KR20000055672A - Recording and/or playback method for variable speed mode and apparatus therefor - Google Patents

Abstract

PURPOSE: A recording and/or reproducing method and apparatus for variable speed mode is provided to embody a slow/steel function easily by providing a picture with a good quality when performing the slow/steel mode. CONSTITUTION: A recording data encoder(202) compresses and encodes inputted recording data. A transmission code(204) has a formatter for converting output data of the recording data encoder(202) into a suitable recording format to be recorded in a digital recording and reproducing apparatus and an ECC encoder for adding a parity to formatted data to perform an error collection when reproducing data. A recording amplifier(206) amplifies output data of the transmission code(204) for recording output data in a recording medium. A recording mechanism provides the amplified recording current to a head and records data in the recording medium. A transfer unit(208) transfers the recording medium. A control unit(210) generates a control signal required in each block and operates a recording system.

Description

Recording and / or playback method for variable speed mode and apparatus therefor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of recording and / or reproducing digital data, and more particularly, to a recording and / or reproducing method and apparatus for a variable speed mode that provides high quality image quality even when performing a variable speed mode such as slow or still.

As an example of the digital recording / reproducing apparatus, a recording area of a recording medium for a digital video cassette recorder (VCR) is separately allocated an area for recording normal reproduction data and an area for recording variable speed reproduction data. This is to perform the variable speed reproduction without affecting the normal reproduction at all by recording and reproducing separate data for the variable speed reproduction only at the position where the reproduction head traces during the variable speed reproduction.

A block diagram of a conventional digital VCR for recording normal playback data and variable speed playback data separately is shown in FIG. 1, and for variable speed playback, a variable speed separate from the encoder 102 and decoder 116 for normal recording and playback is shown. An encoder 104 and a decoder 118 for recording and reproduction are configured.

In other words, the normal recording data encoder 102 converts an input Moving Picture Experts Group (MPEG) -2 bit stream into data that can be recorded on a digital VCR and provides it to a multiplexer (MUX) 106. The variable speed recording data encoder 104 recompresses an intra picture extracted from an input MPEG-2 bit stream to generate record data for variable speed reproduction and provide it to the MUX 106.

The MUX 106 time-divisions the normal and variable speed write data provided from the encoders 102 and 104 to the write signal processor 108, and the write signal processor 108 includes a write amplifier, a channel modulator and an error correction code block (i.e. ECC) encoder and the like, and the final error correction coded bit string is recorded on the recording medium 112 in the form of a magnetic signal through the electric / magnetic conversion system 110.

Data reproduction from the recording medium in which the normal recording data and the variable speed recording data are separately recorded is performed as follows according to the normal reproduction mode and the variable speed reproduction mode.

The signal read out from the recording medium 112 is provided to the reproduction signal processor 114 in the form of an electrical signal via the electric / magnetic conversion system 110. The reproduction signal processor 114 includes a reproduction amplifier, an equalizer, a channel demodulator, an ECC decoder, and the like, and provides the error correction decoded bit stream to the normal reproduction data decoder 116 and the variable speed reproduction data decoder 118. . The normal playback data decoder 116 decodes only error corrected and decoded normal playback data and outputs the demultiplexer (DEMUX) 120, and the variable speed playback data decoder 118 decodes only error corrected and decoded data for variable speed playback. To the DEMUX 120. The DEMUX 120 outputs only the normal playback signal decoded by the normal playback data decoder 116 in the normal playback mode according to the normal / variable speed playback mode signal, and the variable speed playback data decoder in the variable playback mode. By outputting only the variable speed reproduction signal decoded at 118, it corresponds to normal reproduction and variable speed reproduction.

The variable speed data encoder 104 of the conventional digital VCR extracts only data necessary for variable speed reproduction from input normal recording data. In addition, compression is necessary for recording the variable speed reproduction data in the recording area of the variable speed reproduction data which is insufficiently allocated. However, in terms of performance, there is a problem of deterioration of image quality due to loss of information and excessive compression.

For variable speed reproduction, an encoder and decoder for variable speed recording and reproduction must be added separately from the encoder and decoder for normal recording and reproduction, thereby increasing the complexity of the configuration and increasing the price.

In addition, since the variable speed playback data is extracted from the intra picture and recorded in a separate area, the contents may be different from the normal playback data, and there may be a problem that the variable speed playback data and the normal playback data may not match in time.

In order to solve the above problems, it is an object of the present invention to provide a recording and / or reproducing method for smoothly performing a variable speed reproduction, in particular a slow / still function while providing high quality image quality.

Another object of the present invention is to provide a recording and / or reproducing apparatus for smoothly performing a variable speed reproduction, in particular a slow / still function, without reconstructing and recording separate data for variable speed reproduction.

In order to achieve the above object, the recording and / or reproducing method for the variable speed mode according to the present invention is a method for recording and / or reproducing digital data on a recording medium: an independently encoded picture that is input. Compressing and encoding the data to provide compressed source data, and controlling the coding rate of the source data and transmitting the compressed source data in a format suitable for a recording medium.

In addition, the method according to the present invention reproduces data in units of an error correction code block (ECC) from a recording medium, and provides variable speed reproduction data while controlling normal reproduction and stop operations in response to the variable speed mode. And reconstructing the original video signal.

In order to achieve the above another object, the recording and / or reproducing apparatus for the variable speed mode according to the present invention is an apparatus for recording and / or reproducing digital data on a recording medium: And a source encoder for compressing and encoding the source data to provide compressed source data, and a transmission encoder for controlling the coding rate of the source data and transmitting the same in a form suitable for a recording medium.

The apparatus according to the present invention regenerates data provided from a variable speed reproduction signal processor and a variable speed reproduction signal processor which reproduces data in units of error correction code blocks (ECC) from a recording medium to control normal reproduction and stop operations in response to the variable speed mode. And a decoder for restoring the video signal.

1 is a block diagram of a conventional digital video cassette recorder.

2 is a block diagram according to an embodiment of a recording apparatus for a variable speed mode according to the present invention.

3A to 3F are timing diagrams and track configuration diagrams of the recording apparatus shown in FIG.

4 is a block diagram according to an embodiment of a reproducing apparatus for a variable speed mode according to the present invention.

FIG. 5 is a detailed block diagram of the trans codec shown in FIG. 4.

6 is a view for explaining the principle of regeneration in the still / slow operation.

7A to 7H are operation timing diagrams of the trans codec shown in FIG. 4.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the recording and / or playback method and apparatus for a variable speed mode according to the present invention.

In Fig. 2, which is a block diagram according to an embodiment of the recording apparatus according to the present invention, the output data of the recording data encoder 202 and the recording data encoder 202 which compressively encodes the input recording data into the digital recording / reproducing apparatus. A transcodec including a formatter for converting into a suitable recordable format that can be recorded, and an ECC encoder for adding parity to data recorded in the format of a predetermined number of ECC units for correcting errors during playback; 204, the recording amplifier 206 which amplifies the recording current sufficiently so that the output data of the trans codec 204 can be recorded on the recording medium, and the recording which applies the amplified recording current to the head to magnetize the recording medium to record the data. A transfer unit 208 for transferring the recording medium and a control signal required for each block to generate a recording system A control unit 210 is configured to control to operate. Here, the write data encoder 202 may be referred to as a source encoder, and the trans codec 204 may be referred to as a transmission encoder.

Next, the operation of the variable speed recording apparatus shown in FIG. 2 will be described with reference to FIG. 3.

The recording data encoder 202 is an MPEG-2 encoder according to one embodiment, and compressively encodes only intra picture data among input data.

Here, in general MPEG encoding, encoding efficiency is improved by encoding using correlations between frames of an image signal while varying coding rates according to input image information. In other words, MPEG encoding has an advantage of having good image quality while increasing compression efficiency. However, general MPEG encoding has good characteristics in terms of coding efficiency and image quality, but in a recording / reproducing apparatus such as a VCR, it causes a very serious problem in variable speed reproduction.

In other words, it is difficult to control the code amount per screen unit only by the MPEG compression coding scheme. Because MPEG-2 compresses by using the correlation between screens in GOP (group of picture) unit consisting of several screens, if compressed data with such a structure is simply recorded on the recording medium, it is During playback, the screen composition is difficult and does not play properly.

Therefore, in the present invention, in order to be able to perform the variable speed reproduction of the recording / reproducing apparatus smoothly even though the coding efficiency is slightly reduced, first, encoding is performed only within a picture (frame) without performing encoding using the correlation between frames. That is, MPEG-I (Intra) encoding is performed on the input data.

The second is encoding considering the recording format or ECC format of the recording medium. For example, in the DVHS (Digital Video Home System) standard, ECC is performed using the data amount of 6 tracks of a recording medium as one cycle, and has a recording format structure that generates 60 tracks (1800 rpm) per second. In consideration of the DVHS specification, for good loss-free playback, playback should be done in 6 track units phase-matched to the ECC period. In addition, since six frame tracks that are matched with the ECC period must always be able to record an integer number of frame data, assuming that the NTSC signal is composed of 30 frames per second, three frames or six fields of data can be recorded in the six tracks. It is best to make sure.

Third, the coding rate should be the same in ECC units (3 frames or 6 fields), but the coding rate can be varied in the ECC unit. That is, the coding efficiency of each frame or each field can be varied within three frames or six fields, thereby improving the coding efficiency.

The timing diagram and track configuration diagram of the recording apparatus shown in FIG. 2 are shown in FIG. 3 and are considered in units of frames. The record data encoder 202 is connected with the MPEG-2 encoded intra frame data as shown in Fig. 3A so as to match the ECC performed by the trans codec 204 and three frame periods which are track formats. A control signal of three frame periods is provided to the trans codec 204 as shown in 3 (b). When considering in units of fields, one frame may be divided into two fields.

According to another embodiment of the present invention, when MPEG-2 encoding is performed at a constant bit rate on an intra picture in a field or frame unit, the recording data encoder 202 transmits a control signal for recognizing three frames or six field periods. It is not necessary to provide the codec 204, and it is possible to make and use the ECC encoder in the trans codec 204.

On the other hand, the ECC encoder in the trans codec 204 is shown in Fig. 3C in synchronization with the control signal (Fig. 3 (b)) of the three frame (6 field) period provided from the recording data encoder 202. The same ECC encoding start signal is generated, and when an ECC encoding start signal (Fig. 3 (c)) is generated, parity is added to the output data of the write data encoder 202 (Fig. 3 (a)). Therefore, the ECC encoder of the trans codec 204 outputs ECC encoded data in units of three frames (6 fields) corresponding to the three frame (6 fields) periodic signal as shown in FIG.

Here, the data amount input to the ECC encoder is constant at 6 track periods corresponding to ECC units, but the data amount corresponding to each track may not be constant. The formatter in the trans codec 204 evenly distributes the ECC encoded data by track units by the ECC encoder to provide track formatted data as shown in FIG. An additional code such as header data or the like is added to the data and provided to the write amplifier 206. The recording amplifier 206 is configured as a current amplifying amplifier so as to sufficiently magnetize the recording medium so as to flow a recording current through the head in which data provided from the trans codec 204 can be recorded with good quality.

The transfer unit 208 performs a recording operation by converting the electrical output of the recording amplifier 206 into a magnetic signal to magnetize the recording medium. The control unit 210 controls the generation of various control signals required by each block of the recorder and the transfer unit 208. In particular, as shown in FIG. To control the transfer unit 208 to intermittently record on the recording medium.

In FIG. 4, which is a block diagram according to an embodiment of a reproducing apparatus for a variable speed, a control unit 302 for generating a control signal required for each block to organically operate a reproducing system, and a conveying unit 304 for transferring a recording medium. ) ECC decodes the detection data provided from the reproduction amplifier & data detector 306 and the reproduction amplifier & data detector 306 for amplifying the signal reproduced from the recording medium and detecting at the digital level, and converting the ECC decoded data into a variable speed. Playback data for decoding the output data of the trans codec 308 and the trans codec 308 for converting the data into a format required by the reproduction data decoder 310 after performing signal processing corresponding to the reproduction, and restoring the original video signal. The decoder 310 is comprised. Here, the trans codec 308 includes a variable speed reproduction signal processor 318 and a formatter 320 including an ECC decoder 312, first and second memories 314 and 316 as shown in FIG. .

The operation of the playback apparatus shown in FIG. 4 will be described with reference to FIGS. 5, 6 and 7.

The control unit 302 controls the generation of various control signals required in each block of the reproduction system and the transfer unit 304. In particular, the control unit 302 controls the transfer unit 304 to reproduce the six tracks for the ECC structure in a minimum unit. .

The transfer section 304 converts the information recorded on the recording medium by the magnetic head into an electrical signal and provides it to the reproduction amplifier & data detector 306. The reproduction amplifier & data detector 306 amplifies the reproduction signal output through the transfer unit 304 to a level sufficient for processing by the trans codec 308, equalizes the distortion generated during recording and reproduction, and equalizes the signal. Is detected as a digital value by a data detector employing a Partial Response Maximum Likelihood (PRML) algorithm, and the detected data is provided to the ECC decoder 312 of the trans codec 308 shown in FIG.

Here, the reproduction principle of the variable speed reproduction, in particular during the slow / still operation, is shown in FIG. 6, and the operation timing diagram of the trans codec 308 shown in FIG. 5 is shown in FIG. That is, when the slow / still mode is performed, the stop time is set according to the operation section 1 of the normal reproducing mode in which data recorded on the recording medium is reproduced in 6 track periods of ECC units and the variable speed. It has a stop section 2. Continuous playback with 6 track periods without stop section (2) is normal playback mode; normal playback and stop of 6 track data of arbitrary position desired by the user is still mode; operation section (1) and stop with normal playback mode Repeating section (2) is a slow mode.

At this time, the ECC decoder 312 is based on the additional data indicating the position of the track currently being reproduced from the detection data provided from the reproduction amplifier & data detector 306 according to the control signal according to the still / slow mode setting from the control unit 302. To generate an ECC decoding start signal as shown in FIG. The ECC decoder 312 ECC decodes the detection data provided from the reproduction amplifier & data detector 306 in units of three frames (6 fields) which are ECC units according to the internally generated ECC decoding start signal. As shown in FIG. 8, ECC-decoded data is output. As shown in (b) of FIG. 7, the ECC decoded data is reliable data, which is ECC decoded three frame data according to the ECC decoding start signal (FIG. 7 (a)), but the data corresponding to the stop period is reliable. There is no data.

Here, in the slow / still mode for a general VCR, data of one frame or one field is intermittently reproduced in a minimum unit. However, in slow / still mode for DVHS, MPEG decoding should be performed using 3 frames or 6 fields, which are ECC units, as the minimum unit.

In order to perform the slow / steel mode while meeting the DVHS standard, the first and second memories 314 and 316 of the variable speed reproduction signal processor 318 shown in FIG. 5 are operated as follows.

The ECC decoded data reproduced in units of six tracks provided from the ECC decoder 312 is stored in the first and second memories 314 and 316, and read and formatted at regular time intervals in units of data of one frame (or one field). It transmits to the reproduction data decoder 310 shown in FIG. Here, the speed at which data is written to the memories 314 and 316 in six track units and the speed at which data of one frame (or one field) stored in the memories 314 and 316 are dependent on the speed of variable speed reproduction (still / slow) are determined. Configure.

In the embodiment of the present invention, each memory of the variable speed reproduction signal processor 318 including the first and second memories 314 and 316 stores data of an integer multiple of six tracks. Is intended to perform a read operation. However, if the write data and the read data from the memory are large enough to operate independently without overlapping, they can be configured as one memory.

Either memory is provided with ECC decoded data according to the memory write enable signal WR EN as shown in Fig. 7C provided from the ECC decoder 312, as shown in Fig. 7D. Fill in. Assuming the 1/2 slow mode, the other memory is shown in FIG. 7F according to the memory read enable signal RD EN as shown in FIG. 7E provided from the formatter 320. As shown in the drawing, data of the same one frame is read out twice in succession and provided to the formatter 320. In 1 / n slow mode, data of the same one frame is read out n times in succession.

As another example of the data reading method, in response to the memory read enable signal RD EN as shown in FIG. 7G provided from the formatter 320 in the 1/2 slow mode, FIG. As shown in FIG. 2, data of one frame read from the memory is provided to the formatter 320, and the operation of skipping for one frame data read request time is repeated. In 1 / n slow mode, data of one frame is read out and the operation of skipping by the time corresponding to the frame (n-1) is repeated.

The first and second memories 314 and 316 are set to operate only in the slow / steel operation mode so that the ECC decoded data is not passed through the first and second memories 314 and 316 by the ECC decoder 312 except for the still / slow operation mode. It may be bypassed and output to the formatter 320, or the first and second memories 314 and 316 may be used as simple buffers.

Meanwhile, the formatter 320 reformats the output data of the variable speed playback signal processor 318 into data having an MPEG structure that can be recognized by the playback data decoder 310, that is, a display format suitable for the display format. Output to the reproduction data decoder 310. The reproduction data decoder 310 is, for example, an MPEG-2 decoder, and decodes the data of the MPEG structure provided from the trans codec 308 and restores the image data to a display device such as a monitor.

The present invention is suitable for a variable speed reproduction mode of an apparatus for recording and / or reproducing data of an MPEG structure, and particularly in a stationary digital VCR for recording and / or reproducing data of an MPEG structure required as a digital TV broadcast is introduced in earnest. It is suitable for devices that can cope with variable speed reproduction, especially in the case where the function of slow / steel is very important. In addition, the present invention can be very effectively applied to a system combining a recording data encoder that encodes an independently codeable picture (intra picture) and a surveillance VCR (also called a time lapse VCR) that requires a high quality slow / still function. .

In the embodiment of the present invention, the recording medium is described as a tape, but a recording medium such as a disc may be used, and as illustrated in FIGS. 2 and 4, the recording device and the reproduction device are separately configured, but FIG. And the recording and reproducing apparatus having all of the configurations shown in FIG. 4, which can be configured by sharing a control unit with a trans codec.

As described above, the present invention has the effect that it is possible to easily implement the variable speed reproduction, in particular the slow / steel function, while providing high quality image quality without increasing the complexity of the price or configuration.

Claims (15)

A method of recording and / or playing back digital data on a recording medium: (a) compressing and encoding the input independently coded picture data to provide compressed source data; And (b) controlling the coding rate of the source data and transmitting the same in a format suitable for a recording medium. The method of claim 1, wherein in the step (b), the coding rate is constantly controlled in units of an error correction code block (ECC), and the ECC unit is composed of a predetermined number of intra pictures, and each of the pictures in the ECC unit is determined. The coding rate may vary. The method of claim 1, (c) reproducing data from the recording medium in units of ECC, and providing variable speed reproduction data while controlling normal reproduction and stop operations in response to the variable speed mode; And (d) restoring the variable speed playback data to an original video signal. The method of claim 3, wherein the variable speed mode is a slow / still mode, and in the step (c), replaying a predetermined number of times corresponding to the variable speed of the slow / still mode in a picture unit of the data reproduced in the ECC unit is performed. How to feature. 5. The method of claim 4, wherein the variable speed mode is a slow / still mode, and in the step (c), a predetermined number of picture reading times corresponding to the variable speed speed of the slow / still mode are displayed in units of pictures among data reproduced in the ECC unit. And intermittently playing while skipping. An apparatus for recording and / or reproducing digital data on a recording medium: A source encoder for compressing and encoding the input independently coded picture data to provide compressed source data; And And a transmission encoder for controlling a coding rate of the source data and transmitting the same in a form suitable for a recording medium. The apparatus of claim 6, wherein the source encoder provides the transport encoder with a control picture indicating an ECC period and moving picture expert group (MPEG) encoded intra picture data in an error correction code block (ECC) unit. . The method of claim 7, wherein A transfer unit for transferring the recording medium; And And a control unit which controls the transfer unit to intermittently output the output of the transmission encoder to the recording medium in the ECC unit. The method of claim 6, wherein the transmission encoder An ECC encoder for encoding the source data in ECC units to provide ECC encoded data; And And a formatter for equally distributing ECC encoded data by the ECC encoder in track units to provide track formatted data. 10. The method of claim 9, wherein when the intra encoder encodes the intra picture data at a constant bit rate, the ECC encoder generates a control signal corresponding to an ECC period and is provided from the source encoder in synchronization with a control signal generated. And ECC encoding the intra picture data. The method of claim 6, wherein the transmission encoder controls the coding rate in units of ECC, the ECC unit is composed of a predetermined number of intra pictures, the coding rate of each picture in the ECC unit may be variable. Device. The method of claim 6, A variable speed reproduction signal processor for reproducing data from the recording medium in ECC units to control normal reproduction and stop operations in response to a variable speed mode; And And a decoder for restoring data provided from the variable speed reproduction signal processor to an original video signal. The apparatus of claim 12, wherein the variable speed mode is a slow / still mode, and the variable speed reproduction signal processor includes a memory configured to store data of an integer multiple of the number of tracks corresponding to the ECC unit, and to store the data stored in the memory as a picture unit. And repeatedly reading a predetermined number of times corresponding to the variable speed of the low slow / still mode. The apparatus of claim 12, wherein the variable speed mode is a slow / still mode, and the variable speed reproduction signal processor includes a memory configured to store data of an integer multiple of the number of tracks corresponding to the ECC unit, and to store the data stored in the memory as a picture unit. And intermittently reading out a predetermined number of picture reading times corresponding to a variable speed speed in a low slow / still mode. The method of claim 12, A transfer unit for transferring the recording medium; A control unit which recognizes a variable speed mode and controls the transfer unit to reproduce data on the recording medium in the ECC unit; An ECC decoder for error correction decoding the data on the recording medium in the ECC unit to provide ECC decoded data; And And a formatter for converting data provided from the variable speed reproduction signal processor into a format suitable for display and providing the format converted data to the decoder.