JP3648460B2 - Compressed image playback method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a compressed image reproduction method, and more particularly to a compressed image reproduction 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]
[Prior art]
Since video data has a very high data rate, it is difficult to record it on a disk medium such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory without processing the data. Therefore, a method is used in which video data and audio data are encoded with high efficiency to reduce the data rate to a rate that can be recorded on a disk medium without visual or auditory degradation.
[0003]
As an example of the high-efficiency encoding method, there is an MPEG (Moving Picture Experts Group) method.
The characteristics of MPEG are “Motion Compensation (MC)” that was not necessary for still image compression, random access of frames as a precondition for moving image compression, playback by fast forward and rewind playback. (Reverse direction) can be done.
[0004]
In MPEG, as described above, fast-forwarding, rewinding, and playback from the middle are basic, so that a GOP (Group of Pictures) is formed by grouping moving images of a certain unit, and independent for each unit. Playback is possible. As the prediction structure of the screen in the GOP, one picture (picture), I, B, and P picture each representing a moving picture frame is used.
[0005]
The pictures are classified into the following types according to the encoding method.
(1) I picture (Intra-coded picture)
When encoding, only the information that is closed in one image is used. In other words, when decoding, an image can be reconstructed using only the information of the I picture itself. Actually, encoding is performed by DCT (Discrete Cosine Transform) as it is without taking a difference from other images. This encoding method is generally inefficient, but random access and high-speed reproduction are possible if only this I picture is decoded with this in place. Further, reverse decoding can be performed by repeatedly decoding the I picture, storing it in the memory, and reading it in the reverse direction.
(2) P picture (Predictive-coded picture)
As the P picture, an I picture or P picture that has been positioned in time before input and has been decoded is used as a predicted picture (a picture that becomes a reference for obtaining a difference). That is, the frame is predicted from the past to the current one direction. Actually, it is possible to select the more efficient one of encoding the difference from the motion compensated predicted image or encoding without taking the difference (INTRA encoding) for each macroblock.
(3) B picture (Bidirectionally predictive-coded picture)
A B picture is an interpolation made from a previously predicted I picture or P picture that is temporally positioned as a predicted picture, an already decoded I picture or a P picture, and a previously decoded I picture or P picture. Use three types of images.
[0006]
Among the three types of motion-compensated difference encoding and INTRA encoding, the most efficient one can be selected for each macroblock.
In order to encode or decode a B picture in the GOP, the I picture or P picture that is behind in time that becomes the predicted image must be encoded first, so the GOP is configured. However, the I picture, the P picture, and the B picture need a predetermined order. However, the interval between the I pictures and the interval between the P pictures can be freely changed within the GOP.
[0007]
By the way, when an MPEG video or MPEG audio encoded stream (bit string) and other encoded streams are applied to an actual application, they are integrated and integrated into one stream including synchronization. Must be in a data format that conforms to a specific physical format or protocol possessed by storage media or networks.
[0008]
The MPEG2 system includes a program stream (MPEG2-PS, PS: Program Stream) that constitutes one program, and a transport stream (MPEG2-TS, TS: Transport Stream) that can constitute a plurality of programs, as in MPEG1. There is.
[0009]
The MPEG stream is a byte stream that is byte-aligned for each unit such as a header although there are many 1-bit flags. As a structure common to the entire MPEG system, the data portion that is not fixed length is preceded by information indicating the length. If unnecessary, that portion is skipped or the head of the next data group is confirmed and trusted. It has a data structure that enables highly-separated separation processing.
[0010]
An apparatus for receiving compressed video and audio signals in conformity with the MPEG2 encoding system is designed to receive video and audio sampling frequencies on the encoding side in order to prevent overflow and underflow of video and audio data on the decoding side. And the video, audio sampling frequency or STC (System Time Clock) on the decoding side must be matched.
[0011]
Therefore, the decoding apparatus uses PCR (Program Clock Reference) or SCR (System Clock Reference) defined by the MPEG2 system standard (ISO / IEC standard 13818-1). Thus, the video and audio sampling frequencies on the encoding side are matched with the video and audio sampling frequencies on the decoding side.
[0012]
FIG. 13 is a diagram illustrating an example in which a moving image is compressed by the MPEG method.
In FIG. 13, a plurality of parallelograms represent frames constituting a moving image. The process of compressing the moving picture of FIG. 13A by MPEG is shown in FIGS. 13B and 13C.
In MPEG, several frames are collectively called GOP. In FIG. 13B, video frames in the GOP 10 are classified into I frames, P frames, and B frames. The I frame indicates that intra-frame encoding has been performed, and the P frame indicates that forward encoding has been performed forward from the I frame, or forward prediction encoding has occurred from the P frame. The B frame is between the I frame and the P frame or between the P frames, and is predictively encoded from both directions of the I frame and the P frame. As an example, the prediction directions in the P frame 11 and the B frame 12 are indicated by arrows. In MPEG, the frame order shown in FIG. 13B is changed as shown in FIG. 13C to generate video encoded data.
[0013]
Since P frames and B frames are predictively encoded from I frames or video frames that are predictively encoded from I frames, in order to decode all video frames in a GOP, it is necessary to first decode from I frames. That is, when playing back a recorded moving image in the middle of random access or the like, it is necessary to decode from the I frame.
[0014]
In such a multimedia device adopting the MPEG system, it is preferable that so-called trick reproduction such as fast-forwarding can be performed in addition to normal reproduction. In general, in fast-forwarding, only a few frames included in an MPEG stream are often read and decoded and reproduced.
[0015]
In particular, a technique of extracting only I frames and performing decoding reproduction is often seen. At this time, it is necessary to specify the start position and the end position of the I frame. However, since the code amount of each frame of the MPEG compressed video stream is not constant and the start position and the end position are not known, it is displayed at high speed playback. It is difficult to read only frame data to be read one after another.
[0016]
In order to achieve this object, in the compressed image reproduction method described in Japanese Patent Laid-Open No. 7-123357, an MPEG stream of a compressed image obtained by intra-frame coding or inter-frame coding of image information in units of frames is recorded from a recording medium. In a compressed image reproducing apparatus that reads and decodes the read MPEG stream and reproduces image information, after detecting the header of the first intra-frame encoded image data from the MPEG stream read from the recording medium, It is determined that the reading of the first intra-frame encoded data is completed by detecting the header of the inter-frame encoded data immediately following the first intra-frame encoded image data from the MPEG stream, and the recording medium Of new second and third intra-frame encoded image data from the new recording position Is repeated, and the appearance interval of the intra-frame encoded image data in the MPEG stream read out in advance is measured to predict the recording position of the preceding and subsequent intra-frame encoded image data on the recording medium. Thus, the intra-frame encoded image is selectively reproduced.
[0017]
[Problems to be solved by the invention]
However, such a conventional compressed image reproduction method has the following problems. First, in order to identify the start position of intra-frame encoded image data, detection from the data read from the recording medium results in unnecessary access to the recording medium until detection, and the worst 1 GOP worth of data. Because it is necessary to check the data, it is not realistic. Next, in order to predict the interval between the intra-frame encoded data, it is necessary to change the prediction value according to the bit rate of the stream to be read, so that the configuration of the apparatus becomes complicated.
[0018]
In order to identify the end position of the intra-frame encoded data, it is necessary to check the intra-frame encoded data in order to detect the start position of the next frame. In general, since intra-frame encoded data has a larger data amount than other frames, the check range for detection is wide. Furthermore, if the stream is processed and only the intra-frame encoded data is transferred subsequently, the bit rate of the data to be transmitted increases, so that the decoder of the decoding device cannot keep up and the buffer may overflow.
The present invention has been made in view of such problems, and an object of the present invention is to provide a compressed image reproduction method in which the configuration of the apparatus is simple and the end of a frame is detected and the transmission speed is easily controlled. .
[0019]
[Means for Solving the Problems]
The compressed image reproduction method of the present invention reads image data from a recording medium and reads an MPEG stream of a compressed image in which a plurality of the frames are grouped into a frame group by intra-frame encoding or inter-frame encoding of image information in units of frames. In a compressed image reproduction method for reproducing image information by decoding an output MPEG stream, an index storing a header position of frame group data in the MPEG stream on the recording medium is prepared, and A device that reads and decodes data from the position of the header of the frame group data indicated by the index until the header of the inter-frame encoded data is detected from the continuous MPEG stream when reading the MPEG stream It is characterized by transferring to.
[0020]
Accordingly, header detection processing can be reduced by reading from the start position of the GOP from the MPEG stream and transferring the data from the middle of the stream until the header of the next inter-frame encoded data is detected. it can.
The header of the frame group data may be a sequence header code (SHC), and the header of the inter-frame encoded data may be a picture start code (PSC).
Preferably, the decoding device may decode only the first intra-frame encoded data.
[0021]
The compressed image reproduction method of the present invention processes the end of the extracted stream 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. Thus, the end of the picture can be shown to the decoding apparatus.
[0022]
The compressed image reproduction method of the present invention adds a control code to the end of the MPEG stream read from the recording medium, and inserts the control code when transferring the extracted stream to a decoding device. In this case, since it is possible to delay the transfer of the extracted stream thereafter, it is possible to send the stream without overflowing the buffer in the decoding apparatus.
[0023]
In the compressed image reproduction method of 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. In this case, when a control code is inserted when transferring the extracted stream to the decoding device, it is possible to delay the transfer of the extracted stream thereafter. Stream can be sent without overflowing.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a compressed image reproduction method of the present invention will be described in detail 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 from the position indicated by the index is read.
[0025]
Next, it is necessary to detect the end position of the intra-frame encoded data. However, if the start position of the inter-frame encoded data immediately after the intra-frame encoded data (picture start code: hereinafter referred to as PSC) is detected. The detection range becomes wide and the processing load is high. Therefore, in the present invention, a method for detecting the PSC of the inter-frame encoded data from the middle of the read data is adopted. Thereby, 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 a decoding apparatus. Note that it is possible to cope by registering not only SHC but also PSC in the index, but this is not preferable because the capacity of the index increases.
[0026]
In the present invention, the end of the extracted stream is processed. In an apparatus for decoding, the extracted stream is determined by the input of a start of the next picture or a sequence end code (hereinafter referred to as SEC) indicating the end of the GOP in the end of the picture being decoded. Therefore, a device that performs decoding cannot recognize the end of decoding only by sending out one intra-frame encoded data, and cannot display it on the screen. In the present invention, a code indicating the end of the picture is added to the end of the extracted stream to indicate to the decoding device that the end of the intra-frame encoded data. The code added to the end is an arbitrary code indicating the end of the picture, and examples thereof include SEC. 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 the intra-frame encoded data tail is added without overflowing the buffer of the decoding apparatus. Send continuously.
[0027]
First embodiment
The present embodiment provides a compressed image reproduction method for reading from an MPEG stream from the start position of a GOP and transferring the data from the middle of the stream until the header of the next inter-frame encoded data is detected to the decoding apparatus. It is.
[0028]
FIG. 1 is a block diagram showing a configuration of a compressed image reproduction method according to the first embodiment of the present invention based on the above basic concept. The present embodiment is an example applied to an apparatus for realizing a moving image reproduction method using a disc.
In FIG. 1, a disc 1 (recording medium) for recording a compressed image such as an MPEG stream, an SHC index 2 indicating the position of a sequence header (SHC) of the stream in the disc 1 when the MPEG stream is recorded, and an MPEG from the disc 1 Disc reading means 3 for reading a stream, a memory 4 for temporarily storing an MPEG stream read from the disc 1 by the disc reading means 3, a detecting means 5 for detecting a picture start code (PSC) from the MPEG stream, and a decoding Sending means 6 for sending TS packets to means 7, decoding means 7 for decoding an image stream and outputting it as video information, playback control for managing and controlling disc reading means 3, header detecting means 5 and sending means 6, respectively. And means 8.
[0029]
Hereinafter, the operation of the compressed image reproduction method configured as described above will be described.
FIG. 2 is a diagram showing an MPEG stream recorded on the disc 1, FIG. 2 (a) shows a conventional method for detecting the header position (B1), and FIG. 2 (b) shows the present embodiment. The detection method of a header position (B2) is shown.
When only the intra-frame encoded image is cut out, the header position (B1) of the inter-frame encoded image can be searched from the head (A1) of the intra-frame encoded image as in the MPEG stream 31 of FIG. Necessary and very expensive.
[0030]
Therefore, in the present embodiment, the frame data header position (B2) is shifted from the position (A2) appropriately shifted from the header detection position of the intra-frame encoded image data as in the MPEG stream 32 of FIG. Try to detect. Since the amount of data of the inter-frame encoded image is smaller than that of the intra-frame encoded image, the load on header detection is reduced.
[0031]
In FIG. 1, the disk reading means 3 first receives an instruction from the control means 8 and starts reading the MPEG stream recorded in the memory 4 from the start position of the GOP indicated by the SHC index 2. The detecting means 5 detects PSC from the middle of the MPEG stream read out to the memory 4.
[0032]
FIG. 3 is a flowchart showing processing for detecting PSC from an MPEG stream. In the figure, S indicates a flow step.
According to the flowchart of FIG. 3, the detection means 5 first sets the detection start position to α in step S11, determines in step S12 whether the stream or sequence ends, and if not the stream or sequence ends, the PSC is detected in step S13. It is determined whether or not it has been detected. If no PSC is 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 a PSC is detected.
[0033]
When the end of the stream or sequence is detected or the PSC is detected, the position detected in step S15 is sent to the control means 8 as a result, and this flow is ended.
When the detection means 5 detects the PSC from the MPEG stream, the control means 8 instructs the sending means 6 to send the MPEG stream from the MPEG stream start position (A3) to the PSC detection position (B3) shown in FIG. To do.
[0034]
FIG. 4 is a diagram showing an MPEG stream sent from the sending means 6 to the decoding means 7. The section from A3 to B3 in the figure is transferred to the decoding means 7.
Returning to FIG. 1, the MPEG stream sent out by the sending means 6 is decoded by the decoding means 7 and outputted as video information. Simultaneously with the completion of the MPEG stream transmission instruction, the control means 8 instructs the disk reading means 3 to read the MPEG stream from a new position, and thereafter the same operation is repeated.
[0035]
As described above, in the compressed image reproduction method of the first embodiment, when the MPEG stream is recorded, the SHC index 2 indicating the SHC position of the stream in the disk 1 is prepared and the MPEG stream is read from the disk 1. Since the data from the SHC position indicated by the SHC index 2 is read and thereafter the data is read and decoded from the continuing MPEG stream until the header of the inter-frame encoded data is detected. An MPEG stream including an intra-frame encoded image can be easily obtained from the output stream.
[0036]
Also, since the amount of data in the inter-frame encoded image is smaller than that in the intra-frame encoded image, the processing in the PSC detection flowchart of FIG. 3 is less than in the case where the PSC detection is performed sequentially from the beginning of the MPEG stream. Therefore, the PSC detection time can be shortened.
In this embodiment, a sequence header (SHC) is used as an index as a frame group header. However, GSC (Group Start Code) or PSC (Picture Start Code) may be used. .
[0037]
Second embodiment
The present embodiment provides a compressed image reproduction method that can indicate the end of a picture to an apparatus that performs decoding by processing the end of the extracted MPEG stream.
[0038]
FIG. 5 is a block diagram showing a configuration of a compressed image reproduction method according to the second embodiment of the present invention. In the description of the present embodiment, the same components as those in FIG.
In FIG. 5, tail processing means 9 for rewriting the tail of the cut out MPEG stream and adding a code is added to the structure of FIG.
Hereinafter, the operation of the compressed image reproduction method configured as described above will be described.
[0039]
When the MPEG stream is cut out and decoded during trick play such as fast-forwarding, the decoding means 7 cannot detect the end of the frame because the MPEG stream is processed such as cutting out the stream from the MPEG stream. Therefore, in this embodiment, the end of the frame is notified to the decoding means by adding a code notifying the end of the stream to the end of the extracted stream.
[0040]
FIG. 6 is a diagram showing an MPEG stream obtained by processing the end obtained by the present embodiment.
In FIG. 6, reference numeral 41 denotes an MPEG stream obtained by the present compressed image reproduction method, and reference numeral 42 denotes an MPEG stream obtained by rewriting the end of the MPEG stream 41 by the tail processing means 9.
[0041]
After the PSC detection by the PSC detection method described in the first embodiment, the end of the MPEG stream is controlled by the end processing means 9 in FIG. 5 for the MPEG stream obtained after the PSC detection, such as a sequence end code (SEC). The reproduction control means 8 instructs the sending means 6 to send out the processed stream.
[0042]
When the decoding means 7 detects the 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 means 7, so that the decoding means 7 does not fail to detect the end of the frame, and it is possible to prevent malfunction due to failure in detecting the end of the frame.
[0043]
As described above, the compressed image reproduction method according to the second embodiment includes the tail processing means 9 that rewrites the end of the extracted MPEG stream and adds a code, and ends the intra-frame encoded data at the end of the MPEG stream. By adding a code representing, it is possible to reliably indicate the end of the picture to the decoding apparatus.
In the embodiment, SEC is given as an example of the code to be rewritten, but any code may be used as long as it indicates the end of the frame.
[0044]
Third embodiment
In this embodiment, when a control code is inserted when transferring to an apparatus that decodes the extracted stream, the transfer of the extracted stream can be delayed, so that the apparatus that performs decoding is used. It is an object of the present invention to provide a compressed image reproduction method capable of sending a stream without overflowing the internal buffer.
[0045]
FIG. 7 is a block diagram showing a configuration of a compressed image reproduction method according to the third embodiment of the present invention. In the description of the present embodiment, the same components as those in FIG.
In FIG. 7, control code adding means 10 for adding a control code to the end of the extracted MPEG stream is added to the configuration of FIG.
Hereinafter, the operation of the compressed image reproduction method configured as described above will be described.
[0046]
When a stream is extracted and decoded during trick play such as fast-forwarding, an MPEG stream including the extracted intra-frame encoded image is sent to the decoding means. The number of inner encoded images increases. For this reason, data loss due to overflow of the bit buffer or the like due to the bit rate becoming larger than that assumed by the decoding means occurs. Therefore, in the present embodiment, the sending means is controlled by adding a control code to the end of the cut out stream to adjust the sending speed of the stream.
[0047]
FIG. 8 is a diagram showing an MPEG stream obtained by adding a control code to the end obtained by the present embodiment.
In FIG. 8, 51 is an MPEG stream obtained by this compressed image reproduction method, and 52 is an MPEG stream 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.
[0048]
FIG. 9 is a flowchart showing an example of transmission processing using a control code, and shows an example 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 reproduction control means 8 instructs the sending means 6 to send the processed stream.
[0049]
First, in step S21, the sending means 6 starts sending an MPEG stream by a sending start command from the reproduction control means 8, and determines whether or not a control code is detected in step S22. If no control code is detected, the MPEG stream is sent to the decoder means 7 as normal processing until the control code is detected in step S23.
[0050]
When a control code is detected from the MPEG stream to be sent, the sending process is switched in step S24, the sending is interrupted, a waiting period is set in step S25, and the subsequent data is sent after the elapse of the given period.
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, and the reproduction control means 8 waits for the processing of the sending means 6 to end. And another process can be performed.
[0051]
Fourth embodiment
In this embodiment, the control code is output as a packet so that the stream is transferred to a device that decodes the extracted stream even in a format such as an MPEG2 transport stream in which the stream is divided into fixed-length packets. In addition, when a control code is inserted, it is possible to delay the transfer of the extracted stream thereafter, and thus a compressed image reproduction method capable of sending a stream without overflowing the buffer in the decoding apparatus is provided. Is.
[0052]
FIG. 10 is a block diagram showing a configuration of a compressed image reproduction method according to the fourth embodiment of the present invention. In the description of the present embodiment, the same components as those in FIG.
In FIG. 10, 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 extracted MPEG2 transport stream in the configuration of FIG.
Hereinafter, the operation of the compressed image reproduction method configured as described above will be described.
[0053]
In the case of an MPEG2 transport stream in which the stream is divided into fixed-length packets, it is desirable that the control code added to the end of the extracted stream is also a fixed-length packet. Therefore, in this embodiment, the sending means is controlled by adding a control packet to the end of the cut out stream to adjust the sending speed of the stream.
[0054]
FIG. 11 is a diagram showing an MPEG stream obtained by adding a control packet to the end obtained by the present embodiment.
In FIG. 11, 61 is an MPEG stream obtained by this compressed image reproduction method, and 62 is an MPEG stream obtained by adding a control packet to the end of the MPEG stream by the control packet adding means 11 to the MPEG stream 61.
[0055]
FIG. 12 is a flowchart showing an example of transmission processing using a control packet, and shows an example in which the transmission means 6 is controlled by the control code added to the MPEG stream by the control code addition means 11.
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 packet to the end of the MPEG stream by the control packet adding means 11 in FIG. The control means 8 instructs the sending means 6 to send the processed stream.
[0056]
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 whether or not a control packet has been detected in step S32. If no control packet is detected, the 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 process 6 is switched in step S34, the control packet is extracted, and a null packet is transmitted in step S35.
[0057]
In step S36, it is determined whether or not there is a Null packet transmission stop instruction from the reproduction control means 8, and if there is no Null packet transmission stop instruction, the process returns to step S35 until a Null packet transmission stop instruction is received from the reproduction control means 8. Continue sending packets. When a Null packet transmission stop instruction is received from the reproduction control means 8, the process returns to step S32 and the transmission means 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 decoding processing can be prevented.
[0058]
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, Null packet transmission switching of the transmission means is given as an example of the control packet to be added, but other uses such as switching of decoding processing are also conceivable.
[0059]
In each of the above-described embodiments, the present invention is applied to the compressed image reproduction method for inputting and outputting video and audio signals in the MPEG2 system. However, the present invention is not limited to the MPEG system and can be applied to other compressed image reproduction apparatuses. Further, the data stream transferred from the disk may be in any format.
[0060]
Further, in this embodiment, the MPEG system can be applied to all moving image encoding apparatuses based on the MPEG algorithm, which can be performed by, for example, a computer main body. For example, a workstation required as an environment necessary to realize this technique In addition to a personal computer, a dedicated machine with an external MPEG decoder may be used.
[0061]
Further, the type of recording apparatus, the recording method, and the like are not limited and can be applied to all apparatuses. For example, as a recording device, a recording device such as a DVD (Digital Video Disc), a CD-R / RW, or an MD (Mini Disc) in addition to the HDD may be used. In particular, if an HDD with high data transfer speed and random access performance and high-speed access is used as a recording medium, a desired program can be instantly retrieved from programs recorded for a long time and used immediately. Become. A recording device other than the HDD such as a magneto-optical disk may be used, and the same effect can be obtained.
Furthermore, it goes without saying that the number and types of circuits and members constituting the compressed image reproduction method are not limited to the above-described embodiments, and may be realized by software.
[0062]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to realize a compressed image reproduction method that has a simple device configuration and that can easily detect the end of a frame and control the sending 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 for decoding data from the middle of the stream until the header of the next interframe encoded data is detected. Detection processing can be reduced.
[0063]
In the invention according to claim 4, by processing the end of the extracted stream, it is possible to reliably indicate to the decoding apparatus that the end of the picture is reached.
According to the fifth aspect of the present invention, when the control code is inserted when transferring to the device that decodes the extracted stream, it is possible to delay the transfer of the extracted stream thereafter. The stream can be sent without overflowing the buffer in the device to be performed.
[0064]
According to the sixth aspect of the present invention, by outputting the control code as a packet, the stream is transferred to a device that decodes the extracted stream even in a format such as an MPEG2 transport stream in which the stream is divided into fixed-length packets. In this case, when the control 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 apparatus.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a compressed image reproduction method according to a first embodiment of the present invention.
FIG. 2 is a diagram showing an MPEG stream recorded on a disc of the compressed image reproduction method of the present embodiment.
FIG. 3 is a flowchart showing processing for detecting PSC from an MPEG stream in the compressed image reproduction method according to the present embodiment;
FIG. 4 is a diagram showing an MPEG stream sent from the sending means to the decoding means in the compressed image reproduction method of the present embodiment.
FIG. 5 is a block diagram showing a configuration of a compressed image reproduction 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 present embodiment.
FIG. 7 is a block diagram showing a configuration of a compressed image reproduction method according to a third embodiment of the present invention.
FIG. 8 is a diagram showing an MPEG stream in which a control code is added to the end of the compressed image reproduction method of the present embodiment.
FIG. 9 is a flowchart illustrating an example of transmission processing using a control code in the compressed image reproduction method according to the present embodiment;
FIG. 10 is a block diagram showing a configuration of a compressed image reproduction 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 reproduction method according to the present embodiment.
FIG. 12 is a flowchart illustrating an example of transmission processing using a control packet in the compressed image reproduction method according to the present embodiment;
FIG. 13 is a diagram illustrating an example in which a moving image is compressed by the MPEG method of the compressed image reproduction method of the present embodiment.
[Explanation of symbols]
1 disc (recording medium)
2 SHC index
3 Disc reading means
4 memory
5 Detection means
6 Sending means
7 Decoding means
8 Control means
9 Finishing means
10 Control code adding means
11 Control packet addition means

Claims (6)

Image information is encoded in units of frames, intra-frame encoded, or inter-frame encoded, and a plurality of frames are grouped into a frame group to read a compressed image MPEG stream from a recording medium, and the read MPEG stream is decoded. In a compressed image reproduction method for reproducing image information,
Prepare an index storing the position of the header of the frame group data in the MPEG stream on the recording medium,
When reading the MPEG stream from the recording medium, read data from a position shifted by a predetermined amount from the header position of the frame group data indicated by the index,
A compressed image reproduction method, comprising: reading data from the continuing MPEG stream until detecting a header of interframe encoded data and transferring the data to a decoding device. The compressed image reproduction method according to claim 1, wherein the header of the frame group data is a sequence header code (SHC), and the header of the inter-frame encoded data is a picture start code (PSC). 2. The compressed image reproduction method according to claim 1, wherein the decoding apparatus decodes only the first intra-frame encoded data. 2. The compressed image reproduction 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 the header of the inter-frame encoded data is detected. 3. The compressed image reproduction method according to claim 1, wherein a control code is added to the end of the MPEG stream read from the recording medium. 6. The compressed image reproduction method according to claim 5, wherein the control code is a control packet.

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