KR100251930B1 - Apparatus for recording and reproducing video data - Google Patents

Abstract

PURPOSE: A recording and reproducing device for video data is provided to reduce price of the device and to efficiently use a recording medium while varying speed in trick play through recording and playing back the video data after MPEG(Moving Picture Expert Group) coding. CONSTITUTION: The recording and reproducing device contains an intra-frame coding unit, a recording and reading unit, and an intra-frame decoding unit. Herein, a video elementary stream generated by intra-frame coding a video stream is recorded on a recording medium not to repeatedly recording the video stream for trick play. The intra-frame coded video elementary stream is read according to an established speed. The read stream is intra-frame decoded for being reproduced. Moreover, the intra-frame coded stream is supplied to a TV receiver after reconstructing into transport stream packet.

Description

Video data recording and playback device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video data recording and reproducing apparatus, and more particularly, to a device for recording and reproducing video data by MPEG encoding and a method thereof.

The amplifier 2 coding method employs an intra frame coding method and an inter frame coding method. The intra frame encoding method includes a series of processes of quantizing a video stream for a frame after Discrete Cosine Transform (DCT), and variable length encoding the result. Compressed encoded frames are called I frames. The inter frame encoding scheme is divided into two types, one of which is a P frame encoding scheme that predictively encodes a video stream of a corresponding frame based on the I frame, and compresses according to the P frame encoding scheme. The encoded frame is called a P frame. The B frame encoding method, which is another of the inter frame encoding methods, predictively encodes a video stream of a corresponding frame based on the I frame and the P frame, and compresses a frame encoded according to the B frame encoding method. This is called a B frame. The predictive encoding includes a series of processes for detecting a motion vector by detecting interframe activity and encoding the motion vector, and a quantization scale factor is determined by a buffer control. Configure the feedback loop to be adjusted. This predictive encoding process increases the complexity of hardware. This caused a cost increase in the video recording and reproducing apparatus employing the Ampeg 2 coding scheme.

In general, a video elementary stream generated by encoding the video stream in an Ampeg 2 scheme is recorded on a recording medium according to its reproduction scheme, and the reproduction scheme is classified into normal play and trick play. For normal play, the video elementary stream is reconstructed into transport stream packets and then recorded on a recording medium. For trick play, the high speed reproduction is performed by reconstructing the video elementary stream into a transport stream packet and repeatedly recording the number of times corresponding to the double speed. The reason why a transport stream packet is repeatedly recorded many times during the trick play is that the transport of the video elementary stream according to the transport stream packet is possible only when the transport stream packet is completely read and output from the recording medium. Therefore, the transport stream packet is completely read out even when the recording medium is accessed at a high speed.

As described above, since the video elementary stream is reconstructed into a transport stream and recorded many times for trick play, the use of the recording medium has not been effective. In addition, the speed of trick play could not be freely determined since the speed at which the trick play was possible was determined according to the number of repeated recordings.

As described above, the MPEG-2 encoding method includes a predictive encoding process, which has a difficulty in increasing the cost of a video recording and reproducing apparatus employing the MPEG-2 encoding method.

In addition, conventionally, the video elementary stream generated by encoding the video stream using the MPEG-2 encoding method for the trick play is reconstructed into a transport stream and recorded many times. In addition, since the speed of the trick play is determined according to the number of repetitive recordings, there is a difficulty in not being able to freely speed up the trick play.

Accordingly, an object of the present invention is to provide a video data recording and reproducing apparatus which can reduce the cost of a video recording and reproducing apparatus, effectively use a recording medium, and free the speed of trick play.

1 is a block diagram of a video cassette recorder according to a preferred embodiment of the present invention;

2 is a conceptual diagram of a DPCM according to a preferred embodiment of the present invention;

3 is a block diagram of a sync block according to a preferred embodiment of the present invention;

4 is a track arrangement diagram according to a preferred embodiment of the present invention;

5 is a diagram showing disposition of video data in a sync block according to a preferred embodiment of the present invention;

6 is a block diagram of a transport stream packet according to a preferred embodiment of the present invention;

7 is a 1394 packet diagram according to a preferred embodiment of the present invention.

In order to achieve the above object, the present invention provides an intra frame encoding unit for encoding video data using the intra frame encoding method according to the MPEG-2 encoding method, and records the encoded video data on a recording medium, and records the recorded data on the recording medium. And a recording and reading unit for reading and outputting data, and an intra frame decoding unit for decoding the read data using the intra frame decoding method according to the Ampep 2 coding method.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and the annexed drawings, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent to those skilled in the art that the present invention may be practiced without these specific details. And a detailed description of known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

The present invention reduces the cost of video data recording and reproducing apparatus by eliminating inter frame encoding implemented as complex hardware and encoding the video stream using only intra frame encoding.

In addition, the present invention records the video elementary stream itself on a recording medium without reconstructing the video elementary stream generated by intra frame encoding the video stream into a transport stream packet to record the video stream for trick play. It is not necessary to record repeatedly. Here, the video elementary stream recorded on the recording medium as described above is read at a double speed, and can be reproduced by intra frame decoding the read video elementary stream.

The video data recording and reproducing apparatus is a device capable of reproducing video or audio in the form of a transport stream packet, for example, a digital television receiver or the like to process an intra frame encoded video elementary stream recorded on the recording medium. In order to enable output, the intra-frame coded video elementary stream read from the recording medium is reconstructed into a transport stream packet and then provided to the digital television receiver.

Referring to FIG. 1, which shows a block diagram of a camera recorder which is a video data recording and reproducing apparatus according to a preferred embodiment of the present invention, the video stream from the camera 100 and the audio stream from the microphone 102 are subjected to source processing. It is input to the unit 108.

The source processing unit 108 compresses and encodes the audio stream and the video stream when recording video and audio. In this case, the source processing unit 108 compresses and encodes the audio stream using the AC-3 method, compresses and encodes the Amp 2 audio method, or differential pulse code modulation (hereinafter referred to as DPCM). The compression encoding method is used to output the audio elementary stream. The source processing unit 108 receives a video stream in which Y: Cr: Cb has a 4: 2: 2 format, and compresses and encodes the image using an intra frame encoding method of the MPEG-2 encoding method.

Referring to a process of compressing and encoding a video stream according to the intra frame encoding method according to the MPEG-2 encoding method, first, the source processing unit 108 converts the 4: 2: 2 format video stream into a 4: 2: 0 format. The video stream of the 4: 2: 0 format is DCT (Discreted Cosine Transform) in macroblock units. The DCT includes a field DCT and a frame DCT. The source processing unit 108 determines which DCT to perform with respect to the video stream, and performs the DCT according to the determination. do. According to the DCT, the pixels in the macro block of the video stream are separated into direct current (hereinafter referred to as DC) coefficients and alternating current (hereinafter referred to as AC) coefficients.

The source processing unit 108 calculates an activity on the 4: 2: 0 format video stream, determines an initial quantization step, and quantizes the DCT result according to the quantization step. After the quantization, the source processing unit 108 processes the quantization result of the DC coefficients at 8, 9, 10, 11 [bits] according to intra-DC-precision. The information on the intra-DC-precision is recorded in the flag of intra_DC_precision of the picture header extension.

The source processing unit 108 performs DPCM on the processing result. In this case, each of the DPCMs has a predictor for Y, Cr, and Cb. Referring to FIG. 2, which illustrates the order of DPCM, the DPCM for Y includes the first block of the first macro block YM1. DC coefficient YDC1 of B1 ⇒ DC coefficient YDC2 of second block B2 in first macroblock YM1 ⇒ DC coefficient YDC3 of third block B3 of first macroblock YM1 ⇒ DC coefficient YDC4 of fourth block B4 in first macroblock YM1 ⇒ DC coefficient YDC5 of first block B1 in second macroblock YM2 ⇒ second macroblock YM2 DC coefficient YDC6 of the second block B2 in the memory. Proceed to the end of the slice in the order of. Then, the DPCM for Cb is the DC coefficient CbDC1 of the first macro block CbM1? DC coefficient CbDC2 of the second macro block CbM2. Proceed to the end of the slice in the order of. The DPCM for Cr is the DC coefficient CrDC1 of the first macro block CrM1? The DC coefficient CrDC2 of the second macroblock CrM2. Proceed to the end of the slice in the order of.

As described above, as DPCM is performed in units of slices, an initial value for the first macroblock of a slice needs to be determined, which is set to 128,256,512,1024 according to intra-DC-precision.

The source processing unit 108 performs variable length coding on the DPCM DC coefficients, wherein the variable length coding is performed according to Differential DC Size + (Signed Amplitude Of The Difference Data). The source processing unit 108 performs variable length encoding on the quantized AC coefficients using an intra frame variable length encoding table according to an intra frame encoding scheme. Here, the table may be ISO / IEC 13818-2 1995 Table B-14.

That is, the source processing unit 108 encodes the audio stream and outputs it as the first audio elementary stream, and intra-frame encodes the video stream and outputs it as the first video elementary stream.

The source memory unit 110 provides the source processing unit 108 with a memory area that the source processing unit 110 needs to calculate an activity or determine a quantization step during source processing.

The ECC unit 112 performs error correction encoding on the output of the source processing unit 108 when recording video and audio, and the error correction encoding scheme used at this time is the same as the SD (Standard Definition). Here, the output corresponding to the audio data among the outputs of the ECC unit 112 is called a second audio elementary stream, and the output corresponding to the video data is called a second video elementary stream.

In addition, the ECC memory 114 provides the ECC unit 112 with a memory area required for the error correction encoding of the ECC unit 112.

The track formatter and track data extractor 116 reconstructs the output data of the ECC unit 112 in the form of a sync block when recording video and audio. For example, the track formatter and track data extractor 116 The second video elementary data is rearranged in the sync block form shown in FIG. Here, referring to FIG. 3, which shows the shape of a sync block for second video elementary data, the sync block includes a pre sync area, a post sync area, a sync area, and a sync block. It consists of an ID area, a video data area, an outer parity area, an inner parity area, and a VAUX area. After reconstructing the output data from the ECC unit 112 in the form of a sync block, the track formatter and track data extractor 116 arranges the sync blocks on a track for recording on a tape. 4, the second audio elementary stream is arranged in 2 to 10 [sink block], and ECC1, which is error correction data for audio data, is placed in 11 to 15 [sink block]. The second video elementary stream is placed in 21 to 155 [sink block], and ECC2, which is error correction data for the second video elementary data, is placed in 157 to 167 [sink block].

Typically, the second video elementary stream for one frame is recorded over ten tracks, and the recording area of the second video elementary stream for one track is 135 (sink block). However, in the 135 [sink block], which is a second video elementary stream recording area for one track, there are typically more than 135 macroblocks or less than a second video elementary stream, and a second video for one frame. The amount of the second video elementary stream is adjusted at the time of encoding so that the amount of the elementary stream always has a constant range.

Here, referring to FIG. 5 illustrating the arrangement of the second video elementary stream for trick play and the second video elementary stream for normal play in the sync block, one sync block identifies the corresponding sync block. Sink 2 [byte] and ID 3 [byte]. The ID is composed of ID data 2 [bytes] and parity 1 [bytes]. The ID data includes an application ID, a track pair ID, and a sync block number. Referring to Table 1 indicating an application ID for a sync block of the second video elementary stream,

Application ID (3 [bit]) meaning 0 0 0 Consumer digital video cassette recorder 0 0 One Transport stream packets 0 One 0 Second Elementary Stream 0 One One Reserved area One 0 0 Reserved area One 0 One Reserved area One One 0 Reserved area One One One Reserved area

As shown in Table 1, the application ID is composed of 3 [bits], which indicates a consumer digital video cassette recorder when 000, indicates a transport stream packet when 001, and a second element when 010. Represents a stream. The sink block number in the ID is composed of 8 [bits], and this sink block number is used to identify the sink block.

In the sync block, the pure second video elementary stream region is 77 [bytes], and the second video elementary stream region includes a second video elementary stream for trick play and a second video elementary stream for normal play. This is recorded. For the second video elementary stream for trick play, N [bits] of 77 [bytes] are allocated, and N is variable. The normal play second video elementary stream is recorded in an area obtained by subtracting the trick play second video elementary stream recording area from the second video elementary data area. That is, the recording area of the normal play second video elementary stream is 77-N [bytes].

In general, 720 [pixel] × 480 [pixel] video is divided into 1350 macroblocks. One macroblock for the second video elementary stream for trick play is recorded corresponding to one sync block, and is normal. In the racing second video entity stream, 1 [mb] may not correspond to 1 sync. At this time, the DC block and the AC coefficient according to the intra-DC-precision are recorded in the sync block, and the number of the AC coefficients depends on the allocation of the recording area of the trick play second video elementary stream.

For example, when one DC coefficient and two AC coefficients are recorded for one macro block for the trick play second video elementary stream, the normal play second video elementary stream in one sync block is recorded. The recording area for the macro block of is 1 [byte] for the DC coefficient of the macro block for the trick play second video elementary stream at 77 [byte], which is the second video elementary data recording area of one sync block. It can be subtracted 3 [bytes] for the AC coefficient, that is, 73 [bytes].

As described above, the track formatter and track data extractor 116 reconstruct the output of the ECC unit 112 into a sync block during video and audio recording, and output the sync block after rearranging the sync blocks according to the track format. The output of the track formatter and track data extractor 116 is input to a modulator 118, which modulates the output of the track formatter and track data extractor 116 during video and audio recording. 24/25 modulation. The output of the modulator 118 is amplified by the amplifier 120 and then input to the deck unit 122 to be recorded on a recording medium such as a tape.

The video and audio recorded as described above are read by the deck unit 122, and the output of the deck unit 122 is input to the equalization and data detector 104 through the amplifier 120. The equalization and data detector 124 performs equalization on the deck unit 132 amplified by the amplifier 120, restores sync, and detects valid data. Valid data provided by the equalizer and data detector 124 is input to the track formatter and track data extractor 116. The track formatter and track data extractor 116 selects and outputs valid data provided by the equalization and data detector 124 according to the reproduction method during video and audio reproduction. That is, during the trick play, the effective data of the region in which the audio data and the data of the second video elementary stream for trick play are recorded is selectively outputted, and in the normal play, the audio data and the second video element for normal play Valid data of the area in which data on the tree stream is recorded is output.

The data selectively outputted by the track formatter and track data extractor 116 is input to the ECC unit 112. The ECC unit 112 performs error correction decoding on the output of the track formatter and the track data extractor 116, and outputs the second audio elementary stream as the first audio elementary stream, and the second video. The elementary stream is output as the first video elementary stream.

The source processing unit 102 decodes the first audio elementary stream according to the encoding method and outputs the same through the audio output device 106, and the first video elementary stream is an Ampeg 2 intra frame decoding method. Decoded according to the output through the video output device 104.

In contrast to the above, when outputting video and audio to an external device such as a digital television receiver, the track formatter and track data extractor 116 is used to output audio data and a second video elementary stream for normal play. Valid data of the region in which the data is recorded is selected and provided to the transport stream encoder 130. The transport stream encoder 130 reconstructs the valid data into a transport stream and then provides it to the digital interface 132. The digital interface 132 reconstructs the transport stream into 1394 packets and provides them to an external device. In addition, the track formatter and the track data extractor 116 provide the DPCM unit 126 with DC coefficients of the trick play Ampeck 2 video elementary stream at the time of trick play, and AC coefficients and audio of the trick play Ampeg 2 video elementary stream. The data is provided to the transport stream encoder 130. The DPCM unit 126 performs DPCM in units of slices on the DC coefficient of the trick play amplifier 2 video elementary stream. Here, when the DC coefficient is not for the first macro block of the slice, the DPCM unit 126 searches for the number of macro blocks of the number of slices by using an ID, and determines the DC coefficient of the previous macro block. DPCM is performed by stuffing to 0, and DPCM processing only up to the DC coefficient actually read out of the subsequent DC coefficients and stuffing the remaining slice parts. The output of the DPCM unit 126 is input to the variable length encoder 128. The variable length encoder 128 performs variable length coding on the DPCM DC coefficient according to Differential DC Size + (Signed Amplitude Of The Difference Data). The output of the variable length encoder 128 is input to the transport stream encoder 130. The transport stream encoder 130 reconstructs the output of the track formatter and track data extractor 116 and the output of the variable length encoder 128 into transport stream packets. In this case, the transport stream packet is composed of a header, a payload, and an optional part, as shown in FIG. 6, and its size is 188 [bytes]. The transport stream packet is provided to the digital interface 132, and the digital interface 132 reconstructs the transport stream packet into 1394 packets to form 125. μs To external devices. Referring to FIG. 7 illustrating a process of reconstructing the transport stream packet into 1394 packets, after separating a time stamp of 4 [bytes] added to a 188 [bytes] transport stream packet into 24 [bytes] Again, four blocks of 24 [bytes] are bundled together to form a data block.

As described above, the present invention has the advantage of reducing the cost of the video data recording and reproducing apparatus by eliminating inter frame encoding implemented as complex hardware and encoding the video stream using only intra frame encoding.

In addition, the present invention does not require repetitive recording for trick play by recording the encoded video stream itself on a recording medium without reconstructing and recording the intra frame encoded video stream into a transport stream packet. There is an advantage to be able to freely speed.

In addition, there is a convenience in that a conventional digital television receiver or the like can process and output the encoded video stream recorded as described above.

Claims (6)

In the video data recording and playback apparatus, An intra frame encoder which encodes video data by the intra frame encoding method according to the Amppe 2 encoding method, A recording and reading unit for recording the encoded video data on a recording medium, and reading and outputting the data recorded on the recording medium; And an intra frame decoder which decodes the read data by using an intra frame decoding method according to an amplifier 2 coding method. In the video data recording and playback apparatus, An amplifier 2 encoder which encodes video data for trick play and data for normal play according to an amplifier 2 encoding method; An error correction encoding unit for error correction encoding the video data for normal play with the MPEG-2 encoded data and the data for normal play; A track formatter configured to configure an output of error correction for video data for trick play and an output of error correction for data for normal play in one sync block, and to arrange the sync blocks according to a track format; A modulator for modulating the output of the track formatter; A deck unit for recording the modulated output on a tape or reading data from the tape; A data detector for detecting valid data from data read from the tape; A track data extraction unit for selectively outputting data for trick play during trick play and outputting only data for normal play during normal play with respect to the output of the detector; An error correction decoding unit for error correction decoding the output of the track data extraction unit; And an amplifier 2 decoder which decodes the error correction output according to an amplifier 2 decoding method. In the video data recording and playback apparatus, An intra frame encoder which encodes video data for trick play and data for normal play by an intra frame coding method according to the Amppe 2 coding method; An error correction encoding unit for error correction encoding the video data for the encoded trick play and the data for normal play; A track formatter configured to configure an output of error correction for video data for trick play and an output of error correction for data for normal play in one sync block, and to arrange the sync blocks according to a track format; A modulator for modulating the output of the track formatter; A deck unit for recording the modulated output on a tape or reading data from the tape; A data detector for detecting valid data from data read from the tape; A track data extracting unit outputting only data for trick play during trick play and outputting only data for normal play during normal play with respect to the output of the detector; An error correction decoding unit for error correction decoding the output of the track data extraction unit; And an amplifier 2 intra frame decoder which decodes the error correction output by an intra frame decoding method according to the amplifier 2 decoding method. In the video data recording and playback apparatus, Camera, An intra frame encoder for encoding video data for trick play and data for normal play from the camera by an intra frame encoding method according to the Ampep 2 encoding method; An error correction encoding unit for error correction encoding the video data for the encoded trick play and the data for normal play; A track formatter configured to configure an output of error correction for video data for trick play and an output of error correction for data for normal play in one sync block, and to arrange the sync blocks according to a track format; A modulator for modulating the output of the track formatter; A deck unit for recording the modulated output on a tape or reading data from the tape; A data detector for detecting valid data from data read from the tape; A track data extracting unit outputting only data for trick play during trick play and outputting only data for normal play during normal play with respect to the output of the detector; An error correction decoding unit for error correction decoding the output of the track data extraction unit; An amplifier 2 intra frame decoder which decodes the error correction output by an intra frame decoding method according to the amplifier 2 decoding method; And a video output device for displaying the output of the amplifier 2 intra frame decoder. In the video data recording and playback apparatus, An intra frame encoder which encodes video data for trick play and data for normal play by an intra frame coding method according to the Ampep 2 coding method; An error correction encoding unit for error correction encoding the video data for the encoded trick play and the data for normal play; A track formatter configured to configure an output of error correction for video data for trick play and an output of error correction for data for normal play in one sync block, and to arrange the sync blocks according to a track format; A modulator for modulating the output of the track formatter; A deck unit for recording the modulated output on a tape or reading data from the tape; A data detector for detecting valid data from data read from the tape; A track data extracting unit outputting only data for trick play during trick play and outputting only data for normal play during normal play with respect to the output of the detector; A transport stream encoder for reconstructing the output of the track data extractor into a transport stream; And a digital interface for reconstructing and outputting the transport stream into 1394 data packets. In the video data recording and playback apparatus, Discrete cosine transform the video data for trick play, and quantize the DC coefficients and AC coefficients among the discrete cosine results, quantize the AC coefficients and output them by variable-length encoding. Output according to the precision, discrete cosine transform the video data for normal play, quantize the DC coefficient and AC coefficient among the discrete cosine results, differential pulse code modulation for the quantization result of the DC coefficient, A source processing unit for variable length encoding the differential pulse code modulation result and the quantization result of the AC coefficient; An error correction encoder for error correction encoding the output of the source processing unit; A track formatter configured to configure the output of the error correction encoder for trick play and the output of the error correction encoder for normal play in one sync block, and arrange the sync block according to a predetermined track format; A modulator for modulating the output of the track formatter; A deck unit for recording the modulated output on a tape or reading data from the tape; A data detector for detecting valid data from data read from the tape; A track data extracting unit outputting only data for trick play during trick play and outputting only data for normal play during normal play with respect to the output of the detector; A differential pulse code modulator for receiving differential pulse code modulated data from a data for trick play from the track data extractor during the track play; A variable length encoder for variable length encoding the output of the differential pulse code modulator; The track data extracting unit receives the output of the variable length encoder and the data of the AC coefficient among the data for the trick play provided by the track data extracting unit during the trick play. A transport stream encoder configured to receive data for normal play provided by the transport stream packet and And a digital interface for reconstructing and outputting the transport stream packet into a 1394 data packet.

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