JP2005353108A - Data recorder and data recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a data recorder effectively utilizing a limited recording capacity, and also to provide a data recording method. <P>SOLUTION: The data recorder for compressing and recording the data is equipped with a compressing section 103 having a plurality of compression systems 105-108 with different compressibility. By a CPU 112, a dead capacity of a recording medium 111 of a recording section 110 is controlled and the compression system is selected in accordance with the dead capacity of the recording medium 111 to control switches 104 and 109. The data acquired from media 102 which are inserted to a disk section 101 are compressed by the selected compression system and recorded on the recording medium 111. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a data recording apparatus and a data recording method for compressing and recording audio data or the like on a recording medium.

Conventionally, a digital information recording apparatus shown in FIG. 9 is known. As a conventional recording apparatus, in a recording medium, reproduced information (read flag 901) that can specify an information portion that has been reproduced in the past among compressed and recorded information, and among compressed and recorded information It has archive information (archive flag 902) that makes it possible to specify the information portion to be stored, and manages this information. When new recording is required and the recording capacity of the recording medium is insufficient, data with a low recording retention priority is deleted from this management information, and recording is performed while ensuring the recording capacity that requires new recording. (For example, see Patent Document 1).
Japanese Laid-Open Patent Publication No. 2002-190183

  However, according to the above-described prior art, the free capacity of the recording medium when new recording is required is, for example, 4 megabytes, and the amount of recorded data compressed by a certain compression method is, for example, 5 megabytes. In such a case, the free space of 1 megabyte is insufficient, and the data having the lowest recording holding priority among the already recorded data must be selected (for example, 6 megabytes) and deleted. That is, 4 megabytes, which is the free capacity of the recording medium, cannot be used, 6 megabytes of data is deleted, 10 megabytes of free capacity is secured, and 5 megabytes of data are recorded. Further, after recording, a free space of 5 megabytes is generated, and the limited recording capacity cannot be effectively used.

  The present invention has been made in view of the above-described conventional circumstances, and an object thereof is to provide a data recording apparatus and a data recording method capable of effectively utilizing a limited recording capacity.

The data recording apparatus of the present invention includes a compression unit having a plurality of compression methods with different compression rates,
Recording medium management means for managing the free space of the recording medium for recording data;
Compression method selection means for performing control to select a compression method of the compression means according to the free space;
Recording means for recording data compressed by the selected compression method on the recording medium;
Is provided.

  With this configuration, it is possible to provide a data recording apparatus that effectively uses a limited recording capacity by using a plurality of compression methods.

  Further, the compression method selection means calculates a data amount of the data when compressed with at least one of the plurality of compression methods, compares the calculated data amount with the free space, and A compression method in which the calculated data amount is equal to or less than the free capacity is selected.

  With this configuration, by selecting a compression method so that the compressed data is less than the free capacity, it is possible to make maximum use of the limited recording capacity without deleting the already recorded data. Become.

  The compression method selection means sequentially calculates the data amount and compares it with the free capacity, starting from the compression method with the lowest compression rate.

  With this configuration, a compression method with a lower compression rate can be selected, so that data degradation can be minimized.

And further comprising decompression means for decompressing the data compressed by the plurality of compression methods,
The recording medium management means manages the data recorded on the recording medium in association with the compression method,
The decompression means may store at least one of the data recorded on the recording medium when it is determined that the recording medium has insufficient free space when recording new data on the recording medium. Elongate,
The compression means compresses the decompressed data by a compression method having a higher compression rate than the compression method before decompression, based on the compression method corresponding to the managed decompressed data.

  With this configuration, it is possible to generate a free area of the recording medium for data to be newly recorded, and thus it is possible to make the most effective use of the limited recording capacity.

  The compression method selection means selects data recorded by the compression method having a low compression rate as data to be decompressed from among data recorded on the recording medium, and the selected as the free capacity A free capacity is calculated when a compression method having a higher compression ratio than that of the compression method before decompression is performed, and the compression method of the data to be recorded is selected based on the free capacity.

  With this configuration, it is possible to generate a free area and select the recording data, so that a limited recording capacity can be used effectively.

The data recording method of the present invention includes a step of acquiring a free capacity of a recording medium for recording data and a data amount of data to be recorded;
Performing a control to select one of a plurality of compression methods as the data compression method in accordance with the free space;
Recording the data compressed by the selected compression method on the recording medium;
Have

  By this method, it is possible to provide a data recording apparatus that effectively uses a limited recording capacity by using a plurality of compression methods.

The step of selecting the compression method includes
Calculating a data amount of the data when compressed by at least one of the plurality of compression methods;
Comparing the calculated amount of data with the free space;
Selecting a compression method in which the calculated data amount is equal to or less than the free capacity.

  With this method, by selecting a compression method so that the compressed data is less than the free capacity, it is possible to make the most effective use of the limited recording capacity without deleting the already recorded data. Become.

  Further, the calculation of the data amount and the comparison with the free space are performed in order from the compression method with the lowest compression rate.

  By this method, a compression method with a lower compression rate can be selected, so that data degradation can be minimized.

In addition, when it is determined that the recording medium has insufficient free space when recording new data on the recording medium, the decompression means is at least one of the data recorded on the recording medium. Stretching the step;
Compressing the decompressed data with a compression method having a higher compression ratio;
It has further.

  By this method, it is possible to generate a free area of the recording medium for data to be newly recorded, and thus it is possible to make the most effective use of the limited recording capacity.

  The step of selecting the compression method includes the step of decompressing the data recorded by the compression method with the low compression rate among the data recorded on the recording medium, and the selected as the free capacity A step of calculating a free space when a compression method having a higher compression rate than that of the compression method before decompression is performed, and a step of selecting a compression method of the data to be recorded based on the free space.

  By this method, it is possible to generate a free area and select the recording data, so that a limited recording capacity can be used effectively.

  The present invention also provides a data recording program for causing a computer to execute each step of any of the above data recording methods.

  According to the present invention, it is possible to provide a data recording apparatus and a data recording method capable of effectively utilizing a limited recording capacity.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. In the embodiment of the present invention, an audio data recording apparatus that compresses and records audio data as an example of the data recording apparatus will be described as an example. However, the present invention is not limited to the audio data recording apparatus.

(First embodiment)
FIG. 1 is a diagram showing a basic configuration of an audio data recording apparatus according to the first embodiment of the present invention. As shown in FIG. 1, the audio data recording apparatus 100 according to the first embodiment can be compressed with a deck unit 101 using a compression method 105, a compression method 106, a compression method 107, and a compression method 108, each having a different compression rate. A compression unit 103 having a switch 104 and a switch 109 that can select which compression method is used to compress and output data, a recording unit 110 having a recording medium 111 for recording compressed audio data, and a recording medium 111 And a CPU 112 for managing the free space. The compression unit 103 has a function of a compression unit, the recording unit 110 has a function of a recording unit, and the CPU 112 has a function of a compression method selection unit and a recording medium management unit.

  The deck unit 101 reads out audio data such as PCM (Pulse Code Modulation) digitized from the medium 102 inserted from the outside, and outputs it to the compression unit 103. Also, the data amount of audio data recorded in the medium 102 in units of blocks (for example, tracks) is calculated and output to the CPU 112.

  The compression unit 103 compresses the PCM audio data output from the deck unit 101 by the compression method selected according to the switching control of the switch 104 and the switch 109 performed by the CPU 112, and outputs the compressed audio data to the recording unit 110. The recording unit 110 records the compressed audio data output from the compression unit 103 on the recording medium 111 and outputs the free capacity (management information) of the recording medium 111 to the CPU 112.

  The CPU 112 controls the entire operation of the audio data recording apparatus 100, and is configured mainly by a processor that operates according to a predetermined program. Then, the compression method is determined based on the free space of the recording medium 111 output from the recording unit 110 and the amount of PCM audio data output from the deck unit 101, and the switches 104 and 109 of the compression unit 103 are switched. Take control. In this way, compression with the selected compression method becomes possible.

  FIG. 2 is an explanatory diagram illustrating an example of a correspondence relationship between a plurality of compression methods and compression rates. As shown in FIG. 2, in the compression unit 103, the compression method 105, the compression method 106, the compression method 107, and the compression method 108 respectively convert the PCM audio data output from the deck unit 101 to 1/2, 1/5, This is a compression method that can be compressed to 1/10 and 1/20.

  An audio data recording operation of the audio data recording apparatus 100 configured as described above will be described. FIG. 3 is a flowchart showing the data recording method of the first embodiment.

  First, in a state where no compressed audio data is recorded on the recording medium 111 of the recording unit 110 (for example, the total capacity of the recording medium is 740 megabytes, and the free capacity is 740 megabytes from the management information), the CPU 112 The switching control of the switch 104 and the switch 109 of the compression unit 103 is performed so that the compression method 105 (compression rate 1/2) is selected as the normal compression method.

  When the user who uses the audio data recording apparatus 100 inserts the medium 102 into the deck unit 101 and compresses and records the audio data of the track 1, the deck unit 101 calculates the PCM audio data amount of the track 1 and sends it to the CPU 112. Output (step S301). The audio data amount of this PCM is assumed to be 50 megabytes, for example.

  The CPU 112 calculates the amount of audio data (25 megabytes) compressed after the PCM audio data (50 megabytes) acquired in step S301 is compressed by the compression method 105 (compression ratio 1/2), which is a normal compression method (step megabytes). S302). Thereafter, the free space (740 megabytes) of the recording medium 111 output by the recording unit 110 is compared with the amount of compressed data obtained by calculation (step S303).

  When the free capacity (740 megabytes) of the recording medium 111 is equal to or greater than the compressed audio data amount (25 megabytes) (YES in step S304), it is determined that recording is possible, and the compression method 105 (compression rate 1/2) is selected. Thus, the switching control of the switch 104 and the switch 109 of the compression unit 103 is performed (step S305). In this case, since the compression method 105 is originally selected, the switch 104 and the switch 109 are not switched.

  The deck unit 101 outputs the PCM audio data (50 megabytes) of track 1 to the compression unit 103. Since the compression unit 105 is selected by the CPU 112 in the compression unit 103, the PCM audio data (50 megabytes) output from the deck unit 101 is compressed at a compression ratio of 1/2, and the compressed audio data (25 megabytes) is compressed. Output to the recording unit 110. The recording unit 110 records the compressed audio data (25 megabytes) output from the compression unit 103 on the recording medium 111, and outputs the free space after recording (715 megabytes) to the CPU 112. The CPU 112 records the free space after recording (715 megabytes) as management information.

  By performing the above operation whenever it is necessary to record, audio data compressed at a compression ratio of 1/2 is recorded on the recording medium 111 one after another, and the free capacity of the recording medium 111 is reduced.

  Here, for example, a case where the free space of the recording medium 111 is 5 megabytes and the amount of PCM audio data is 50 megabytes will be described. The CPU 112 calculates the amount of compressed audio data when the compression method 105 (compression rate 1/2), which is the normal compression method, is selected as 25 megabytes. Then, the CPU 112 compares the free space (5 megabytes) of the recording medium 111 with the compressed audio data amount (25 megabytes) when the compression method 105 (compression rate 1/2) is selected (step S303). . As a result, since the free capacity is 5 megabytes <25 megabytes of compressed data, the compressed data quantity is less than the free capacity (NO in step S304), and it is determined that recording is impossible.

  Next, the CPU 112 calculates again the amount of compressed audio data when the compression method 106 (compression rate 1/5) having a higher compression rate than the compression method 105 is selected (step S306), and the calculated audio data amount And the free space are compared (step S303). As a result of the comparison, the free capacity of the recording medium 111 becomes less than the amount of compressed audio data (5 megabytes <10 megabytes) when the compression method 106 (compression ratio 1/5) is selected (NO in step S304), and recording is performed. It is judged impossible.

  Next, the CPU 112 recalculates the amount of compressed audio data when the compression method 107 (compression rate 1/10) having a higher compression rate than the compression method 106 is selected (step S306) and similarly compared with the free space. (Step S303). As a result of the comparison, the free capacity of the recording medium 111 is equal to or greater than the amount of compressed audio data when the compression method 107 (compression ratio 1/10) is selected (5 megabytes = 5 megabytes) (YES in step S304), and recording is performed. Judged to be possible.

  Then, switching control of the switch 104 and the switch 109 of the compression unit 103 is performed so as to select the compression method 107 (compression rate 1/10), and audio data compressed by the compression method 107 (compression rate 1/10) is obtained. It is recorded on the recording medium 111. In this way, since the data amount is calculated and compared with the free capacity in order from the compression method with the lowest compression rate, a compression method with a lower compression rate can be selected, and data degradation can be minimized.

  Here, even if the compression method 107 (compression rate 1/10) is selected, if the free space is less than the amount of compressed audio data, the compression method 108 (compression rate 1/20) is compared. As a result of comparison, if the free space is less than the amount of compressed audio data, there is no compression method with a higher compression rate, so there is no free space that can be recorded by the user. It notifies that it is necessary to delete any recorded data in order to record.

  FIG. 4 is an explanatory diagram illustrating an example of recorded contents and management information of the recording medium according to the first embodiment. As described above, when recording is performed only with the normal compression method 105, a free space of 5 megabytes cannot be used. However, with a plurality of compression methods, the CPU 112 manages the free capacity of the recording medium 111 and selects and records the compression method according to the free capacity of the recording medium 111, so that recording to the maximum free space is possible. It becomes possible to reduce the capacity that cannot be done. (The capacity that cannot be used in the above embodiment is 0 bytes)

  According to the first embodiment, the audio data recording apparatus that compresses and records audio data includes the compression unit having a plurality of compression methods with different compression rates, manages the free space of the recording medium, and records the data. By selecting and recording a compression method according to the free space of the medium, it is possible to provide an audio data recording apparatus that can make maximum use of the limited recording capacity without deleting already recorded data.

  Note that the number of compression methods (four methods) and the compression rates (1/2, 1/5, 1/10, 1/20) in this embodiment are not limited to those in this embodiment, and the compression rates differ. The same effect can be obtained if a compression unit having a plurality of compression methods is provided, the free space of the recording medium is managed, and the compression method is selected and recorded according to the free space of the recording medium.

  In addition, the normal compression rate (1/2) in the present embodiment is not limited to this embodiment, and the same effect can be obtained as long as the compression method is not the compression method with the highest compression rate among a plurality of compression methods. .

(Second Embodiment)
FIG. 5 is a diagram showing a basic configuration of an audio data recording apparatus according to the second embodiment of the present invention. In the figure, the same reference numerals are given to the portions overlapping those in FIG. 1 described in the first embodiment.

  The audio data recording apparatus 200 according to the present embodiment selects any one of the decompression method 215, the decompression method 216, the decompression method 217, and the decompression method 218 that can decompress the audio data compressed by the compression unit 103 using each compression method. The expansion unit 213 includes a switch 214 and a switch 219 that can select whether to expand and output. The audio data recording apparatus of the present embodiment may further include a D / A conversion, an amplifier, and a speaker, and may have the function of an audio data recording / reproducing apparatus that reproduces audio data expanded by the expansion unit 213. The extension unit 213 has a function of extension means.

  The CPU 212 manages the compression method of the compressed audio data recorded on the recording medium 111 of the recording unit 110, and performs switching control of the switch 214 and the switch 219 of the decompression unit 213 from the management information, and is selected. It is configured to enable expansion. The decompression unit 213 has a configuration capable of outputting the decompressed PCM audio data to the compression unit 103, and the decompressed PCM audio data can be compressed again by any of the compression methods of the compression unit 103. . At this time, the input switching control of the PCM audio data output from the deck unit 101 and the expanded PCM audio data output from the expansion unit 213 is performed by the CPU 212 switching the switch 104.

  FIG. 6 is an explanatory diagram illustrating an example of a correspondence relationship among a plurality of compression methods, compression rates, and decompression methods. As shown in FIG. 6, in the compression unit 103, the compression method 105, the compression method 106, the compression method 107, and the compression method 108 convert the PCM audio data output from the deck unit 101 to 1/2, 1/5, This is a compression method that can be compressed to 1/10 and 1/20. In the decompression unit 213, the decompression method 215, the decompression method 216, the decompression method 217, and the decompression method 218 are respectively compressed by the compression method 105, the compression method 106, the compression method 107, and the compression method 108 that are output from the recording medium 111. This is a decompression method capable of decompressing audio data into PCM audio data.

  An audio data recording operation of the audio data recording apparatus 100 configured as described above will be described. FIG. 7 is a flowchart showing a data recording method according to the second embodiment.

  Steps S701 to S705 in FIG. 7 are the same steps as steps S301 to S305 in FIG. 3 described in the first embodiment. That is, when the data amount of the audio data is acquired, the data amount when compressed by the normal compression method is calculated, the data amount is compared with the free space, and if the compressed data amount is less than the free space, the switch 104 and The switching control of 109 is performed to compress and record audio data. Note that the CPU 212 records, as management information, the free space after recording, the compression method of the audio data compressed and recorded, and the recording area of the recording medium 111.

  If it is determined in step S704 that the compressed data amount is equal to or less than the free capacity (NO in step S704), it is determined whether the compression method that is the basis for calculating the compressed data amount is the compression method with the highest compression rate. (Step S706). If there is a compression method with a higher compression rate than the compression method (NO in step S706), the amount of data when compressed with a compression method with a higher compression rate, as in step S306 in the first embodiment. Is calculated (step S707). Thereafter, the process returns to step S703, and the compressed data amount is compared with the free capacity.

  In step S706, if the compression method that is the basis for calculating the compressed data amount is the compression method with the highest compression rate, the compression method recorded on the recording medium 111 and recorded with the compression method with the lowest compression rate is used. Data is detected (step S708). Then, the data amount when the detected data is expanded and compressed at a higher compression rate and the free capacity at that time are calculated (step S709). Then, returning to step S702, the data amount when the audio data is compressed by the normal compression method is calculated.

  The above-described data recording method will be described using a specific example. FIG. 8 is an explanatory diagram illustrating an example of recorded contents and management information of the recording medium according to the second embodiment. As shown in FIG. 8, it is assumed that data has already been recorded in the recording medium 111 until the free space is 0 bytes.

  In this state, when the user further inserts the medium 102 into the deck unit 101 and compresses and records the audio data on the recording medium 111 (PCM audio data output from the deck unit 101 is, for example, 50 megabytes), the CPU 112 The free space (0 bytes) of the management information is compared with the compressed audio data amount when a compression method having a high compression rate is selected in order from the compression method 105.

  Here, since the free space is 0 bytes, the data amount when compressed by the compression method 108 having the highest compression rate does not become less than the free space (NO in S704), and the compression method 108 is the most compressed. This is a compression method with a high rate (YES in step S706). That is, recording is impossible with all compression methods.

  The CPU 212 searches the audio data compressed by the compression method 105 (compression ratio 1/2) from the compressed audio data management information already recorded on the recording medium 111, and is compressed by the compression method 105. Audio data is detected (a region of 0 to 25 megabytes in FIG. 8 is detected). This data search may be performed from audio data having a low compression rate or from audio data having a large amount of data. Moreover, you may search using both of these.

  The CPU 212 performs expansion corresponding to the compression method 105 of the detected area, and when the compression method 106 having a higher compression rate than the compression method 105 is selected again, the amount of compressed data and the free space on the recording medium 111 at that time The capacity is calculated (step S709). In this example, the compressed audio data of 25 megabytes is expanded to become 50 megabytes (2 times) of PCM audio data, recompressed at a compression rate 1/5 of the compression method 106, and compressed to 10 megabytes of audio data. Therefore, a free space of 25-10 = 15 megabytes is generated.

  After that, when the calculated free space of 15 megabytes and the newly recorded PCM audio data (50 megabytes) are compared in order from the compression scheme 205, the compressed data amount when the compression scheme with the higher compression rate is selected is compared (step S703). ) Since the audio data compressed with respect to the free space of 15 megabytes is 10 megabytes (YES in step S704), it is determined that recording is possible with the compression method 206.

  The CPU 212 performs the above calculation and performs switching control of the switch 214 and the switch 219 so that the 0 to 25 megabyte area from the recording medium 211 is expanded by the expansion unit 215 of the expansion unit 213. The expanded PCM audio data is output to the compression unit 103, and the CPU 212 performs switching control of the switch 104 and the switch 109 of the compression unit 103, and the compression method 106 is selected and recompressed.

  The audio data recompressed by the compression unit 103 is recorded again on the recording medium 111 of the recording unit 110, and a free space of 15 megabytes is generated and newly recorded as management information. Recording can be performed in this 15 megabyte area by the same procedure as described above, and PCM audio data (50 megabytes) to be newly recorded is compressed by the compression method 106 of the compression unit 103 and recorded on the recording medium 111. (Step 705).

  According to the second embodiment, the audio data recording apparatus that compresses and records audio data is selected from a compression unit having a plurality of compression methods with different compression rates and a plurality of compression methods with different compression rates. A decompression unit that decompresses audio data compressed by the compression method, manages the free space of the recording medium and the compression method of the compressed audio data that has already been recorded, and has already been recorded by the free space of the recording medium Audio data recording and playback that maximizes the limited recording capacity without erasing the already recorded data by recording the audio data on the recording medium again with a high compression method while expanding the audio data An apparatus can be provided.

  Note that the number of compression methods (four methods) and the compression rates (1/2, 1/5, 1/10, 1/20) in this embodiment are not limited to those in this embodiment, and the compression rates differ. The same effect can be obtained if a compression unit having a plurality of compression methods is provided, the free space of the recording medium is managed, and the compression method is selected and recorded according to the free space of the recording medium.

  In addition, the normal compression rate (1/2) in the present embodiment is not limited to this embodiment, and the same effect can be obtained as long as the compression method is not the compression method with the highest compression rate among a plurality of compression methods. .

  Furthermore, the procedure for performing recompression in this embodiment is not limited to this embodiment, and free space is generated by decompressing audio data that has already been recorded, compressing it at a higher compression rate, and recording it. A similar effect can be obtained.

  As described above, the data recording apparatus and the data recording method according to the present invention have an effect that a limited recording capacity can be effectively used, and are useful as an audio data recording apparatus and an audio data recording method.

The figure which shows the basic composition of the audio data recording device in the 1st Embodiment of this invention. Explanatory drawing which shows the example of the correspondence of several compression methods and compression ratios The flowchart which shows the data recording method of 1st Embodiment Explanatory drawing which shows an example of the recording content and management information of the recording medium in 1st Embodiment The figure which shows the basic composition of the audio data recording device in the 2nd Embodiment of this invention. Explanatory drawing which shows the example of correspondence of a plurality of compression methods, compression rate, and decompression method The flowchart which shows the data recording method of 2nd Embodiment Explanatory drawing which shows an example of the recording content and management information of the recording medium in 2nd Embodiment Illustration of a conventional digital information recording system

Explanation of symbols

100, 200 Audio data recording device 101 Deck unit 102 Media 103 Compression unit 104, 109, 214, 219 Switch 105-108 Compression method 110 Recording unit 111 Recording medium 112, 212 CPU
213 Extension part 215-218 Extension method

Claims (11)

Compression means having a plurality of compression methods with different compression rates;
Recording medium management means for managing the free space of the recording medium for recording data;
Compression method selection means for performing control to select a compression method of the compression means according to the free space;
Recording means for recording data compressed by the selected compression method on the recording medium;
A data recording device comprising: The data recording device according to claim 1, wherein
The compression method selection means calculates a data amount of the data when compressed with at least one of the plurality of compression methods, compares the calculated data amount with the free capacity, and calculates the data amount. A data recording apparatus for selecting a compression method in which a data amount is equal to or less than the free capacity. The data recording device according to claim 1 or 2,
The data recording apparatus, wherein the compression method selection means performs the calculation of the data amount and the comparison with the free capacity in order from a compression method with a low compression rate. A data recording device according to any one of claims 1 to 3,
Further comprising decompression means for decompressing the data compressed by the plurality of compression methods;
The recording medium management means manages the data recorded on the recording medium in association with the compression method,
The decompression means may store at least one of the data recorded on the recording medium when it is determined that the recording medium has insufficient free space when recording new data on the recording medium. Elongate,
The data recording apparatus that compresses the decompressed data by a compression method having a higher compression rate than the compression method before decompression based on the compression method corresponding to the managed decompressed data. The data recording device according to claim 4, wherein
The compression method selection means selects, as data to be decompressed, data recorded by the compression method having a low compression rate among data recorded on the recording medium, and selects the selected data as the free capacity. A data recording apparatus that calculates a free space when a compression method having a higher compression rate than a compression method before decompression is performed, and selects a compression method of the data to be recorded based on the free space. Obtaining a free capacity of a recording medium for recording data and a data amount of data to be recorded;
Performing a control to select one of a plurality of compression methods as the data compression method in accordance with the free space;
Recording the data compressed by the selected compression method on the recording medium;
A data recording method comprising: A data recording method according to claim 6, wherein
The step of selecting the compression method includes:
Calculating a data amount of the data when compressed by at least one of the plurality of compression methods;
Comparing the calculated amount of data with the free space;
Selecting a compression method in which the calculated data amount is equal to or less than the free capacity. The data recording method according to claim 6 or 7,
In the data recording method, the calculation of the data amount and the comparison with the free space are performed in order from a compression method with a low compression rate. The data recording method according to claim 6, wherein:
When it is determined that there is not enough free space on the recording medium when recording new data on the recording medium, the decompression means decompresses at least one of the data recorded on the recording medium. And steps to
Compressing the decompressed data with a compression method having a higher compression ratio;
A data recording method further comprising: The data recording method according to claim 9, wherein
The step of selecting the compression method includes the step of decompressing the data recorded by the compression method with the low compression rate among the data recorded on the recording medium, and the selected data as the free capacity. A data recording method comprising: calculating a free space when a compression method having a higher compression rate than a compression method before decompression is performed; and selecting a compression method for the data to be recorded based on the free space .   A data recording program for causing a computer to execute each step according to any one of claims 6 to 10.

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