JP2002006885A - Method for recording and reproducing conditional digital information, reproducing method, and storage medium used for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for recording and reproducing digital information, a reproducing method, and a recording medium used for them, which indirectly inform a user of digital information that a term of reproducing expires and surely protect secrecy of contents of digital information after expiration of the term of reproducing. SOLUTION: In order to reproduce and output digital information accompanied with condition information indicating the term of reproducing from the recording medium in this recording and reproducing device, a control means discriminates whether the term of reproducing expires or not on the basis of conditional information (step #5), and the control means selects data from digital information at random (steps #10 and #15) when discriminating expiration of the term of reproducing, and changed or erased digital information of selected data is updated and recorded in the recording medium (step #29), and the position of changed or erased data is recorded in the recording medium (step #25).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing apparatus and a reproducing method for reproducing digital information provided with a condition that the reproduced content deteriorates with time, and a recording medium used for the same.

[0002]

2. Description of the Related Art In recent years, music, movies, and the like have been digitized, and their use forms have been widely spread. For example, by connecting a terminal owned by an individual to a host computer by wire or wirelessly and distributing the digital information from the host computer to the terminal, music, movies, and the like can be enjoyed individually.

[0003] Accordingly, it is possible to provide music information to individuals on a tune-by-tune basis via the Internet. Also,
Since digital information can be easily copied, vending machine systems have been proposed in which information such as music is copied to personal terminals by paying money to vendors installed in various places.

[0004] One of the conveniences of such digital information is that it does not deteriorate. However, there is a risk that information such as music having copyright may be illegally copied. Therefore, at present, a method of performing flag management so that the original information can be copied by serial copy management, but the copied information cannot be further copied.

[0005] In addition, there has been proposed digital information with a time limit in which the digital information is provided with a playback time limit and the playback becomes impossible when the time limit is reached. This time-limited digital information is useful not only for copyright protection but also for use as music information for trial listening for the purpose of promoting the sales of music CDs, for example.

[0006] These digital information are recorded and reproduced by a recording and reproducing apparatus. Each device is provided with a digital signal processor that performs arithmetic processing for compressing digital information, and a number of information compression techniques have been proposed and standardized. Recently, a recording / reproducing apparatus using a tape-based recording medium by applying these compression methods, a portable audio apparatus and a video apparatus based on a disk medium, and the like have been put to practical use. Also, a recording / reproducing apparatus in which the compression method is applied to a semiconductor memory has been developed.

[0007]

However, in the method in which duplication of digital information is prohibited by flag management, since the information itself remains in the recording means, duplication is possible if the flag is tampered with maliciously. become. The same applies to digital information with a time limit. If the configuration makes reproduction impossible by flag management, it can be easily reproduced by falsification of the flag.

When digital information with a time limit is used, most users do not remember the time limit. Therefore, the user is confused because the expiration date arrives without knowing and sudden reproduction becomes impossible. Therefore, in some cases, it also causes a nonsense call.

Further, when the time-limited digital information becomes unreproducible due to the time limit, it is often erased from the viewpoint of effective use of the recording medium. Therefore, in order to obtain the same digital information, it is necessary to record all the digital information again, and much time is required.

Further, in a recording / reproducing apparatus for reproducing digital information with a time limit, it is of course possible to manage the time limit. However, a portable device has a clock function and a timer under the restriction of software and hardware. Functions, counting functions, management tables, etc. must be designed efficiently. In fact, these data can be a significant burden on software and hardware, and are not very realistic in terms of cost.

An object of the present invention is to provide an apparatus and a method for recording and reproducing conditional digital information which solve the above-mentioned problems.

[0012]

In order to achieve the above object, a recording / reproducing apparatus of the present invention can reproduce and output digital information to which condition information indicating a reproduction time limit is added from a recording medium. The recording / reproducing apparatus includes control means for deteriorating the content represented by the digital information to which the condition information is attached based on the reproduction time limit indicated by the condition information, and updating and recording the degraded digital information on the recording medium. I have.

This control means changes or deletes a part of the data of the digital information to which the condition information is added, based on the reproduction period indicated by the condition information. Then, the position of the changed or deleted data is recorded on the recording medium. Therefore, if the digital information is reproduced and output from the recording medium thereafter, the contents will be degraded due to data change or erasure.

In the recording / reproducing apparatus according to the present invention, the control means converts a part of the data of the digital information to which the condition information is added based on the reproduction time limit indicated by the condition information to another content represented by the data. Change to data obtained by superimposing the contents.

While the data before the change and the data after the change are recorded in the recording medium in advance, the control means controls the digital information to which the condition information is added before the change based on the reproduction time limit indicated by the condition information. Alternatively, either the changed data is reproduced. As a result, the data before the change is reproduced before the expiration of the reproduction time limit, and the data after the change is reproduced after the expiration of the reproduction time limit.

Further, in the recording / reproducing apparatus of the present invention, the condition information includes a parameter indicating a gradient of deterioration, and the control means controls the content represented by the digital information to which the condition information including the parameter is attached based on the parameter. Deteriorates.

Also, a method for reproducing digital information to which condition information indicating a reproduction time limit is added from a recording medium by the recording / reproducing apparatus of the present invention includes a step of judging the arrival of the reproduction time limit based on the condition information; The step of changing or erasing a part of the data of the digital information to which the condition information is attached when it is determined that the information has arrived; and the step of updating and recording the digital information having the part of the data changed or deleted on a recording medium. Reproducing the updated and recorded digital information from the recording medium.

Also, a method for reproducing from a recording medium digital information to which condition information indicating a reproduction time limit is added by the recording / reproducing apparatus of the present invention, wherein a step of judging the arrival of the reproduction time limit based on the condition information; When it is determined that the playback time limit has not arrived, the data before change recorded on the recording medium is selected. When it is determined that the playback time limit has arrived, the data after change recorded on the recording medium has been selected. And deleting the pre-change data and reproducing the selected pre-change or post-change data.

Further, the method for reproducing from a recording medium digital information to which condition information including a parameter indicating a slope of deterioration by the recording / reproducing apparatus of the present invention is applied is a method for reproducing digital information having a parameter indicating a slope of deterioration included in the condition information. A step of changing or erasing a part of the data of the digital information to which the condition information is added, a step of updating and recording the digital information with a part of the data changed or erased on the recording medium; Reproducing the digital information from the recording medium.

Further, the recording medium of the present invention provides a recording / reproducing apparatus capable of reproducing and outputting digital information to which condition information indicating a reproduction time limit is attached from a recording medium based on the reproduction time limit indicated by the condition information. A program for deteriorating the content represented by the digital information to which the condition information is added is recorded.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. Each embodiment is directed to digital music information as conditional digital information, and the recording / reproducing apparatus used includes a speaker for outputting music and voice. Of course, the conditional digital information may be audio information or video information. In this case, the recording / reproducing apparatus has an output device corresponding to each information.

FIG. 1 shows the configuration of the recording / reproducing apparatus used in each embodiment. Reference numeral 1 denotes a system microcomputer which controls the entire recording / reproducing apparatus. Reference numeral 2 denotes an operation key, and a signal transmitted by a user operation is input to the system microcomputer 1. Reference numeral 3 denotes a display device such as an LCD, the display of which is controlled by the system microcomputer 1.

Reference numeral 4 denotes an external interface protocol control circuit for mediating between the system microcomputer 1 and a host computer 11 as an external device; 5, a recording means (recording medium) such as a flash memory; It is a memory controller that reads and writes information from and to the recording unit 5.

Reference numeral 7 denotes an encryption / decryption circuit for encrypting information or decrypting the encrypted information, 8 denotes a voice expansion circuit for expanding compressed information, and 9 denotes a voice expansion circuit 8.
A digital-to-analog (D / A) conversion circuit for digital / analog conversion of the information decompressed in step (1) is a speaker that outputs a converted analog signal.

The host computer 11 previously extracts digital music information from the CD drive by using an application program stored therein, encodes the digital music information in a compression method and an encryption method corresponding to the recording / reproducing apparatus, and stores the encoded music information in a memory as a music information file. deep. In the recording / reproducing apparatus, the music information file is downloaded from the host computer 11 via the Internet, and is recorded on the recording means 5 by the system microcomputer 1 via the external interface protocol control circuit 4.

In order to reproduce the data, first, the data of the music information file recorded in the recording means 5 is sequentially read from the recording means 5 by the system microcomputer 1 and decrypted by the encryption / decryption circuit 7, and the audio expansion circuit Elongate at 8.
Then, the analog signal is output from the speaker 10 by the D / A conversion circuit 9.

A first embodiment using such a recording / reproducing apparatus will be described. In the present embodiment, a reproduction date, which is a reproduction time limit, is encrypted and attached to the music information file as condition information.

The method of reproducing conditional digital information will be described with reference to the flowchart shown in FIG. A program for implementing the conditional digital information reproducing method is read out from a recording medium such as a program ROM or a CD-ROM (not shown) and the host computer 11, and
It is executed by the system microcomputer 1. When the music information file starts playing, the flowchart starts,
In step # 5, the reproduction date read by the system microcomputer 1 is compared with a date indicated by a clock (not shown) incorporated in the system microcomputer 1, and it is determined whether or not the reproduction time limit has come. If the clock of the system microcomputer 1 is configured to always automatically adjust to the correct time by a radio clock or the like, it is possible to more strictly manage the reproduction time limit.

In step # 5, if the reproduction time limit has not come, the process proceeds to step # 35, and the music information file is continuously reproduced. If the playback time limit has come, the process proceeds to step # 10, and the system microcomputer 1 generates a random numerical value A and a random numerical value B by a random function. Then, in step # 15, a deterioration target in the music information file is determined from the obtained random numerical values A and B.

The object to be deteriorated will be described. As shown in FIG. 3, the music information file is composed of “MAX” frames. The random number A determines the A-th frame from the beginning (frame A), and the random number B determines the B-th byte of the data constituting the frame A from the beginning. The data in the B byte of the frame A is to be degraded.

In FIG. 2, in the next step # 20, the obtained data to be degraded is updated to a music information file in which another data is rewritten. Note that each frame has a meta description portion indicating the number of bytes and bit rate held, but this meta description portion is not to be rewritten.

Here, when the recording means 5 is a flash memory, the data is erased in units of blocks, so that the data is rewritten as follows. That is, first, data in blocks is saved from the original music information file, and the data in the music information file corresponding to the saved data is deleted. Rewriting is performed for several bytes of the saved data in block units, and this is written to a data erased portion in the music information file.

Of course, the rewriting of data need not be limited to this. For example, the above processing takes too much time to rewrite data of a specific number of bytes. However, if the data rewriting method disclosed in Japanese Patent Application Laid-Open No. H11-306767 is used, it is necessary to erase data in block units. No processing time is required.

When the data rewriting is completed in step # 20, in step # 25, the position information of the deterioration target, that is, the random numerical values A and B, is recorded in a specific area in the music information file. It is determined whether or not the position information has reached a predetermined number. If the number does not reach the predetermined number, the process returns to step # 10, and the random data A and B are generated in the same manner as above, and the obtained data to be deteriorated is rewritten.

If the position information of the deterioration target has reached the predetermined number in step # 30, the process proceeds to step # 35, where the music information file is continuously reproduced, and the flowchart ends. At this time, since the music information file has been rewritten to improper data at several places, the sound quality deteriorates when reproduced.

Therefore, according to the reproducing method of this embodiment,
For example, when a user listens to a plurality of music pieces and one of them has reached the playback time limit, the sound quality of only one of the songs deteriorates, and the user can be informed implicitly that the playback time limit has arrived. Therefore, the reproduction is not suddenly impossible as in the prior art, so that the user is not confused.

Further, since the above-described sound quality deterioration processing is performed every time a music information file is reproduced, the sound quality deterioration gradually progresses, and the viewer cannot endure viewing. Here, since the data to be changed is selected at random, repairing the degraded music information file maliciously requires a great deal of effort, which is practically impossible.

In order to repair a deteriorated music information file by a proper means, since the address information of the rewritten data remains in the music information file, a repair request message is sent to the host computer 11 and a normal repair request message is sent therefrom. It is good to download data and rewrite. At this time, since it is not necessary to download all the music information files, this process is completed immediately.

The quick restoration process is effective when this embodiment is applied to a system for purchasing a music information file by a vending machine. That is, the music quality of the music information file purchased by the system deteriorates after the reproduction period expires, so that the user purchases the same music information file again at the vending machine. At this time, since the download is completed immediately, there is no need to wait in front of the vending machine for many minutes, which is very convenient for the user. Also, if the download is performed quickly, it is also effective in suppressing illegal dubbing.

In the first embodiment described above, the playback time limit of the music information file is specified by the due date, but the present invention is not limited to this. For example, it may be specified by the number of times of reproduction.
In this case, the system microcomputer 1 is provided with a reproduction count management table (not shown) for each music, and when the music information file of each music is reproduced until a predetermined timing, the reproduction frequency 1 is set.
Counting is performed as times, and the count information is recorded by a recording unit provided separately from the recording unit 5. Then, the count information is compared with a predetermined number of times of reproduction to determine whether a reproduction time limit has come.

In addition, the playback time limit of the music information file can be specified by the total playback time. In this case, the system microcomputer 1 is provided with a cumulative playing time management table (not shown) for each music piece, and counts and counts the playing time of the music information file of each music piece. Recording is performed by a separately provided recording means. Then, the count information is compared with a predetermined total playback time to determine whether the playback time limit has come.

It is desirable that the recording means provided separately from the recording means 5 for recording the number of times of reproduction and the count information of the total reproduction time cannot be externally referred to. It is further preferable that the confidentiality of the count information be enhanced by encryption.

The sound quality deterioration processing in the present embodiment is not limited to the method of rewriting a predetermined number of data every time a music information file is reproduced as shown in the flowchart of FIG. For example, as shown in the flowchart of FIG. 2, for a certain period of time after the expiration of the playback time limit, information degraded is rewritten with other information to degrade the sound quality. Good. by this,
When the sound is reproduced, the sound is skipped, and the deterioration further progresses.

Further, the sound quality of only a sound in a specific band can be deteriorated. In this case, the address in the frame A corresponding to the parameter indicating the specific band is determined as the degradation target position, and the data is rewritten for the byte group. Then, the sound quality of only the sound in the specific band deteriorates.

Further, all information other than the address management information of the frame A determined to be degraded may be initialized. As a result, the sound can be reproduced in a skipped state. In particular, if the recording means 5 is a flash memory, the data is initialized in units of blocks, but since the erased blocks are larger than each frame of the music information file, the sound skipping becomes larger. Since initializing the music information file in units of frames is the same as erasing data, it is easy to restore this frame next.

In addition, when the reproduction is repeated after the expiration of the reproduction time limit, the file may be automatically deleted after performing the sound quality deterioration processing several times.

Next, a second embodiment according to the present invention will be described. FIG. 4 is an explanatory diagram showing a music information file reproducing method according to the present embodiment. Here, the host computer 11 distributes the frame groups S1, S2, S to the recording / reproducing apparatus as a plurality of music information files.

The frame group S1 has a reproduction content of only music. Further, the frame group S2 is
This is a recording in which the same music as in No. 1 and a predetermined voice (announcement) are superimposed and recorded, and is composed of music information and voice information. If this audio information is 100 kbps in information amount and is about 10 seconds long, it will be about 125 kbytes. If this is converted into the number of frames (processing units by the compression method), it corresponds to several hundred frames depending on the compression method. Further, the frame group S has a playback content of only music, and is combined with the frame group S1 to form a series of music information.

First, in the first reproduction, the frame group S2 is linked to the frame group S and reproduced as shown in FIG. Therefore, at first, the sound is superimposed on the music by the frame group S2, and thereafter, only the subsequent music is reproduced by the frame group S. (B) in the figure after the second reproduction
As shown in the figure, the frame group S1 is linked to the frame group S and reproduced, and the reproduced content does not overlap with the sound.

Then, when the playback expiration date comes, (c) in FIG.
Since the frame group S2 is linked to the frame group S and reproduced as shown in (1), sound always overlaps at the beginning of music. Therefore, the user can be notified of the expiration of the reproduction time limit without causing confusion. It is assumed that the playback time limit and the determination of its arrival are the same as in the first embodiment.

When the playback time limit has come, the frame group S
1 is deleted. This prevents the frame group S1 from being maliciously reproduced. In order to repair the frame group S1 by regular means, the host computer 1
Only the frame group S1 needs to be downloaded from 1.
The process is completed immediately.

In the second embodiment, only one type of voice information is provided by the frame group S2. However, a plurality of types of voice information can be obtained by using another frame group. That is, in the third embodiment, the frame group S3 is also delivered from the host computer 11 together with the frame groups S1, S2, S as shown in FIG.

Like the frame group S2, the frame group S3 is obtained by recording the same music as the frame group S1 and a predetermined voice in a superimposed manner, and includes music information and voice information. However, “voice A” of frame group 2 and frame group 3
The content of the announcement is different from “voice B”.

In the present embodiment, the first and second and subsequent reproductions are the same as in the above-described second embodiment, as shown in FIGS. When the playback time limit has come, the frame group S3 is linked to the frame group S for playback as shown in (c) in the figure, and the frame group S1 is deleted.

Accordingly, when the playback time limit has come, the sound B is output at the beginning of the music so as to be overlapped, and the user can be notified of the time limit without causing confusion. Also,
To prevent the frame group S1 from being maliciously reproduced, the frame group S1 is deleted.

In the above-described second and third embodiments, the audio is output both at the first time and after the expiration of the playback time limit. However, the audio may be output at any time. That is, in the configuration of FIG. 4, the audio information (frame group S2) may be reproduced only for the first time, and when the reproduction time limit has come, only the frame group S may be reproduced so that the first half of the music cannot be viewed. Alternatively, only the music information (the frame group S1 and the frame group S) may be reproduced after the first time, and the audio information (the frame group S2) may be reproduced when the reproduction time limit has come.

When the sound quality deterioration processing described in the first embodiment is combined with the second and third embodiments, the arrival of the playback time limit can be notified more effectively.

Further, when the reproduction is repeated after the reproduction time limit has expired, the file may be automatically deleted after the announcement is reproduced several times.

Since the content of the announcement and the timing of reproduction can be set arbitrarily, the use of the above-described embodiment is not limited only to the purpose of limiting the reproduction period of the music information. For example, a CM sponsor is attached to the announcement, and the announcement at the time of the first playback is played, "This song will be sent with the offer of ~ ~", and after the expiration of the playback time limit, the announcement will be sent "This song will be sent with the offer of ~ ~" I did it. " By attaching a CM sponsor in this way, music information can be distributed to users at low cost or free of charge.

Next, a fourth embodiment will be described. In the present embodiment, a parameter indicating the inclination when the music information file is degraded is encrypted and attached to the music information file as the condition information.

FIG. 6 is a flowchart showing a method for reproducing conditional digital information according to the present embodiment. This flowchart starts when the reproduction of the music information file is started, and in step # 105, the system microcomputer 1 reads a parameter indicating the inclination of deterioration attached to the music information file. The music information file continues to be played
(Step # 110), it is determined whether or not the reproduction of the music information file has been completed in Step # 115.

When the reproduction is completed, the process proceeds to step # 120, where random numbers A and B are generated by a random function. In the next step # 125, the B-th byte data of the frame A (see FIG. 3) is determined from the obtained random numerical values A and B as a deterioration target in the music information file.

In step # 130, the data to be deteriorated is updated to the rewritten music information file. The number of bits of the data to be rewritten is determined by the degradation slope parameter, and the data is rewritten from the bit (generally, the lower bit) having little effect on the sound quality. Alternatively, the number of frames or bytes to be degraded may be determined from a parameter indicating the gradient of degradation, and data may be rewritten for each.

In the next step # 135, the position information of the deterioration target, that is, random numerical values A and B, is recorded in a specific area in the music information file. In the next step # 140, whether the position information has reached a predetermined number is determined. It is determined whether or not. If the number does not reach the predetermined number, the flow returns to step # 120, and the deterioration object is obtained and the data is rewritten as described above. Step # 14
If the number of position information items to be deteriorated has reached the predetermined number at 0, this flowchart ends.

As described above, in the present embodiment, the process of deteriorating the sound quality is performed each time the reproduction is performed. However, since the data is rewritten from the bit having less influence on the sound quality, the deterioration of the sound quality is not affected while the number of reproductions is small. I can't feel it. And
When the number of times of reproduction reaches a certain level, the deterioration becomes remarkable and the viewing becomes difficult. In particular, by controlling the degradation slope parameter, it is possible to easily manage the time when the degradation of the sound quality becomes remarkable.

Also, as in the first embodiment, since the data to be rewritten is selected at random, it takes a great deal of effort to maliciously repair a degraded music information file. Impossible.

Since the address information of the rewritten data remains in the music information file, the restoration process can be completed quickly.

Further, as in the first embodiment, a clock function, a timer function, a count function,
Since there is no need to provide a management table or the like, it is suitable for using a portable recording and reproducing apparatus.

Here, the data is rewritten after the reproduction of the music information file, but the timing is not limited to this. For example, it may be at the time of starting reproduction, at the time of inserting a memory card into the recording / reproducing apparatus, or at the time of turning on the power.

[0070]

As described above, according to the present invention, even if the playback time limit arrives during the playback of the conditional digital information, the playback does not suddenly stop, so that the playback time limit is not confused to the user. We can announce the arrival. Further, if the reproduction is repeated, the reproduction state gradually deteriorates, so that it cannot be used reliably.

Further, since the normal digital information before the deterioration has already disappeared, the contents of the digital information can be surely kept confidential after the reproduction time limit as compared with the conventional flag management method. In particular, when the data to be changed is selected at random, a great deal of effort is required to maliciously repair the deteriorated digital information, which is practically impossible.

In the digital information after the expiration of the reproduction time limit, a part of data or a part of the file has been changed or deleted. You just need to enter and record the information. That is, since it is not necessary to update all the digital information, the restoration process can be completed immediately.

Further, in the present invention, the condition information and the like recorded in the meta description part of the conditional digital information must be always encrypted, but the other information does not need to be encrypted. It is possible to reduce encryption more than that. Therefore, the load on the system is lightened.

When reproducing digital information to which condition information including a parameter indicating a gradient of deterioration is reproduced, the recording / reproducing apparatus does not need to be provided with a clock means, a function for managing a reproduction time limit, and a recording table. Therefore, the burden on software and hardware can be reduced. Therefore, the present invention is suitable for a portable recording / reproducing apparatus having limited software and hardware.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a method for reproducing conditional digital information according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a configuration of a music information file according to the first embodiment.

FIG. 4 is an explanatory diagram showing a method for reproducing conditional digital information according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a method for reproducing conditional digital information according to a third embodiment of the present invention.

FIG. 6 is a flowchart illustrating a method for reproducing conditional digital information according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 System microcomputer 5 Recording means 6 Memory controller 7 Encryption and decryption circuit 8 Audio decompression circuit 9 D / A conversion circuit 10 Speaker 11 Host computer

Claims (10)

[Claims] 1. A recording / reproducing apparatus capable of reproducing and outputting digital information to which condition information indicating a reproduction time limit is attached from a recording medium, wherein the condition information is attached based on the reproduction time limit indicated by the condition information. And degrade the content represented by the digital information
A recording / reproducing apparatus comprising control means for updating and recording the degraded digital information on the recording medium. 2. The apparatus according to claim 1, wherein the control unit changes or deletes a part of the data of the digital information to which the condition information is added based on a reproduction time limit indicated by the condition information. Recording and playback device. 3. The recording / reproducing apparatus according to claim 2, wherein the control unit records the position of the changed or erased data on the recording medium. 4. The control means obtains a part of the digital information data to which the condition information is added based on the reproduction time limit indicated by the condition information by superimposing another content on the content represented by the data. 2. The recording / reproducing apparatus according to claim 1, wherein the data is changed to data. 5. The recording medium pre-records the data before the change and the data after the change, and the control means adds the condition information based on the reproduction time limit indicated by the condition information. 2. The recording / reproducing apparatus according to claim 1, wherein either the data before or after the change of the digital information is reproduced. 6. The condition information includes a parameter indicating a slope of deterioration, and the control unit deteriorates the content represented by the digital information to which condition information including the parameter is attached based on the parameter. The recording / reproducing apparatus according to claim 1, wherein: 7. A method for reproducing, from a recording medium, digital information to which condition information indicating a reproduction time limit is attached by a recording / reproducing device, the method comprising: determining the arrival of the reproduction time limit based on the condition information; When it is determined that the reproduction time limit has arrived, a step of changing or erasing a part of the data of the digital information to which the condition information is added; and storing the digital information having a part of the data changed or deleted on the recording medium. A method for reproducing conditional digital information, comprising: a step of updating and recording; and a step of reproducing the updated and recorded digital information from the recording medium. 8. A method for reproducing, from a recording medium, digital information provided with condition information indicating a reproduction time limit by a recording / reproducing apparatus, the method comprising: judging the arrival of the reproduction time limit based on the condition information; When it is determined that the playback time limit has not arrived, the data before change recorded on the recording medium is selected, and when it is determined that the playback time limit has arrived, the data is recorded on the recording medium. Selecting the data after the change and erasing the data before the change, and reproducing the selected data before or after the change, the conditional digital information comprising: How to play. 9. A method of reproducing, from a recording medium, digital information to which condition information including a parameter indicating a slope of deterioration is recorded by a recording / reproducing apparatus, wherein the parameter indicating the slope of deterioration included in the condition information Changing or erasing part of the data of the digital information to which the condition information is attached, updating and recording the digital information with the part of the data changed or erased on the recording medium, Reproducing the obtained digital information from the recording medium. 10. A recording / reproducing device capable of reproducing and outputting digital information to which condition information indicating a reproduction time limit is attached from a recording medium, wherein the condition information is attached based on the reproduction time limit indicated by the condition information. A recording medium on which a program for deteriorating the content represented by the digital information is recorded.