JP2003308650A - Data reproducing method, data reproduding apparatus, data recording and reproducing method, and data recording and reproducing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To limit the number of times of reproducing a medium only once while securing data security. <P>SOLUTION: The data recording and reproducing apparatus 20 comprises: a demodulation circuit 38 for demodulating data reproduced from a disk 10; a buffer memory 42 for receiving a demodulation output via an error correction decoding circuit 40; and a control section 35 for controlling them. The buffer memory is controlled to perform write processing of data at a read speed of the data and to read the data having already been read at a data transfer speed slower than the read speed. Utilizing a time difference between the data read speed and the data transfer speed rewrites all or part of data recorded on the disk. Since reproduced data themselves are written into random data during data reproduction in this way and it results in limiting second use of the data, one-time rental or the like is attained by limiting the number of utilizing times while securing the data security. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data reproducing method, a data reproducing apparatus, a data recording / reproducing method and a data recording / reproducing apparatus. Specifically, when renting a packaged media at a rental shop or the like, the number of times that the packaged media can be played is limited so that the content included in the rented packaged media can be illegally copied or cannot be used without restriction. It is a thing.

[0002]

2. Description of the Related Art With the advent of the broadband era, users are in an environment where they can easily obtain a wide variety of contents. There are various contents available such as music and video. It is possible to purchase these contents from content distributors (record shops etc.) each time, but when the contents are video etc., the purpose is often fulfilled by just watching it once, so mania etc. With the exception of, the package media is not generally purchased and stored by the user. Assuming such a situation, it is conceivable that the user will frequently rent and use the intended package media at a rental shop or the like.

[0003]

By the way, since the method of using the packaged media lent to the customer is left to the customer, depending on the customer, there is a case where the object is achieved by only reproducing once. It is also possible to repeatedly play a moving scene or song.

In some cases, it may be possible to copy contents from this package medium. This copy may deviate from the scope of personal use, in which case it is less preferable from the viewpoint of copyright protection.

In consideration of such a situation, it is better to limit the number of times the package media that has been lent out is used. For example, it is preferable to construct a packaged media system that limits the number of times of use to one and cannot use the media from the second time onward so that the media can be rented for one time.

Therefore, the present invention has solved such a conventional problem, and limits the number of times the package medium is used and prohibits the use exceeding the limit. It proposes a playback device.

[0007]

In order to solve the above-mentioned problems, in the data recording / reproducing method according to the present invention described in claim 1, during reproducing the data recorded on the recording medium, during the reproduction of the data. Alternatively, it is characterized in that all or part of the above data is rewritten immediately after data reproduction.

In the data recording / reproducing apparatus according to the present invention described in claim 9, the demodulation circuit for demodulating the data reproduced from the recording medium, and the demodulated data are supplied via the error correction decoding circuit. The data write processing is performed at the data read speed, and the buffer memory means for reading the already written data at a data transfer speed slower than the read speed and the buffer memory means are controlled. A control unit for controlling the data is provided, and all or part of the data recorded on the recording medium is rewritten by utilizing the time difference between the data reading speed and the data transfer speed.

In the data reproducing method according to the seventeenth aspect of the present invention, when reproducing the data recorded on the recording medium, the light emission power of the light source used during the data reproduction is selected according to the reproducing condition. It is characterized by having done.

In the data reproducing apparatus according to the present invention as defined in claim 23, a demodulating circuit for demodulating data reproduced from a recording medium, an error correction decoding circuit to which the demodulated data is supplied, and the demodulating circuit. A subcode decoder to which the output of the circuit is supplied, a control command discrimination circuit to which the output of the subcode decoder is supplied, a control unit for controlling the recording / reproducing mode, and a light emission power control controlled by the output of this control unit. It is configured by a circuit and an optical pickup unit having a light source controlled by the light emission power, and the light emission power of the light source at the time of reproduction is controlled based on the determination output of the control command. And

In the data recording / reproducing apparatus according to the present invention as defined in claim 28, a demodulation circuit for demodulating data reproduced from a recording medium, an error correction decoding circuit to which the demodulated data is supplied, A subcode decoder to which the output of the demodulation circuit is supplied, a control command discrimination circuit to which the control command inserted in this subcode decoder is supplied, a control unit for controlling the recording / reproducing mode, and control by the output of this control unit. And a light pickup unit having a light source controlled by the light emission power, wherein the control command is a command for controlling the light emission power of the light source during recording or reproduction, The light emission power is controlled based on the determination output of this control command.

The present invention is intended for a rewritable package medium such as an optical disc as a recording medium. In order to limit the number of times the data (content data, etc.) recorded on this recording medium is used, that is, at the stage where the content is being reproduced or at the stage when the content reproduction is completed, for example, for one-time use, it is recorded on the recording medium. The data, for example, the content data itself is rewritten. Then, reuse (playback processing) becomes impossible, and if the package media is package media lent from the rental shop,
One-time lending can be realized.

If the package media whose use is prohibited again is returned to a rental shop or the like, it can be reused by sending it to the factory, so that resale is possible and limited resources can be effectively used.

Rewriting of data is not limited to content data, but information added to this content data can be rewritten. As additional information, in addition to synchronization bits, header information, etc., key data for decryption when authentication data or content data is encrypted (when using a combination of multiple key data, all or part of it) Key data) and so on. Rewriting the additional information can also prevent reuse of the content. This is because, when the additional information such as the sync bit cannot be detected on the data recording / reproducing apparatus side, the content data becomes an error and the content data cannot be restored.

The data rewriting timing is not limited to the timing at which the reproduction of the content is completed, and may be during the reproduction of the content. When the content is being played back, by changing the data read speed from the recording medium and the speed at which the read data is transferred to the playback amplifier, etc., the time difference between the read speed and the transfer speed is used to transfer the data. Is rewritten. This is because the data read speed is usually faster than the transfer speed. By using this time difference and intermittently switching to the recording mode, the content data can be rewritten almost at the same time as the content reproduction. As a result, illegal use of content can be effectively and reliably eliminated.

Rewriting of data can be achieved by erasing the data itself, overwriting (overwriting) the data, or rewriting with meaningless data. The rewriting of data does not have to be all of it, and a part of it may be rewritten so that the content cannot be reused.

Since the one-time package medium is different from the normal package medium, its identification information (identification data) is inserted into the recording data. For example, this identification data can be inserted in a subcode that is auxiliary information to the content data. For that purpose, for example, the data area of the Q channel may be used.
On the data recording / reproducing apparatus side, the identification data inserted in the Q channel is monitored, and when the identification data is detected, it is determined that the medium is a one-time package medium and the above-mentioned data rewriting process may be performed.

Instead of rewriting the data recorded on the recording medium, the data reproduced by a simple reproduction process can be rewritten to meaningless data. When the data recorded on the recording medium is reproduced using a light emission power intermediate between the light emission power of the light source used during data recording and the light emission power of the light source used during data reproduction, despite the fact that the data is reproduced, Since the writing state (recording state) is reached, at the stage when the reproduction is completed, completely different data (random data) from the reproduction data is recorded on this recording medium, which is the reproduction mode. Nevertheless, it is possible to rewrite the recorded data. Hereinafter, the mode for reproducing the data with the intermediate light emission power is referred to as a secure mode.

This secure mode is executed for a one-time package medium. Therefore, a control command is inserted in the recording medium. This control command is a command for determining the light emission power. When the control command designates the secure mode, during reproduction of the recording medium, data is reproduced with an intermediate emission power, content data is reproduced, and new random data is written.

Writing of data is not always performed, and by repeating writing of random data or leaving it as it is, the same result as rewriting to random data can be obtained as a whole. . The control command is inserted in the data area of the Q channel.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Next, one embodiment of a data reproducing method, a data reproducing apparatus, a data recording / reproducing method and a data recording / reproducing apparatus according to the present invention will be described in detail with reference to the drawings. First, a first invention will be described in which content data recorded on a disc (package medium) which is a recording medium is rewritten during or after the reproduction of the content data.

FIG. 1 is a system diagram of essential parts showing an embodiment of a data recording / reproducing apparatus according to the present invention to which a data reproducing method, a data reproducing apparatus and a data recording / reproducing method according to the present invention are applied, and FIG. A configuration example of the data recording medium 10 used at that time will be shown.

For convenience of explanation, referring to FIG. 2, the recording medium 10 is a writable recording medium (hereinafter referred to as a disc), and in a compact disc CD, a write-once type CD-R or a rewritable type CD-R. RW etc.,
In case of digital versatile disc DVD, write-once type D
A VD-R, a rewritable DVD-RW, or the like can be used. Hereinafter, a CD-R will be exemplified as the writable disc.

The basic structure of the disc 10 is the same as that of a known disc, and as shown in FIG. 2, a lead-out area 12 is located at the outermost periphery and a program area (PA) which is a content recording area inside thereof. ) 14 are present. On the inner circumference side of the program area 14, TOC (Tabl
e of Contents) Lead-in area 16 for recording information
There is a program memory area (P
MA) 18 is provided. The program area 14 is the main recording area, and the lead-in area 16 and the program memory area 18 correspond to the auxiliary recording area.

As is well known, the program memory area 18 records temporary TOC information before completion processing or finalization processing. While the temporary TOC is recorded in the program memory area 18, contents can be written in the program area 14. However, when the operation for completing the process is performed, the TOC information is written in the lead-in area 16, and the subsequent writing (recording) process cannot be performed.

A subcode is recorded in the program memory area 18. FIG. 3 shows the frame structure of the Q channel of the subcodes. As is well known, this is 4-bit control data, 4-bit address data,
It is composed of bit data and a 16-bit error detection code CRC (Cyclic Redundancy Check Code).

The address data ADR is ADR = 1 (=
0001), the following data is T
Since OC information has been inserted, ADR = 2 (=
In the case of (0010), maker optional data is inserted in the next data area.

In the present invention, the identification data is inserted into the disc 10 in order to distinguish between the existing disc and the disc to which the present invention is applicable. The identification data only needs to be within the data recorded on the disc 10, and therefore, can be overwritten on the content data recorded in the program area 14 or the program memory area 1
It can also be inserted in a part of the subcode recorded in No. 8.

An example of inserting the subcode in a part will be described with reference to FIGS. 4 and 5. In case of subcode, Q
You can use a part of the channel. The data structure of the Q channel is as shown in FIG. In FIG. 4, synchronization patterns S0 and S1 (2 bits) are provided at the beginning of the frame.
Is added, followed by the control bit (4
Bits), followed by address bits (4 bits).

The area following the data area is
The number TNO of the movement recorded on the disc 10, the point POINT, the minute (MIN), the second (SEC) and the frame number (FRAME) are inserted as data indicating the elapsed time (time information) in the movement. After inserting zero data, the absolute time (minutes, seconds and frame number, which functions as address information) of the contents of point is inserted. Finally, the CRC code (16 bits) which is the error correction code described above is added to form one frame. Everything after the movement number is composed of 8-bit units.

The above-mentioned identification data can be inserted as shown in FIG. 5, for example, instead of the time information and address information in a specific frame. In the case of FIG. 5, since the identification data can be inserted using up to 56 bits, the identification data includes the disc label name (title) and other supplementary information (if the number of uses is limited, Information indicating a limit number of times) can also be added. The address data ADR of the frame in which the identification data is inserted is
ADR = 2.

Subsequently, the data recording / reproducing apparatus 2 shown in FIG.
0 embodiment will be described in detail. When the reproduction mode is selected by operating the key operation unit (which may be a remote controller) 48, the optical pickup unit 32 causes the disc 10 to operate.
The recording data is read from. The read data is supplied to the demodulation circuit 38 via the RF amplifier 36, and the EF
After M demodulation, that is, (8-14) demodulation, the data is supplied to the error correction decoding circuit 40, and error correction and decoding processing is performed.

As the error correction processing, the well-known CIRC is used.
An error correction coding process (double error correction process) by (Cross Interleave Reed-Solomon Code) is applied.
Although not shown as an embodiment, in a DVD disc, which is a kind of writable recording medium,
-Error correction and coding processing using PC (Reed-Solomon Product Code) is performed.

The content data that has been subjected to error correction and decoding processing is supplied to the buffer memory means 42.
The buffer memory means 42 can use a semiconductor memory such as a RAM. Hereinafter referred to as buffer memory. In this example, the writing process to the buffer memory 42 is performed at the data reading speed from the disk 10. And
Since the reproduction amplifier system is connected to the subsequent stage of the buffer memory 42, the data is read at a normal read speed (transfer speed for data reproduction (constant speed)). If the content is music, the music can be played at a normal speed, and if the content is a video, the video can be reproduced at a constant speed. The write and read operations for the buffer memory 42 will be described later.

A part of the demodulated output demodulated by the demodulation circuit 38 is further supplied to the subcode decoder 44 to execute the subcode decoding process, and the decoded output is supplied to the control section 35 equipped with a CPU. Q out of subcode
The presence or absence of identification data inserted in the channel is determined.

When there is no identification data, the disc is a normal disc, so the processing peculiar to the present invention is not performed. When the identification data is detected, the data recorded on the disk 10 is rewritten using the free time for writing in the buffer memory 42 while reproducing the data.

For this data rewriting process, a buffer monitor 50 for monitoring the amount of data recorded in the buffer memory 42 and a recording circuit 52 for recording random data on the disk 10 are provided. Furthermore, the optical pickup unit 3 is provided in the recording area for recording random data.
In order to move 2, the control unit 35 controls the servo controller 46.

This recording operation will be described in connection with the writing and reading operations of the buffer memory 42 with reference to FIG. Generally, the data read speed from the disk 10, and hence the write speed to the buffer memory 42, is faster than the read speed at which data is read from the buffer memory 42, that is, the data transfer speed. It becomes like FIG. 6A, B, C.

FIG. 6A is a timing chart when reading data from the disk 10. Data is read in predetermined units. The predetermined unit is the buffer memory 42.
It is determined by the capacity of the above, and a plurality of frames can be set as a read unit if the frame unit described above is acceptable. The embodiment is a case where several frames are read as the read unit RT.

The data read from the disk 10 is
Data is written in the buffer memory 42 at the same speed as the data reading speed (FIGS. 6A and 6B). On the other hand, when the data is read from the buffer memory 42, it is slower than the data writing speed, and the timing chart at that time is as shown in FIG. 6C. That is, a time difference ΔT as shown in the figure occurs between the data writing speed and the data reading speed to the buffer memory 42.

Utilizing this time difference ΔT, data rewriting is performed on the data read immediately before. For example,
As shown in FIG. 6A, when the time required to rewrite the data in the read unit RT is ΔTa (<ΔT), the control unit 35 monitors the buffer monitor 50 and the time when the data writing to the buffer memory 42 is completed. If it is determined that the recording mode is satisfied, the recording mode is switched to the recording mode for a period of ΔTa from that point. Then, the optical pickup unit 32 is tracked to the data area read immediately before, and the area is rewritten with the random data generated by the recording circuit 52.

By doing so, the read data (content data) is rewritten to another data (data unrelated to the content data) immediately after that, and thus the content cannot be reused again. become. The data rewriting period is shown as “OW” in FIG. 6A, and the data read suspension period is shown as “S”.

Since the time required for rewriting data is ΔTa and the time difference is ΔT, the time difference ΔT in this example.
From the time point α before the end of, that is, after (ΔTa + ΔTb) has elapsed, a process of reading the next data from the disk 10 by a predetermined unit is performed, and thereafter, similar read and write operations are repeated. In this way, the data can be read from the buffer memory 42 without interruption, so that the continuity of the reproduction time can be ensured even in the case of music.
No sound breaks occur. The above-described α may be zero, that is, the reading process may be performed slightly after the data writing process to the buffer memory 42.

The data can be rewritten by random data as described above, or the same rewriting can be performed by completely erasing the data itself. The rewriting of data may be performed not only on all the recorded data but also on some of the data intermittently. In short,
This is because the rewriting process may be performed so that the reproduced data cannot be reused.

The data to be rewritten is the content data itself recorded in the program area 14 in the above example, but the rewriting of data is not limited to the content data, and the information added to this content data can be rewritten. . As additional information, in addition to synchronization bits, header information, etc., key data for decryption when authentication data or content data is encrypted (when using a combination of multiple key data, all or part of it) Key data) and so on. Rewriting the additional information can also prevent reuse of the content. This is because, when the additional information such as the sync bit cannot be detected on the data recording / reproducing apparatus side, the content data becomes an error and the content data cannot be restored. Of course, for example, the subcode data (synchronization bits, header information, and the key data described above) recorded in the program memory area 18 may be used. If these data are rewritten, the data cannot be synchronized during playback, or the header cannot be detected to demodulate the actual data, resulting in a data error. As a result, it is the same as when the content data was rewritten. Because.

When the time required for rewriting data is not ΔTa but the same as the data read time RT, the operation as shown in FIG. 7 is performed. In this case, the data read time from the buffer memory 42 is assumed to take 2RT or more, and the data read mode is switched at a stage later than the time when the data rewriting is completed.

The above-mentioned identification data is explained on the premise of one-time read, but when the disc 10 is limited in the number of times of use, the information limiting the number of times of use in this identification data is the title of the disc or the like. Included with information. The control unit 35 monitors the number of times of use (reproduction number) of the same title, and when the number of times of use reaches the limit, the above-mentioned data rewriting process is performed.

Next, the second invention will be described with reference to FIG. The second invention is to rewrite data by using the secure mode. When data is normally recorded on the disk 10 and the light source used when reading the data from the disk 10 is a laser, the emission power PA (laser power) at the time of data recording is usually 30 m.
It is about W. The light emission power PC at the time of reading data is controlled to about 3 mW, and this light emission power P
Data can be sufficiently read with C.

On the other hand, the light emission power PA of the light source used at the time of data recording and the light emission power PC of the light source used at the time of the data reproduction, for example, 10 mW.
When the data recorded on the recording medium is reproduced by using the light emission power PB of, the recorded data can be normally reproduced (read out), but it can be written even though the data is reproduced. Status (recording status)
And, the state that can not be written occurs randomly. Therefore, at the stage when the reproduction is finished, completely different data (random data) from the reproduced data is recorded on the entire recording medium or partially recorded on the recording medium. Despite that, the data on the disk 10 can be rewritten.

It should be noted that if the package media, which is prohibited from being used again, is returned to a rental shop or the like, it can be reused by sending it to the factory, so that it can be resold and effectively utilize limited resources. it can.

The second invention utilizes the secure mode in which the data is reproduced with the intermediate light emission power PB as described above. However, even in this case, it is necessary to identify the existing disc and the disc applicable to the present invention, and record the information regarding which light emission power should control the light source. Information to be recorded including this identification information is generically called a control command.

In the present invention, this control command is recorded on the disk 10. The area to be recorded shows the case where the subcode is used as in the first invention. In particular, when using the data area of the Q channel, a control command is inserted instead of the identification data as shown in FIG.

FIG. 8 is a system diagram of essential parts showing an embodiment of a data recording / reproducing apparatus according to the present invention to which the data recording / reproducing method according to the present invention is applied. The parts corresponding to those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

The decoded output of the subcode decoder 44 is supplied to the control command discrimination circuit 54, the content thereof is decoded, and the decoded result is supplied to the control unit 35 as a light emission power designation signal. The control command includes at least identification data that is the target of the secure mode and a command that specifies the operation mode.

On the other hand, in the optical pickup unit 32,
A laser 33 is provided as a light source, and the emission power for this laser 33 is controlled by the output from the emission power control circuit 60. Specifically, the emission power control circuit 60 is configured as an applied voltage source for the laser 33, and the emission power is controlled by changing the applied voltage. Therefore, as shown in FIG. 9, the light emission power control circuit 60 is provided with three stages of light emission power sources (laser power sources) 62, 64, 66 and a switching means 68 in this example, and the switching means 68 is provided.
Is selected by the control signal CTL from the control unit 35. The control unit 35 generates the control signal CTL based on the light emission power designation signal.

FIG. 10 shows an example of this light emission power control. A control command is extracted from the subcode data (Q channel data) (step 71), and when the control command is a command designating the recording mode, the control command is extracted. The emission power PA to be used at this time is specified (step 7
2, 73), when the reproduction mode is set, the emission power PC used at that time is designated (step 7).
4,75). When the control command is a command for designating the secure mode, the light emission power PB for the secure mode is designated (steps 74, 76).

In the above-described embodiments, the optical disk is exemplified as the recording medium, but other writable magneto-optical disks, magnetic recording media, semiconductor memories and the like can be used.

[0058]

As described above, in the recording / reproducing method and the data recording / reproducing apparatus according to the present invention, the data recorded on the recording medium is prevented from being reused during the reproduction of the data or after the end of the data reproduction. It was done.

According to this, when the content data recorded on the recording medium exceeds the limit of the number of times that it can be used, the content data can no longer be reused. For example, this method is rented from a rental shop or the like. If it is applied to the data reproducing system of the package media, one-time lending can be realized, and thus, there is a practical benefit that the illegal use can be surely excluded while ensuring the security of the contents recorded on the recording medium.

Further, if the packaged media whose use is prohibited again is returned to the rental shop or the like, it can be reused by sending it to the factory, so that resale is also possible and the limited resources are effectively utilized. it can.

[Brief description of drawings]

FIG. 1 is a system diagram of essential parts showing an embodiment of a data recording / reproducing apparatus according to the present invention to which a data recording / reproducing method according to the present invention is applied.

FIG. 2 is a block diagram of a recording medium that can be used in the present invention.

FIG. 3 is a diagram showing a frame structure in a Q channel of subcode.

FIG. 4 is a diagram showing a data structure of a Q channel.

FIG. 5 is a diagram showing a data structure of a Q channel in which identification data is inserted.

FIG. 6 is a timing chart showing an example of data rewriting processing applicable to the present invention (No. 1).

FIG. 7 is a timing chart showing an example of data rewriting processing applicable to the present invention (part 2).

FIG. 8 is a system diagram of essential parts showing an embodiment of a data recording / reproducing apparatus according to the present invention to which the data recording / reproducing method according to the present invention is applied.

FIG. 9 is a diagram showing a specific example of a laser power control circuit.

FIG. 10 is a flowchart showing an example of a data reproduction process according to the present invention.

[Explanation of symbols]

10 ... Writable recording medium, 18 ... Program memory area, 38 ... Demodulation circuit, 40 ... Error correction decoding circuit, 42 ... Buffer memory, 44
... Sub-code decoder, 50 ... Buffer monitor, 52 ... Recording circuit, 54 ... Control command determination circuit, 60 ... Emission power control circuit, 33 ...
..Laser light source

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ identification code FI theme code (reference) G11B 7/005 G11B 7/005 A (72) Inventor Tatsuya Inokuchi 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo No. Sony Corporation (72) Inventor Shunsuke Furukawa 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) Inventor Junichi Hasegawa 6-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni -In-house F-term (reference) 5D044 BC01 BC04 CC04 DE55 DE70 EF05 FG10 FG18 GK12 HH07 HH15 5D090 AA01 BB03 BB04 CC07 DD03 GG17 HH01 KK03

Claims (32)

[Claims] 1. A data recording / reproducing method characterized in that, when reproducing data recorded on a recording medium, all or part of the data is rewritten during or immediately after reproducing the data. 2. The data recording / reproducing method according to claim 1, wherein the data is either content data or additional data added to the content data. 3. The data according to claim 2, wherein the additional data is any one of synchronization data added to the content data, header data, and key data when the content data is encrypted. Recording and playback method. 4. The data recording / reproducing method according to claim 1, wherein when the identification data inserted in the data area of the Q channel of the subcode is detected, the rewriting processing of the data is performed. 5. The data recording / reproducing method according to claim 1, wherein all or part of the data is rewritten by erasing, overwriting, or rewriting the data. 6. The method according to claim 1, wherein all or part of the data is rewritten by utilizing a time difference between a data read speed from the recording medium and a read data transmission speed. Data recording and reproducing method. 7. The data recording / reproducing method according to claim 6, wherein the recording mode is transited to the recording mode only during the time difference to rewrite all or part of the data. 8. The data recording / reproducing method according to claim 1, wherein the recording medium is any one of a writable optical disc, a magneto-optical disc, a magnetic recording medium, and a semiconductor memory. 9. A demodulation circuit for demodulating data reproduced from a recording medium, and the demodulated data is supplied through an error correction decoding circuit, and a writing process of the data is performed at a reading speed of the data. A buffer memory means for reading the already written data and a control section for controlling the buffer memory means are provided at a data transfer speed slower than the read speed, and the data read speed and data A data recording / reproducing apparatus, wherein all or part of the data recorded on the recording medium is rewritten by utilizing a time difference from a transfer speed. 10. The data recording / reproducing apparatus according to claim 9, wherein the data is either content data or additional data added to the content data. 11. The data according to claim 9, wherein the additional data is any one of synchronous data added to the content data, header data, and key data when the content data is encrypted. Recording / playback device. 12. The data recording / reproducing apparatus according to claim 9, wherein identification data for rewriting the data is inserted in a part of the data. 13. The data recording / reproducing apparatus according to claim 9, wherein the identification data is inserted in a data area included in the Q channel of the subcode. 14. The data recording / reproducing apparatus according to claim 9, wherein all or part of the data is rewritten by erasing, overwriting, or rewriting the data. 15. The recording mode is switched to the rewriting process of all or part of the data after the writing of the data to the buffer memory unit for each predetermined unit is completed. 9. The data recording / reproducing apparatus according to item 9. 16. The data recording / reproducing apparatus according to claim 9, wherein the recording medium is one of a writable optical disc and a magneto-optical disc. 17. A data reproducing method, characterized in that when reproducing data recorded on a recording medium, the light emission power of a light source used at the time of data reproducing is selected according to the reproducing condition. 18. When reproducing the data recorded on the recording medium and rewriting all or part of the data at the same time, the emission power of the light source used during the data recording and the light source used during the data reproduction are controlled. 18. The data reproducing method according to claim 17, wherein the data recorded on the recording medium is reproduced by using a light emission power intermediate to the light emission power. 19. The data reproducing method according to claim 18, wherein a laser light source is used as the light source. 20. When the control command inserted in the data recorded on the recording medium specifies an intermediate emission power, the data is reproduced with the intermediate emission power. Claim 18
The data reproduction method described. 21. The data reproducing method according to claim 20, wherein the control command is inserted in a data area of a Q channel included in a subcode. 22. The data reproducing method according to claim 17, wherein the recording medium is any one of a writable optical disc, a magneto-optical disc, and key data when the content data is encrypted. 23. A demodulation circuit for demodulating data reproduced from a recording medium, an error correction decoding circuit to which the demodulated data is supplied, and a subcode decoder to which an output of the demodulation circuit is supplied. A control command discrimination circuit to which the control command inserted in the subcode decoder is supplied, a control unit for controlling the recording / reproducing mode, a light emission power control circuit controlled by the output of this control unit, and a light emission power control unit. And a light pickup unit having a light source for controlling the light emission power of the light source during reproduction, based on the determination output of the control command. 24. When reproducing the data recorded on the recording medium and at the same time rewriting all or part of the data, the control command causes the light emission capable of rewriting all or part of the data. 3. A reproduction command for designating power.
3. The data reproducing device described in 3. 25. The data reproduction according to claim 24, wherein the emission power is an emission power intermediate between the emission power of the light source used for recording the data and the emission power of the light source used for reproducing the data. apparatus. 26. The data reproducing apparatus according to claim 23, wherein the control command is inserted into a data area of a Q channel included in a subcode. 27. The data reproducing apparatus according to claim 23, wherein the recording medium is any one of a writable optical disc, a magneto-optical disc, and key data when the content data is encrypted. 28. A demodulation circuit for demodulating data reproduced from a recording medium, an error correction decoding circuit to which the demodulated data is supplied, and a subcode decoder to which the output of the demodulation circuit is supplied. A control command discrimination circuit to which the control command inserted in the subcode decoder is supplied, a control unit for controlling the recording / reproducing mode, a light emission power control circuit controlled by the output of this control unit, and a light emission power control unit. And an optical pickup unit having a light source for controlling the light emission power of the light source at the time of recording or reproduction, and the light emission power is controlled based on the discrimination output of the control command. A data recording / reproducing apparatus characterized in that 29. When the data recorded on the recording medium is reproduced and at the same time all or part of the data is to be rewritten, the control command causes the light emission to rewrite all or part of the data. 3. A reproduction command for designating power.
8. A data recording / reproducing apparatus according to item 8. 30. The data recording according to claim 29, wherein the emission power is an emission power intermediate between the emission power of the light source used during data recording and the emission power of the light source used during data reproduction. Playback device. 31. The data recording / reproducing apparatus according to claim 28, wherein the control command is inserted into a data area of a Q channel included in a subcode. 32. The data recording / reproducing apparatus according to claim 28, wherein the recording medium is any one of a writable optical disc, a magneto-optical disc, and key data when the content data is encrypted.