JPH08265695A - Digital compressed data playback device - Google Patents

Abstract

(57) [Abstract] [Purpose] Compressed image data for one frame is recorded when reproducing a still image file in which only the audio signal is temporally sequentially reproduced while the image signal is stationary. It can be realized only by A reproduction time information regarding digital compressed image data and compressed audio data is extracted from a time-axis-multiplexed digital data sequence. Set the playback time information about the extracted audio data in a predetermined cycle,
Counts at a predetermined frequency except when set. During reproduction of a still image file, control is performed so that the output of the reproduced image signal is frozen until the count value becomes equal to the reproduction time information regarding the image data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention reproduces multiplexed digital data in which time-multiplexed digital compressed image data having reproduction time information recorded on an optical disk and digital compressed audio data having reproduction time information. The present invention relates to a digital compressed data reproducing device, and more particularly to a digital compressed data reproducing device suitable for application to a still image file system.

[0002]

2. Description of the Related Art ISO / IEC13818-1 is a method for time-multiplexed recording of digital compressed image data and compressed audio data on a recording medium such as an optical disk.
Standard methods are known. An outline of a time-axis multiplexing system for digital compressed image data and compressed audio data in this system will be briefly described below. First, digital compressed image data and compressed audio data are each divided into units called access units. The access unit is
In the case of image data, it is in image frame units, and in the case of audio data, it is in audio frame units. Next, an access unit in which each of image data and audio data is continuous is divided into units called packets, and when each packet includes the first digital data of the access unit of each of image data and audio data, the access unit is divided. PTS (Presenta) indicating playback time information of
A signal called tion Time Stamp) is added. This packet is time-multiplexed with this packet as the minimum unit.

[0003]

When reproducing the digital multiplexed data recorded on the optical disk by using such a system, the PTS indicates the reproduction time of the access unit belonging to the packet to which the PTS is added. Therefore, when both the image signal and the audio signal such as a movie file are sequentially reproduced in frame units, there is no access unit corresponding to the signal of all image frames, but it does not matter, but the image signal is still. When reproducing a still image file in which only the audio signal is sequentially reproduced in this state, if the compressed image data for one frame of the still image is recorded, only one frame period Since it is not played back, it is necessary to record the compressed image data for the frames necessary for the still image playback period, regardless of the still image. Narazu, recording efficiency of the optical disk may be reduced.

In view of the above point, the present invention records compressed image data for one frame when an image signal such as a still image file is in a stationary state and only audio signals are sequentially reproduced in time. It is an object of the present invention to provide a digital compressed data reproducing device which can be realized only by doing.

[0005]

In order to achieve the above object, the present invention extracts reproduction time information about digital compressed image data and compressed audio data from time-axis multiplexed digital data to obtain a still image file. At the time of reproduction, the output of the reproduction image signal is controlled according to the reproduction time information until the time described in the reproduction time information regarding the new image data is reached.

Further, at the time of reproducing the still image file, the data reading is stopped immediately before the time described in the reproduction time information regarding the new image data is reached, and the next data is recorded until the standby release signal is input from the outside. The configuration is such that the reading is waited.

[0007]

With the above structure, the present invention can be realized by only recording one frame of digital compressed image data when reproducing a still image file.

Further, the user can operate the still image file in a desired time unit, and the interactive property can be improved.

[0009]

【Example】

(Embodiment 1) Hereinafter, Embodiment 1 of the present invention will be described with reference to the drawings. 1 is a block diagram of a digital compressed data reproducing apparatus according to a first embodiment of the present invention.

Reference numeral 101 denotes an image information extraction circuit for extracting reproduction time information relating to digital compressed image data from the multiplexed digital data string and selecting and outputting only the digital compressed image data. Reference numeral 102 denotes the multiplexed digital data string. An audio information extraction circuit for extracting reproduction time information relating to digital compressed audio data from the inside and selecting and outputting only digital compressed audio data.
Reference numeral 03 is an image decoding circuit for decoding digital compressed image data, 104 is a PTSv delay device for delaying the image reproduction time information by the time required for the processing of the image decoding circuit 103, 1
Reference numeral 05 is an audio decoding circuit for decoding digital compressed audio data, 106 is a PTSa delay device for delaying the audio reproduction time information by the time required for the processing of the audio decoding circuit 105, 1
Reference numeral 07 is an image signal output control circuit for controlling the output of the reproduced image signal, and 108 is a counting circuit for setting the signal from the delay device 106 at a predetermined cycle, and for counting at a predetermined frequency otherwise.

The operation will be described in detail with reference to FIG.
The input terminal 100 has, for example, ISO / IEC13818
The MPEG program stream time-multiplexed according to the -1 standard is reproduced from an optical disc or the like and input. FIG. 2 schematically shows an example of this stream.

FIG. 2A shows a time-axis multiplexed image and audio access unit, which is shown by connecting a movie file portion and a still image file portion. I,
Reference characters B and P denote access units for digital compressed image data, and ISO / IEC1381 respectively.
The access unit is intra-coded, the bidirectional predictive coded access unit, and the unidirectional predictive coded access unit based on the 8-2 standard. A indicates an access unit for digital compressed voice data. The number added to each indicates the order of the reproduction time for each image and sound. Figure 2
When packetized in units as shown in (b) (number indicates packet number), P of image data and audio data is recorded.
The TS will be stored in the stream at the locations shown in FIGS. 2 (c) and 2 (d). The PTS stores the reproduction time information of the access unit represented by the arrow, and there are also access units such as B ₂ and B ₅ that do not have a PTS. Therefore, in this embodiment, FIG.
As shown in FIG. 3, the PTS is always added only to the access unit that is intra-coded (the access unit indicated by I in FIG. 2A).

This MPEG program stream is input to the image information extraction circuit 101 and the audio information extraction circuit 102. The image information extraction circuit 101 extracts reproduction time information (hereinafter abbreviated as PTSv) from the MPEG program stream for each access unit in which digitally compressed image data is intra-coded, and extracts this PTS.
In addition to outputting to the v delay device 104, only digital compressed image data is output to the image decoding circuit 103. Similarly, the audio information extraction circuit 102 extracts reproduction time information (hereinafter referred to as PTSa) from the MPEG program stream for each packet of digital compressed audio data,
This is output to the PTSa delay device 106, and at the same time, only the digital compressed audio data is output to the audio decoding circuit 105. The image decoding circuit 103 decodes the bit stream compressed and encoded using the MPEG2 system, and outputs the reproduced image signal to the image signal output control circuit 107.
On the other hand, PTSv is necessary for processing up to decoding and reproduction by the access units (I ₃ , I ₇ , and I _{8 in} FIG. 2) that have been intra-coded by the PTSv delay device 104. After being delayed by the time, it is input to the image signal output control circuit 107. Also, the speech decoding circuit 105
Outputs the bit stream compressed and encoded using the AC3 method to the output terminal 110. On the other hand, P
TSa is an access unit to which the PTS of the audio decoding circuit 105 is added by the PTSa delay unit 106 (see FIG. 2).
A ₁ , A ₃ , A ₅ , A ₇ ) are delayed by the time required for the processing up to the decoding and reproduction, and are input to the counting circuit 108. The counting circuit 108 sets P at every preset cycle.
The counter is set to the value of PTSa output from the TSa delay unit 106, and is configured by a counter that counts up every 90 kHz in other periods, and the counter value (hereinafter, abbreviated as PTSm) is an image signal output control circuit. 1
It outputs to 07.

The image signal output control circuit 107 outputs an image signal obtained by decoding the access unit I ₃ when PTSm becomes equal to PTS ₃ output from the PTSv delay unit 104 at the time of reproducing the movie file portion of FIG.
To the output terminal 109 at a frame cycle. The image signals obtained by decoding the access units B ₄ , B ₅ , and P ₆ thereafter are output at the frame cycle. The image signals obtained by decoding the access units B ₁ and B ₂ are output to the output terminal 109 earlier in time than the image signals obtained by decoding the access unit I ₃ . On the other hand, FIG.
PTSv delay device 10 when reproducing the still image file portion of
When PTSm becomes equal to PTS ₇ output from P4, the image signal obtained by decoding the access unit I ₇ is output to the output terminal 109, and freezes until PTSm becomes equal to PTS ₈ . Also, the image signal decoded by the access unit P ₆ is frozen until PTSm becomes equal to PTS ₇ . That is, when the decoded image signal of the access unit which has been intra-coded is reproduced next, P
The frame being output is frozen until TSm becomes equal to the value output from the PTSv delay device 104.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a block diagram of a digital compressed data reproducing apparatus according to the second embodiment of the present invention.

Reference numeral 301 is an optical disk on which multiplexed digital data is recorded, 302 is an optical system head for irradiating a semiconductor laser, and the reflected light thereof is converted into an electric signal, 303 is rotation of the optical disk, and a machine of the optical system head 302. A drive control circuit for controlling a dynamic operation, and a reproduction signal processing circuit 304 for processing a reproduction signal from the optical system head 302.

The operation will be described in detail with reference to FIGS. 2 and 3. The multiplexed digital data recorded on the optical disc 301 is read by the optical system head 302 and input to the reproduction signal processing circuit 304. The reproduction signal processing circuit 304 reproduces the clock signal necessary for internal processing from the reproduction signal input from the optical system head 302, performs necessary processing on the reproduction signal such as error correction, and then outputs only the MPEG program stream to the image information. It is output to the extraction circuit 101 and the voice information extraction circuit 102. Hereinafter, in the blocks other than the image signal output control circuit 107, the same processing as that described in the first embodiment is performed.

The image signal output control circuit 107 outputs the image signal obtained by decoding the access unit I ₃ when PTSm becomes equal to PTS ₃ output from the PTSv delay unit 104 at the time of reproducing the movie file portion of FIG.
To the output terminal 109 at a frame cycle. The image signals obtained by decoding the access units B ₄ , B ₅ , and P ₆ thereafter are output at the frame cycle. The image signals obtained by decoding the access units B ₁ and B ₂ are output to the output terminal 109 earlier in time than the image signals obtained by decoding the access unit I ₃ . On the other hand, FIG.
PTSv delay device 10 when reproducing the still image file portion of
The image signal decoded access units I ₇ when the PTS ₇ is PTSM becomes equal outputted from 4 outputting to the output terminal 109, with PTSM freezes until it equals the PTS _8, PTSM equals PTS ₈ The drive standby signal is output to the drive control circuit 303 immediately before. Upon receiving the drive standby signal, the drive control circuit 303 controls the operations of the optical disc 301 and the optical system head 302, and waits immediately before the multiplexed digital data of packet number 10 shown in FIG. Data reading is stopped until the standby release signal is input from the input terminal 305. When the standby release signal is input from the input terminal 305, the drive standby signal is reset and then the multiplexed digital data of packet number 10 is read. The processing described above is repeatedly performed during the reproduction period of the still image file.

In the first and second embodiments, the determination as to whether the file is a movie file or a still image file is based on ISO which is what encoding is applied to the access unit.
Although it can be performed by the image decoding circuit 103 by decoding the information defined by the / IEC13818-2 standard, the image signal output control circuit 107 externally supplies information indicating that it is in the reproduction mode of a still image file. You can type in.

[0020]

As described above, according to the present invention, when the decoded image signal of the intra-coded access unit is reproduced next, the reproduction time of the intra-coded access unit is reproduced. Output control is performed so that the frame being output is frozen until it becomes, so that it is necessary during the still image playback period in a still image file in which only the audio signal is played sequentially in time with the image signal still. It is not necessary to record the compressed image data for one frame, and it can be realized by only recording the compressed image data for one frame, and the recording efficiency of a recording medium such as an optical disk can be improved.

Further, when the decoded image signal of the intra-coded access unit is reproduced next, the data is read from the optical disk immediately before the reproduction time of the intra-coded access unit. The optical disc drive mechanism is controlled and kept in standby at that position until the signal is stopped and the standby release signal is input from the outside, so that the user can operate the still image file in the desired time unit, which is highly interactive. An optical disk reproducing device can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram of a digital compressed data reproducing device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of an MPEG program stream.

FIG. 3 is a block diagram of a digital compressed data reproducing device according to a second embodiment of the present invention.

[Explanation of symbols]

 101 Image Information Extraction Circuit 102 Audio Information Extraction Circuit 103 Image Decoding Circuit 104 PTSv Delay Device 105 Audio Decoding Circuit 106 PTSa Delay Device 107 Image Signal Output Control Circuit 108 Counting Circuit 301 Optical Disk 302 Optical System Head 303 Drive Control Circuit 304 Playback Signal Processing circuit

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Claims (4)

[Claims] 1. An apparatus for reproducing multiplexed digital data in which time-multiplexed digital compressed image data having reproduction time information and digital compressed audio data having reproduction time information are reproduced from the multiplexed digital data. Means for extracting first reproduction time information regarding the digital compressed image data, means for extracting second reproduction time information regarding the digital compressed audio data from the multiplexed digital data, and the digital compressed image data An image decoding means for decoding and obtaining a reproduced image signal; an audio decoding means for decoding the digital compressed audio data to obtain a reproduced audio signal; and a first reproduction time information for processing of the image decoding means. A first delay means for delaying by a necessary time; and a second decoding time information for the second reproduction time information. Second delay means for delaying by a time required for processing, and the value is set for each predetermined cycle in accordance with the audio reproduction time information output from the second delay means. The counting means for counting is compared with the count value Tm output from the counting means and the image reproduction time information Tv output from the first delay means, and the image decoding is performed until Tm becomes equal to the value of Tv. And an image signal output control means for controlling so as to freeze the output of the reproduced image signal previously obtained by the converting means. 2. An apparatus for reading and reproducing multiplexed digital data obtained by time-multiplexing digital compressed image data having reproduction time information and digital compressed audio data having reproduction time information from a recording medium such as an optical disk. Means for extracting first reproduction time information relating to the digital compressed image data from the multiplexed digital data, and means for extracting second reproduction time information relating to the digital compressed audio data from the multiplexed digital data. An image decoding means for decoding the digital compressed image data to obtain a reproduced image signal, an audio decoding means for decoding the digital compressed audio data to obtain a reproduced audio signal, and the first reproduction time information. A first delay unit for delaying a time required for processing of the image decoding unit; Second delay means for delaying the reproduction time information of No. 2 by the time required for the processing of the audio decoding means; and the value thereof is set for each predetermined cycle in accordance with the audio reproduction time information output from the second delay means. The count value Tm output from the count means and the image reproduction time information Tv output from the first delay means are compared with each other by counting means Tm that counts at a predetermined frequency except when set. Means for stopping the reading of the multiplexed digital data from the optical disk immediately before the value of Tv becomes equal to the value of Tv, and waiting the optical disk reading mechanism at the reading stop position until an external stop release signal is input, The count value Tm output from the means and the image reproduction time information Tv output from the first delay means are compared, and the image decoding means until Tm becomes equal to the value of Tv. Thus compressed digital data reproduction apparatus characterized by comprising an image signal output control means for freezing the output of the reproduced image signal obtained it previously. 3. The digital compressed data reproducing apparatus according to claim 1, wherein said image signal output control means operates based on a mode signal designated from the outside. 4. The digital compressed data reproducing apparatus according to claim 3, wherein the mode signal designated from the outside is a signal indicating reproduction information of a still image file.