JP2007213634A - Digital information recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To guarantee recording time when recording directly on a removable recording medium in a digital information recorder. <P>SOLUTION: The inner controller 108 determines which to record out of the received bit stream or the bit streams formed in the information re-compressing section depending on the total bit volume of the program and the remaining capacity of the recording medium, then controls the information recording section 107 to start to record the program. It corrects the recording method by changing the resolutions, frame rates, and coding methods depending on the bit volume of the program portion yet to record and the remaining capacity of the recording medium until the program recording is completed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a digital information recorder that records a digital broadcast on a removable recording medium.

  In recent years, an analog recorder that digitizes a received analog broadcast program and records it on an optical disk such as a DVD-RAM or a hard disk device has become widespread (see, for example, Patent Document 1).

  Some analog recorders as described above can perform recording in various recording modes called XP mode, SP mode, LP mode, and EP mode depending on the recording rate. For example, if a DVD-RAM disc is used as a recording medium, recording can be performed for 1 hour in the XP mode with the highest recording rate, recording for 2 hours in the SP mode with the next highest recording rate, recording for 4 hours in the LP mode, and EP. In mode, it can record for 6 hours. This is relatively similar to the recording mode of the recorder for recording on the VHS tape, in which the normal recording mode can record for 2 hours and the triple recording mode can record for 6 hours. In other words, the recording time is guaranteed for each recording rate, and the recording mode can be selected without any discomfort to the user.

On the other hand, with the recent spread of terrestrial digital broadcasting, digital recorders that record received digital signals as they are on a hard disk device have appeared. Digital broadcasting, such as terrestrial digital broadcasting, transmits a digitized and compressed bit stream. For example, in terrestrial digital broadcasting, there are SD (standard image quality) and HD (high quality image quality) broadcast modes having different image quality. A digital recorder that records a digital broadcast program can also record the program on a hard disk device at a recording rate corresponding to each broadcast mode.
JP 11-339374 A

  However, in the digital recorder, the recording time of the digital broadcast is not guaranteed for each recording rate unlike the analog recorder. This is because, in digital broadcasting, there is a difference in the amount of information (bit amount) required to record a program for the same time depending on the content of the program, whether it is a program of the same SD or a program of the same HD. This is because the bit amount to be recorded cannot be simply determined from the recording mode and the recording time of the program.

  Therefore, even if the amount of bits to be recorded is predicted from the recording mode and the recording time at the start of recording, there may be a case where recording of a larger amount of bits than actually expected is required. In such a case, for example, a removable recording medium such as a DVD-RAM may not have a sufficient recording capacity depending on the set recording mode.

  Therefore, when the digital recorder is configured so that a digital broadcast program can be directly recorded on a removable recording medium, the selection of the recording mode is inappropriate, as compared with the case of recording on the hard disk device. There is a high possibility that recording will fail (the program cannot be recorded to the end).

  In digital broadcasting, a standard compression rate (bit rate) of a program whose image quality is SD is 4 Mbps to 6 Mbps. That is, SD does not have a fixed compression rate. On the other hand, the compression rate of a program with high image quality is about 20 Mbps. Therefore, even if the program content is the same, the time that can be recorded on the recording medium differs by five times depending on whether it is SD or HD.

  In recent years, semiconductor memory cards (for example, SD memory cards and memory sticks) mainly used for mobile devices and various optical disks (for example, DVD-RAM, Blu-Ray Disc, HD-DVD) used for stationary devices. The types of removable recording media such as are increasing. Furthermore, in addition to the FOMA of the 3rd generation mobile phone that uses MPEG4-SP with a low recording rate that has already begun service on mobile phones, 1-segment (segment) digital broadcasting for mobile that uses MPEG4-AVC as the compression standard Started in 2006, and it can be said that the compression standard is also in a turbulent state.

  In such a situation, it can be said that it is very difficult to understand which recording mode is appropriate for a person who has become an analog recorder so far, and is difficult to use. For this, for example, assuming the maximum bit rate of a program (for example, 6 Mbps for a program with an image quality of SD), the digital recorder is configured to automatically select a recording mode according to the capacity of the recording medium. However, in this case, the image quality of the recorded program may be deteriorated more than necessary, or the recording capacity of the recording medium may be wasted.

  The present invention has been made paying attention to the above-described problem, and a digital recorder that can reliably record a program (that is, can guarantee a recording time) when recording directly onto a removable recording medium ( Hereinafter, it is also intended to provide a digital information recorder.

In order to solve the above problems, the invention of claim 1
A digital information recorder for recording a bit stream obtained by receiving a digital broadcast program on a removable recording medium,
A bit rate information indicating a bit rate of the bit stream, and a decoding unit that decodes the bit stream and returns it to a baseband signal;
An information recompression unit that encodes the baseband signal using a predetermined encoding method to generate a new bitstream;
An information recording unit for recording either the bit stream obtained by receiving the program or the new bit stream on the recording medium;
At the start of recording the program, the total bit amount when the program is recorded at the bit rate indicated by the bit rate information is obtained, and the information recording unit determines the total bit amount and the remaining capacity of the recording medium according to the total bit amount. Control which bitstream is recorded, and further determine the amount of unrecorded bits when the unrecorded part of the program is recorded at a predetermined bit rate until the recording of the program ends, An internal controller that re-controls which bitstream the information recording unit records according to the amount of unrecorded bits and the remaining capacity of the recording medium;
It is provided with.

  As a result, the recording system is modified according to the amount of unrecorded bits and the remaining capacity of the recording medium until the recording of the program is completed, so recording is performed when recording directly on a removable recording medium. You can guarantee time.

The invention of claim 2
The digital information recorder of claim 1, comprising:
The information recompression unit is configured to perform the encoding after changing at least one of a resolution and a frame rate of the bit stream decoded by the decoding unit.

  Thereby, since the resolution or frame rate of the bit stream obtained by receiving the program is changed, the amount of bits to be recorded can be reduced.

The invention of claim 3
The digital information recorder of claim 1, comprising:
The information recompression unit is configured to support a plurality of types of encoding methods,
The internal controller determines an encoding method to be performed by the information recompression unit according to the total bit amount and the remaining capacity of the recording medium at the start of recording of the program, and performs encoding using the determined encoding method. The information recompressing unit is controlled in accordance with the amount of unrecorded bits and the remaining capacity of the recording medium until the recording of the program is completed. Is determined, and the information recompressing unit is re-controlled so that encoding is performed according to the determined encoding method.

  Thus, the encoding method (compression method) is corrected according to the amount of unrecorded bits and the remaining capacity of the recording medium until the recording of the program ends.

The invention of claim 4
The digital information recorder of claim 1, comprising:
Furthermore, when there are two or more recording media having a capacity capable of recording the program, a user interface is provided that allows the user to select which recording medium to record.

  Thereby, the user can easily select a recording medium for recording the program.

The invention of claim 5
The digital information recorder of claim 1, comprising:
The internal controller controls the information recording unit to record on a recording medium selected according to a predetermined priority when there are two or more recording media having a capacity capable of recording the program. It is comprised so that it may do.

  Thereby, a recording medium for recording the program is automatically selected.

The invention of claim 6
The digital information recorder of claim 1, comprising:
The removable recording medium is an erasable recording medium,
The internal controller is configured to erase already recorded data when the current remaining capacity of the removable recording medium is less than the total bit amount.

  Thereby, the program recorded later is recorded preferentially.

The invention of claim 7
The digital information recorder of claim 1, comprising:
The internal controller is configured to stop recording the program when the current remaining capacity of the removable recording medium is less than the total bit amount.

  As a result, it is possible to prevent the recording medium from being wasted by writing to the recording medium that can be written only once even though there is not enough free space.

The invention of claim 8
The digital information recorder of claim 1, comprising:
The internal controller selects a recording medium having a capacity capable of recording the total bit amount when there are two or more recording media, and the information recording unit performs recording on the selected recording medium. It is comprised so that it may control to.

  Thereby, a recording medium having a capacity capable of recording a program is automatically selected.

  According to the present invention, since the recording system is modified according to the amount of unrecorded bits and the remaining capacity of the recording medium until the recording of the program ends, direct recording is performed on the removable recording medium. In case you can guarantee the recording time.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a digital information recorder 100 according to an embodiment of the present invention. The digital information recorder 100 can remove a digitized and compressed bit stream in accordance with an instruction from the user via the user interface 10 (a semiconductor memory card 20 and an optical disc 30 shown in the figure). To record. The bit stream is data of a program (data such as video data and audio data) obtained by receiving, for example, terrestrial digital broadcasting. Further, the semiconductor memory card 20 is a semiconductor memory such as an SD memory card (SD: Secure Digital), and the optical disk 30 is an optical disk such as a DVD-RAM (Digital Versatile Disc-RAM). In this embodiment, the recording medium to be recorded is determined by including the information in the program reservation information and instructing the digital information recorder 100 via the user interface 10 when the user reserves the recording of the program. .

(Configuration of digital information recorder 100)
As shown in FIG. 1, the digital information recorder 100 includes a buffer 101, a decoding unit 102, a resolution / frame rate conversion unit 103, an MPEG4AVC encoding unit 104, an MPEG4SP encoding unit 105, an MPEG2 encoding unit 106, An information recording unit 107 and an internal controller 108 are provided.

  The buffer 101 stores the input bit stream for a predetermined time. As the buffer 101, for example, a semiconductor memory such as a DRAM (Dynamic RAM) or a hard disk device can be used.

  The decoding unit 102 decodes the bit stream, returns it to the baseband, and outputs it to the resolution / frame rate conversion unit 103. Further, the decoding unit 102 is configured to extract encoding parameters and output them to the internal controller 108 in the decoding process. Here, the encoding parameters are the bit rate, frame rate, and resolution of the decoded bit stream.

  The resolution / frame rate conversion unit 103 performs resolution conversion and frame rate conversion on the bitstream stored in the buffer 101 under the control of the internal controller 108. Here, the resolution conversion is to expect a compression effect by converting an image having an image quality of HD into an image having an image quality of SD, for example. The frame rate conversion is, for example, converting 30 images per second into 24 images per second and expecting a compression effect.

  The MPEG4AVC encoding unit 104 recompresses the output of the resolution / frame rate conversion unit 103 by the MPEG4AVC method.

  The MPEG4SP encoding unit 105 recompresses the output of the resolution / frame rate conversion unit 103 by the MPEG4SP method.

  The MPEG2 encoding unit 106 recompresses the output of the resolution / frame rate conversion unit 103 using the MPEG2 method. The MPEG4 AVC encoding unit 104, the MPEG4SP encoding unit 105, and the MPEG2 encoding unit 106 are collectively referred to as an encoding unit. The resolution / frame rate conversion unit 103 and each encoding unit are collectively referred to as an information recompression unit.

  The information recording unit 107 selects either the bit stream recompressed by the encoding unit such as the MPEG4 AVC encoding unit 104 or the bit stream itself stored in the buffer 101 under the control of the internal controller 108. Recording is performed on a removable recording medium.

  The internal controller 108 determines a recording method (resolution / frame rate and encoding (compression) method) when the information recording unit 107 performs recording on the recording medium based on the encoding parameter, and the determined recording Depending on the system, the resolution / frame rate conversion unit 103, the MPEG4AVC encoding unit 104, the MPEG4SP encoding unit 105, the MPEG2 encoding unit 106, and the information recording unit 107 are controlled, and the designated program (bitstream) is controlled. ) Is recorded on a removable recording medium. Specifically, the internal controller 108 determines the recording method and controls the resolution / frame rate conversion unit 103 and the like as in the flowchart shown in FIG.

  First, in step S001, recording time information is acquired from already acquired program reservation information via the user interface 10. Next, in step S002, the bit rate included in the encoding parameter is extracted.

  In step S003, the bit amount to be recorded is calculated from the bit rate and the recording time. Here, the bit amount to be recorded is a bit amount (total bit amount) that is expected to occur when the input bit stream is recorded as it is for the entire program at the start of program recording. Specifically, the total bit amount is obtained from the bit rate included in the encoding parameter extracted by the decoding unit 102 and the recording time information acquired from the program reservation information. Further, as described later, when a part of a program has already been recorded, the bit amount to be recorded is the bit amount expected to be generated when the rest of the program is recorded at a predetermined bit rate (unrecorded bit). Amount). The predetermined bit rate is the bit rate included in the encoding parameter or the bit rate in each encoding unit.

  In step S004, the recording method is determined. Specifically, it is determined from the remaining capacity of the recording medium whether or not the bit amount of data obtained in S003 can be recorded. If it is determined that recording is possible, the bit stream stored in the buffer 101 can be removed. Record on a recording medium. If recording is not possible, the resolution and compression method (that is, any one of the MPEG4 AVC encoding unit 104, the MPEG4SP encoding unit 105, and the MPEG2 encoding unit 106 are set so that the program can be stored in a removable recording medium. Decide whether to employ an encoding unit).

  As a determination method, for example, the MPEG4AVC encoding unit 104 is an encoding tool capable of encoding at 8 Mbps with respect to an input of HD image quality, and the MPEG4SP encoding unit 105 is an input of QCIF. The encoding unit 106 for MPEG2 can be used as an encoding tool capable of encoding 4 Mbps with respect to an input of SD quality so that the capacity of the recording medium is used as much as possible. It is conceivable to select from these tools. This selection criterion is an example. Although each encoding method is not originally fixed to the above bit rate, it is generally used in the above manner in the actual application.

  In step S005, the resolution / frame rate conversion unit 103 and the selected encoding unit are controlled, and the newly generated bitstream is recorded on the removable recording medium for a predetermined time via the information recording unit 107. To do.

  In step S006, if the recording of the program has not ended, the control shifts to step S002.

  As described above, the internal controller 108 determines the recording method and controls the resolution / frame rate conversion unit 103 and the like a plurality of times at predetermined time intervals until the bitstream recording is completed. That is, in the digital information recorder 100, the resolution and the compression method may be corrected multiple times before the bitstream recording is completed.

(Operation of Digital Information Recorder 100)
The buffer 101 stores the input bit stream for a predetermined time. The decoding unit 102 decodes the bit stream stored in the buffer 101 and returns it to the baseband. Further, the decoding unit 102 extracts encoding parameters and outputs them to the internal controller 108. The internal controller 108 calculates the bit amount to be recorded from the bit rate and the recording time. Here, for example, when the obtained bit amount can be recorded in view of the remaining capacity of the recording medium, the information recording unit 107 records the bit stream stored in the buffer 101 on a removable recording medium for a predetermined time. . Thereafter, the internal controller 108 extracts the bit rate included in the encoding parameter again, and calculates the bit amount expected to occur when the rest of the program is recorded.

  In digital broadcasting, the amount of information is not fixed until the bitstream is actually received, so even if it is determined immediately after the start of the program that the entire program can be recorded on the recording medium, the bit that should be recorded more than expected. The amount may increase. In that case, depending on the remaining capacity of the recording medium, there is a possibility that the program cannot be recorded to the recording medium to the end. Therefore, the digital information recorder 100 corrects the recording method at predetermined time intervals until the bitstream recording is completed.

  When the internal controller 108 determines that the obtained bit amount cannot be recorded in view of the remaining capacity of the recording medium, the internal controller 108 determines the resolution and compression method so that the remaining part of the program can be accommodated in the removable recording medium. . For example, when the remaining capacity of the recording medium is 1 GB and the bit amount expected when the remaining part of the program is compressed by the MPEG2 system (encoding system in the MPEG2 encoding unit 106) is 2 GB, The internal controller 108 changes the resolution in the resolution / frame rate conversion unit 103 so that the resolution is less than half the current level. Thereafter, the internal controller 108 controls the resolution / frame rate conversion unit 103, the selected encoding unit (for example, the encoding unit for MPEG2), and the information recording unit 107, and uses the newly determined resolution and compression method. The remaining part of the program is recorded for a predetermined time. In the digital information recorder 100, the determination of the recording method and the recording for a predetermined time are repeated until the recording of the designated program is completed.

  As described above, according to the present embodiment, the recording method of the bit stream is corrected according to the amount of unrecorded bits and the remaining capacity of the recording medium until the recording of the program is completed. Recording time can be guaranteed.

  As described above, it is not always necessary to re-compress after converting the resolution. For example, only re-compression may be performed.

  Further, only the frame rate may be changed and then recompressed for recording, or both the frame rate and the resolution may be changed and then recompressed for recording.

  In addition, if the recording cannot be performed on the recording medium even after resolution conversion or recompression, recording may be stopped. As a result, it is possible to prevent the recording medium from being wasted by writing to the recording medium that can be written only once even though there is not enough free space.

  When a plurality of types of recording media can be selected, the internal controller 108 may determine which recording medium can be recorded. For example, DVD-R dual-layer recording (9.4 GB) disc and Blu-Ray disc (50 GB) can be selected as removable recording media. Also, it is assumed that the input bit stream (program) is a two-hour movie with an image quality of HD, and the bit rate after decoding by the decoding unit 102 is 25 Mbps. In this example, the Blu-Ray disc can be recorded for 4 hours or more at this recording rate, so that it can be directly recorded on the Blu-Ray disc without any problem. Also, a DVD-R dual-layer recording disc can be recorded for more than 2 hours if it is decoded by the decoding unit 102 and then recompressed (encoded) to 8 Mbps by the MPEG4 AVC encoding unit 104. Become one. As described above, when the bit rate, the recording time, and the free space of the recording medium are determined, the optimum combination of the encoding tool and the recording medium can be obtained. If the encoding unit is mounted so that it can operate in parallel, for example, it is possible to simultaneously record on the two recording media as described above.

  Further, when it is determined that recording is possible on two or more types of recording media, for example, the user can select which recording medium can be recorded via the user interface 10 and the user can select the recording medium on which recording is to be performed. Alternatively, the priority order of recording media to be used may be determined in advance, and the recording medium to be used may be selected according to the priority order.

  Further, when the recording medium is a recording medium from which data can be erased and the current remaining capacity is less than the amount of bits to be recorded, already recorded data may be erased.

  Further, the internal controller 108 may be configured to correct the recording method each time a predetermined amount of data is recorded, for example.

  In the digital information recorder according to the present invention, the recording method is modified according to the unrecorded bit amount and the remaining capacity of the recording medium until the recording of the program is completed. This has the effect of guaranteeing the recording time when performing direct recording, and is useful as a digital information recorder or the like that records a digital broadcast on a removable recording medium.

It is a block diagram which shows the structure of the digital information recorder based on embodiment of this invention. 3 is a flowchart showing the operation of the internal controller 108.

Explanation of symbols

10 User interface
20 Semiconductor memory card
DESCRIPTION OF SYMBOLS 30 Optical disk 100 Digital information recorder 101 Buffer 102 Decoding part 103 Resolution and frame rate conversion part 104 MPEG4AVC encoding part 105 MPEG4SP encoding part 106 MPEG2 encoding part 107 Information recording part 108 Internal controller

Claims (8)

A digital information recorder for recording a bit stream obtained by receiving a digital broadcast program on a removable recording medium,
A bit rate information indicating a bit rate of the bit stream, and a decoding unit that decodes the bit stream and returns it to a baseband signal;
An information recompression unit that encodes the baseband signal using a predetermined encoding method to generate a new bitstream;
An information recording unit for recording either the bit stream obtained by receiving the program or the new bit stream on the recording medium;
At the start of recording the program, the total bit amount when the program is recorded at the bit rate indicated by the bit rate information is obtained, and the information recording unit determines the total bit amount and the remaining capacity of the recording medium according to the total bit amount. Control which bitstream is recorded, and further determine the amount of unrecorded bits when the unrecorded part of the program is recorded at a predetermined bit rate until the recording of the program ends, An internal controller that re-controls which bitstream the information recording unit records according to the amount of unrecorded bits and the remaining capacity of the recording medium;
A digital information recorder characterized by comprising: The digital information recorder of claim 1, comprising:
The information recompressing unit is configured to perform the encoding after changing at least one of a resolution and a frame rate of the bit stream decoded by the decoding unit. vessel. The digital information recorder of claim 1, comprising:
The information recompression unit is configured to support a plurality of types of encoding methods,
The internal controller determines an encoding method to be performed by the information recompression unit according to the total bit amount and the remaining capacity of the recording medium at the start of recording of the program, and performs encoding using the determined encoding method. The information recompressing unit is controlled in accordance with the amount of unrecorded bits and the remaining capacity of the recording medium until the recording of the program is completed. A digital information recorder configured to determine an encoding method to be performed and to re-control the information recompression unit so that encoding is performed according to the determined encoding method. The digital information recorder of claim 1, comprising:
Furthermore, when there are two or more recording media having a capacity capable of recording the program, a digital information recorder is provided with a user interface that allows the user to select which recording medium to record. The digital information recorder of claim 1, comprising:
The internal controller controls the information recording unit to record on a recording medium selected according to a predetermined priority when there are two or more recording media having a capacity capable of recording the program. A digital information recorder characterized by being configured to do so. The digital information recorder of claim 1, comprising:
The removable recording medium is an erasable recording medium,
The internal controller is configured to erase already recorded data when the current remaining capacity of the removable recording medium is less than the total bit amount. Recorder. The digital information recorder of claim 1, comprising:
The internal controller is configured to stop recording the program when the current remaining capacity of the removable recording medium is less than the total bit amount. vessel. The digital information recorder of claim 1, comprising:
The internal controller selects a recording medium having a capacity capable of recording the total bit amount when there are two or more recording media, and the information recording unit performs recording on the selected recording medium. A digital information recorder characterized in that the digital information recorder is controlled.

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