JP2001157206A - Image recording method and image decoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image decoder that decodes stored in a recording medium without the need for external data read rate control from the recording medium while realizing quick restoration to a correct decoding start time even when start of decoding is delayed. SOLUTION: A table that a DTS extracted by a DTS extract means 103, an ID issued by each picture from an ID addition means 104 is related to an address of an input buffer 105 storing a head of a picture is created in a DTS, ID, storage address storage memory 106. Utilizing this table can realize quick restoration at a correct decoding start time even when start of decoding is delayed. Then an input control means 112 monitors residual capacity information fed from the input buffer 105 and a residual capacity of the DTS, ID, storage address storage memory and controls reading of image data from a recording medium 113 so that both of the residual capacities are not zero.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image decoding method and an image decoding apparatus for decoding data such as MPEG in which decoding start time information is added to data obtained by encoding a video.
In particular, the present invention relates to an image decoding method and an image decoding device for reading and decoding data recorded on a recording medium.

[0002]

2. Description of the Related Art Japanese Patent Laid-Open Publication No.
No. 16532. This is decoding start time information (hereinafter, referred to as
DTS) is written in the reception buffer together with the encoded image data, and control is easily performed based on the DTS read from the reception buffer when decoding in frame units is started.

That is, before starting decoding, the DTS at the beginning of the frame is compared with a reference time (hereinafter referred to as STC) held by the decoder, and the STC is set to DTS.
Is controlled after reading the data and decoding is started.

Further, in such a conventional system, since all information necessary for decoding is stored in a receiving buffer, when data is reproduced from a recording medium such as an HDD, the data read rate from the recording medium is externally read. Even without performing the above control, the data can be decoded without any problem by reading the data from the recording medium and writing the data in the reception buffer so as not to overflow, by checking the remaining amount of the reception buffer.

However, there is an error in the coded data input to the decoder when it is being broadcast or when it is reproduced from a recording medium, so that the decoder does not perform the decoding operation properly and the start of decoding is delayed. There are cases where it rolls. Once the decoding start time is delayed, the data written together with the DTS is read from the receiving buffer with a delay, and even if the next image is decoded by comparing the DTS and the STC, the decoding is always delayed and the normal decoding operation is continued. There is a problem that it is difficult to return to the normal decoding operation, or it takes time to return to the normal decoding operation. If the decoding start is delayed, data in the receiving buffer may overflow.

[0006]

As described above, in the above-mentioned conventional method, once the start of the decoding operation is delayed for some reason, it is difficult to return to the correct decoding start time. There was a problem that the receiving buffer might overflow.

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and realizes an external data reading rate from a recording medium while realizing quick recovery at a correct decoding start time even if decoding start is delayed. It is an object of the present invention to provide an image decoding method and an image decoding device that perform an operation of decoding data stored in a recording medium without performing control.

[0008]

(Solution) A bit stream including encoded image data is input, a clock is reproduced based on a clock reference included in the image data, and an STC counter is operated. In the image decoding apparatus which decodes the image data based on the value of the STC counter and the decoding start time information included in the image data,
D, means for extracting the decoding start time information from the image data, means for extracting decoding start time information, buffer means for holding the image data, the ID for each added image, and the extracted decoding. Memory means for holding the start time information in association with the storage address of the image data on the buffer means; and comparing means for comparing the value of the STC counter with the decoding start time information held in the memory means. Determining whether decoding should be started based on the result of the comparison, and when decoding should be started, obtaining the ID associated with the decoding start time information; Decoding means for reading and decoding the image data from a storage address on the buffer means, and a bit stream obtained from a recording medium In decoding, characterized by comprising a control means for controlling the reading of the bit stream from the recording medium using the remaining amount of the remaining amount and said memory means of said buffer means.

(Solution) A bit stream including coded image data is input, and a clock is reproduced based on a clock reference included in the image data.
In an image decoding method for operating the STC counter to count the clock and decoding the image data based on the value of the STC counter and decoding start time information included in the image data, an ID is added to each image. First
A second step of extracting the decoding start time information from the image data, a third step of storing the image data in a buffer means, the ID of each added image and the extracted decoding A fourth step of associating start time information with a storage address of the image data on the buffer means and holding the same in a memory means;
A fifth step of comparing the value of the C counter with the decoding start time information held in the memory means, and determining whether to start decoding based on the result of the comparison, When to start, obtain the ID associated with the decoding start time information,
A sixth step of reading and decoding the image data from a storage address on the buffer means associated with the buffer means; and a step of decoding the bit stream obtained from a recording medium and the remaining capacity of the buffer means and the memory means. And controlling the reading of the bit stream from the recording medium using the remaining amount of the bit stream.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of an image decoding device according to the present invention.

The data input from 101 is MPEG
This is a terminal to which image data or the like encoded by an encoding method such as is input.

From the input data, a PCR (program clock reference) (or SCR (system clock reference)) as a clock reference is extracted by a PCR (SCR) extracting means 102, and decoding start time information (DCR) is extracted by a DTS extracting means 103. Hereinafter, it is called DTS.)
Is extracted, the picture header is detected by the ID adding means 104, an ID is added for each picture, and the picture header is stored in the input buffer 105.

Here, PCR (SCR) extraction means 102
PCR (or SCR) extracted by STC (sy
(time time clock) counter 107 and is used for generating the STC.

In the DTS, ID, storage address holding memory (table) 106, as shown in FIG.
The DTS extracted by the S extracting unit 103, the ID issued for each picture by the ID adding unit 104, and the address of the input buffer 105 storing the head of the picture are held in association with each other. Note that the ID added for each picture may be replaced by position information on the storage address holding memory (table) 106.

The comparing means 108 compares the DTS information held in the table of the DTS, ID and storage address holding memory 106 with the count value of the STC 107 counter to determine whether there is image data to start decoding. Is confirmed, and if it exists, the ID of the picture to be decoded is sent to the decoding control means 109.

In the decoding control means 109, the transmitted I
DT is the address where the picture corresponding to D is stored.
The data is read from the S, ID, storage address holding memory 106, and the decoder 110 is given a read position of image data to be decoded and a decoding start instruction. The decoder 110
The image data is sequentially read from the designated address in the input buffer 105 and decoded.

The image data input to 101 is not the image data transmitted by broadcasting, but rather the image data (including PCR (or SCR) and DTS) once stored in a recording medium such as an HDD, and is read out. When inputting to the image decoding apparatus without rate control using the PCR (or SCR) information added to the image data, input control for appropriately stopping input of image data is required.

In the input control method of the present invention, information for decoding input image data is stored separately in the input buffer 105 and the DTS, ID, and storage address holding memory 106. Input control must be performed so that the storage area does not overflow.

Therefore, the input control means 112 monitors the remaining capacity of the input buffer sent from the input buffer 105 and the remaining capacity of this memory sent from the DTS, ID and storage address holding memory 106. Remaining capacity
By controlling the reading of the image data from the recording medium 113 (HDD or the like) so as not to become 0, the data held in the recording medium 113 can be decoded without having a means for externally controlling the rate.

FIGS. 3 (a) to 3 (c) show flowcharts of respective routines when the apparatus according to the present invention is controlled by software processing.

These are (a) DTS, ID,
FIG. 6 shows a flowchart of a table creation routine created in the storage address holding memory 106, (b) a flowchart of a decode control routine, and (c) a flowchart of an input control routine for reading data stored in a recording medium. In the above example, D
Although the TS and the address on the input buffer 105 are managed, when the DTS and the address on the input buffer 105 are clearly associated with each other, the ID is unnecessary.

[0022]

As described above, according to the present invention, D
By changing the TS management method and generating a table separately from the input buffer to manage the DTS, it is possible to quickly restore the correct decoding start time even if the decoding start is delayed.
The decoding operation of the image data held in the recording medium such as the HDD can be appropriately performed without controlling the data reading rate from the external recording medium.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an image decoding device according to the present invention.

FIG. 2 is a DTS, ID, storage address holding memory 106;
FIG. 6 is a diagram for explaining the contents of a table stored in the table.

FIG. 3 is a flowchart illustrating an image decoding method according to the present invention.

[Explanation of symbols]

102 ·· PCR (SCR) extraction means, 103 · DT
S extraction means, 104 ID addition means, 105 input buffer, 106 DTS, ID, storage address holding memory (table), 107 STC counter, 10
8 ··· Comparison means, 109 ·· Decoding control means, 110 ···
Decoder, 112... Input control means.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C053 FA23 FA27 GB06 GB08 GB37 JA21 JA24 KA04 KA05 KA19 KA24 5C059 KK35 MA00 RB01 RB14 RC22 SS12 TA73 TB04 TC15 TD12 UA05 UA32 UA38

Claims (2)

[Claims] 1. A bit stream including encoded image data is input, a clock is reproduced based on a clock reference included in the image data, and an STC counter is operated to count the clock. S
An image decoding device for decoding the image data based on a value of a TC counter and decoding start time information included in the image data; a means for adding an ID for each image; Decoding start time information extracting means for extracting information; buffer means for holding the image data; and storing the ID of each added image, the extracted decoding start time information, and the storage address of the image data on the buffer means. Memory means for associating and holding; comparing means for comparing the value of the STC counter with the decoding start time information held in the memory means; whether decoding should be started based on the result of the comparison When decoding is to be started, the ID associated with the decoding start time information is obtained, and the ID is associated with this ID. Decoding means for reading and decoding the image data from a storage address on the buffer means, and decoding a bit stream obtained from a recording medium, the remaining capacity of the buffer means and the remaining capacity of the memory means. Control means for controlling reading of the bit stream from the recording medium by using the image decoding apparatus. 2. A bit stream including encoded image data is input, a clock is reproduced based on a clock reference included in the image data, and an STC counter is operated to count the clock. S
In an image decoding method for decoding the image data based on a value of a TC counter and decoding start time information included in the image data, a first step of adding an ID for each image; A second step of extracting decoding start time information; a third step of storing the image data in a buffer unit; the ID of each added image, the extracted decoding start time information, and the buffer of the image data. A fourth step of associating a storage address on the means and holding the same in the memory means; a fifth step of comparing the value of the STC counter with the decoding start time information held in the memory means; Based on the result, it is determined whether or not to start decoding, and when decoding should be started, the decoding is associated with the decoding start time information. A sixth step of obtaining the ID, reading the image data from a storage address on the buffer means associated with the ID, and decoding the image data; and decoding the bit stream obtained from a recording medium. A seventh step of controlling reading of the bit stream from the recording medium using the remaining amount of the memory means and the remaining amount of the memory means.