JP2002203371A - Digital signal recorder and digital signal recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To record a digital signal while maintaining its quality and to suppress the disturbance of reproduced image and sound associated with the variation of the recording rate of the digital signal to the minimum. SOLUTION: A digital signal recorder is provided with: a receiving part which receives a digital signal whose recording rate showing a speed at which the signal is recorded is varying; a recording rate judging part which judges the recording rate of the digital signal received by the receiving part; and a storage part which stores the maximum recording rate showing the maximum value of the recording rate which has been varying, updates the recording rate when the recording rate judged by the recording rate deciding part is higher the currently stored maximum recording rate by adopting the recording rate as a maximum recording rate and storing it; and a recording part which records the digital signal on recording media according to the maximum recording rate stored into the storage part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a technique for recording digital signals such as BS digital broadcasts.

[0002]

2. Description of the Related Art With the start of BS digital broadcasting in earnest from the end of 2000, expectations in the market for the high quality of images and the like broadcasted by BS digital broadcasting are growing. At the same time, a digital VT that can record BS digital broadcast programs with the same quality
The need for R is also increasing.

[0003] Hereinafter, a video recording apparatus proposed so far will be described by taking a case where a digital signal is a video signal as an example. FIG. 4 is a block diagram showing a configuration of a conventional video recording device 40. The video recording device 40 includes a digital signal receiving unit 41, a digital signal recording unit 42, an operation unit 43
And a recording rate determination unit 44.

[0004] The components of the video recording device 40 will be specifically described. The digital signal receiving unit 41 receives a digital signal including video information, audio information, and channel information from the outside. The recording rate judging section 44 is based on the digital signal input from the digital signal receiving section 41,
Determine the recording rate. “Recording rate” refers to the speed at which a digital signal should be recorded. This is synonymous with the reception speed of the digital signal and the transmission speed of the digital signal transmitted from the broadcasting station. The operation unit 43 receives instructions such as a recording rate, recording start, and stop from the user to the digital signal recording unit 42. Digital signal recording unit 42
Records the digital signal input from the digital signal receiving unit 41 on the recording medium based on the recording rate determined by the recording rate determining unit 44 and the instruction from the operation unit 43.

[0005] Regarding digital signals of BS digital broadcasting,
The broadcast station can insert information of the maximum value of the bit rate of each program for each program. Whether or not to insert it is arbitrary for the broadcasting station.

[0006] Based on these, the video recording device 40
Will be described. First, the digital signal receiving unit 41
When connected to the digital signal output of the S digital tuner, the digital signal receiving unit 41 sends the input digital signal to the digital signal recording unit 42 and the recording rate determining unit 44. When the input digital signal includes information on the maximum value of the bit rate, the recording rate determination unit 44 detects the information and determines the recording rate based on the detection result. Then, the determination result is transmitted to the digital signal recording unit 42. Alternatively, the user operates the operation unit 4
When the recording rate is set to the automatic mode by operating 3, the operation unit 43 transmits the setting to the digital signal recording unit 42.

[0007] When the recording rate is set, the user operates the operation unit 43 and sends a recording start instruction to the digital signal recording unit 42 when the program to be recorded is started. The digital signal recording unit 42, according to the instruction of the operation unit,
Digital recording is started at the recording rate specified by the recording rate determining unit 44.

[0008]

If a specific recording rate has not been set, the recording rate determining section 44 determines the speed of the received digital signal and determines the recording rate based on the determination. Therefore, when recording a digital signal whose reception rate changes with time,
It is necessary to temporarily stop recording, change the recording rate, and then start recording again. Alternatively, it is necessary to change the operation speed of the recording medium (for example, the rotation speed of the magnetic tape) to a speed corresponding to the recording rate and continue recording. In this case, the program being recorded is interrupted every time the recording rate is changed, which makes it difficult for the user to see and very unpleasant.

It is an object of the present invention to record a digital signal while maintaining the quality thereof, and to minimize disturbance of reproduced images and sounds due to a change in the recording rate of the digital signal.

[0010]

A digital signal recording apparatus according to the present invention comprises: a receiving section for receiving a digital signal whose recording rate indicating a recording speed is to be changed; and a recording rate of the digital signal received by the receiving section. A recording rate determining unit for determining the maximum recording rate indicating the changed maximum value of the recording rate, wherein the recording rate determined by the recording rate determining unit is the maximum stored rate. If higher than the recording rate, a storage unit that updates and stores the recording rate as the maximum recording rate,
According to the maximum recording rate stored in the storage unit,
A recording unit for recording the digital signal on a recording medium, whereby the above object can be achieved.

The storage unit may maintain the maximum recording rate when the recording rate determined by the recording rate determination unit is lower than the stored maximum recording rate.

[0012] The apparatus further comprises an operation unit for inputting an instruction to start recording of the digital signal and an instruction to stop recording, and when an instruction to start recording of the digital signal is input from the operation unit. The storage unit may initialize the maximum recording rate at the start of recording.

[0013] The digital signal includes channel information for specifying a broadcasting station from which the signal has been transmitted. A receiving unit detects a change in the channel information. , The maximum recording rate may be initialized.

[0014] The digital signal may include a video signal.

[0015] The digital signal may include an audio signal.

The digital signal recording method according to the present invention comprises the steps of: receiving a digital signal having a recording rate indicating a recording speed to be changed; determining a recording rate of the received digital signal; A step of storing a maximum recording rate indicating a maximum value of a rate, and when the determined recording rate is higher than the stored maximum recording rate, updating the recording rate as a maximum recording rate. And recording the digital signal on a recording medium according to the stored maximum recording rate, thereby achieving the above object.

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In this embodiment, a recording device for recording a digital signal will be described. The digital signal is a signal representing a BS digital broadcast program including a video signal.

First, the digital signal will be described. Digital signals have different transmission speeds depending on the quality of the content they represent. Therefore, the receiving speed and the recording rate on the receiving side are also different. "Recording rate" refers to the speed required to record a received digital signal without deteriorating the quality. For example, for video, the recording rate for securing high-definition image quality is about 28 Mb.
The recording rate for securing image quality of ps and standard resolution is about 14 Mbps, and the recording rate for securing image quality of low resolution with an emphasis on recording time is about 4.7 Mbps.
As described below, the recording rate can be specified by detecting the frequency of the received signal. When continuously recording programs having different recording rates, the recording rate naturally changes during recording. However, the recording rate may change even within the same program.

When a program to be broadcast includes video,
Usually, the broadcasting station determines the type of the video (1125i, 750
P, 525P, and 525i) are inserted. Channel information (program # number) for specifying a broadcasting station is also inserted in the digital signal.
By detecting the channel information, it is possible to specify from which broadcast station the digital signal being received is transmitted.

Hereinafter, the video recording apparatus according to the present embodiment will be described. FIG. 1 is a block diagram illustrating a configuration of the video recording device 10. The video recording device 10 records, for example, a television program of BS digital broadcast and reproduces the D-VHS.
Digital VTR (trademark of Victor Company of Japan)
It is. The video recording device 10 includes a digital signal receiving unit 11
, A digital signal recording unit 12, an operation unit 13, a recording rate determination unit 14, a maximum recording rate storage unit 15, and a recording rate instruction unit 16.

Each component of the video recording apparatus 10 will be specifically described. First, the digital signal receiving unit 11 receives a digital signal including video information, audio information, channel information, and the like of a program via an external device (for example, an antenna).

The recording rate determination section 14 determines a recording rate based on the digital signal input from the digital signal receiving section 11. The “recording rate” is synonymous with the reception speed of a digital signal or the transmission speed of a digital signal transmitted from a broadcasting station. Digital signal reception speed is
It can be obtained by detecting the received radio signal and specifying the frequency.

The maximum recording rate storage section 15 stores the maximum recording rate. More specifically, the maximum recording rate storage unit 15 first compares the current recording rate determined by the recording rate determination unit 14 with the stored maximum recording rate. As a result of the comparison, if the current recording rate is higher than the stored maximum recording rate, the current recording rate is updated as the maximum recording rate. Updating of the maximum recording rate is performed from the start to the end of the recording, or from the start of the recording until the channel is changed. The start and end of recording are input by the user from the operation unit 13. Or
In the case of scheduled recording, the control unit (not shown) of the video recording device 10 instructs based on the set scheduled time. On the other hand, whether or not the channel has been changed may be determined by detecting a change in channel information included in the digital signal. The change in the channel information may be detected by either the digital signal receiving unit 11 or the recording rate determining unit 14.

The recording rate instructing section 16 reads out the maximum recording rate stored in the maximum recording rate storage section 15,
The information is transmitted to the digital signal recording unit 12. Upon receiving the recording start instruction, the digital signal recording unit 12 records the digital signal on the recording medium at the maximum recording rate received from the recording rate instruction unit 16. Recording media are, for example,
It is a magnetic recording medium such as a magnetic tape or an optical recording medium such as a DVD. For example, when the recording medium is a magnetic tape, the digital signal is recorded by rotating the magnetic tape at a rotation speed corresponding to the maximum recording rate. Therefore, the digital signal recording unit 12 always records the digital signal at the maximum recording rate up to that time. In other words, the digital signal recording unit 12 may frequently change the maximum value of the recording bit rate of the digital signal or the recording bit rate itself during recording of the digital signal (that is, during recording of the program). No change to a lower rate.

The digital signal recording unit 12 can also record digital signals at a recording rate specified by the user using the operation unit 13. The operation unit 13 receives an instruction from the user, such as a recording rate desired to be used, start and stop of recording, and sends the instruction to the digital signal recording unit 12.

Next, referring to FIG.
The operation of FIG. 1 will be described. FIG. 2 shows a video recording device 10
2 is a flowchart showing the operation of FIG. First, upon receiving a recording start instruction, the video recording device 10 (FIG. 1)
(Not shown) generates an initialization signal to initialize the storage contents of the maximum recording rate storage unit 15 (FIG. 1). Then, the digital signal receiving unit 11 (FIG. 1) starts receiving digital signals (step 21).
The maximum recording rate storage unit 15 (FIG. 1) stores the recording rate of the received digital signal as the maximum recording rate. Note that the lowest settable recording rate or the recording rate set by default by the user may be stored as the initial maximum recording rate.

As described above, the recording rate of a digital signal may change during recording of a program. Therefore, the recording rate determination unit 14 (FIG. 1)
Every 1 second), the recording rate of the digital signal being received is determined (step 23). Maximum recording rate storage unit 15
(FIG. 1) indicates that the recording rate at that time determined by the recording rate determination unit 14 (FIG. 1) is the maximum recording rate storage unit 15.
(Figure 1) is higher than the stored maximum recording rate,
It is determined whether it is low (step 24).

If the recording rate at that time is lower than the maximum recording rate, the recording rate instruction section 16 (FIG. 1) updates the maximum recording rate stored in the maximum recording rate storage section 15 (FIG. 1). The maximum recording rate is transmitted to the digital signal recording unit 12 (FIG. 1). Then, the digital signal recording unit 12 (FIG. 1) starts recording the digital signal at the maximum recording rate (step 25).

On the other hand, if the recording rate at that time is higher than the maximum recording rate, the maximum recording rate storage 15
(FIG. 1) updates the recording rate at that time as the maximum recording rate (step 26). Thereafter, the digital signal recording unit 12 (FIG. 1)
Start recording digital signals at the maximum recording rate.

Subsequently, the recording rate determination unit 14 (FIG. 1)
Alternatively, the control unit (not shown) determines whether the channel information of the digital signal has been changed (step 2).
7). If it is determined that the channel information has been changed, the process returns to step 21. That is, the digital signal input unit 11 (FIG. 1) generates an initialization signal and initializes the contents stored in the maximum recording rate storage unit 15 (FIG. 1). This is because the processing is performed assuming that the recording is newly started. When the channel information is changed, the optimum recording rate can be set again by initializing the maximum recording rate storage unit 15 (FIG. 1).

If it is determined that the channel information has not been changed, it is next determined whether or not an instruction to end recording has been given (step 28). The recording end instruction is transmitted from the user using the operation unit 13 (FIG. 1), or transmitted from the control unit (not shown) when the scheduled recording end time comes. If there is no recording end instruction, the process returns to step 23, and the acquisition of the recording rate at that time and the recording of the digital signal are continued. Note that the digital signal is not immediately recorded on the recording medium immediately after reception, but is temporarily stored in a buffer (not shown). When the recording rate is changed, it is necessary to perform a predetermined process such as a change in the encoding process. However, by storing the processed data in a buffer (not shown), the data can be continuously processed without interruption. Can be recorded.

How the maximum recording rate is updated by the operation of the video recording apparatus 10 (FIG. 1) described above will be specifically described. FIG. 3 is a diagram illustrating the relationship between the recording rate of a digital signal and the maximum recording rate. As shown in the graph, it is assumed that the recording rate of the received digital signal changes according to time. From time T1 to T
Up to 2 are represented as [T1, T2].

Times [0, T1], [T1, T2], [T2,
T3], the maximum recording rate is 5 Mbps, 7 Mbps, 14 Mbps according to the recording rate of the digital signal.
ps has been updated to a higher value. But time
In [T3, T4], the recording rate of the digital signal is 14M
bps to 7 Mbps, but the maximum recording rate remains 14 Mbps and does not change. This is the same after time T5.

It should be noted here that if the recording rate of the digital signal is changed during recording, when the changed portion is reproduced,
Video and audio are interrupted, and it takes a while before it is reproduced again. The reason is that the encoding process needs to be changed. For example, in a video recorded according to the MPEG2 standard, an I picture search, a B picture,
Since it is necessary to acquire a P picture, it takes time to display the video again.

Therefore, according to the above-described processing, even when the recording rate of the digital signal is higher than before, the recording can be reliably performed, and the change in the recording rate is small, so that the interruption of the video and audio can be reduced. .

As described above, the video recording device 10
(FIG. 1) records digital signals at the maximum recording rate up to that time. When the recording rate of the digital signal being received becomes higher than the maximum recording rate, the recording rate is updated, and recording is performed at the updated higher recording rate. On the other hand, if the recording rate of the digital signal being received becomes lower than the maximum recording rate, the recording rate is not changed, and recording is continued at the maximum recording rate. Even if the maximum bit rate included in the digital signal being recorded or the bit rate itself frequently changes, the recording rate is not changed to a lower rate. The number of interruptions of video and audio due to changes can be minimized. Each time recording is started, the maximum recording rate storage unit 15
Since the storage contents of FIG. 1 are initialized, the optimum recording rate can always be set.

In the above description, the recording rate determining unit 1
4 (FIG. 1) acquires the recording rate based on the reception frequency of the digital signal. However, for digital signals,
When information on the bit rate of the digital signal (for example, information on the maximum value of the bit rate) is included, the recording rate may be acquired using the information. Alternatively, information about the type of the video signal may be detected, and the recording rate may be determined based on the information.
Similar effects can be obtained in these cases.

Although the case where the recording medium is a magnetic tape has been described as an example, the recording medium may be a DVD, for example. Briefly describing a case where a digital signal is recorded on a DVD, an input digital signal is temporarily
It is stored in a write buffer and each time the buffer is full it is written to a DVD that is rotated at a constant speed. That is, data is continuously recorded regardless of the recording rate. However, since the encoding process and the like differ according to the change in the recording rate, the change in the recording rate is minimized by performing the processing described in FIG. 2 by the DVD recorder. Can minimize the number of interruptions of video and audio. Regardless of the type of the recording medium, discontinuity of data occurs according to the change of the recording mode.
Or, if the sound is interrupted, it will be easily understood that the present invention is applicable.

In the above-described example, the description has been made assuming that the digital signal mainly includes the video signal. However, a signal representing only video or only audio may be used. In the case of only audio, the above “recording” may be read as “recording”. When not only recording of a video signal but also recording of an audio signal or the like is included, the “recording rate” may be replaced with the “recording rate”.

The video recording apparatus 10 described in the present embodiment
The processing operation (FIG. 2) of FIG. 1 can be realized as a computer program for causing a computer to execute such processing. Such a computer program is recorded on an optical disk such as a CD or a DVD, a magnetic recording medium such as a flexible disk, or a semiconductor recording medium such as a flash memory. Alternatively, such a computer program is transmitted as an electric signal via a network such as the Internet.

[0042]

According to the present invention, only when the recording rate of a digital signal to be recorded is higher than the previous recording rate, recording is performed by changing the recording rate to a higher value.
When the recording rate decreases, the recording is continued without changing the recording rate. Thereby, the number of interruptions of video and / or audio due to a change in the recording rate during reproduction can be minimized.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a video recording device.

FIG. 2 is a flowchart illustrating an operation of the video recording device.

FIG. 3 is a diagram illustrating a relationship between a recording rate of a digital signal and a maximum recording rate.

FIG. 4 is a block diagram illustrating a configuration of a conventional video recording device.

[Explanation of symbols]

 Reference Signs List 10 Video recording device 11 Digital signal receiving unit 12 Digital signal recording unit 13 Operation unit 14 Recording rate determination unit 15 Maximum recording rate storage unit 16 Recording rate instruction unit

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Kazuhide Yanase, 1006 Kazuma Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Katsunori Mochida 1-1-1, Matsushita-cho, Ibaraki-shi, Osaka Matsushita, Inc. F-term (reference) in Avicie Technology 5C053 FA20 FA22 GA11 GB11 GB17 GB21 JA01 JA21 LA06 LA07 5D044 AB05 AB07 BC01 BC04 CC03 CC04 DE43 EF05 GK08 GK10

Claims (7)

[Claims] 1. A receiving unit for receiving a digital signal whose recording rate indicating a recording speed changes, a recording rate determining unit for determining a recording rate of the digital signal received by the receiving unit, and the recording having changed A storage unit storing a maximum recording rate indicating a maximum value of the rate, wherein when the recording rate determined by the recording rate determination unit is higher than the stored maximum recording rate, the recording rate is set to A storage unit that updates and stores the maximum recording rate, and according to the maximum recording rate stored in the storage unit,
A digital signal recording device comprising: a recording unit that records the digital signal on a recording medium. 2. The storage unit according to claim 1, wherein the storage unit maintains the maximum recording rate when the recording rate determined by the recording rate determination unit is lower than the stored maximum recording rate. Digital signal recording device. 3. An operation unit for inputting an instruction to start recording of the digital signal and an instruction to stop recording of the digital signal, wherein an instruction to start recording of the digital signal is input from the operation unit. The digital signal recording device according to claim 2, wherein the storage unit initializes the maximum recording rate at the start of recording. 4. The digital signal includes channel information that specifies a broadcasting station that has transmitted the signal, a receiving unit detects a change in the channel information, and a storage unit detects that the receiving unit has detected a change in the channel information. 3. The method according to claim 2, wherein the maximum recording rate is initialized in the case.
3. The digital signal recording device according to claim 1. 5. The digital signal includes a video signal.
The digital signal recording device according to claim 1. 6. The digital signal includes an audio signal.
The digital signal recording device according to claim 1. 7. A step of receiving a digital signal whose recording rate indicating a speed to be recorded changes, a step of determining a recording rate of the received digital signal, and a step of indicating a maximum value of the changed recording rate. Storing a recording rate, and when the determined recording rate is higher than the stored maximum recording rate, updating and storing the recording rate as a maximum recording rate; Recording the digital signal on a recording medium according to the set maximum recording rate.