JP2002305721A - Compressed image reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compressed image reproducing method using a device of a simplified configuration by which detection of an end of frames and control of a transmission speed are facilitated. SOLUTION: The compressed image reproducing method comprises preparing an SHC(sequence header code) denoting a position of an SHC of a stream in a disk 1 at recording of an MPEG stream, reading data from a position of the SHC indicated by the SHC index 2 and reading and decoding the data until a header of an inter-frame coding data is detected from consecutive MPEG streams.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a compressed image reproducing method, and more particularly to a compressed image reproducing method for reading an MPEG stream of a compressed image from a recording medium and decoding the read MPEG stream to reproduce image information. .

[0002]

2. Description of the Related Art Since video data has a very high data rate, it is difficult to record the data on a disk medium such as a magnetic disk, an optical disk, a magneto-optical disk or a semiconductor memory without processing the data. For this reason, a method has been used in which video data and audio data are efficiently encoded to reduce the data rate to a recordable rate on a disk medium without any visual or auditory deterioration.

[0003] As an example of the high efficiency coding method, MPEG
(Moving Picture Experts Group) method. MPE
The features of G are that it performs “Motion Compensation (MC)” which is unnecessary in still image compression, that random access to frames can be performed as a precondition for moving image compression, playback by fast forward and rewind playback ( (In the opposite direction).

As described above, in MPEG, fast-forwarding, rewinding, and playback from the middle are fundamental, so that a certain unit of moving image is grouped together into a GOP (Group of Pic
tures) to enable independent playback in that unit. As the prediction structure of the screen in the GOP, each image (picture) meaning a frame of a moving image,
I, B, and P pictures are used.

[0005] The pictures are classified into the following types according to the encoding method. (1) I picture (Intra-coded picture: INTRA coded picture) When coded, only closed information is used in one picture. In other words, when decoding, an image can be reconstructed using only the information of the I picture itself. Actually, DCT (Discrete Cosine Tr
ansform) and encode. Although this encoding method is generally inefficient, random access and high-speed reproduction can be achieved by decoding the I-picture only by putting it anywhere.
Further, if the I picture is decoded, stored in the memory, and read in the reverse direction, reverse reproduction can be performed. (2) P picture (Predictive-coded picture: forward predictive coded picture) A P picture is a predictive picture (a reference picture for taking a difference).
And the previously decoded I
Use a picture or P-picture. That is, the frame is predicted in one direction from the past. In practice, it is possible to select, on a macroblock-by-macroblock basis, whether to encode the difference from the motion-compensated predicted image or to encode without taking the difference (INTRA encoding). (3) B picture (Bidirectionally predictive-coded pi
cture: bidirectionally predicted coded image) A B picture is a temporally preceding I-picture or P-picture that is located earlier in time as a predicted image, an already-decoded I-picture or P-picture that is located later in time, And three types of interpolated images made from both.

The most efficient one of the three types of difference coding after motion compensation and INTRA coding can be selected for each macroblock. And in the GOP, B
In order to encode or decode a picture, an I picture or a P picture which is a temporally backward picture serving as a predicted picture must be coded first.
Requires a predetermined order for the I picture, the P picture, and the B picture.
The intervals between pictures are free and may vary within a GOP.

By the way, when the present invention is applied to an actual application including an encoded stream (bit string) of MPEG video or MPEG audio and other encoded streams, they are integrated into one including synchronization, and are integrated into one. It is necessary to convert the stream into a data format conforming to a unique physical format or protocol of a storage medium or a network.

[0008] In the MPEG2 system, a program stream (MPEG2-PS, PS: Program Stream) constituting a single program and a transport stream (MPEG2-TS, TS: Transport Stream).

The MPEG stream is a byte stream that has many 1-bit flags but is byte-aligned for each unit such as a header. As a structure common to the entire MPEG system, information indicating the length is placed before the data portion that is not fixed length, and when unnecessary, the portion is skipped, and the head of the next data group is checked and reliable. It has a data structure that enables highly-separable separation processing.

A device that receives a compressed video and audio signal in accordance with the MPEG2 encoding system is used to prevent video and audio data overflow and underflow on the decoding side. It is necessary to match the audio sampling frequency with the video, audio sampling frequency or STC (System Time Clock) on the decoding side.

For this reason, in the decoding apparatus, PCR (Program Clock Reference: Program Clock Reference Reference) or SCR (System Clock Reference) specified by the MPEG2 system standard (ISO / IEC standard 13818-1).
ce: system time reference value), the video and audio sampling frequencies on the encoding side and the video and audio sampling frequencies on the decoding side were matched.

FIG. 13 is a diagram showing an example of compressing a moving image by the MPEG method. In FIG. 13, a plurality of parallelograms represent frames constituting a moving image. FIG.
FIG. 13 shows a process of compressing the moving image of FIG.
(B) and FIG. 13 (c). In MPEG, several frames are collectively called a GOP. In FIG. 13B, video frames in GOP10 are classified into I frames, P frames, and B frames. The I frame indicates that the frame has been intra-coded, and the P frame indicates that the frame has been predictively coded forward from the I frame or forward. The B frame is between the I frame and the P frame or between the P frames, and is predictively coded from both directions of the I frame and the P frame. As an example, the directions of prediction in the P frame 11 and the B frame 12 are indicated by arrows. In MPEG, the frame order in FIG. 13B is changed as shown in FIG. 13C to create video encoded data.

Since P frames and B frames are predictively coded from I frames or video frames predicted and coded from I frames, to decode all video frames in a GOP, it is necessary to first decode from I frames. is there. In other words, when playing back a recorded moving image from the middle due to random access or the like, it is necessary to decode from an I frame.

In such a multimedia device employing the MPEG system, it is preferable to be able to perform so-called trick reproduction such as fast forward in addition to normal reproduction. In general, in fast-forwarding, only a few frames included in an MPEG stream are read and decoded and reproduced in many cases.

In particular, a technique of extracting only I frames and performing decoding and reproduction is often seen. At this time, it is necessary to specify the start position and the end position of the I frame. However, in the video stream compressed by MPEG, the code amount for each frame is not constant, and both the start position and the end position are unknown.
It is difficult to sequentially read only frame data to be displayed at high speed reproduction.

To achieve this object, Japanese Patent Application Laid-Open No. 7-12 / 1995
In the compressed image reproducing method described in Japanese Patent No. 3357, an MPEG stream of a compressed image that has been subjected to intra-frame encoding or inter-frame encoding is read out from a recording medium for each frame of image information, and the read MPEG stream is decoded. In a compressed image reproducing apparatus for reproducing image information,
After detecting the header of the first intra-frame encoded image data from the MPEG stream read from the recording medium, the first
The detection of the header of the inter-frame coded data immediately following the intra-frame coded image data determines that the reading of the first intra-frame coded data has been completed, and a new recording from the new recording position on the recording medium. The reading of the second and third intra-frame coded image data is repeated, and the appearance interval of the intra-frame coded image data in the previously read MPEG stream is measured. The intra-frame coded image is selectively reproduced by predicting the recording position of the image data on the recording medium.

[0017]

However, such a conventional compressed image reproducing method has the following problems. First, in order to specify the start position of the intra-frame encoded image data, if the detection is performed from the data read from the recording medium, the recording medium is accessed wastefully until the detection is performed, and the worst case is one GOP. It is not realistic because you have to check the data.
Next, to predict the interval of intra-frame encoded data,
Since it is necessary to change the prediction value according to the bit rate of the stream to be read, the configuration of the device becomes complicated.

To detect the start position of the next frame in order to specify the end position of the intra-frame coded data,
It is necessary to check for coded data in the frame.
Generally, since the intra-frame coded data has a larger data amount than other frames, the check range for detection becomes wide. Furthermore, if the stream is processed and only the intra-frame coded data is subsequently transferred,
Since the bit rate of the data to be transmitted is high, the decoder of the decoding device may not be able to keep up and the buffer may overflow. The present invention has been made in view of such a problem, and an object of the present invention is to provide a compressed image reproducing method that has a simple configuration of a device, and that can easily detect the end of a frame and control the transmission speed. .

[0019]

According to the present invention, there is provided a compressed image reproducing method comprising the steps of:
Alternatively, in the compressed image reproducing method for reading from a recording medium an MPEG stream of a compressed image in which a plurality of the frames are grouped into a frame group by inter-frame encoding, and decoding the read MPEG stream to reproduce image information, An index storing the position of the header of the frame group data in the MPEG stream on the recording medium is prepared, and when reading the MPEG stream from the recording medium, the data from the position of the header of the frame group data indicated by the index is read. It is characterized in that data is read from the MPEG stream to be read and continued until the header of the inter-frame coded data is detected and transferred to a device for decoding.

As a result, the G stream is converted from the MPEG stream.
The header detection process can be reduced by reading from the start position of the OP and transferring the data from the middle of the stream to the device that decodes the header of the next inter-frame coded data until the header is detected. Further, the header of the frame group data may be a sequence header code (SHC), and the header of the inter-frame coded data may be a picture start code (PSC). Further, preferably, the decoding device may decode only the first intra-frame encoded data.

According to the compressed image reproducing method of the present invention, the end of the extracted stream is added by adding a code indicating the end of the intra-frame encoded data to the end of the MPEG stream after detecting the header of the inter-frame encoded data. By processing, the end of the picture can be indicated to the decoding device.

According to the compressed image reproducing method of the present invention, a control code is added to the end of the MPEG stream read from the recording medium so that the extracted stream can be transferred to a decoding apparatus. When the code is inserted, it is possible to delay the transfer of the stream extracted thereafter, so that the stream can be transmitted without overflowing the buffer in the decoding device.

In the compressed image reproducing method according to the present invention, the control code is a control packet, and the control code is output as a packet, so that the stream is divided into fixed-length packets. Even in such a format, when a control code is inserted when transferring an extracted stream to a device that performs decoding, it is possible to delay the transfer of a stream that is subsequently extracted. Stream can be sent without overflowing the internal buffer.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. First, the basic concept of the present invention will be described. In the present invention, an index storing the position of a sequence header code (hereinafter, referred to as SHC) in a stream on a recording medium is prepared, and data is read from the position indicated by the index.

Next, it is necessary to detect the end position of the intra-frame coded data. However, the start position (picture start code: hereinafter, referred to as PSC) of the inter-frame coded data immediately after the intra-frame coded data is detected. If so, the detection range is widened and the processing load is high. Therefore, the present invention employs a method of detecting the PSC of the inter-frame coded data from the middle of the read data. This allows
Since the search range can be narrowed, the processing load can be reduced. Although the detected range may include a plurality of pictures, it can be dealt with by decoding and displaying only the first intra-frame encoded data by the decoding device. In addition, not only SHC in the index,
This can be dealt with by registering the PSC, but it is not preferable because the index capacity becomes large.

In the present invention, the end of the extracted stream is processed. In the extracted stream, the decoding device determines the end of the picture being decoded based on the start of the next picture or the input of a sequence end code (hereinafter referred to as SEC) indicating the end of the GOP. Therefore, a device that performs decoding cannot recognize the end of decoding by simply sending out one intra-frame encoded data, and cannot display it on a screen. In the present invention, a code indicating the end of a picture is added to the end of the extracted stream to indicate to the decoding device that the intra-frame coded data has ended. The code added to the end is an arbitrary code indicating the end of the picture, for example, SEC or the like. Further, in the present invention, by adding a control code to the end of the extracted stream, the interval between the extracted streams is controlled, and without overflowing the buffer of the decoding device, the intra-frame encoded data tail can be added. Send continuously.

First Embodiment In this embodiment, an MPEG stream is read from the start position of a GOP and transferred to a device that decodes data from the middle of the stream until the next interframe encoded data header is detected. To provide a compressed image reproducing method.

FIG. 1 is a block diagram showing a configuration of a compressed image reproducing method according to the first embodiment of the present invention based on the above basic concept. This embodiment is an example in which the present invention is applied to an apparatus for realizing a moving image reproducing method using a disk. In FIG. 1, a disk 1 (recording medium) for recording a compressed image such as an MPEG stream, an SHC index 2 indicating a position of a sequence header (SHC) of the stream in the disk 1 when the MPEG stream is recorded, A disk reading means 3 for reading a stream, a memory 4 for temporarily storing an MPEG stream read from the disk 1 by the disk reading means 3,
Picture start code (PS) from MPEG stream
C) a detecting means 5 for detecting, a transmitting means 6 for transmitting a TS packet to a decoding means 7, and a decoding means 7 for decoding an image stream and outputting it as video information.
And a reproduction control means 8 for managing and controlling the disk reading means 3, the header detecting means 5 and the sending means 6, respectively.

The operation of the above-structured compressed image reproducing method will be described below. FIG. 2 is a diagram showing an MPEG stream recorded on the disk 1.
(A) shows a conventional header position (B1) detection method,
FIG. 2B shows a method for detecting the header position (B2) according to the present embodiment. When cutting out only the intra-frame coded image, like the MPEG stream 31 in FIG.
It is necessary to search for the header position (B1) of the inter-frame coded image from the beginning (A1) of the intra-frame coded image, which is very burdensome.

Therefore, in the present embodiment, M in FIG.
Like the PEG stream 32, a position (A) that is appropriately shifted from the header detection position of the intra-frame encoded image data
From 2), the header position (B2) of the frame data is detected. Since the data amount of the inter-frame coded image is smaller than that of the intra-frame coded image, the load on the header detection is reduced.

In FIG. 1, first, the disk reading means 3
Receives an instruction from the control means 8 and outputs the SHC index 2
The reading of the recorded MPEG stream from the memory 4 to the memory 4 is started from the start position of the GOP.
The detecting means 5 detects a PSC from the middle of the MPEG stream read into the memory 4.

FIG. 3 shows the PSC from the MPEG stream.
9 is a flowchart showing a process for detecting the. In the figure,
S indicates a step in the flow. According to the flowchart of FIG. 3, the detection means 5 first sets the detection start position to α in step S11, determines whether or not the stream or the sequence ends in step S12. It is determined whether or not it has been detected. If the PSC is not detected, the detection start position α is incremented by +1 in step S14, and the process returns to step S12 to repeat the detection process until the PSC is detected.

At the end of the stream or sequence, or when a PSC is detected, the position detected in step S15 is sent to the control means 8 as a result, and the present flow ends. The control means 8 uses the detection means 5
When the PSC is detected from the EG stream, the transmission unit 6 is instructed to transmit the MPEG stream from the MPEG stream start position (A3) to the PSC detection position (B3) shown in FIG.

FIG. 4 shows that the transmitting means 6 and the decoding means 7
FIG. 2 is a diagram showing an MPEG stream transmitted to the. The section from A3 to B3 in the figure is transferred to the decoding means 7.
Returning to FIG. 1, the MPEG stream sent by the sending means 6 is decoded by the decoding means 7 and output as video information. At the same time when the sending instruction of the MPEG stream ends, the control means 8 instructs the disk reading means 3 to read the MPEG stream from a new position,
Thereafter, a similar operation is repeated.

As described above, the compressed image reproducing method according to the first embodiment prepares the SHC index 2 indicating the SHC position of the stream on the disk 1 when the MPEG stream is recorded, and converts the MPEG stream from the disk 1 At the time of reading, data from the position of SHC indicated by SHC index 2 is read, and thereafter, data is read and decoded from the continuous MPEG stream until the detection of the header of the inter-frame coded data.
From the stream read by the disk reading means 3, an MPEG stream including an intra-frame encoded image can be easily obtained.

Since the inter-frame coded image has a smaller amount of data than the intra-frame coded image, the MP
Since the number of processes in the PSC detection flowchart of FIG. 3 is reduced as compared with the case where PSCs are detected sequentially from the beginning of the EG stream, it is possible to reduce the PSC detection time. In the present embodiment, a sequence header (SHC) is used as an index as a header of a frame group, but GSC (Group Start Code: GOP start synchronization code) or PSC (Picture Start Code) may be used. .

Second Embodiment In this embodiment, a compressed image reproducing method capable of indicating the end of a picture to a decoding apparatus by processing the end of an extracted MPEG stream. Is provided.

FIG. 5 is a block diagram showing a configuration of a compressed image reproducing method according to the second embodiment of the present invention. In the description of the present embodiment, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description of the overlapping portions will be omitted. In FIG. 5, a tail processing means 9 for rewriting the tail of the cut-out MPEG stream and adding a code is added to the configuration of FIG. Hereinafter, the operation of the compressed image reproducing method configured as described above will be described.

When the MPEG stream is cut out during trick play such as fast forward and decoding is performed, the MPEG stream
The decoding means 7 cannot detect the end of the frame because it processes the MPEG stream such as cutting out the stream from the stream. Therefore, in the present embodiment, the end of the frame is notified to the decoding means by adding a code indicating the end of the stream to the end of the cut-out stream.

FIG. 6 is a view showing an MPEG stream obtained by processing the end obtained by the present embodiment. FIG.
In the figure, 41 is an MPEG stream obtained by the present compressed image reproducing method, and 42 is an MPEG stream obtained by rewriting the MPEG stream 41 at the end of the MPEG stream by the end processing means 9.

After the PSC detection by the PSC detection method described in the first embodiment, the MP obtained after the PSC detection is obtained.
The EG stream is processed by rewriting the end of the MPEG stream to a control code such as a sequence end code (SEC) by the end processing means 9 in FIG.
The reproduction control means 8 instructs the sending means 6 to send the processed stream.

When the decoding means 7 detects a control code from the transmitted MPEG stream, it switches the decoding process. As a result, the end of the frame is forcibly notified to the decoding unit 7, so that the decoding unit 7 does not fail to detect the end of the frame, and the malfunction due to the failure of the detection of the end of the frame can be prevented.

As described above, the compressed image reproducing method according to the second embodiment includes the tail processing means 9 for rewriting the tail of the cut-out MPEG stream and adding a code.
By adding a code indicating the end of the intra-frame coded data to the end of the MPEG stream, it is possible to reliably indicate the end of the picture to the decoding device. In the embodiment, SEC is described as an example of the code to be rewritten. However, any code that indicates the end of the frame can be used.

Third Embodiment According to the present embodiment, when a control code is inserted when transferring an extracted stream to a device that decodes the stream, the transfer of an extracted stream after that is delayed. Accordingly, the present invention provides a compressed image reproducing method capable of transmitting a stream without overflowing a buffer in a decoding device.

FIG. 7 is a block diagram showing a configuration of a compressed image reproducing method according to the third embodiment of the present invention. In the description of the present embodiment, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description of the overlapping portions will be omitted. 7, a control code adding means 10 for adding a control code to the end of the cut-out MPEG stream is added to the configuration of FIG. Hereinafter, the operation of the compressed image reproducing method configured as described above will be described.

When a stream is cut out and decoded for trick play such as fast-forwarding, an MPEG stream including the cut-out intra-frame coded image is sent to the decoding means. The number of intra-frame coded images is larger than in the state. For this reason, data loss occurs due to overflow of the bit buffer due to the bit rate becoming higher than what the decoding means assumes. Therefore, in the present embodiment, the sending means is controlled by adding a control code to the end of the cut-out stream, and the sending speed of the stream is adjusted.

FIG. 8 is a diagram showing an MPEG stream obtained by adding a control code to the end obtained according to the present embodiment. In FIG. 8, reference numeral 51 denotes an MPEG stream obtained by the compressed image reproducing method, and reference numeral 52 denotes an MP obtained by adding a control code to the end of the MPEG stream by the control code adding means 10 to the MPEG stream 51.
EG stream.

FIG. 9 is a flow chart showing an example of a transmission process using a control code, in which the transmission means 6 is controlled by the control code added to the MPEG stream by the control code addition means 10. After the PSC detection by the PSC detection method described in the first embodiment, the MPEG stream obtained after the PSC detection is processed by adding a control code to the end of the MPEG stream by the control code adding means 10 in FIG. The playback control means 8 instructs the sending means 6 to send the processed stream.

First, in step S21, the sending means 6 starts sending an MPEG stream according to a sending start command from the reproduction control means 8, and determines in step S22 whether a control code has been detected. If no control code is detected, an MPEG stream is sent to the decoder means 7 as normal processing until the control code is detected in step S23.

When the control code is detected from the transmitted MPEG stream, the transmission process is switched in step S24 to interrupt the transmission, and in step S25, a predetermined period of time is waited, and after the predetermined period has elapsed, the subsequent data is transmitted. As a result, the transmission speed of the MPEG stream to be transmitted can be controlled, so that data loss due to buffer overflow or the like during decoding processing can be prevented, and the reproduction control means 8 waits for the processing of the transmission means 6 to end. And another process can be performed.

Fourth Embodiment In the present embodiment, the control code is output as a packet, so that the stream is divided into fixed-length packets.
Even in a format such as a PEG2 transport stream, when a control code is inserted when transferring the extracted stream to a device that decodes the stream, it is possible to delay the transfer of the subsequently extracted stream. Another object of the present invention is to provide a compressed image reproducing method capable of transmitting a stream without overflowing a buffer in a decoding device.

FIG. 10 is a block diagram showing a configuration of a compressed image reproducing method according to the fourth embodiment of the present invention. In the description of the present embodiment, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description of the overlapping portions will be omitted. 10, a control packet adding means 11 for adding a control packet having the same length as the MPEG transport stream packet is added to the end of the cut-out MPEG2 transport stream in addition to the configuration of FIG. Hereinafter, the operation of the compressed image reproducing method configured as described above will be described.

In the case where the stream is an MPEG2 transport stream divided into fixed-length packets, it is preferable that the control code added to the end of the extracted stream is also a fixed-length packet. Therefore, in the present embodiment, the sending means is controlled by adding a control packet to the end of the cut-out stream, and the sending speed of the stream is adjusted.

FIG. 11 is a diagram showing an MPEG stream obtained by adding a control packet to the end obtained according to the present embodiment. In FIG. 11, reference numeral 61 denotes an MPEG stream obtained by the present compressed image reproducing method, and 62 denotes an MPE.
The control stream adding means 11 adds M
This is an MPEG stream obtained by adding a control packet to the end of the PEG stream.

FIG. 12 is a flow chart showing an example of a transmission process using a control packet.
1 shows an example in which the sending means 6 is controlled by the control code added to the MPEG stream by 1. First
After the PSC detection by the PSC detection method described in the embodiment, the MPEG stream obtained after the PSC detection is controlled by the control packet adding means 11 in FIG.
Processing is performed by adding a control packet to the end of the G stream, and the control unit 8 instructs the transmitting unit 6 to transmit the processed stream.

First, in step S31, the sending means 6 starts sending an MPEG stream in response to a sending start command from the reproduction control means 8, and determines in step S32 whether a control packet has been detected. If no control packet is detected, an MPEG stream is sent to the decoder means 7 as normal processing until a control code is detected in step S33. When a control packet is detected from the transmitted MPEG stream, the transmission processing 6 is switched in step S34, the control packet is extracted, and a null
Send out 1 packet.

In step S36, it is determined whether or not there is a Null packet transmission stop instruction from the reproduction control means 8.
If there is no Null packet transmission stop instruction, step S3
Returning to step 5, the transmission of Null packets is continued until a Null packet transmission stop instruction is received from the reproduction control means 8. When receiving the Null packet transmission stop instruction from the reproduction control unit 8, the process returns to step S32, and the transmission unit 6 returns to the normal processing. As a result, the transmission speed of the MPEG stream to be transmitted can be controlled, so that data loss due to buffer overflow or the like during the decoding process can be prevented.

Further, since the control code is in the form of a TS packet, it is possible to prevent a malfunction due to a packet synchronization error or the like. In the present embodiment, the null packet transmission switching of the transmission means is described as an example of the control packet to be added. However, other uses such as switching of decoding processing can be considered.

In each of the above embodiments, the MPEG2
Although the present invention is applied to a compressed image reproducing method for inputting and outputting video and audio signals in a system, the present invention is not limited to the MPEG system and can be applied to other compressed image reproducing devices. Also,
The data stream transferred from the disc may be of any format.

Also, in the present embodiment, the MPEG system can be implemented by, for example, a computer.
The present invention can be applied to all moving picture encoding devices based on the MPEG algorithm. For example, a dedicated machine having an externally provided MPEG decoder in addition to a workstation or a personal computer may be used as an environment required to implement this technique.

The type and recording method of the recording apparatus are not limited, and can be applied to all apparatuses. For example, as a recording device, in addition to an HDD, a DVD (Digital Video Disc)
Or a CD-R / RW or an MD (Mini Disc). In particular, if an HDD that has high data transfer speed and random access performance and allows high-speed access is used as a recording medium, it is possible to instantly search for a desired program from programs recorded for a long time and use it immediately. Become. Also,
A recording device other than the HDD such as a magneto-optical disk may be used, and the same effect can be obtained. Further, it goes without saying that the number and types of circuits and members constituting the compressed image reproducing method are not limited to the above-described embodiment.
It may be realized by software.

[0062]

As described above in detail, according to the present invention, it is possible to realize a compressed image reproducing method which has a simple structure of the apparatus and can easily detect the end of a frame and control the transmission speed. Specifically, the following effects can be obtained. According to the first to third aspects of the present invention, the header is read from the MPEG stream from the start position of the GOP, and transferred to a device that decodes data from the middle of the stream until the header of the next inter-frame coded data is detected. Detection processing can be reduced.

According to the fourth aspect of the present invention, by processing the end of the extracted stream, the end of the picture can be reliably indicated to the decoding apparatus. According to the fifth aspect of the present invention, when a control code is inserted when transferring an extracted stream to a device that decodes the stream, it is possible to delay the transfer of a stream that is subsequently extracted. The stream can be transmitted without overflowing the buffer in the device.

According to the sixth aspect of the present invention, the control code is output as a packet, so that the extracted stream is decoded even in a format such as an MPEG2 transport stream in which the stream is divided into fixed-length packets. When a control code is inserted during transfer to a device, it is possible to delay the transfer of a stream extracted afterward, so that the stream can be transmitted without overflowing the buffer in the device performing decoding. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a compressed image reproducing method according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an MPEG stream recorded on a disc according to the compressed image reproducing method of the present embodiment.

FIG. 3 is a flowchart illustrating a process of detecting a PSC from an MPEG stream in the compressed image reproducing method according to the present embodiment.

FIG. 4 is a diagram showing an MPEG stream transmitted from a transmitting unit to a decoding unit in the compressed image reproducing method according to the present embodiment.

FIG. 5 is a block diagram illustrating a configuration of a compressed image reproducing method according to a second embodiment of the present invention.

FIG. 6 is a diagram showing an MPEG stream obtained by processing the end obtained by the embodiment.

FIG. 7 is a block diagram illustrating a configuration of a compressed image reproducing method according to a third embodiment of the present invention.

FIG. 8 is a diagram showing an MPEG stream with a control code added to the end of the compressed image reproducing method according to the present embodiment.

FIG. 9 is a flowchart illustrating an example of transmission processing by a control code in the compressed image reproduction method according to the present embodiment.

FIG. 10 is a block diagram illustrating a configuration of a compressed image reproducing method according to a fourth embodiment of the present invention.

FIG. 11 is a diagram illustrating an MPEG stream in which a control packet is added to the end of the compressed image reproducing method according to the present embodiment.

FIG. 12 is a flowchart illustrating an example of a transmission process using a control packet in the compressed image reproduction method according to the present embodiment.

FIG. 13 shows MPEG of a compressed image reproducing method according to the present embodiment.
FIG. 3 is a diagram illustrating an example of compressing a moving image by a method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disk (recording medium) 2 SHC index 3 Disk reading means 4 Memory 5 Detecting means 6 Sending means 7 Decoding means 8 Control means 9 End processing means 10 Control code adding means 11 Control packet adding means

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kaoru Hishikawa 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Yukiki Shimizu 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka (72) Inventor Akio Ichikawa 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka F-term (reference) 5C053 FA23 FA27 GA11 GB06 GB08 GB37 HA33 KA04 5C059 KK31 KK35 MA04 MA05 MC24 PP05 PP07 RB02 RB09 RB15 RC09 SS11 UA34

Claims (6)

[Claims] 1. An MPEG stream of a compressed image in which a plurality of frames are grouped into a group of frames by reading intra-frame coding or inter-frame coding of image information on a frame basis from a recording medium.
In a compressed image reproduction method for decoding a G stream to reproduce image information, an index storing a position of a header of frame group data in an MPEG stream on the recording medium is prepared, and the MPEG stream is read from the recording medium. When reading, read the data from the position of the header of the frame group data indicated by the index, and read the data from the continuous MPEG stream until the header of the inter-frame coded data is detected,
A method for reproducing a compressed image, comprising: transferring the compressed image to a device that performs decoding. 2. A header of the frame group data is a sequence header code (SHC), and a header of the inter-frame coded data is a picture start code (PHC).
2. The compressed image reproducing method according to claim 1, wherein 3. The compressed image reproducing method according to claim 1, wherein the decoding device decodes only the first intra-frame encoded data. 4. The compressed image reproducing method according to claim 1, wherein a code indicating the end of the intra-frame encoded data is added to the end of the MPEG stream after detecting the header of the inter-frame encoded data. 5. The MP read from the recording medium
3. The compressed image reproducing method according to claim 1, wherein a control code is added to the end of the EG stream. 6. The compressed image reproducing method according to claim 5, wherein the control code is a control packet.