recording a video / audio signal on an optical disc will be described. Optical disk drive 10 of video recorder 201
The optical disk 109 is inserted into the disk 8 and is formatted so that a computer file can be written. When recording is started, the input video / audio signal is compressed by the compression unit 203 via the video / audio signal input unit 102. In this embodiment, the compression unit 203 uses the MPEG method,
There are three types of data encoded by the EG method: an I frame that is compressed using target frame data alone, and a P frame and a B frame that are compressed from other frame data using predictive coding. That is, the P frame or the B frame cannot be decoded alone. The I frame, the P frame, and the B frame are grouped in a unit called a GOP (group of pictures), and the P frame or the B frame in the GOP is Decoding can be performed using only data in the same GOP. G for each GOP
There is an OP header, and by reading this, the position of the boundary between GOPs can be known. The CPU 105 reads out the compressed data to the memory 104 and writes it as a file on the optical disk 109 inserted into the optical disk drive 108 via the SCSI control unit 107.
When recording is performed multiple times, multiple files are
09 is written.

Next, a procedure for capturing the video and audio data written on the optical disk 109 to the hard disk 115 of the nonlinear editing machine 220 will be described. First, the optical disk 109 is inserted into the optical disk drive 110 of the nonlinear editing machine 220.

The user first selects a file to be captured from a plurality of files recorded on the optical disk 109 (step S228). The capture start point is determined in the selected file, and the frame number is designated to the nonlinear editing machine 220 (step S22).
9).

When a file is to be played back to determine the starting point, the playback is instructed to the nonlinear editing machine 220 via the controller 119. When playback is instructed,
The CPU 114 reads the data of the file on the optical disk 109 inserted in the optical disk drive 110 via the SCSI control unit 111 and the bus 112, and
13 is stored. Next, this data is transferred to the MPEG decompression unit 2.
16 and restored to a video / audio signal, and output from the video / audio signal output unit 117. In this way, the user can view the reproduced video and audio signals.

When the user specifies the frame number of the starting point using the controller 119, the CPU 114 reads the data of the frame number from the optical disk 109, and determines whether the frame is a GOP boundary.
If the determined result is a GOP boundary, the frame number specified by the user may be left as it is. However, if the result of determination is not a GOP boundary, the G
Let the position of the boundary of OP be a starting point. Thus, even after the data is captured, the encoded data at the start point specified by the user can be expanded (step S230).

Similarly, the user sets the controller 119
When the frame number of the end point is designated by using (step S231), the CPU 114 reads out the data of the frame number from the optical disc 119, and
It is determined whether or not the boundary is the OP boundary. The result is GOP
, The frame number specified by the user may be left as it is. However, if the result of the determination is not the boundary of the GOP, the position of the boundary of the GOP including the data is set as the end point. Thus, even after the data is captured, the encoded data at the end point specified by the user can be expanded (step S232).

By repeating steps S228 to S232, the entire capture range is stored in the nonlinear editing machine 220 (step S233). In this manner, data similar to that of FIG. 2 is stored in the memory 113.

Once the range to be captured is determined,
The non-linear editor 220 shifts to the step of automatically capturing these. First, the CPU 114 reads the data in the first written range of the table of FIG. 2 from the optical disk 109 via the SCSI control unit 111,
Writing to the memory 113 (step S234).

Next, the CPU 114 writes the data read and stored in the memory 113 as a new file on the hard disk 115 via the SCSI controller 111 (step S235). As described above, in the present embodiment, unlike the conventional technique using the VTR, the time for cueing the tape and the time for pre-rolling are unnecessary. Also, compared to the method of copying the entire file, only the necessary portion of the file is copied, so that the storage capacity of the hard disk 115 can be used efficiently.

Steps S234 to S235 are repeated N times. If N locations stored in the table of FIG.
The process ends (steps S236 and S237).

In each of the embodiments described above, the method of capturing from the optical disk to the hard disk has been described. However, the same effect can be obtained when capturing from the optical disk to the optical disk. In addition, although the non-linear editing machine has been described, similar effects can be obtained in an authoring system that handles video and audio files.

In each of the above embodiments, the case where an optical disk is used as a removable disk has been described. However, the present invention is not limited to an optical disk but can be applied to any removable disk.

[0049]

As described above, according to the present invention,
In the video / audio data file designated to be copied, a frame position to be a start point and an end point of the copy is designated, and the file name, the start frame position and the end frame position are stored correspondingly. And read the audio / video data in the copy range specified by the end frame position from the removable disk, and write the read audio / video data as a new file to the hard disk or the removable disk. This eliminates the need for time for pre-roll and pre-roll, thus improving efficiency. In addition, since only necessary parts are specified and copied, the storage capacity of the disk can be used effectively.

Further, according to the present invention, when the coded data of the frame at the start frame position designated to be copied is not a GOP boundary with respect to a removable disk in which video and audio data is compressed and recorded by the MPEG system, If the start frame position is changed to the position of the boundary of the GOP, and the encoded data of the frame at the end frame position is not the boundary of the GOP, the end frame position is changed to the boundary of the GOP.
Necessary portions can be copied without omission even with video / audio data using inter-frame compression such as the MPEG system.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a video editing device according to an embodiment of the present invention.

FIG. 2 is a table showing data at the time of capture by the video editing device shown in FIG. 1;

FIG. 3 is a flowchart showing the operation of the video editing device shown in FIG.

FIG. 4 is a block diagram showing a configuration of a video editing apparatus according to another embodiment of the present invention.

5 is a flowchart showing the operation of the video editing device shown in FIG.

FIG. 6 is a block diagram illustrating a configuration of a conventional video editing device.

FIG. 7 is a table showing data at the time of capture by the conventional video editing device shown in FIG. 6;

FIG. 8 is a flowchart showing the operation of the conventional video editing device shown in FIG.

[Explanation of symbols]

 101 Video Recorder 103 JPEG Compressor 109 Removable Optical Disk 110 Optical Disk Drive 113 Memory 114 CPU 115 Hard Disk (HDD) 116 JPEG Decompressor 119 Controller 203 MPEG Compressor 216 MPEG Decompressor

Claims (6)

[Claims] 1. A video editing device comprising a disk drive for inserting a removable disk and a hard disk, and copying video and audio data recorded on the removable disk inserted into the disk drive to the hard disk, File specifying means for specifying a video / audio data file to be copied among the files recorded on the disk; and specifying a frame position as a copy start point in the video / audio data file specified by the file specifying means. Start frame position designating means to perform, an end frame position designating means for designating a frame position to be an end point of copying in the video / audio data file designated by the file designating means, and a file designated by the file designating means Name, the start frame position designating means and the Copy range storage means for respectively storing the start frame position and the end frame position respectively designated by the end frame position designation means, and the start frame position and the end frame position designated by the start frame position and the end frame position stored in the copy range storage means. A video reading device for reading video / audio data in a copy range from the removable disk, and a data writing device for writing the video / audio data read by the data reading device as a new file to the hard disk. Editing device. 2. The removable disk records video and audio data by compressing the video and audio data by intra coding, and expands the video and audio data recorded by compressing and recording the video and audio data by intra coding on the removable disk. 2. The video editing apparatus according to claim 1, further comprising a decompression output means for outputting the decompressed and restored video and audio data. 3. The removable disk records video and audio data by compressing the data in an MPEG format, and the start frame position designating means and the end frame position designating means comprise the designated start frame position and end frame position. The encoded data of each frame at the position is G
Determining means for determining whether or not the frame is at the boundary of the OP; and, if the determination result indicates that the encoded data of the frame at the start frame position is not at the boundary of the GOP, the start frame position is set to the position of the boundary of the GOP. 2. The apparatus according to claim 1, further comprising: changing means for changing the end frame position to a GOP boundary when it is determined that the encoded data of the frame at the end frame position is not on the boundary of the GOP. Video editing device. 4. At least two disk drives into which a removable disk is inserted, wherein video / audio data recorded on the removable disk inserted into one disk drive is inserted into the other disk drive. What is claimed is: 1. A video editing apparatus for copying to a removable disk, comprising: a file specifying unit that specifies a video / audio data file to be copied among files recorded on the one disk; and a video specified by the file specifying unit. A start frame position designating unit for designating a frame position to be a copy start point in the audio data file; and a frame position to be a copy end point in the video / audio data file designated by the file designating unit. End frame position specifying means, and file name specified by the file specifying means Copy range storage means for storing the start frame position and the end frame position respectively specified by the start frame position specification means and the end frame position specification means, and the start frame stored in the copy range storage means Data reading means for reading video and audio data in a copy range specified by a position and an end frame position from the one disk, and data writing means for writing the video and audio data read by the data reading means to the other disk as a new file And a video editing device. 5. The one removable disk records video / audio data by compressing the data by intra coding, and the video recorded by compressing the audio / video data by intra coding on the one removable disk. 5. The video editing apparatus according to claim 4, further comprising a decompression output means for decompressing the audio data and outputting the decompressed video / audio data. 6. The one removable disk records video and audio data by compressing the data in an MPEG format, and each of the start frame position designating means and the end frame position designating means stores the designated start frame. Determining means for determining whether the encoded data of each frame at the position and the end frame position is a boundary of a GOP,
When it is determined that the encoded data of the frame at the start frame position is not at the boundary of the GOP, the start frame position is changed to the position of the boundary of the GOP, and the encoded data of the frame at the end frame position is changed to the GOP boundary. If it is determined that the end frame position is not the boundary of
5. The video editing apparatus according to claim 4, further comprising: changing means for changing to a boundary of P.