JPH1092104A - Digital data processing method and digital data processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the editing data which does not generate sound missing or noise at the time of reproduction of data by connecting a digital data having the substantially the same frame size by controlling a frame size of the raw material data at the time of editing the digital audio data of different frame sizes with a digital VTR. SOLUTION: A frame size of the base data is detected by making reference to audio complementary data, and matching the frame size of the raw material data with that of the base data by an audio frame sequence generating section 12 having the function to control the frame size of raw material data depending on the frame size of base data. The frame size of data and sampling frequency are substantially set continuously at the editing point by matching the frame positions of the base data and raw material data before the editing point to connect these data by mans of the audio frame sequence generating section 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to digital data processing for editing a digital data having a different number of samples or a different frame phase by controlling a frame size, and more particularly to a digital VTR. Digital data processing method and digital data processing apparatus capable of preventing the occurrence of sound loss and noise at edit points while maintaining the relative phase between a video signal and an audio signal when editing audio signals having different frame sizes It is about.

[0002]

2. Description of the Related Art A digital video tape recorder (digital VTR) is known as a video tape recorder which records and reproduces a television signal using a magnetic tape, as it can record and reproduce the television signal without substantially deteriorating the television signal. Proposed.

A digital VTR records a television signal composed of a video signal, an audio signal, a control signal and the like as digital data on a magnetic tape, and reproduces the digital data recorded on the magnetic tape to reproduce the television signal. Get the signal. The digital data, which is a television signal, is recorded by being written on a magnetic tape via a magnetic head, and is reproduced by being read from the magnetic tape via a magnetic head.

[0004] An area on a magnetic tape on which digital data that is a television signal (hereinafter, also simply referred to as a television signal) is recorded is called a track. This track is generally a tilted recording track (hereinafter, also simply referred to as a track) formed by a rotating magnetic head (hereinafter, also simply referred to as a head) arranged to be inclined with respect to the longitudinal direction of the magnetic tape. is there.

[0005] In addition, the digital VTR can minimize signal deterioration by performing data error correction based on the fact that a television signal recorded and reproduced on a magnetic tape is a digital signal. it can. For this reason, an analog VTR that can relatively easily perform data processing such as variable-speed reproduction, repetition of editing and duplication on a television signal recorded on a magnetic tape, and the like.
It has different features from

[0006] Regarding the digital VTR, for example, a document published by Nikkei BP: "NIKKEI ELECTRONICS", 10-11 1993 (No. 59)
2), pp. 115-122.

First, how a television signal is recorded on a magnetic tape as digital data in a digital VTR will be described with reference to FIG.

Digital data, which is a television signal recorded on a magnetic tape, is recorded in units of one frame of a video signal. At this time, an audio signal, a control signal, and the like are simultaneously recorded on the magnetic tape as digital data together with the video signal for one frame.

FIG. 7A shows a state of an inclined recording track formed by writing a television signal on a magnetic tape by a rotating magnetic head. The television signal for one frame is recorded by being distributed to ten adjacent inclined recording tracks on the magnetic tape. The inclined recording track is formed by a rotating magnetic head for writing digital data on a magnetic tape, which is arranged to be inclined with respect to the running direction of the magnetic tape, and scans the magnetic tape. Arrows DY and DH in FIG. 7A indicate the traveling direction of the magnetic tape and the scanning direction of the rotating magnetic head with respect to the magnetic tape, respectively.

[0010] Each track TK formed on the magnetic tape as described above is arranged from the beginning to the end thereof with reference to the structure of digital data recorded on the track and the data position when editing or the like. An area IT in which a signal used as a signal is recorded, an area AD in which an audio signal in a television signal is recorded, an area VD in which a video signal in a television signal is recorded, and a time code representing time information are recorded. A region SC is formed.

The data recorded on each track is recorded and reproduced in the order of audio data, video data, and subcode, as indicated by arrows in FIG. 7B.

Next, a format when each of the above-described audio data, video data, and subcode is recorded on a magnetic tape will be specifically described with reference to FIG.

FIG. 8A shows a format in which audio data for one frame is recorded on a magnetic tape, and the order in which the data is reproduced. One frame of audio data is composed of ten tracks as described above. The audio data, which is a digitized audio signal, is composed of an inner parity and an outer parity in which the first 5 bytes of the audio data area are used as audio auxiliary data and then used for code error correction.

FIG. 8B shows a format in which one frame of video data is recorded on a magnetic tape, and the order in which the data is reproduced. One frame of video data is composed of video data which is a digitized video signal and inner parity and outer parity used for code error correction.

FIG. 8C shows the format in which one frame of subcode is recorded on a magnetic tape, and the order in which it is reproduced. The subcode for one frame is composed of a subcode used for control and an inner parity used for code error correction.

[0016]

A digital VTR is used to insert digital data recorded on another magnetic tape into digital data recorded on a magnetic tape in the format described above, So-called data editing is performed in which different digital data are connected and photographed. Data editing performed by a digital VTR used for business purposes is performed in a so-called lock mode in which a relative phase between a video signal and an audio signal is maintained based on a high-precision clock. However, data editing mainly performed by a digital VTR used for home use is often performed in a so-called unlock mode in which the relative phase between a video signal and an audio signal is not guaranteed due to reasons such as price.

The sampling frequency of digital data recorded and reproduced in the unlock mode is determined by the accuracy of the original oscillator of the clock of the digital VTR used for recording and reproduction, and the frame size which is the number of samples per frame is determined. Decided. For this reason, for example, when connecting material data to be inserted to base data that is the main body at the time of editing, or connecting and shooting different data using the same tape, the frame size of those data is changed. Due to the difference, the video signal and the audio signal are not synchronized, so that the audio signal does not accompany the video signal, so-called sound missing phenomenon,
Noise or the like was caused by discontinuity of the sampling frequency at the data connection.

Hereinafter, a description will be given of how the above-mentioned sound missing phenomenon occurs when audio data is edited by a digital VTR. Hereinafter, a case will be described as an example in which material data recorded in the unlock mode is inserted into background data recorded in the lock mode.

It is assumed that the background data recorded in the lock mode is an audio signal of an NTSC format television signal having a sampling frequency of 48 kHz. In digital data which is an audio signal of the NTSC television signal, since the number of data samples per frame does not become an integer value, the number of samples in each frame becomes an integer value in units of 5 frames. Is assigned a sample number.

FIG. 9 shows a frame size configuration of audio data in which the number of samples is assigned to each frame as described above.

The number of samples per 5 frames of the above audio data is 8008. The number of samples in the first frame is set to 1600, and the number of samples in the other 4 frames is set to 1602.

On the other hand, as shown in FIG. 10, the material data is recorded in the unlock mode, and the number of audio data samples per five frames is smaller than the above-described background data, for example. 7900.

In the case of editing by a digital VTR, the above-described material data having the number of samples per 5 frames of 7900 is, as shown in FIG.
Is directly inserted into the above-described background data.

On the other hand, when playing back the edited base data, the video data is synchronized. Therefore, the audio data corresponding to the video data is not edited in the edited portion where the material data having a different number of samples is inserted. Run out of samples. That is, a sound missing phenomenon in which an audio signal is not attached to a video signal occurs. In addition, in the above-mentioned editing, since the phase management between the background data and the material data is not performed, the sampling frequency may be discontinuous at a connection portion between the background data and the material data, and noise may be generated.

As described above, when digital data is edited by the conventional VTR, the quality of the original data may not be maintained and the quality of the edited data may be deteriorated. Was desired.

The present invention has been made to solve such a problem. For example, the above-described digital VTR
Edited data that preserves the quality of the original data without causing sound loss or noise even when editing the data by connecting different data with different frame sizes and sampling frequencies. It is an object of the present invention to provide a digital data processing method and a digital data processing device capable of obtaining the following.

[0027]

A digital data processing method according to the present invention, proposed to solve the above-mentioned problems, comprises a first method in which the number of samples for each frame is determined according to a predetermined frame sequence. Digital data and the second
The connection with the digital data of the first
Detecting the frame size, which is the number of samples in each frame of the digital data, and controlling the number of samples in each frame of the second digital data based on the detected frame size. Is connected to the first digital data.

According to the digital data processing method according to the present invention having the above-described features, the present invention is applied to editing of a television signal to perform editing by connecting data having different frame sizes and sampling frequencies.
It is possible to obtain edited data that maintains the quality of the original data without causing a sound dropout phenomenon due to a difference in frame size of the data to be edited and noise due to discontinuity in the sampling frequency.

Further, a digital data processing apparatus according to the present invention proposed to solve the above-mentioned problem includes a first digital data in which the number of samples for each frame is determined according to a predetermined frame sequence; The first digital data is for connecting to the second digital data having a different sampling frequency or frame phase,
Means for detecting a frame size that is the number of samples in each frame of the first digital data; and means for controlling the number of samples in each frame of the second digital data based on the detected frame size. Means for making connection in accordance with the frame phase of the second digital data in which the number of samples in the frame is controlled, in accordance with the frame phase of the first digital data.

According to the digital data processing method according to the present invention having the above-described features, the present invention is applied to editing of a television signal to perform editing by connecting data having different frame sizes and sampling frequencies.
It is possible to obtain edited data that maintains the quality of the original data without causing a sound dropout phenomenon caused by a difference in frame size or noise caused by discontinuity of a sampling frequency.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration and functions of the main parts of a digital VTR to which a digital data processing method according to the present invention is applied will be described below with reference to FIG.

The digital VTR includes a reproduction system, a recording system, a control system, and a tape running system.

In the reproducing system, digital data, which is a television signal recorded on a magnetic tape (not shown), is read out through a reproducing head 1 and subjected to amplification, signal processing and the like in a reproducing circuit section 2. Further, in the reproduction circuit unit 2, the video signal and the audio signal included in the television signal are separated.

More specifically, a reproduced signal output from the reproducing head 1 is amplified by a reproducing amplifier 2a, corrected to a predetermined frequency characteristic by an equalizer 2b, and supplied from a source oscillator (not shown) by a PLL circuit 2c. The clock is phase-locked to the clock and supplied to the channel decoder 2e. In the channel decoder 2e, the reproduced signal that has been encoded so as to be suitable for magnetic recording is decoded and supplied to the error correction unit 2f. The error correction unit 2f performs necessary error correction on the reproduced signal and supplies the reproduced signal to the audio data extraction unit 2g and the video signal processing unit 6. In the audio data extracting section 2g, only the audio data is separated from the reproduced signal and supplied to the audio interleave processing section 3. Audio interleave processing unit 3
In, the reproduced signals recorded on the magnetic tape in a distributed manner on a plurality of tracks are arranged in a time-series signal. The output of the audio interleave processing unit 3 is D
The signal is supplied to the / A converter 4, converted into an analog audio signal, and output from the terminal 5. On the other hand, the error correction unit 2
The reproduction signal supplied from f to the video signal processing unit 6 is subjected to amplification, signal processing, and the like for video data, is output, is supplied to the D / A converter 7, is converted to an analog video signal, and is 8 is output.

In the recording system, a television signal, which is digital data, is subjected to signal processing, amplification, and the like in the recording circuit section 16, and is recorded on a magnetic tape (not shown) via the recording head 18.

Specifically, the analog audio signal input from the terminal 9 is supplied to the A / D converter 10 to be converted into a digital audio signal, and is input to the audio frame sequence generator 12. The digital audio signal input from the terminal 11 is directly supplied to the audio frame sequence generator 12 without passing through the A / D converter 10.

Audio frame sequence generator 12
When editing background data recorded in the lock mode and material data recorded in the lock mode or the unlock mode, frame alignment of the above data is performed. Specifically, at the editing point, the timing control for matching the frame positions of the base data and the material data, and the frame size of the material data recorded in any one of the unlock mode and the lock mode are set as described above. The frame size is controlled so as to match the frame size of the background data recorded in the lock mode. The above-described frame matching process will be described later.

The output from the audio frame sequence generator 12 is supplied to an audio interleave processor 16a. The audio interleave processing unit 16a disperses time-series audio signals into a plurality of tracks and arranges the signals on a magnetic tape. Then, the digital audio signal is mixed with a video signal described later and supplied to the error information adding unit 16b. In the error information adding section 16b, information for performing error correction is added to the television signal. On the other hand, the analog video signal input from the terminal 13 is input to the video signal processing unit 17 via the A / D converter 14.
The digital video signal input from the terminal 15 is
The video signal processing unit 17 directly without passing through the A / D converter 14
Is input to Then, in the video signal processing unit 17, the video signal subjected to amplification, signal processing and the like is mixed with the output from the above-described audio interleave processing unit 16a and supplied to the error information adding unit 16b. Then, the television signal output from the error information adding unit 16b is supplied to the channel coder 16c. In the channel coder 16c, the television signal is subjected to encoding suitable for magnetic recording, amplified by the recording amplifier 16d, and supplied to the recording head 18.

The control system 19 controls the operations of the above-described reproducing system, recording system, and tape running system described later.
A control signal including a synchronization signal, frame size information, and the like is exchanged between the control unit 19 and the reproduction circuit unit 2, the recording circuit unit 16, and the tape traveling system 20.

The tape running system 20 is a mechanism for running, rewinding, or fast-forwarding the magnetic tape during reproduction or recording based on a control signal from the control system 19.

When digital data is edited by the digital VTR, the first digital data obtained from the magnetic tape (not shown) via the reproducing head 1 is usually called base data. The second digital audio signal input from is referred to as material data to be inserted into the base data.

Next, the operation of the audio frame sequence generating section 12 of the digital VTR will be described with reference to FIG. 2 as an example of a case where the digital data recorded in the lock mode is connected.

In the following, it is assumed that the background data and material data recorded in the lock mode are, for example, audio data of the NTSC television signal having a sampling frequency of 48 kHz. And
The audio data is described as having a frame sequence having a sample number configuration in which only the number of samples in the first frame is 1600 and the number of samples in the other four frames is 1602, with a period of 5 frames. I do. Further, the above-described base data corresponds to the first digital data, and the material data corresponds to the second digital data. The numbers written in the frames of each data in FIG. 2 indicate the frame numbers indicating the order in which the above-mentioned five frames form the frame sequence.

First, the manner in which the audio frame sequence generator 12 detects the frame phases of the background data and material data recorded in the lock mode will be described.

Audio frame sequence generator 12
Detects the number of samples in each frame of the background data, that is, the frame size, sequentially with reference to audio frame size information in audio auxiliary data described later. When a frame having a frame size of 1600 samples and four subsequent frames having a frame size of 1602 samples are detected, the frame having the frame size of 1600 samples is determined to be the first frame. In this way, the audio frame sequence generator 12 detects the frame phase of the background data.

Then, the audio frame sequence generating section 12 continuously generates a frame sequence of material data having a cycle of 5 frames as described above, following the first frame of the detected background data. That is, the audio frame sequence generation unit 12 performs control to synchronize the timing of the first frame of the base data with the timing of the first frame of the material data at the preset point P _A before the editing point P _B. Perform a preset. In this way, the audio frame sequence generator 12 is able to reliably synchronize the frame between the underlying data and the material data in the editing point P _B after the above-mentioned preset point P _A.

When the audio frame sequence generating section 12 detects a frame having a frame size of 1600 samples, it may immediately determine that the frame is the first frame of the frame sequence. In the above description, the audio frame sequence generator 12 has been described to generate a predetermined sequence of frames upon detection of a first frame of the frame sequence in the preset point P _A as performing preset, said preset At the point P _A , an arbitrary frame in the frame sequence may be detected and preset may be performed.

Next, a procedure in which the audio frame sequence generator 12 detects a frame phase and performs a frame matching process will be described with reference to the flowchart of FIG.

First, as shown in step S1, the audio frame sequence generator 12 determines whether or not the background data is data recorded in the lock mode. At this time, the above determination is made by referring to a lock mode flag in the audio auxiliary data described later. If the background data is not in the lock mode, the processing is terminated without performing frame alignment.

If the background data is in the lock mode, as shown in step S2, the audio frame sequence generator 12 determines the number of samples of each frame forming the frame sequence of the background data, that is, the frame size, as will be described later. It is detected by referring to the frame size information in the audio auxiliary data to be processed.

Then, as shown in step S3, the audio frame sequence generator 12 determines whether each frame is the first frame based on the detected frame size. Here, if the first frame is not detected, the process ends without performing the frame alignment.

If the first frame is detected in step S3, as shown in step S4, a preset for generating a frame sequence following the detected first frame is performed.

The above steps S1 to S
Steps 4 to 4 are sequentially performed on each frame forming the frame sequence of the base data based on the synchronization signal supplied from the control system 19, but the first frame is detected. The generation of the subsequent frame sequence is performed by the free-running oscillation of the audio frame sequence generation unit 12.

In order for the audio frame sequence generator 12 to read the frame size from the audio auxiliary data and reliably detect the above frame size, the sampling frequency of the digital data must be 48 kHz.
5 frames or more in case of, 15 in case of 32 kHz
It is desirable to read more than a frame.

Next, the above-described audio auxiliary data will be described. The audio auxiliary data is data indicating information about an audio signal recorded on a magnetic tape as digital data, and is recorded on the magnetic tape together with the audio data.

FIG. 4 shows an example of the configuration of a main area of audio auxiliary data composed of a main area and a sub area. The audio auxiliary data in this example is based on a format called a DV format used for a digital VTR, and its main area and sub-area are each written in a plurality to improve the reliability.

In the main area of the audio auxiliary data recorded on each track on the magnetic tape, data representing information on six types of audio signals including a lock mode flag and audio frame size is recorded. . The six types of data are recorded as a pack consisting of 5 bytes (1 byte of header + 4 bytes of data).

FIG. 5 shows an example of a pack in the main area of the audio auxiliary data. This pack is composed of 5 bytes from PC0 to PC4, and contains 1 byte.
The byte PC0 is called a pack header.

Lock mode flag LF at the head of PC1 in 4 bytes from PC1 to PC4 representing data
Is information indicating whether the data is in the lock mode. That is, if the value of LF is 0, it indicates the lock mode, and if the value is 1, it indicates the unlock mode.
The above-described audio frame sequence generation unit 12
When the frame matching process is started, it is determined by referring to the value of the lock mode flag LF that the background data is data recorded in the lock mode.

The audio frame size AF SIZE in the PC 1 is information indicating the number of samples in one frame of audio data.

Next, how the audio frame sequence generator 12 controls the frame size of the material data recorded in the unlock mode will be described with reference to FIG.

Material data recorded in the unlock mode often has a different frame size from digital data recorded in the lock mode. For this reason, as described above, digital data edited by being connected to data recorded in the lock mode may cause a sound missing phenomenon or the like during reproduction.

Therefore, the audio frame sequence generating section 12 sets the frame size of the above-mentioned material data when editing the frame of the material data recorded in the unlock mode with the background data recorded in the lock mode. Is controlled to match the frame size of the background data.

That is, as shown in FIG. 6, when the frame size of the material data is smaller than the frame size of the base data, there is a shortage of data corresponding to the hatched portion in the frame of the material data. . Therefore, the frame size control is performed by interpolating the sample of the material data connected to the base data or borrowing the sample from the data of the preceding and succeeding frames to compensate for the lack of the data. On the other hand, if the frame size of the material data is larger than the frame size of the background data, a method such as thinning out the material data samples or discarding material data samples exceeding the frame size of the background data is used. To control the frame size.

The frame size control of such material data as audio data is performed, for example, in units of five frames. For this reason, the difference between the video signal and the audio signal due to the above-described frame size control can be suppressed to about several hundred samples per the above-described five frames, and it is possible to obtain edited data having no problem in terms of hearing. Then, by performing the above-described frame size control and the above-described frame matching process, it is possible to connect the material data recorded in the unlock mode to the base data recorded in the lock mode.

[0066]

As described above, according to the digital data processing method and digital data processing apparatus of the present invention, the frame size of digital data is detected, and the frame matching process and the frame of material data are performed based on the detected frame size. By performing the size control, for example, when editing digital data that is a television signal by a digital VTR, even if data having different frame sizes and sampling frequencies are connected to each other,
There is no occurrence of noise dropping due to a difference in frame size or noise due to discontinuity in sampling frequency.

As a result, even if the editing of the digital data as the television signal is repeated, the phase shift between the video signal and the audio signal can be minimized, and the edited data can be obtained while maintaining the quality of the original data. . ,

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a digital VTR to which a digital data processing device according to the present invention is applied.

FIG. 2 is a diagram illustrating a frame matching process for digital data.

FIG. 3 is a flowchart illustrating a procedure of a frame matching process of digital data.

FIG. 4 is a diagram illustrating a configuration of a main area of audio auxiliary data recorded on a magnetic tape.

FIG. 5 is a diagram showing a configuration of a pack in a main area of audio auxiliary data recorded on a magnetic tape.

FIG. 6 is a diagram illustrating frame size control.

FIG. 7 is a diagram illustrating a track on which a television signal is recorded on a magnetic tape by a digital VTR. It is.

FIG. 8 is a diagram showing a format in which digital data is recorded on a magnetic tape by a digital VTR.

FIG. 9 is a diagram illustrating a frame size of audio data of an NTSC television signal.

FIG. 10 is a diagram illustrating how digital data having different frame sizes are edited.

[Explanation of symbols]

Reference Signs List 1 playback head, 2 playback circuit section, 2a playback amplification section, 2b equalizer section, 2c PLL section, 2
d, 10, 14 A / D converter, 2e channel decoder, 2f error correction unit, 2g audio data extraction unit, 3 audio interleave processing unit,
4,7 D / A converter, 6,17 video signal processing unit, 12 audio frame sequence generation unit,
16 recording circuit section, 16a audio interleave processing section, 16b error information addition section, 16c channel coder, 16d recording amplification section, 18 recording head, 19 control system, 20 tape running system

Claims (6)

[Claims] 1. A digital data processing method for connecting a first digital data having a predetermined number of samples for each frame according to a predetermined frame sequence to a second digital data. Detecting a frame size that is the number of samples in each frame of data; controlling the number of samples in each frame of the second digital data based on the detected frame size; controlling the number of samples in the frame Connecting the obtained second digital data to the first digital data. 2. The digital data is an audio signal of a television signal, a frame size of the digital data is recorded together with the audio signal as audio auxiliary data, and the audio auxiliary data is reproduced when the digital data is reproduced. By reading data, the frame size of each digital data is detected, and the number of samples in the frame of the second digital data is controlled based on the detected frame size of each digital data. 2. The digital data processing method according to claim 1, wherein the digital data as the audio signal is connected to each other while maintaining the relative phase of the television signal to the video signal while maintaining the same frame size. 3. The digital data is an audio signal of a television signal, wherein the number of samples in the first frame is 1600, and the number of samples in the other four frames is 1602, each having a period of 5 frames. The digital data processing method according to claim 1, wherein 4. A first digital data in which the number of samples for each frame is determined according to a predetermined frame sequence, and a second digital data having a sampling frequency or a frame phase different from the first digital data. Means for detecting a frame size that is the number of samples in each frame of the first digital data; and a means for detecting each of the second digital data based on the detected frame size. Means for controlling the number of samples in a frame; and means for connecting the frame phase of the second digital data in which the number of samples in the frame is controlled to match the frame phase of the first digital data. Digital data processing device characterized by the above-mentioned. 5. The digital data is an audio signal of a television signal, and the means for detecting the frame size of each digital data includes reading out the audio auxiliary data recorded together with the audio signal, thereby obtaining each frame size. 5. The digital data processing device according to claim 4, wherein the digital data processing device has a function of detecting an error. 6. For each of the above frame sizes, for digital data quantized at a sampling frequency of 48 kHz, 5 frames or more are read out, and for digital data quantized at a sampling frequency of 32 kHz, 15 frames are read out. 6. The digital data processing apparatus according to claim 5, wherein the digital data is detected by reading the above.