JP3001085B2 - Moving image data recording apparatus and moving image data recording method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION In a device such as a digital VTR for recording or reproducing moving image data on a recording medium, a moving image data recording device and a moving image corresponding to special reproduction such as high-speed image search. It relates to a data recording method .

[0002]

2. Description of the Related Art A conventional moving picture data recording apparatus, moving picture data reproducing apparatus, and moving picture data recording medium will be described by taking a high-speed search in a digital VTR as an example. 2. Description of the Related Art A digital VTR that records or reproduces moving image information (hereinafter, also referred to as moving image data) in which a moving image signal is digitized by high-efficiency coding or the like requires special reproduction functions such as high-speed search. A high-speed image search (hereinafter, also referred to as a high-speed search) for reproducing an image at a high speed of 5 to 50 times the original reproduction speed is an essential function.
In the case of this high-speed search, the track of the helical scan recording is read obliquely, and a part of the image is obtained in a fragmented state. In an analog VTR, one screen is divided and displayed as a result. High-efficiency coding is used in consumer digital VTRs, where information is compressed using variable length codes. In this case, since the recording position on the tape and the position of the image signal on the screen are not synchronized, an appropriate high-speed search image such as a position on the screen deviating from a regular position in the data obtained by the search. Is difficult to obtain.

Therefore, a method has been considered in which information dedicated to high-speed search (hereinafter also referred to as special reproduction image data or search data) is separately recorded at a predetermined position on a tape. For example a predetermined number points in the information track direction as a recording position of high-speed search information, keep it in repeat the same information I over a period of 10 tracks recorded. in this case,
In the case of a high-speed search up to 10 times, any one of the 10 tracks is always read, so that all information (image data for special reproduction) dedicated to the high-speed search can be obtained, and a complete frame or field (hereinafter, representative) (Referred to as a frame). At this time, the information dedicated to the high-speed search recorded at a predetermined position on the track cannot record one frame for one place.
One frame is divided into several parts and recorded.

[0004] For example the 10 split, if the same data is repeatedly recorded I over a period of 10 tracks as described above, will be recorded I high speed search only information for one frame is extend over 100 tracks . FIG. 3 is a diagram showing a configuration example of a conventional moving image data recording device. In FIG. 3, moving image data provided from a data input 1 is data compressed by high-efficiency coding using inter-frame prediction, and a buffer 5 and a search data generator 31 are provided.
Given to. Here, in the moving image data, one frame out of every 10 to 30 frames is independently encoded within the frame, which is called an intra-frame or an I-frame and becomes special reproduction image data.

The search data forming unit 31 separates only this intra frame (I frame), and if it is difficult to record all data of one frame according to the amount of information that can be recorded, 4 × 4 It is processed into only low-frequency information of an image such as an average value of pixels, and is given to the search data memory 32 as image data for special reproduction. Search data memory 3
Reference numeral 2 stores information for one track, and outputs search data to the multiplexer 33 in order to record the same data over a plurality of tracks.

On the other hand, general moving image data used in normal reproduction is supplied from a data input 1 to a buffer 5. The buffer 5 intermittently outputs the moving image data in accordance with the multiplexing and supplies the moving image data to the multiplexer 33. The multiplexer 33 converts the moving image data and the image data for special reproduction into Expressions 10 to 1
A data string is created while switching in sector units of about 00 bytes, and is provided to the signal recorder 7. Here, in the multiplexing process, the special reproduction image data is recorded in a specific portion of a predetermined track. Further, the trick play image data in accordance with the search speed of the fastest, the same information is used I over a period of several tens of tracks from several tracks.

If the transfer rate of the moving image data to be recorded is lower than the recording transfer rate, stuff data (invalid data) is inserted to make the apparent transfer rate the same as the recording transfer rate. The signal recorder 7 adds an error correction code to the data sequence for recording on the recording medium 8, modulates the signal into a signal suitable for recording on the recording medium 8, and records the signal on the recording medium 8. . The recording medium 8 is a video tape, for example, in which search data is recorded in a specific portion of a track, and general moving image data is recorded in other portions.

FIG. 4 is a diagram showing a configuration example of a conventional moving picture data reproducing apparatus. In FIG. 4, the signal regenerator 21
The signal read from the recording medium 8 is demodulated and subjected to error correction processing, and the obtained data string is provided to the demultiplexer 41. The demultiplexer 41 determines the type of the data of the sector from the sector number or the like inserted in the header of the sector, separates and outputs the special reproduction image data during special reproduction, and outputs the moving image data during normal reproduction. Is separated and output.

Each output data is supplied to a buffer 24. Then, the discontinuity of the data sequence due to the separation of the respective data is absorbed by the buffer 24 and output from the data output 25 as reproduction data. Here, in the special reproduction (high-speed search), if the search speed is n, only 1 / n information is read. However, since the same search information is repeatedly recorded, all of the search information up to the number of repetitions is obtained. Will be obtained.

When recording on a tape with two heads having different azimuth angles, information cannot be read unless the azimuth of the track and the azimuth of the head match, so that the recording method must be adapted to that. Specifically, information is divided for each track of each azimuth angle, and repetitive recording is also performed on tracks of the same azimuth. In addition, search information is recorded only on one track with an azimuth angle,
Reading may be performed by only one head.

[0011]

In the high-speed search information recording method as shown in the conventional example, the area for recording moving image data and the area for recording data for special reproduction (search) are fixed. Each recording transfer rate is determined. When the transfer rate of moving image data to be recorded is low, blank (stuff) data is inserted and recorded. The special reproduction image data is recorded at a constant transfer rate regardless of the transfer rate of the moving image data.

On the other hand, since the special reproduction image data needs to be repeatedly recorded at the same magnification as the search speed, it is difficult to secure a sufficient transfer rate, and the resolution and the resolution of the special reproduction image data recorded as a result are reduced. Frame numbers tended to drop. The present invention has been made by focusing on the above points, and when reproducing a recording medium on which moving image data is recorded,
An object of the present invention is to increase the resolution of an image at the time of trick play and to make the motion smooth.

[0013]

SUMMARY OF THE INVENTION The present invention provides a method for recording moving image data for normal reproduction and image data for special reproduction.
Depending on the transfer rate of the moving image data to be recorded, the ratio between the moving image data and the special reproduction image data is changed in the recording format, and if the moving image data transfer rate is low, the special reproduction image data The transfer rate can be increased. Here, the recording format means a recording form on a recording medium, and is a structure (logical format) of digital information to be recorded. As described above, according to the present invention, when recording moving image data on a recording medium, a transfer rate of moving image data to be recorded is subtracted from a predetermined medium recordable transfer rate, and a special value set from the difference value is set. Based on the transfer rate of the image data for reproduction, generate image data for special reproduction from the moving image data,
Provided are a moving image data recording apparatus and a moving image data recording method for multiplexing moving image data and its special reproduction image data in a recording format according to a transfer rate, and recording the obtained data string at a predetermined position on a recording medium. Things .

[0014]

According to the present invention, when recording the moving image data for normal reproduction and the image data for special reproduction, the moving image data and the image data for special reproduction are recorded in accordance with the transfer rate of the moving image data to be recorded. When the transfer rate of moving image data is low, the transfer rate of special reproduction image data is increased by changing the recording format, and blank (stuff) data is conventionally inserted. The special reproduction image data is inserted into the portion where the reproduction has been performed, so that the resolution of the special reproduction image is increased, and the frame rate is increased, so that a special reproduction image with smooth motion can be obtained.

[0015]

1 shows a moving picture data recording apparatus according to the present invention.
FIG. 3 is a diagram showing an embodiment of a moving image data recording method .
In FIG. 1, parts corresponding to those of the conventional example of FIG. 3 are denoted by the same reference numerals, and the difference from the conventional example of FIG. 9, a format setting device 10 is provided. Also,
Search data former 3, the operation of the multiplexer 6 search data former 31 of Figure 3 differs from the operation of the multiplexer 33. Although the basic processing flow is the same in both devices, the transfer rate and multiplexing method of the special reproduction image data are different. Hereinafter, the flow of recording signal formation will be described with reference to FIG. The moving image data input from the data input 1 is
The data is input to the buffer 5, the search data generator 3, and the rate information separator 2. General moving image data for normal playback
The data is stored in the buffer 5 in order to cope with discontinuous reading at the time of multiplexing. That is, in the multiplexer 6, while the data is being read from the search memory 4, the reading from the buffer 5 is suspended, and the moving image data is accumulated in the buffer 5.

The rate information separator 2 analyzes the moving image data to be recorded, separates the transfer rate information of the data string from the header portion, and sets the search rate setter 9
Given to. The search rate setting unit 9 subtracts the moving image data transfer rate from the recordable total transfer rate,
An available transfer rate available for search data is calculated. The recordable total transfer rate refers to a maximum total transfer rate that can be recorded on a recording medium. The search data transfer rate is obtained by dividing the empty transfer rate by the number of times of repetitive recording of the search data, and is given from the search data forming unit 3 to the format setting unit 10.

Here, the number of times of repetitive recording is set in advance in accordance with the maximum speed of the high-speed search. For example, if the maximum speed is 5 times, the number of times of repetitive recording is five. The transfer rate value set for the special reproduction image data does not change continuously because the recording format is changed in units of sectors, as described later, and does not change continuously. It changes at a constant multiple of the number. In the search data forming unit 3, the moving image data is analyzed, and only the independent image encoded by the image data in the frame is detected. This independent image is not limited to the frame-based independent image (I frame),
In encoding using inter-frame prediction, only a part of an image may be independently encoded in a frame, and the part may be moved for each frame, and this is also included.

Even in the case of such an independent image, one frame of independent image information can be obtained by synthesizing a partial independent image for one cycle of its movement, and can be handled in the same manner as an intra frame. Since the time varies depending on the part of the image, the image is an image in which the part is discontinuous when the image moves. Hereinafter, the intra-frame created in this manner will be described as one I-frame. Search data is
From all the information of the intra-frame, only the amount of information in accordance with the transfer rate of search data supplied from the search rate setting unit 9 is taken out. Intra frames are usually inserted about once every 0.5 seconds, but not all of them are used, but are used by thinning them out according to the transfer rate. In addition, we reduce information spatially,
According to the transfer rate, only the DC component of the 8 × 8 DCT or only the AC coefficient corresponding to the low frequency is used.

The search data thus formed is applied to a search data memory 4. The search data memory 4 stores search data recorded for one track. Therefore, the capacity corresponding to the maximum value
This is necessary for the data memory 4. On the other hand, the format setting unit 10 sets the format of which sector is to be the search data according to the transfer rate of the search data provided from the search rate setting unit 9 and provides the information to the multiplexer 6.

The multiplexer 6 time-division multiplexes the moving image data stored in the buffer 5 and the search data recorded in the search data memory 4 in sector units in accordance with the format given from the format setting unit 10.
The created recording data sequence is given to the signal recorder 7. Here, the same search data is read out and multiplexed five times in the case of 5 × speed. The data string formed in this manner is subjected to error correction code addition and modulation by the signal recorder 7 in the same manner as in the conventional example, and is recorded on the recording medium 8.

Next, a specific recording arrangement (format) on a tape will be described with reference to FIG. FIG. 5 is a diagram showing a recording format of a moving image data recording medium recorded by using the moving image data recording device according to the present invention.
In FIG. 5, each track is finely divided in the vertical (vertical) direction by a thin line, and the recording position of the search data is surrounded by a thick line. In the case of the helical scan, the actual track is oblique to the tape, but is shown vertically in FIG. 5 for convenience. The oblique line indicates the head scanning at the time of special reproduction (5 × speed search), and is oblique to the track.

FIG. 5A shows the case where the transfer rate of the moving image is high and the transfer rate of the search data is low, and FIG. 5B shows the case where the transfer rate of the moving image is low and the transfer rate of the search data is high. The recording position of the search data on the tape is 1
There are two predetermined areas on the track. (B) has more search data than (a). However, the continuous recording length of each search data on one track is set to such an extent that all the tracks can be continuously read even if the track is read diagonally by the high-speed search.

FIG. 6 shows a moving picture data recording apparatus according to the present invention.
FIG. 4 is a diagram showing a state of a sector in one track of a moving image data recording medium recorded by using an apparatus . In the figure, one track is shown enlarged, and one section represents one sector.
Each recording area of the moving image data and the search data changes in units of sectors, and the area of the search data indicated by oblique lines is
Increase / decrease by making the center position almost the same. In FIG. 6, if one track has 28 sectors and the total transfer rate of the combined moving image data and search data is 28 Mbps, 4 sectors are used for the search data in the upper stage, and the moving image data is 24 Mbps. , The search data becomes 4 Mbps. Similarly, the middle row is 20/8 Mbps each, and the bottom row is 1 each.
6/12 Mbps. For example, if the moving image data to be encoded is 18 Mbps, the middle recording format is selected, and 2 Mbps stuff data is inserted into the moving image data. When the number of sectors per track is larger, the transfer rate can be more finely switched, and the amount of inserted stuff data is smaller. In FIG. 5 and FIG. 6, two search data recording areas are shown on one track. However, even if the recording position is three or more, the purpose of the moving image data recording medium of the present invention is not changed. It does not deviate.

FIG. 2 shows a moving picture data recording apparatus according to the present invention.
FIG. 11 is a diagram showing an embodiment of a moving image data reproducing apparatus for reproducing a moving image data recording medium recorded using a device. Parts corresponding to those in the conventional example of FIG. 4 are denoted by the same reference numerals. 4 in that a format identifier 22 is provided. In the signal reproducer 21, the signal read from the recording medium 8 becomes a data string, and the format discriminator 22 and the demultiplexer 23
Given to. The format discriminator 22 detects format information multiplexed in the data string, and recognizes to which sector the moving image data and the search data of the data string are allocated. The demultiplexer 23 determines moving image data and search data from the format information, and separates and outputs only one of the data as in the conventional example. Each data is supplied to the buffer 24 to absorb the discontinuity of the data string due to the data separation as described above, and the data output 25
Output.

[0025]

According to the first or third aspect of the present invention, when recording moving image data for normal reproduction and image data for special reproduction, the transfer rate of the moving image data to be recorded is reduced. If the transfer rate of the moving image data is low, the transfer rate of the special reproduction image data is increased accordingly, so that the conventional blank ( The special reproduction image data is inserted into the portion where the (stuff) data is inserted, and the resolution and frame rate of the special reproduction image can be increased. As a result, a search image with smoother motion and higher resolution can be obtained without increasing the recording transfer rate.

According to the second or fourth aspect of the present invention, the special reproduction image data is divided into a plurality of substantially equal areas and arranged in a plurality of areas on the track. By changing, the center position of each special reproduction image data is fixed, the special reproduction image data is recorded in the vicinity, and even if the read head scans obliquely with respect to the recording track in the special reproduction, all the special reproductions are performed. Image data can be easily read .

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a moving image data recording apparatus according to the present invention.

FIG. 2 shows a video data recording apparatus according to the present invention.
FIG. 1 is a diagram illustrating an embodiment of a moving image data reproducing apparatus for reproducing a recorded moving image data recording medium .

FIG. 3 is a diagram illustrating a configuration example of a conventional moving image data recording device.

FIG. 4 is a diagram showing a configuration example of a conventional moving image data reproducing device.

FIG. 5 shows a moving image data recording apparatus according to the present invention.
Shows a recording format of the recorded moving picture data recording medium.

FIG. 6 shows a moving image data recording apparatus according to the present invention.
It is a diagram showing a state of sectors in one track of the recorded moving picture data recording medium.

[Explanation of symbols]

Reference Signs List 2 transfer rate detecting means (rate information separator) 3 special reproduction data forming means (search data forming apparatus) 4 search data memory 6 multiplexing means (multiplexing apparatus) 7 signal recording means (signal recording apparatus) 8 recording medium 9 Rate setting means (search rate setting device) 10 Format setting means (format setting device) 21 Signal reproducing means (signal reproducing device) 22 Format discriminating means (format discriminator) 23 Demultiplexing means (multiplex demultiplexer)

Claims (4)

(57) [Claims] 1. A moving image data recording apparatus for recording moving image data on a recording medium, comprising: transfer rate detecting means for obtaining information on a transfer rate of moving image data to be recorded; Rate setting means for subtracting the transfer rate of the moving image data from the permissible transfer rate and setting a transfer rate of the special reproduction image data based on the difference value; and at the transfer rate set by the rate setting means, Special reproduction data forming means for generating special reproduction image data corresponding to moving image data; format setting means for setting a recording format from a transfer rate of the special reproduction image data and outputting format information; multiplexing hand for multiplexing in accordance with the format information and the image data the the trick play image data and said full <br/> formatted information When moving picture data recording apparatus characterized by having a signal recording means for recording the multiplexed data train in predetermined positions of said recording medium. 2. A moving image data recording apparatus according to claim 1, wherein said recording medium for recording said moving image data is a magnetic tape, and said image data for recording special reproduction is recorded on one track. format when recording in substantially equally divided into a plurality of realm, to set the recording format changed in accordance with the transfer rate of the special reproduction image data recording area length of each trick play image data to the divided recording A moving image data recording device having a setting unit. 3. A moving image data recording method for recording moving image data on a recording medium, comprising: obtaining information on a transfer rate of moving image data to be recorded; and a maximum allowable transfer rate at the time of recording on the recording medium. Subtracting the transfer rate of the moving image data from the moving image data, and setting the transfer rate of the special reproduction image data based on the difference value; and using the set transfer rate for the special reproduction corresponding to the moving image data. and generating image data, wherein the set recording format from the transfer rate of the special reproduction image data, wherein the step of outputting the format information, and the moving image data wherein the trick play image data off <br/> a step of multiplexing and formatting information in accordance with the format information, to record the multiplexed data sequence at a predetermined position of said recording medium A moving image data recording method. 4. A moving image data recording method according to claim 3 , wherein said recording medium for recording said moving image data is a magnetic tape, and said image data for recording special reproduction is recorded on one track. In the case where the recording is performed by dividing the recording data into a plurality of areas substantially equally, the step of setting the recording format by changing the recording area length of each special reproduction image data to be divided and recorded according to the transfer rate of the special reproduction image data is performed. A moving image data recording method, comprising: