JP2003087749A - Image data reproducing device and image data reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce unnaturalness of screen transitions at the start of skip reproduction in the case of sequentially reading and reproducing image data written at a fixed data rate on a recording medium. SOLUTION: A memory 12 temporarily stores data sequentially read from a magnetic tape 2, a memory read section 13 sequentially reads the data stored in the memory 12, and gives the data to a video decoder 18 and an audio decoder 19. Further, in an ordinary reproduction, an I picture detection section 22 detects an I picture from the data read from the memory 12 to acquire a read address of head data in the memory 12 and stores the address to a picture address storage section 23. When the skip reproduction mode is selected, a read address control section 14 acquires the newest address stored in a picture address storage section 23 to designate a memory read section 13 to shift the read address on the memory 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image data reproducing device, an image data recording / reproducing device, an image data reproducing method and image data for sequentially reading and reproducing an image data stream recorded on a recording medium at a fixed data rate according to the MPEG standard. Recording / reproducing method.

[0002]

2. Description of the Related Art In recent years, MPEG (Moving) has been adopted as an international standard for compressing and encoding video data.
The Picture Expert Group) standard is widely known. M
The PEG standard uses an encoding method characterized by utilizing the correlation between screens for video data.

FIG. 9 shows picture types included in a video stream coded according to the MPEG standard. According to the MPEG standard, a video stream has a screen group structure called GOP (Group Of Picture) composed of a plurality of frames, and is coded in units of GOP. In addition, a sequence header is provided at the beginning of each GOP structure, and random access can be performed by detecting this sequence header during reproduction.

A GOP is made up of three types of pictures, I, P and B. As shown in FIG. 9, an I picture is coded in the frame independently of other pictures. P-pictures are generated by inter-frame forward coding, which is encoded by using an I- or P-picture that exists in time earlier, and a B-picture exists before and after in time. It is generated by the inter-frame bidirectional encoding that is encoded by using the I or P picture. Therefore, although I picture can be decoded independently, P picture and B picture
In order to decode a picture, an I picture or a previously decoded B picture is required.

In addition, for example, a digital VTR (Video Tape Rec) for reproducing a recording medium on which a video stream is recorded is used.
Some playback devices such as order) are provided with a function called interlaced playback in which recorded video data is played back at intervals of frames. This interlaced reproduction is used, for example, for confirming the recorded video by reproducing the thinned images at a low speed.

When interlaced reproduction is performed using a video stream recorded according to the MPEG standard, usually, only I pictures or only I and P pictures are extracted, decoded at fixed time intervals, and reproduced and output. Also,
During these decodings, copy pictures are generated and still images are displayed. By such a method, the video data that is interlaced and reproduced is maintained in the state of the encoded stream before decoding, for example, IEEE (the Institut
e of Electrical and Electronic Engineers) 1394
It is also possible to output to the outside from the interface based on the standard.

[0007]

By the way, when interlaced reproduction is performed using a video stream coded in accordance with the MPEG standard, since predictive coding is performed between a plurality of frames, at the start thereof, another Decoding for an I-picture coded independently of the picture is first required. Therefore, for example, Japanese Patent Publication No. 3127884.
The publication discloses a case where interlaced reproduction is performed using a video stream recorded on an optical disc.
According to this publication, within a sector on an optical disc,
By recording the head of the GOP sequence header so that the head of the recording area following the header information for the sector such as the MPEG system header always matches, it is possible to detect the I picture in a short time during the interlaced reproduction. It is possible.

However, when performing interlaced reproduction by a digital VTR, it is generally necessary to perform data sync detection, parity check, etc. after sequentially reading data, so that data read from a recording medium is used. It is difficult to directly detect the position of the I picture. Also,
In the case of a system using a recording medium having a data structure for sequentially reading data written at a fixed data rate, such as this digital VTR, in order to fix the data rate at the time of recording, the beginning of a picture or other It is also difficult to match the head portion of the specific data with the head portion of the sector on the recording medium.

Therefore, the I picture is detected after the sync data is decoded, and the operation mode is skipped and the reproduction mode is changed to the reproduction mode when the I picture is detected. It takes a long time to change to, and the transition of the reproduced image during this period becomes unnatural, and the viewer feels uncomfortable.

The present invention has been made in view of the above problems, and in the case of sequentially reading and reproducing image data written in a recording medium at a fixed data rate, there is no screen transition at the start of interlaced reproduction. It is an object of the present invention to provide an image data reproducing device capable of reducing the naturalness.

Another object of the present invention is to reduce the unnaturalness of the screen transition at the start of the interlaced reproduction when the image data written in the recording medium at a fixed data rate is sequentially read and reproduced. It is an object of the present invention to provide an image data reproducing method capable of performing the above.

[0012]

According to the present invention, in order to solve the above problems, an image data reproducing apparatus for sequentially reading and reproducing an image data stream recorded at a fixed data rate on a recording medium according to the MPEG standard is sequentially read. Temporary storage means for temporarily storing the output recording data of the recording medium, data reading means for sequentially reading the recording data stored in the temporary storage means, and the recording data stored in the temporary storage means When an address acquisition unit for acquiring the storage address on the temporary storage unit for the head data of the I picture in the image data stream and a request to change to the operation mode for interlaced reproduction are received from the address acquisition unit Start reading data again from the stored memory address Serial and read control means for controlling the data reading means, the image data reproducing apparatus, characterized in that it comprises a are provided.

In such a data reproducing apparatus, the temporary storage means temporarily stores the data sequentially read from the storage medium, and the data reading means sequentially reads the stored data. At the same time during normal reproduction, the address acquisition means acquires the storage address on the temporary storage means for the head data of the I picture in the image data stream from the data stored in the temporary storage means.
The address acquiring unit acquires the storage address by detecting the I picture data from the data read by the data reading unit and acquiring the read address of the I picture from the temporary storage unit at this time, for example. . Alternatively, the address acquisition unit acquires the storage address based on the information indicating the recording position of the head data of the I picture, which is recorded on the recording medium together with the image data stream. Further, when the read control means receives a request to change to the operation mode for performing the interlaced reproduction, it controls the data read means to start reading data again from the storage address acquired by the address acquisition means.

Further, according to the present invention, in the image data reproducing method for sequentially reading and reproducing the image data stream recorded at a fixed data rate on the recording medium according to the MPEG standard, the recording data of the recording medium is sequentially read and stored in the semiconductor memory. The recording data that is temporarily stored and stored in the semiconductor memory is sequentially read to decode the image data stream, and a storage address on the semiconductor memory for the head data of an I picture in the image data stream is read. When receiving the request to change to the operation mode for performing the interlaced reproduction, the reading of the data from the semiconductor memory is started again from the acquired storage address, and the I picture and the I picture are read from the read image data stream. Decoding only P pictures Image data reproducing method according to claim is provided.

In such an image data reproducing method, the data sequentially read from the storage medium is temporarily stored in the semiconductor memory, and this data is sequentially read and decoded to form an image data stream. It is reproduced and output. Along with this, I in the image data stream
The storage address on the semiconductor memory for the head data of the picture is acquired. The acquisition of the storage address is performed, for example, by detecting the I picture data from the data read from the semiconductor memory and acquiring the read address of the I picture from the semiconductor memory at this time. Alternatively, the acquisition of the storage address is recorded on the recording medium together with the image data stream,
This is performed based on the information indicating the recording position of the head data of the I picture. When a request to change to the operation mode for interlaced reproduction is received, data reading is started again from the acquired storage address, and I picture and P picture are read from the read image data stream.
Only the picture is decoded and reproduced and output.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, a first embodiment example of the present invention will be described. FIG. 1 shows the configuration of a data reproducing apparatus according to a first embodiment of the present invention.

The data reproducing device 1 shown in FIG. 1 is a device for writing and reading a video stream and an audio data stream to and from the magnetic tape 2. The helical scan method is used to record data in a helical fashion. In addition to the normal reproduction mode, the data reproduction device 1 has an interlaced reproduction mode for reproducing the recorded video data at a frame interval, as will be described later, as an operation mode for the video data and the audio data. is doing.

The data reproducing apparatus 1 receives a signal read from the magnetic tape 2 by a rotary head (not shown) and decodes it into digital data in sync block units, and a decoded sync block data. A memory 12 for temporarily storing the data, a memory reading unit 13 for reading and outputting recorded data of the memory 12 from a specified address, and a read position control unit for controlling a data reading position from the memory 12 by the memory reading unit 13. 14, a parity error detection unit 15 that detects an error based on the result of a parity check on the data from the memory reading unit 13, and a sync block that is input from the parity error detection unit 15 via an I-picture detection unit 22 described below. From the data, MPEG-2 standard TS (Transport Stream) to extract and output
Conversion unit 16 and PSI (Program Specific Information) which is program specification information recorded in the header of the TS
And PID (Packet I
dentification) and separates it into a video stream and an audio stream.
, A video decoder 18 and an audio decoder 19 for decoding each separated data stream, and an iLink (registered trademark) output unit 20 which is an output interface for outputting the TS output from the TS conversion unit 16 to the outside.
And a continuity error detection unit 21 that detects an error with respect to the continuity of TS.

In addition to these, the data reproducing apparatus 1
Is stored in the I picture detection unit 22 for detecting an I picture in the video stream from the data from the parity error detection unit 15 and the memory 12 for the detected I picture as a structure for the interlaced reproduction mode. The picture position storage unit 23 that stores the selected position, the mode transition control unit 24 that controls the operation of the read position control unit 14 when the operation mode is switched, and the I supplied from the TS supplied via the continuity error detection unit 21. I / P picture extraction unit 25 for extracting data of pictures and P pictures
And a copy picture generation unit 2 for outputting data for outputting a copy picture to the video decoder 18.
6, a TS generation unit 27 that generates a TS based on a reproduced image during interlaced reproduction, and PSI and PCR during interlaced reproduction
(Program Clock Reference) and AUX (auxilial
y) PSI / PCR / AU for generating each TS packet
The X generation unit 28 is provided.

The reproduction system signal processing section 11 performs sync pattern detection, predetermined demodulation / decoding processing, etc. on the signal read from the magnetic tape 2 and outputs sync block data. Each sync block data is the magnetic tape 2
In the above, the signal is error-correction coded by the Reed-Solomon code and recorded, and when the reproduction system signal processing unit 11 detects a sync pattern, it functions as a trellis decoder for decoding this Reed-Solomon code, and so on. The sync block data constituting the is extracted.

The memory 12 is, for example, a DRAM (Dynamic
It is a semiconductor memory such as Random Access Memory) and temporarily stores the composited sync block data. In the memory 12, writing of output data from the reproduction system signal processing unit 11 and reading of the written data by the memory reading unit 13 are sequentially performed.
The memory 12 uses 1 GOP (Group Of Picture) in the video stream so that at least one I picture exists in the written sync block data.
s) Has a storage capacity of at least the above. It is possible to perform a parity check on the data read from the magnetic tape 2 on the memory 12.

The memory read section 13 reads sync block data from the read start address designated by the read position control section 14 in accordance with the address incremented in the forward direction. In addition, the memory reading unit 13 notifies the I picture detection unit 22 of the address of the read sync block data.

The read position control section 14 designates a data read address from the memory 12 to the memory read section 13 at a predetermined timing for each operation mode. When the mode transition control unit 24 makes a request for transition to the interlaced playback mode, the memory reading unit 1
3, the latest address stored in the picture position storage unit 23 is designated to start data reading from this address, and the continuity error detection unit 2
For 1, the flag data indicating that the operation mode has changed is output.

The parity error detection unit 15 includes a memory 12
Based on the detection result of C1 parity and C2 parity of the stored data therein, it is determined whether or not the sync block data read from the memory 12 is used as correct data.

The TS conversion section 16 includes an I picture detection section 22.
TS packets are extracted from the data input via the PSI / PID analysis unit 17 and the iLink output unit 20.
And to the continuity error detector 21. In the interlaced reproduction mode, the extracted TS packet is output to the I / P picture extraction unit 25 via the continuity error detection unit 21.

The PSI / PID analysis unit 17 analyzes the PSI from the input TS packet to obtain the program specification information, then extracts each video and audio coded stream based on the PID, and extracts each video stream. It outputs to the decoder 18 and the audio decoder 19.

The video decoder 18 and the audio decoder 19 are STC (System Tim) calibrated by PCR.
(e Clock), the data of each encoded stream input from the PSI / PID analysis unit 17 is decoded according to the time stamp and output. Further, in the interlaced reproduction mode, the picture output from the I / P picture extraction unit 25 is decoded and reproduced and output, and when the output data from the copy picture generation unit 26 is received, it is the same as the image previously output. Output the image.

The iLink output unit 20 uses the IEEE (the
Institute of Electrical and Electronic Engineers)
According to the 1394 interface standard, the TS conversion unit 16
Alternatively, the TS packets from the TS generator 27 are sequentially output to the outside.

The continuity error detecting section 21 includes a TS converting section 1
The cyclic counter information (continuity counter) recorded in the TS packet including the video ES from 6 is detected, and it is determined whether the TS packet is a series or not. When there is a rejected one, an error code is output to the video decoder 18. Further, in the interlaced reproduction mode, the continuity / continuity in the supplied TS packet is determined according to the flag data output from the read position control unit 14.
The value of the counter and the value of the temporal reference, which is a value indicating the picture order in the GOP, are modified so as to maintain continuity.

Further, the I picture detecting section 22 monitors the picture start code and picture type in the video ES from the sync block data outputted from the parity error detecting section 15, and when the I picture is detected, the memory reading is carried out. The read address from the memory 12 for this I picture notified from the unit 13 is notified to the picture position storage unit 23. Picture position storage unit 23
Stores the read address of the I picture notified from the I picture detection unit 22. Mode transition control unit 24
Recognizes the designation of the operation mode by, for example, detecting the input of an operation button (not shown) by the user, and notifies the read position control unit 14 of the designated operation mode.

In the interlaced reproduction mode, the I / P picture extraction unit 25 receives the TS packets extracted by the TS conversion unit 16 via the continuity error detection unit 21 and outputs the I and P picture data. To extract.
In addition, the data of each picture extracted is output to the video decoder 18 and the TS generation unit 27 at a rate of once per predetermined period with respect to the frame period of the video data.

The copy picture generation unit 26 synchronizes with the frame period between the output of the picture data from the I / P picture extraction unit 25 and the output of the next picture data, and before that. Data for outputting a copy picture of the input picture is output to the video decoder 18 and the TS generation unit 27.

In the interlaced reproduction mode, the TS generation unit 27 generates TS packets for external output based on the picture data from the I / P picture extraction unit 25 and the copy picture generation unit 26, and the iLink output unit. Two
Output for 0. PSI / PCR / AUX generator 2
8 is PSI, PCR and AUX TS for external output
A packet is generated and output to the iLink output unit 20.

Next, an example of a recording format for the magnetic tape 2 will be described. First, referring to FIG.
An outline of the standard data structure is shown. In the MPEG-2 standard, ES (Elementary Stream) shown in FIG.
PES (Packetized Elementary Strea) shown in (B)
m) and each packet level of the TS shown in (C) are defined. As shown in FIG. 2A, as the ES, for example, an encoded stream of video data (video E
S), an encoded stream of audio data (audio ES), and the like. These ESs are multiplexed in pack units to generate a system stream. As shown in FIG. 2B, the PES packet is a PES packet.
It is composed of a header and a payload part, and the PES header stores control information such as various flags and time stamps.
The data of the system stream in which ES is multiplexed is divided and stored in the payload part.

Further, as shown in FIG. 2C, the TS packet has a data length of 188 bytes and is composed of a TS header and a payload part. PES in the payload section
Data is divided and stored, for example, video and audio data, control information such as PSI, time information, and the like are stored. Further, the TS header stores a PID that identifies a packet attribute such as a packet including video and audio data, or a packet including control information such as PSI, and other various control information. Further, when the PES data ends in the middle of the payload portion, "NULL" data is stored in the remaining area.

Next, FIG. 3 conceptually shows an example of arrangement of sync blocks on the magnetic tape 2. As shown in FIG. 3, helical tracks are formed on the magnetic tape 2, and data is recorded on each track in sync block units. In each track, 170 sync blocks of normal reproduction data in which TS packets are stored, 6 sync blocks of additional control data called subcodes, 18 sync blocks of fast-forwarding image data for special reproduction, and the like. Two
Each recording area of C2 parity for four sync blocks is arranged. The sync block formed in each recording area is error-correction coded by the Reed-Solomon code, and the sync pattern exists at the head part thereof, and as described above, the sync pattern is detected and detected by the reproduction system signal processing section 11. The sync block data is extracted by being decoded.

Next, FIG. 4 shows an example of the data structure of the sync block in the recording area of the normal reproduction data. In the normal reproduction data recording area, one TS packet is divided into two sync blocks as shown in FIGS. 4 (A) and 4 (B). 4A shows the data structure of even-numbered sync blocks when counting from 0, and FIG. 4B shows the data structure of odd-numbered sync blocks. In both of these, the data length of one sync block is 114 bytes, a control flag for various signal controls and a sync block ID which is identification information for the sync block, totaling 7 bytes, are recorded in the head part and the last part is recorded. 11 bytes of C1 parity data is recorded, and a TS data area is provided between them. Among these, the sync block ID included in the first 7-byte recording area is the 8-bit track number in which this sync block is recorded, and the 8-bit sync block number assigned to each sync block in the track. Etc. are included. In addition to this, in the even-numbered sync blocks, a recording area for a time stamp of 4 bytes is provided after the sync block ID and the control flag.

The data structure of the sync block in the recording area of the special reproduction data and the C2 parity is also
Although the data structure is similar to that shown in FIG. 4B, the sync block in the subcode recording area has a total data length of 30 bytes.

The C1 parity on the sync block and the C2 parity on the track make it possible to perform a bidirectional parity check on the sync block data stored in the memory 12.

Next, the operation of reproducing the data recorded on the magnetic tape 2 based on the above recording format in the data reproducing apparatus 1 shown in FIG. 1 will be described. The sync block data read from the magnetic tape 2 and decoded by the reproduction system signal processing unit 11 is temporarily stored in the memory 12 sequentially. Further, the stored data is sequentially read by the memory reading unit 13 at a predetermined timing under the control of the reading position control unit 14.
As a result, the memory 12 serves as an intermediate buffer for synchronizing the data read from the magnetic tape 2 at a constant data rate with the clock information recorded in the MPEG-compliant data stream.

In the normal reproduction mode, TS packets are extracted from the sync block read from the memory 12 and the validity of which has been confirmed by the parity error detector 15 in the TS converter 16, and the PSI / PID analyzer 1
At 7, it is separated into a video ES and an audio ES. The data reproducing apparatus 1 is provided with a STC generator (not shown) that is a reference time for decoding and reproducing output, and this STC is the encoder side by the PCR recorded in the adaptation field of the TS packet. It is calibrated to the intended value of. In the video decoder 18, decoding and reproduction output are started when the time stamp added to the PES packet so as to correspond to each picture of the input video ES matches the STC value. Similarly, the audio decoder 19 also performs decoding and reproduction output according to the time stamp given to each audio frame of the input audio ES.

The TS packet extracted by the TS converter 16 is supplied to the iLink output unit 20 so that the recorded data on the magnetic tape 2 can be output to an external device.

As described above, the data reproducing device 1
Has an interlaced reproduction mode as an operation mode in addition to the normal reproduction mode. This interlaced playback mode
The recorded video ES is reproduced and output while leaving a frame interval between the recorded video ES, and is used, for example, for confirming a recorded image by reproducing a thinned image at a low speed. In this interlaced reproduction mode, only I pictures and P pictures are extracted from the video ES, decoded at fixed time intervals, and reproduced and output. Also, during these decodings, copy pictures are generated and still images are displayed. By such a method, it is possible to output the interlaced reproduced video data from the iLink output unit 20 to the outside in the state of TS packets.

Further, when transitioning from the normal reproduction mode to the interlaced reproduction mode, the I picture must be decoded first, but at this time, if the time until the I picture is extracted becomes longer, The transition of the reproduced image becomes unnatural. Also, in addition to the interlaced playback mode, for example, an I picture is similarly extracted and output from the video ES even in a pause state of the playback operation, but the I picture is also extracted when transitioning from the normal playback mode to the pause state. Delays, similar unnatural image transitions occur.

Therefore, in the data reproducing apparatus 1 according to the first embodiment of the present invention, the sync block data read from the magnetic tape 2 and decoded is temporarily stored in the memory 12, and By acquiring the storage address of the I picture in the storage data in advance, the I address on the memory 12 can be changed at the start of the transition of the operation mode or the suspension.
Instantly read and decode pictures.

Specifically, at the time of normal reproduction, the memory reading unit 13 notifies the sync block data read from the memory 12 as well as the read address of this data from the memory 12, and the I picture detecting unit 22.
When the I picture is detected from the supplied sync block data, notifies the picture position storage unit 23 of the read address notified from the memory reading unit 13 at this time. The notified read address is stored in the picture position storage unit 23, so that the latest I picture read from the memory 12 is always stored in the picture position storage unit 23 as the head data of the latest I picture on the memory 12. The storage address is updated and stored in the picture position storage unit 23. Since the memory 12 has a storage capacity of 1 GOP or more, one or more I pictures are always stored.

Therefore, at the time of transition to the interlaced reproduction mode or at the start of the pause, the read position control unit 14 specifies the stored address to the memory read unit 13 so that the I picture is read from the memory 12. Re-reading from the first data of is immediately started.

The sync block read at this time is
The TS packet is converted into a TS packet by the TS converter 16, and the I / P picture extractor 2 is passed through the continuity error detector 21.
5 is supplied. The I / P picture extraction unit 25 extracts the I picture and P picture data from the supplied TS packet and outputs the data to the video decoder 18. At this time, the head data of the I picture is at the head of the supplied TS packet. Since it is included, the data of this I picture is instantaneously extracted and output to the video decoder 18, decoded and reproduced and output. Therefore, it is possible to output an image in a very short time compared to the conventional case without detecting the I picture on the magnetic tape 2 again from the time when the instruction to switch to the interlaced reproduction mode is issued.

Further, at the time of transition to the interlaced reproduction mode, the flag data is output from the read position control section 14 and supplied to the continuity error detection section 21. When the mode is changed to the interlaced reproduction mode, the read address from the memory 12 is changed, so that the continuity of the value of the continuity counter attached to the TS packet is interrupted. By receiving the flag data, the TS supplied from the TS converter 16
The value of the continuity counter and the value of the temporal reference are rewritten so as to maintain continuity without detecting a continuity error with respect to a packet, and an error occurrence in the video decoder 18 is prevented.

After the transition to the interlaced reproduction mode, the recording data is written into the memory 12 via the reproduction system signal processing unit 11 while the reading speed from the magnetic tape 2 is adjusted, and the memory from the memory 12 is changed. The read block 13 sequentially reads the sync block data. The sync block data is subjected to a parity check by the parity error detection unit 15, converted into a TS packet by the TS conversion unit 16, and supplied to the I / P picture extraction unit 25.

The I / P picture extraction unit 25 extracts the data of the I picture and the P picture from the supplied TS packet, for example, 5 for the frame period of the video ES.
The data of the extracted picture is output to the video decoder 18 at a timing of one sheet. Further, the copy picture generation unit 26 outputs the data for outputting the copy picture to the video decoder 18 in synchronization with the frame period during the image output from the I / P picture extraction unit 25.
As a result, the video decoder 18 outputs the extracted picture by the I / P picture extraction unit 25 as a still image of 5 frames. Further, since only the I picture or P picture is supplied to the video decoder 18, it is sufficient to sequentially decode and output these pictures, and it is not necessary to control the decoding timing and the output timing.

Further, when outputting the interlaced reproduced image to an external device, the TS generator 27 generates a TS packet according to the picture data from the I / P picture extractor 25 and the copy picture generator 26. The generated TS packet and the packet generated by the PSI / PCR / AUX generation unit 28 are output from the iLink output unit 20.

When the reproduction operation is paused,
After the pause is requested and the sync block data including the I picture data is read from the memory 12, the same I picture data is repeatedly read by the address designation of the memory reading unit 13, and the TS conversion unit 16 Is supplied to the I / P picture extraction unit 25 via. I / P
The picture extraction unit 25 uses the supplied I-picture data at a rate of, for example, one in every 15 frames.
8 to the copy picture generator 2
The same image is inserted by the data from 6.

Next, FIG. 5 shows a flowchart of processing in the data reproducing apparatus 1 when the normal reproducing mode is changed to the interlaced reproducing mode. In step S501, the normal reproduction mode is designated for the mode transition control unit 24, and the normal reproduction operation is started. In the normal reproduction mode, for example, the user makes a reproduction start request such as pressing a reproduction button (not shown), and the mode transition control unit 2
In response to this request, 4 instructs the read position control unit 14 and the reproduction mechanism unit (not shown) for the magnetic tape 2 to start the normal reproduction operation.

In step S502, the magnetic tape 2
The sync block data read from the memory 12 is sequentially stored in the memory 12, then read by the memory reading unit 13, converted into TS packets by the TS conversion unit 16 and supplied to the PSI / PID analysis unit 17, and the video is read. ES
And the audio ES, and are decoded by the video decoder 18 and the audio decoder 19. At the same time, from the sync block data read from the memory 12 by the memory reading unit 13, I
The picture detection unit 22 detects the I picture data by monitoring the picture start code and picture type in the video ES, and the picture position storage unit 23 stores the storage address of the I picture on the memory 12. .

In step S503, the mode transition control unit 24 monitors whether or not there is a request for changing the operation mode. If there is no request, the process returns to step S502 to continue the separation and decryption processing of each ES. With
The process of detecting the I picture and storing the address is repeated. If there is a request to change the operation mode to the interlaced reproduction mode, the process proceeds to step S504.

In step S504, the read position control unit 14 refers to the latest storage address stored in the picture position storage unit 23 at the time when the interlaced reproduction mode is designated by the mode transition control unit 24, and this storage is performed. The address is designated to the memory reading unit 13.

In step S505, the memory reading unit 13 changes the read address from the memory 12 to the storage address designated by the read position control unit 14, and starts reading data again. As a result, among the pictures already read from the memory 12, the reading is sequentially started from the sync block data including the head data of the latest I picture. The read data is converted into a TS packet by the TS converter 16 and supplied to the continuity error detector 21.

Since the memory 12 has a storage capacity of 1 GOP or more, one or more I picture data is always stored in the memory 12. However, immediately before the transition from the normal operation mode to the interlaced playback mode, the memory 1
Since the writing of the read data from the magnetic tape 2 and the reading by the memory reading unit 13 are always performed on the disk 2, the writing position and the reading position may be close to each other. In this case, for example, it is conceivable that a part of the I picture data of the read address newly designated at the time of the operation transition is already overwritten.

For this reason, when the operation transition is started, the read position control unit 14 causes the picture position storage unit 23 to have a sufficient interval so that the write address and the read address on the memory 12 do not overlap each other. The memory reading unit 1 that obtains the stored storage address
Specify 3 Therefore, the I picture first read from the memory 12 after the transition is actually either the last I picture read before the transition of the operation mode or the I picture first appearing after the transition.

In step S 506, the read position control unit 14 sends flag data indicating the interlaced reproduction mode to the continuity error detection unit 21. In response to the input of the flag data, the continuity error detection unit 21 rewrites the values of the continuity counter and the temporal reference for the video data in the supplied TS packet so as to maintain the continuity, and the I / P It is output to the picture extraction unit 25.

In step S507, the I / P picture extraction unit 25 extracts the I picture and the P picture from the TS packet and outputs them to the video decoder 18 at fixed time intervals for decoding. Video decoder 1
8, the picture that is the same as the I picture that was output immediately before or immediately after the transition of the operation mode is started and the sequentially supplied pictures are decoded and output, and the frames are complemented by the data from the copy picture generation unit 26. To do.

By the processing shown in the above flow chart, when transitioning from the normal reproduction mode to the interlaced reproduction mode, the I picture stored in the memory 12 is very short without newly detecting the I picture from the magnetic tape 2. It becomes possible to read and decode in time, the unnaturalness of the output image at the time of the operation mode transition is reduced, and the viewer does not feel uncomfortable. Further, such an effect can be obtained only by the processing on the data reproducing apparatus 1 without changing the recording format of the magnetic tape 2.

In the above flowchart, in the I picture detection by the I picture detection unit 22 in step S502, the end data as well as the head data of the I picture is detected and stored in the picture position storage unit 23. May be. This makes it possible to confirm whether the detected I-picture data is complete data for one frame. For example, when the I-picture that the memory reading unit 13 has started to read again does not have the data of the entire picture due to the edit point in the middle of the transition of the operation mode, this is detected. By waiting until the next I picture is stored in the memory 12, it becomes possible to output the complete I picture data again.

In the paused state of the reproducing operation, the I-picture data stored in the memory 12 is repeatedly read by the memory reading section 13. Therefore, by storing the respective storage addresses of the head data and the end data of the I picture in the picture position storage unit 23, a start address for the memory reading unit 13 to repeatedly read from the memory 12 in the temporary stop state is stored. It is possible to specify the end address.

Next, a second embodiment of the present invention will be described. FIG. 6 shows the configuration of a data reproducing apparatus according to the second embodiment of the present invention. Note that in FIG.
Functional blocks having the same processing functions as those of the data reproducing apparatus 1 shown in FIG. 6 are denoted by the same reference numerals, and description of these functional blocks is omitted here.

A data reproducing device 3 shown in FIG. 6 is a device for writing and reading a video stream and an audio data stream to and from the magnetic tape 4, and, like the data reproducing device 1 shown in FIG. It has a mode and an interlaced reproduction mode.

In the data reproducing apparatus 3, instead of detecting the I picture from the data read from the memory 12 and acquiring the read address of the I picture from the memory 12, the I picture is temporarily stored in the memory 12. A subcode reading unit 31 is provided which detects an I picture and obtains its storage address by reading subcode data from the sync block data.
That is, to the subcode, data indicating the storage position of the head data of the I picture is added in advance at the time of recording on the magnetic tape 4, and from the subcode of the sync block data stored in the memory 12 at the time of reproduction. Read this data.

Here, FIG. 7 shows an example of the structure of the sync block in the recording area of the subcode on the magnetic tape 4.
The data structure of the track formed on the magnetic tape 4 is the same as the data structure described in FIG. Therefore,
The recording area of the subcode in one track is 6 sync blocks, and the data length of one sync block in this recording area is 30 bytes. As shown in FIG. 7 (A), in the sync block in the sub-code recording area, control flags for various signal control are recorded in 2 bytes from the head, and in the following 4 bytes, the sub block is recorded in the sync block. It is a sync block ID indicating that code data is stored. In addition, 11 at the end of the sync block
C1 parity data is recorded in bytes, and the subcode data recording area is 12 bytes.

FIG. 7B shows an example of the structure of the data recording area of this subcode. In this embodiment, from the second bit from the beginning of this recording area, I is recorded in the track containing this sync block. A flag (I-Pic) indicating whether or not the head data of a picture exists is recorded as 1-bit data, and further, in the area before 8 bits from the end of this recording area, each of the above When the flag is set, the track number (Video Tr No.) and sync block number (Video SB No.) in which the leading data of the I picture is recorded.
Are recorded as 8-bit data.

The data of these subcodes is the video E
When S is multiplexed with audio ES and recorded on the magnetic tape 4, it is recorded at the same time. Then, when this magnetic tape 4 is set in the data reproducing device 3 and the reproducing operation is started in the normal reproducing mode, the recording signal of the magnetic tape 4 is decoded by the reproducing system signal processing section 11 and sequentially stored in the memory 12. It Prior to the data reading from the memory 12 by the memory reading unit 13, the sub-code reading unit 31 pre-reads only the sync block including the sub-code data from the storage data on the memory 12, and the I-Pi
When the c flag is set, the track number and sync block number recorded in this subcode are acquired.

When the memory reading unit 13 reads the stored data in the memory 12, the sync block I attached to the sync block read at this time is read.
When the D recording area is detected and the track number and sync block number recorded in this recording area match the track number and sync block number acquired from the subcode, the read address of this sync block Is acquired, and this is used as the picture position storage unit 2
Notify 3 and store.

The storage process of the read address of such an I picture is sequentially performed as the data is written in the memory 12. Then, when transitioning to the interlaced reproduction mode, the read position control unit 14 causes the picture position storage unit 23 to operate.
By acquiring the address stored in the memory reading section 13 and designating this address to the memory reading section 13, the sync block including the head portion of the I picture data is instantaneously read from the memory 12. Then, the read sync block is converted into a TS packet by the TS conversion unit 16 via the parity error detection unit 15, and is passed to the video decoder 18 via the continuity error detection unit 21 and the I / P picture extraction unit 25. Supplied. The subsequent operation is the same as the first operation described above.
This is the same as the embodiment described above.

Next, FIG. 8 shows a flowchart of processing in the data reproducing apparatus 3 when the normal reproducing mode is changed to the interlaced reproducing mode. In step S801, the normal reproduction mode is designated for the mode transition control unit 24, and the normal reproduction operation is started. Step S80
2, after the sync block data read from the magnetic tape 2 is sequentially stored in the memory 12, the sub code data is read by the sub code reading unit 31 as described above, and the I-Pic flag is detected. Then, the storage address of the head data of the I picture in the memory 12 is acquired and stored in the picture position storage unit 23. Along with this, the storage data in the memory 12 is sequentially read by the memory reading unit 13, converted into TS packets by the TS conversion unit 16, and converted into PSI / PID.
It is supplied to the analysis unit 17, separated into a video ES and an audio ES, and decoded by the video decoder 18 and the audio decoder 19.

In step S803, the mode transition control unit 24 monitors whether or not there is a request for changing the operation mode. If there is no request, the process returns to step S802 to repeat the I picture detection and address storage processing. At the same time, the separation and decryption processing of each ES is continued. If there is a request to change the operation mode to the interlaced reproduction mode, the process proceeds to step S804.

In step S804, the read position control unit 14 causes the picture position storage unit 23 to store the data in the memory 12 and the read position by the memory read unit 13 at intervals such that the write position does not overlap with each other. The latest stored address that has been stored is referred to, and this storage address is specified for the memory reading unit 13.

In step S805, the memory reading unit 13 changes the read address from the memory 12 to the storage address designated by the read position control unit 14, and starts reading data again. As a result, the sequential reading is started from the sync block data including the head data of the latest I picture among the pictures already read from the memory 12 or the I picture appearing next in the video ES. To be done.
The read data is converted into a TS packet by the TS converter 16 and supplied to the continuity error detector 21.

In step S 806, the read position control unit 14 sends flag data indicating the interlaced reproduction mode to the continuity error detection unit 21. In response to the input of the flag data, the continuity error detection unit 21 rewrites the values of the continuity counter and the temporal reference for the video data in the supplied TS packet so as to maintain the continuity, and the I / P It is output to the picture extraction unit 25.

In step S807, the I / P picture extraction unit 25 extracts the I picture and the P picture from the TS packet and outputs them to the video decoder 18 at fixed time intervals for decoding. Video decoder 1
8, the picture that is the same as the I picture that was output immediately before or immediately after the transition of the operation mode is started and the sequentially supplied pictures are decoded and output, and the frames are complemented by the data from the copy picture generation unit 26. To do.

In the second embodiment of the present invention described above, each data of the I-Pic flag, track number and sync block number is added to the subcode in advance when the data is recorded on the magnetic tape 4. , The memory 1 which has read the recorded data of the magnetic tape 4 during reproduction
2, the subcode reading unit 31 specifies the position of the sync block including the head data of the I picture and acquires the storage address on the memory 12. Therefore, when transitioning from the normal playback mode to the interlaced playback mode, the I picture stored in the memory 12 can be read and decoded in a very short time without newly detecting the I picture from the magnetic tape 2. Therefore, the unnaturalness of the output image at the time of the operation mode transition is reduced, and the viewer is less likely to feel uncomfortable. Moreover, since the data indicating the recording position of the I picture is recorded on the magnetic tape 4 in advance, the detection processing of the recording address of the I picture on the data reproducing device 3 can be simplified.

In each of the above embodiments, the magnetic tapes 2 and 4 are used as the external recording medium into which the data reproducing devices 1 and 3 read the data. However, for example, the magnetic tapes 2 and 4 are used. Similarly to the above, the present invention provides an optical disk, a hard disk, etc. in which a data stream is recorded at a fixed data rate, data is sequentially read during reproduction, and recorded using a recording format in which random access is impossible. It is also possible to apply to.

[0082]

As described above, in the data reproducing apparatus of the present invention, the temporary storage means temporarily stores the data sequentially read from the storage medium, and the data reading means sequentially reads the stored data. At the same time, during normal reproduction, the address acquisition unit uses the I stored in the image data stream from the data stored in the temporary storage unit.
The storage address on the temporary storage means for the head data of the picture is acquired. Further, when the read control means receives a request to change to the operation mode for performing the interlaced reproduction, it controls the data read means to start reading data again from the storage address acquired by the address acquisition means. Therefore, when transitioning to the operation mode in which interlaced reproduction is performed, the I picture stored in the temporary storage means can be read and decoded in a very short time without newly detecting the I picture.
Unnaturalness of the output image at the time of the operation mode transition is reduced.

In the image data reproducing method of the present invention,
The data sequentially read from the storage medium is temporarily stored in the semiconductor memory, and the image data stream is reproduced and output by sequentially reading and decoding the data. At the same time, the storage address on the semiconductor memory for the head data of the I picture in the image data stream is acquired. When a request to change to the operation mode for interlaced reproduction is received, data reading is restarted from the acquired storage address, and only I and P pictures are decoded from the read image data stream. It is reproduced and output.
Therefore, it becomes possible to read and decode the I picture stored in the temporary storage means in a very short time without newly detecting the I picture when transitioning to the operation mode in which the interlaced reproduction is performed. Unnaturalness of the output image at the time of transition is reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a data reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an outline of a data structure of the MPEG-2 standard.

FIG. 3 is a diagram conceptually showing an arrangement example of sync blocks on a magnetic tape.

FIG. 4 is a diagram showing an example of a data structure of a sync block in a recording area of normal reproduction data.

FIG. 5 is a flowchart showing a process in the data reproducing device when the normal reproducing mode is changed to the interlaced reproducing mode in the first embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a data reproducing device according to a second embodiment of the present invention.

FIG. 7 is a diagram showing a configuration example of a sync block in a subcode recording area on a magnetic tape according to a second embodiment of the present invention.

FIG. 8 is a flowchart showing a process in the data reproducing device when a transition is made from the normal reproduction mode to the interlaced reproduction mode in the second embodiment example of the present invention.

[Fig. 9] Fig. 9 is a diagram illustrating picture types included in a video stream encoded according to the MPEG standard.

[Explanation of symbols]

1 ... data reproducing device, 2 ... magnetic tape, 11 ... reproducing system signal processing unit, 12 ... memory, 13 ... memory reading unit, 14 ... reading position control unit, 15 ... parity error detecting unit, 16 ... TS converter, 17 ... PSI
/ PID analysis unit, 18 ... video decoder, 19 ... audio decoder, 20 ... iLink output unit, 21 ...
… Continuity error detector, 22 …… I picture detector, 2
3 ... Picture position storage unit, 24 ... Mode transition control unit, 25 ... I / P picture extraction unit, 26 ... Copy picture generation unit, 27 ... TS generation unit, 28 ... PSI /
PCR / AUX generator

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5C018 JC04 LA03                 5C053 FA22 GA11 GB06 GB08 GB15                       GB37 HA24 HA33 JA24 KA01                       KA24 LA06                 5C059 KK33 LB07 MA00 PP05 SS17                       UA05 UA36 UA37 UA38                 5D044 AB07 BC01 CC03 DE38 DE83                       FG10 FG18 FG23 GK08

Claims (10)

[Claims] 1. An image data reproducing apparatus for sequentially reading and reproducing an image data stream recorded at a fixed data rate on a recording medium according to the MPEG standard, wherein the sequentially read recording data of the recording medium is temporarily stored. Temporary storage means, data reading means for sequentially reading the recording data stored in the temporary storage means, and the head data of the I picture in the image data stream from the recording data stored in the temporary storage means When an address acquisition unit that acquires a storage address on the temporary storage unit and a request to change to an operation mode that performs interlaced reproduction are received, data reading is restarted from the storage address acquired by the address acquisition unit. Read control means for controlling the data read means The image data reproducing apparatus characterized by having a. 2. The address acquisition unit detects data of the I picture from the data read by the data reading unit, and acquires a read address of the I picture at this time from the temporary storage unit. The image data reproducing apparatus according to claim 1, wherein the storage address is acquired by the above. 3. The address acquisition unit detects the I-picture data by detecting a picture start code and a picture type from the data read by the data reading unit. 2. The image data reproducing device described in 2. 4. The address acquiring means acquires the storage address based on information indicating a recording position of the head data of the I picture recorded on the recording medium together with the image data stream. The image data reproducing device according to claim 1, characterized in that 5. When the recording medium is a magnetic tape,
The address acquisition means records the I-code recorded in the subcode of the track in which the head data of the I-picture exists.
The image data reproducing device according to claim 4, wherein the storage address is acquired based on information indicating a recording position of a picture. 6. The read control means uses the storage address of the I picture acquired at the latest by the address acquisition means at the time of receiving a request to change to the operation mode for performing the interlaced reproduction, The image data reproducing apparatus according to claim 1, wherein the data reading means is controlled. 7. A picture extraction for extracting I picture data and P picture data from the data newly read from the storage address by the data reading means under the control of the reading control means, and outputting at a predetermined time interval. Means, copy picture output means for outputting data indicating that the picture is a copy picture of a picture immediately before the picture output means, and each of the output pictures from the picture extraction means. The image data reproducing apparatus according to claim 1, further comprising: image data decoding means for decoding the copy picture based on picture data and output data from the copy picture output means. 8. An image data reproducing method for sequentially reading and reproducing an image data stream recorded at a fixed data rate on a recording medium according to the MPEG standard, wherein the recording data of the recording medium is sequentially read and temporarily stored in a semiconductor memory. Then, the recording data stored in the semiconductor memory is sequentially read, the image data stream is decoded, and a storage address on the semiconductor memory for the leading data of the I picture in the image data stream is obtained. When receiving a request to change to the operation mode for interlaced reproduction, reading of data from the semiconductor memory is started again from the acquired storage address, and only I and P pictures are read from the read image data stream. Image to be decrypted Data reproduction method. 9. The acquisition of the storage address is performed by detecting the data of the I picture from the data read from the semiconductor memory before receiving the request to change the operation mode of the interlaced reproduction. 9. The image data reproducing method according to claim 8, which is performed by acquiring a read address of the I picture from the semiconductor memory. 10. The acquisition of the storage address is performed based on information indicating a recording position of the head data of the I picture, which is recorded on the recording medium together with the image data stream. 8. The image data reproducing method described in 8.