JP2004228758A - Apparatus for recording and reproducing digital signal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for recording and reproducing a digital signal capable of copying to a portable record medium at a high speed in a state, where deterioration in an image quality is small, in addition to the record and reproduction of normal picture and speech signals. <P>SOLUTION: An input picture signal and a speech signal are digitally converted by A/D circuits 2, 10 before an encode signal having a plurality of different bit rates is generated by encode blocks 3, 15 by the selection of an user according to an intended purpose after reproduction for recording at a data accumulation section 14. In usual viewing/listening, an encode signal having a high bit rate is reproduced in real time from the data accumulation section 14. In copying to the portable record medium, an encode signal having a low bit rate is reproduced at a high speed from the data accumulation section 14 for quickly copying to a memory card 32 in a memory card I/F circuit 31. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus for converting an analog video signal and an audio signal into digital signals, reducing the bit rate and then multiplexing them, and recording the same video program on a recording medium. The present invention relates to a digital signal recording / reproducing apparatus which is effective when using differently.
[0002]
[Prior art]
Conventionally, a digital signal recording / reproducing apparatus using a non-removable large-capacity recording medium such as a hard disk determines the bit rate of a digital video signal to be recorded in consideration of the recording time. The higher the bit rate, the lower the bit rate reduction ratio (compression ratio) and thus the higher the image quality, but the higher the amount of data per unit time, the shorter the recording time. In general, it is said that a standard image quality can be obtained with an NTSC video signal if the bit rate is about 6 Mbps in a compression method called MPEG2. If recording is performed for one hour at this bit rate, the amount of data generated is 2.7 GB. In this state, recording can be performed for about 44 hours using a 120 GB hard disk.
[0003]
2. Description of the Related Art A program recorded by such a digital signal recording device is copied to a portable recording medium, and is easily viewed anywhere on a relatively small screen. As a recording medium used in such a case, for example, there is a memory card having a built-in flash memory. However, for example, when a 6 Mbps moving image is stored in a 512 MB memory card, only about 11 minutes can be recorded, so that the recording time is insufficient. Therefore, it has been practiced to return the reproduced digital video signal to an analog video signal once, then generate a low bit rate digital video signal again and record it on a memory card to extend the recording time.
Hereinafter, the configuration and problems of such a conventional example will be described with reference to the accompanying drawings.
[0004]
FIG. 3 is a block diagram showing a conventional configuration example of the above-described apparatus. The analog video signal connected to the input terminal 1 is converted into a digital video signal by the A / D circuit 2 and then reduced by the video encoding block 4 to a bit rate of 6 Mbps by, for example, MPEG2 encoding.
Similarly, the analog audio signal connected to the input terminal 9 is converted to a digital audio signal by the A / D circuit 10 and then reduced to a bit rate of 192 kbps by the audio encoding block 11 by, for example, MPEG1 encoding.
The digital video signal and the audio signal whose bit rate has been reduced then enter the multiplexer circuit 8 where they are time-division multiplexed to form one system of encoded signals and stored in the internal data storage unit 14 to the internal hard disk. Be recorded.
[0005]
Next, on the reproduction side, the encoded signal reproduced from the data storage unit 14 is connected to the external connection I / F circuit 29 and the low bit rate conversion circuit 33. The encode signal input to the external connection I / F circuit 29 is output from the output terminal 30 to the outside. For example, the output encoded signal is returned to the original analog video signal and audio signal by an external decoding device and viewed.
On the other hand, the encoded signal input to the low bit rate conversion circuit 33 is subjected to bit rate conversion here. Although there are various bit rate conversion methods, in the case of an MPEG encoded signal, a method of once decoding (decoding) an analog video signal and an audio signal and then encoding each at a low bit rate again is generally used. Done. The encoded signal converted to a low bit rate in this manner is recorded on a removable memory card 32 by the next memory card I / F circuit 31. At this time, if the converted bit rate is set to 1.1 Mbps, a moving image of about 62 minutes can be recorded with a 512 MB memory card.
[0006]
[Problems to be solved by the invention]
However, in the bit rate conversion method in the above-described apparatus, since the amount of information of the original video signal is reduced when the MPEG2 encoded signal is first generated in the video encode block 4, re-conversion is performed using this encoded signal after reproduction. However, there is a problem that the image quality of the converted encoded signal is considerably degraded as compared with a signal obtained by directly encoding the original video signal at a low bit rate.
In addition, even when the recording transmission speed of the memory card 32 is high, in this configuration, the reproduction speed multiple of the data storage unit 14 cannot be so high because the bit rate of the encoded signal handled at the time of reproduction is relatively high. The signal processing speed of the low bit rate conversion circuit 33 is also limited, and there is a problem that copying cannot be performed at high speed. An object of the present invention is to provide a high-speed copy to a portable recording medium without deteriorating the image quality, in addition to the recording and reproduction of the normal video and audio signals, in view of the situation of the problem of the conventional example. Another object of the present invention is to provide a digital recording and reproducing apparatus.
[0007]
Patent Document 1 below discloses a technique for converting a bit rate as a known document, and Patent Document 2 discloses a technique for recording digital video signals and audio signals having a plurality of bit rate values on the same recording medium. ing.
[0008]
[Patent Document 1]
JP 2002-10200 A [Patent Document 2]
JP 2002-369145 A
[Means for Solving the Problems]
Means for solving the above problems include the following means (1) to (4). That is,
(1) The input analog video signal and audio signal are converted into digital signals by A / D conversion means, respectively, and these digital video signals and audio signals are further reduced to a predetermined bit rate by bit rate reduction means. In a digital signal recording device for multiplexing and recording on a recording medium,
A plurality of bit rate reduction means are provided corresponding to the digital video signal and the audio signal, respectively, and a plurality of bit rate reduced digital video signals and a plurality of bit rate reduced digital audio signals obtained by these bit rate reduction means are provided. Means for generating a plurality of multiplexed signals by arbitrarily combining
A digital signal recording apparatus comprising: a selection circuit for determining whether or not each of the generated multiplexed signals is to be recorded on the recording medium.
(2) The digital video signal bit rate reducing means resamples pixel data in one frame to reduce the number of pixels, a frame rate changing circuit to reduce the number of frames per unit time, and a digital video signal. And a circuit for compressing and encoding the signal. Each of these circuits operates by being supplied with the parameters of the number of pixels in one frame, the number of frames per unit time, and the reduced bit rate value from an external circuit. Along with
The digital audio signal bit rate reducing means includes a resampling circuit for converting the number of samples per unit time, and a circuit for compressing and encoding the digital audio signal. 2. The digital signal recording apparatus according to claim 1, wherein each of the parameters and the bit rate value after the reduction is supplied and operated.
(3) The parameters supplied to the digital video signal bit rate reduction means and the digital audio signal bit rate reduction means are supplied from parameter generation means for generating a plurality of parameter groups in which arbitrary values are combined. ,
3. The digital signal recording apparatus according to claim 1, wherein one of the plurality of parameter groups is selected and supplied by a selection circuit means.
(4) An apparatus for reproducing a multiplexed signal of a plurality of bit rate-reduced digital video signals and audio signals recorded by the recording apparatus according to claim 1, 2, or 3.
Means for reproducing at least one of the reproduced multiplexed signals in a time shorter than a recording time;
Means for copying the multiplexed signal obtained by this means to another recording medium.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings by way of preferred examples. (Note that, for the sake of simplicity, the same components as those in the conventional example are denoted by the same reference numerals.)
[0011]
FIG. 1 is a block diagram for explaining an embodiment of a digital signal recording and reproducing apparatus according to the present invention, and FIG. 2 shows an example of a screen display when a user sets recording conditions. .
In FIG. 1, an analog video signal connected to an input terminal 1 is converted into a digital video signal by an A / D circuit 2 and then supplied to two systems of an encode block 3 and an encode block 15, respectively.
Similarly, the analog audio signal connected to the input terminal 9 is converted into a digital audio signal by the A / D circuit 10 and is similarly supplied to two systems of the encode block 3 and the encode block 15, respectively.
Here, the function of the encode block is to provide a circuit for reducing the bit rate of the input digital video signal and audio signal to a predetermined value according to an external parameter, and a video signal and audio signal whose bit rate has been reduced. Are multiplexed by a multiplexer circuit. In this embodiment, two encode blocks, which are the minimum number required in the present invention, are used. However, the present invention is not limited to this, and three or more encode blocks may be used depending on the use of the apparatus.
[0012]
The digital video signal that has entered one encode block 3 then enters the video encode block 4, where three types of bit rate reduction processing are performed. The first resizing circuit 5 changes the image size of the video frame by reducing the number of pixels of the input digital video signal by resampling according to the size parameter from the controller 24.
Next, the resized digital video signal enters the frame rate conversion circuit 6, where the number of image frames per unit time is also changed according to the frame rate parameter from the controller 24.
The resized and frame rate-converted digital video signal enters the next video encoding circuit 7, where it is encoded (encoded) to a predetermined bit rate in accordance with the bit rate parameter from the controller 24. Then, the digital video signal encoded to a predetermined bit rate becomes one input of the multiplexer circuit 8. In this embodiment, MPEG2 is used for a high bit rate, and MPEG1 or MPEG4 is used for a low bit rate.
In the video encoding block 4, the operation of the resizing circuit 5 or the frame rate converting circuit 6 may be omitted depending on the reduction amount of the bit rate.
[0013]
The digital video signal input to the other encoding block 15 enters the video encoding block 16 in the same manner as described above except that three types of parameter values from the controller 24 are different, and the resizing circuit 17 and the frame rate conversion circuit 18 By the respective bit rate reduction processes of the video encoding circuit 19, the video signal is encoded to a predetermined bit rate and becomes one input of the multiplexer circuit 20.
[0014]
The digital audio signal input to the encode block 3 then enters the audio encode block 11, where two types of bit rate reduction processing are performed. The first resampling circuit 12 resamples the input digital audio signal according to the sampling rate parameter from the controller 24 and converts it into a low sampling rate digital audio signal.
Next, the resampled digital audio signal enters the audio encoding circuit 13, where it is encoded to a predetermined bit rate according to the bit rate parameter from the controller 24. Then, the digital audio signal encoded to a predetermined bit rate becomes the other input of the multiplexer circuit 8. In this embodiment, the MPEG1-Layer 2 system or the Layer 3 system is used as the audio encoding system.
In the audio encode block 11, the operation of the resampling circuit 12 may be omitted depending on the reduction amount of the bit rate.
[0015]
Similarly, the other digital audio signal input from the A / D circuit 10 to the encode block 15 enters the audio encode block 21 in the same manner as described above except that two types of parameter values from the controller 24 are different. By the respective bit rate reduction processes of the resampling circuit 22 and the audio encoding circuit 23, the data is encoded to a predetermined bit rate and becomes the other input of the multiplexer circuit 20.
[0016]
The multiplexer circuit 8 separates a digital video signal encoded at a predetermined bit rate by the video encoding block 4 and a digital audio signal encoded at a predetermined bit rate by the audio encoding block 11 into arbitrary bit sizes (packetization). ), And multiplex them to generate one encoded signal. (Hereinafter referred to as a first encoded signal)
Further, the multiplexer circuit 20 generates an encoded signal in which the digital video signal and the digital audio signal are multiplexed and has a bit rate different from that of the first encoded signal by a similar operation. (Hereinafter referred to as a second encoded signal)
Next, the first encoded signal and the second encoded signal are time-divisionally processed by the data storage unit 14 and recorded on the internal hard disk recording medium.
[0017]
Next, the recording reservation setting of the controller 24 and the user will be described.
As shown in FIG. 1, the controller 24 is connected with a parameter generation circuit 27, a parameter generation circuit 27, and a user selection circuit 26.
The parameter generation circuit 27 is a circuit that generates a plurality of parameters used in each of the bit rate reduction circuits that constitute the encode block 3. The parameter generation circuit 28 is a circuit that generates each of the bit rates that constitute the encode block 15. This is a circuit that generates a plurality of parameters used in the circuit. Then, the controller 24 selects and outputs from these parameters according to an instruction from the user selection circuit 26.
[0018]
The user selection circuit 26 is a circuit that holds the user selection information input from the input terminal 25 and gives an instruction to the controller 24.
FIG. 2 is an example of a setting screen when a user makes a recording reservation for the apparatus according to the present invention. Although not shown, the setting screen is created by a system control unit that performs overall control including a tuner and a timer attached to the apparatus.
In the figure, setting steps 40 to 42 are for setting the date, time and channel to be recorded, and the next setting step 43 is a setting place for determining the parameters of the encode block 3.
As shown in the figure, in the present embodiment, three kinds of parameters of "high image quality", "standard" and "long time" are prepared as parameters of the encoding block 3, and the user selects one of them. The setting step 44 is a setting place for determining the parameters of the encoding block 15, and "medium screen" and "small screen" are prepared.
These expressions are associated with the bit rate value of the encoded signal to be recorded. “High image quality” indicates 9 Mbps, “standard” indicates 6 Mbps, and “long time” indicates 4 Mbps. The “medium screen” is about 2 Mbps, and the “small screen” is about 1 Mbps. The setting step 44 is an item for selecting an encode signal on the premise of copying to a portable recording medium. The “medium screen” is a medium screen mobile personal computer, and the “small screen” is a PDA (portable information terminal) or memory. It is assumed to be viewed on a mobile phone using a card.
As is clear from the above description, the items selected by the user include the three types of digital video signal bit rate reduction circuits and the two types of digital audio signal bit rate reduction circuits in the above-described encode block. The parameters to be used are included in a previously arbitrarily combined form.
[0019]
The selection is made when "OFF" is selected in the selection items of the setting steps 43 and 44 and the signal of the encoded block does not need to be recorded. This is because, when the purpose of use at the time of reproduction is determined in advance, the capacity of the recording medium is effectively used by not recording both encoded signals. This information is sent from the controller 24 to the data storage unit 14 and controlled by the data storage unit 14.
When the setting of each step of the recording reservation is completed, the decision 45 is clicked. This records the state set at the specified time.
[0020]
Next, the operation on the reproduction side will be described.
In FIG. 1, a first encoded signal and a second encoded signal recorded on a hard disk are independently reproduced from a data storage unit 14. The reproduced first encoded signal is connected to the external connection I / F circuit 29, and the second encoded signal is connected to the memory card I / F circuit 31.
When viewing a recorded program, the first encoded signal is reproduced in real time, and the first encoded signal output from the terminal 30 is returned to the original analog video signal and audio signal by an external decoding device. Watch.
When copying a recorded program to a memory card, the data storage unit 14 reproduces the second encoded signal at a low bit rate at a high speed, and the memory card I / F circuit 31 responds to the signal. The second encoded signal is copied to the memory card 32 in a short time. At this time, the speed of high-speed reproduction is mainly determined by the maximum reproduction speed of the data storage unit 14. For example, when the bit rate of the second encode signal is 1.1 Mbps, about 10-times speed reproduction is sufficiently possible. Can be copied in 1/10 of real time.
Although not shown, if the second encode signal is directly connected to the memory card I / F circuit 31 at the time of recording by switching, a configuration in which recording on the memory card can be performed in real time without passing through the data storage unit 14 is also possible. become.
[0021]
【The invention's effect】
As described above, according to the digital signal recording and reproducing apparatus of the present embodiment, the video and audio signals of one program can be selected by the user by having a plurality of encode block units for reducing the bit rate. Can be recorded on a recording medium at different bit rates.
This is because, for example, when viewing with high picture quality and high sound quality during reproduction, a high bit rate is selected and recorded, and when copying to a portable recording medium such as a memory card is planned, a low bit rate is simultaneously used. You can keep a record. Accordingly, when copying to a portable recording medium having a low bit rate, high-speed copying such as, for example, 10 times speed is possible. Further, since an encoded signal of a low bit rate is directly generated from an input video / audio signal, it is possible to have a feature that deterioration of image quality is minimized.
Further, since it is possible to select to record only one of the plurality of encoding block units, there is an effect that the capacity of the data storage unit can be effectively used.
[Brief description of the drawings]
FIG. 1 is a block diagram of a digital signal recording and reproducing apparatus for simultaneously recording at a plurality of bit rates applied to an embodiment of the present invention.
FIG. 2 is an example of a screen display for setting a recording condition in the embodiment of the present invention.
FIG. 3 is an example of a block diagram of a conventional digital signal recording and reproducing apparatus.
[Explanation of symbols]
1 ... input terminal, 2 ... A / D circuit, 3 ... encode block,
4: video encode block, 5: resize circuit,
6: frame rate conversion circuit, 7: video encoding circuit, 8: multiplexer circuit, 9: input terminal, 10: A / D circuit, 11: audio encoding block,
12 resampling circuit, 13 audio encoding circuit, 14 data storage unit, 15 encode block, 16 video encode block,
17 resize circuit, 18 frame rate conversion circuit, 19 video encoding circuit, 20 multiplexer circuit, 21 audio encode block,
22: resampling circuit, 23: audio encoding circuit, 24: controller, 25: input terminal, 26: user selection circuit, 27: parameter generation circuit,
28: parameter generation circuit, 29: external connection I / F circuit, 30: output terminal,
31: memory card I / F circuit, 32: memory card,
33 ... Low bit rate conversion circuit
40: setting step (year, month, day), 41: setting step (time),
42 ... setting step (channel),
43 setting step (encode 1)
44 setting step (encode 2), 45 setting step (decision)

Claims (4)

The input analog video signal and audio signal are converted into digital signals by A / D conversion means, respectively, and these digital video signals and audio signals are further reduced to a predetermined bit rate by bit rate reduction means, and then multiplexed. Digital signal recording device for recording on a recording medium
A plurality of bit rate reduction means are provided corresponding to the digital video signal and the audio signal, respectively, and a plurality of bit rate reduced digital video signals and a plurality of bit rate reduced digital audio signals obtained by these bit rate reduction means are provided. Means for generating a plurality of multiplexed signals by arbitrarily combining
A digital signal recording apparatus comprising: a selection circuit for determining whether or not each of the generated multiplexed signals is to be recorded on the recording medium. The digital video signal bit rate reducing means resamples pixel data in one frame to reduce the number of pixels, a frame rate changing circuit to reduce the number of frames per unit time, and compresses the digital video signal. Encoding circuits, each of which operates by being supplied with the parameters of the number of pixels in one frame, the number of frames per unit time, and the reduced bit rate value from an external circuit,
The digital audio signal bit rate reducing means includes a resampling circuit for converting the number of samples per unit time, and a circuit for compressing and encoding the digital audio signal. 2. The digital signal recording apparatus according to claim 1, wherein each of the parameters and the bit rate value after the reduction is supplied and operated. The parameters supplied to the digital video signal bit rate reduction means and the digital audio signal bit rate reduction means are supplied from parameter generation means for generating a plurality of parameter groups in which arbitrary values are combined,
3. The digital signal recording apparatus according to claim 1, wherein one of the plurality of supplied parameter groups is selected by a selection circuit. An apparatus for reproducing a multiplexed signal of a plurality of bit rate reduced digital video signals and audio signals recorded by the recording apparatus according to claim 1, 2, or 3.
Means for reproducing at least one of the reproduced multiplexed signals in a time shorter than a recording time;
Means for copying the multiplexed signal obtained by this means to another recording medium.

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