KR100336501B1 - A method and decoder for synchronizing textual data to MPEG-1 multimedia streams - Google Patents

Abstract

The present invention relates to a method of synchronizing additional text data in an MPEG-1 multimedia stream and to an MPEG-1 decoder supporting the same. The present invention divides text data into slides, which are units of synchronization, gives each slide a time stamp indicating the time at which the slide should be played, and then encodes each slide in a predetermined bit format (slide frame). The new MPEG-synchronized text is formed by forming individual bit strings of text, packetizing the slide bit strings, and inserting each packet at a predetermined position in the existing MPEG-1 system bit strings according to the playback time stamp of the slides contained in the packet. Synchronize text data into existing MPEG-1 multimedia streams by generating a system bit stream. In addition, the text-synchronized new MPEG-1 system stream is decoded by an MPEG-1 decoder supporting text synchronization including a text decoder and a text buffer. The present invention can economically and efficiently synchronize text data by multiplexing text onto an MPEG-1 multimedia stream in which audio and video are already synchronized. In addition, text data is merged and present in the MPEG-1 system stream, thereby making it easy to maintain the stream. In addition, since the multiplexing method complies with the MPEG-1 standard, it has the advantage of being perfectly reproduced by the existing MPEG-1 player except the synchronized text.

Description

A method and decoder for synchronizing textual data to MPEG-1 multimedia streams}

The present invention relates to a method of synchronizing additional text data in an MPEG-1 multimedia bit stream and to an MPEG-1 decoder supporting the same.

MPEG-1 is an international standard for the compression and representation of digital audio and video information. It is used to encode and decode the elementary streams of audio (ISO / IEC 11172-3) and video (ISO / IEC 11172-2). In addition to the definition, the system stream (ISO / IEC 11172-1) is defined by multiplexing individual streams.

The MPEG-1 system bit stream adopts a packet multiplexing scheme which is frequently used in time division multiplexing. In the packet-based multiplexing scheme, for example, when video and audio are multiplexed, the video and audio individual streams are divided into bitstreams of appropriate lengths called packets, and multiplexed with additional information such as headers. The header of each packet is appended with information for identifying whether the packet is video or audio.

In particular, in MPEG-1, bit streams are efficiently transmitted by grouping packets into units called packs. 1 shows the structure of a system bit string defined in MPEG-1 (ISO / IEC 11172-1).

MPEG-1 uses time stamps for synchronization between individual streams. That is, time information called a time stamp indicating when to decode and when to reproduce is added to each access unit, which is a unit of decoding and reproduction of an individual stream.

In particular, in MPEG video, since a sequence of bit streams is special, two types of time stamps are used: presentation time stamps (PTS), which are reproduction time information, and decoding time stamps, DTS, which are decoding time information. . PTS is time management information of reproduction output and DTS is decoding time management information. For reference, the video access unit is a picture and the audio access unit is a frame.

The timestamp value represents a 33-bit length that is measured with a clock of 90 kHz. The timestamp is compared to a clock in a decoder called a system time clock, which uses a system clock reference (SCR) to set this clock to a value intended by the encoder. The SCR is sent to the pack header of the system bit stream and is given a clock of 90 kHz, like a timestamp (see Figure 1).

MPEG-1 defines how audio and video individual bit strings are synchronized and forms of bit strings for multiplexing, but textual information that can be attached to audio and video, e.g., lecture materials such as slides for lecture videos, movie videos In the case of the dialogue caption display, and the music video does not support the form or the synchronization method for the lyrics display.

However, as MPEG-based multimedia applications increase and their fields become wider, synchronization of text information as well as audio and video becomes important.

Accordingly, there is a need for a text data synchronization method that satisfies the multiplexing and synchronization framework defined in MPEG-1.

An object of the present invention devised by the above-described request is to provide a method of synchronizing text data into an MPEG-1 multimedia stream that satisfies the multiplexing and synchronization framework defined in MPEG-1.

Another object of the present invention is to provide a decoder capable of decoding text data synchronized with an MPEG-1 multimedia stream.

1 is a structure and format diagram of an MPEG-1 system bit string

2 is a structure and form diagram of a slide frame and a text bit string

3 is a main flowchart showing an MPEG-1 multiplexing process according to the present invention.

4 is a sub-flow diagram for MPEG-1 end code processing in the multiplexing process of FIG.

FIG. 5 is a sub-flow diagram for pack header processing in the multiplexing process of FIG.

6 is a sub-flow diagram for processing a system header in the multiplexing process of FIG.

7 is a sub-flow diagram for packet processing in the multiplexing process of FIG.

8 is a sub-flow diagram for processing residual MPEG-1 bit stream in the multiplexing process of FIG.

9 is an exemplary diagram for explaining an MPEG-1 multiplexing process according to the present invention.

10 is a block diagram of an MPEG-1 decoder supporting text synchronization according to the present invention

The text data synchronization method of the present invention for achieving the above object is not to generate MPEG-1 system bit stream by multiplexing MPEG-1 audio and video individual bit streams and text data, but nondestructive to existing MPEG-1 system bit stream. This feature is characterized by generating new MPEG-1 system bit stream by multiplexing text data. That is, the existing MPEG-1 player which does not support the text-synchronized MPEG-1 system bit stream of the present invention is implemented to be able to reproduce except text data.

To this end, the present invention divides the text data into slides, which are units of synchronization, gives each slide a timestamp indicating the time at which the slide should be played, and then encodes each slide in a predetermined bit form (slide frame). After forming an individual bit string of text 1, packetize the slide bit string of the text material and insert each packet at a predetermined position of the existing MPEG-1 system bit string according to the playback time information (PTS) of the slide included in the packet. By synchronizing the text data with the existing MPEG-1 multimedia stream, we create a new MPEG-1 system bit stream.

In addition, the MPEG-1 decoder of the present invention that supports text synchronization includes a text decoder and a text buffer to decode the text-synchronized MPEG-1 system bit string.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

To synchronize text data in an MPEG-1 multimedia stream, it is necessary to (1) define the format of the text bit stream, (2) multiplex the text bit stream and the MPEG-1 bit stream, and (3) decode the new MPEG-1 bit stream with the text data synchronized. The method should be defined.

This is explained in order.

In the present invention, text synchronization is performed on a slide basis. A slide is a unit in which text is scattered on a screen and generally corresponds to one screen. Thus, the slide is the access unit and playback unit of the bit string. The size of the slide may be at least 1 byte and at most 2 ¹³ bytes, and slides of different sizes may exist in the same text bit string.

2 shows the format of a text bit string comprised of slides.

As shown in the figure, the main components of a slide include slide start code prefix, slide length, presentation time stamps (PTS), slide data, and ancillary. data).

First the slide start code indicates the start of the slide. The area of one slide in the text bit string is from the start code to the bit just before the next start code. The slide length is a field indicating the size of the slide and indicates the length from the next bit to the slide material. Slide length must be byte-aligned.

The reproduction time information is a clock of 90 kHz frequency represented by 33 bits as the synchronization information of the slide. The structure and meaning are the same as in the MPEG-1 system bit string (see ISO / IEC 11172-1 bit string format in FIG. 1). That is, it indicates that the slide should be played at the PTS time. The slide data portion is text data attached to the MPEG-1 stream. In general, the amount is negligible compared to audio and video, so no special encoding or compression is required, and the byte must be aligned.

Finally, ancillary data is additional data that can be attached to a slide. There is no limit on length, but it must be byte aligned. Additional data are not included in the slide length. Therefore, the interval of additional data is from the next bit indicated by the slide length to the bit just before the next slide start code. For reference, additional information may be attached to the slide, such as the title and author. It can also be used for future expansion of the slide format.

The multiplexing process of the MPEG-1 bit string and the text bit string will be described.

The multiplexing of the MPEG-1 bit stream and the text bit stream conceptually consists of (1) packetization of the text bitstream, (2) reordering of text and MPEG-1 packets, and (3) packing.

First, the text bit string must be divided into packets, which are multiplexing units of MPEG-1. Depending on the target application, one packet may contain one or more slides. Also, the slide boundary does not have to coincide with the packet boundary. However, in the present embodiment, it is assumed that only one slide is included in a packet and the boundary lines thereof match.

The precision of the multiplexing determines the form of the reordering and packing steps. For example, if very high precision is required, it can be reordered packet by packet. In this case, however, there is a burden of first unpacking the MPEG-1 pack in packet units, reordering the packet in consideration of the text packet, and grouping the pack back into the pack. In addition, the MPEG-1 pack header has to be rewritten to suit the newly created pack.

Therefore, in the present invention, since the slide of the educational video as the main object does not require high precision, it is multiplexed in pack units. That is, multiplexing occurs between the existing MPEG-1 pack and the slide packet. Also, slides don't change often, so one slide pack contains only one slide packet.

3 is a main flowchart illustrating a multiplexing process of text data in an MPEG-1 bit string according to the present invention.

The multiplexing of the MPEG-1 bit stream and the text bit stream is performed by receiving the MPEG-1 system bit stream (see FIG. 1) and the text bit stream (see FIG. 2) as input and outputting a text-synchronized new MPEG-1 system bit stream. At this time, the MPEG-1 bit stream is read in pack units and the text bit stream is read in slide units, and the playback time information (PTS) is used as a comparison standard and merged in ascending order. The PTS of the MPEG-1 pack is defined as the PTS of the first packet having the PTS among the packets included in the pack. Note that in MPEG-1, since PTS is optional, not all packets have a PTS.

In the multiplexing process, as shown in the drawing, a slide is inputted from a text bit stream, a PTS of the slide is extracted, and a check is made to see if the input slide is the last slide. And processing the next start code in the MPEG-1 bit string if the input slide is not the last, and selecting one of end code processing, pack header processing, system header processing, or packet processing according to the type of the found start code. It is done with the steps.

This will be described in detail.

First read the next slide from the string of text bits (step 10). At this time, if the slide is normally input, the PTS of the slide is extracted according to the bit string form of FIG. 2. Next, it is checked whether the input slide is the last (end of text bit string) (step 20).

If the input slide is the last, in step 90 the remaining MPEG-1 bit strings that have not yet been processed are processed and the multiplexing ends. This will be described later.

As a result of the check in step 20, if the inputted slide is not last, the search is performed from the MPEG-1 bit string to the next start code (step 30). At this time, the searched content up to the start code is stored in the internal buffer. For reference, the beginning of a major element such as a pack, a packet, etc. in the MPEG-1 bit string is represented by a start code having a specific bit pattern (see FIG. 1).

In step 40, end code processing (step 50), pack header processing (step 60), system header processing (step 70), and packet processing (step 80) are performed according to the type of the found start code. Is done.

Details of the end code process (step 50), the pack header process (step 60), the system header process (step 70), and the packet process (step 80) selectively performed according to the type of start code are shown in Figs. It was.

4 embodies the end code process (step 50) of FIG.

In MPEG-1, an end code having a specific bit pattern is used to indicate the end of a system bit string. Searching for an exit code means that the MPEG-1 bit stream is all multiplexed.

Therefore, in step 510, the current slide is packetized and then packed and output. As mentioned above, in the present invention, each slide constitutes an independent pack. Next, recursively multiplex all remaining unprocessed slides in the text bit stream. That is, the next slide is read in step 520 and checked for last in step 530. If it is the last, the multiplexing is completed by outputting the MPEG-1 bit string termination code in step 540. If not, return to step 510 to continue multiplexing the remaining slides.

5 embodies the pack header process (step 60) of FIG.

First, the internal buffer which stores the contents of the previous pack which has not yet been output is output and initialized (step 610). Next, the pack header start code is stored in the internal buffer (step 620), and the contents contained in the system header, that is, the SCR, are read from the MPEG-1 bit string according to a defined form and stored in the internal buffer (step 630). Finally, an internal variable used for multiplexing packets, such as compared and merge, is initialized (step 640).

The internal variable compared indicates whether the PTS of the pack currently being processed is compared to the PTS of the current slide. If compared is TRUE, even if the packet being processed currently has a PTS, there is no need to compare it with that of the slide (see the description of packet processing in FIG. 7 below).

In addition, the variable merge indicates which of the currently processed pack and the current slide should be multiplexed when the PTS of the current pack and the PTS of the current slide are compared. If merge is TRUE, the PTS of the pack currently being processed is preceded by the current slide PTS, and the current packet should be multiplexed before the slide (see the description of packet processing in FIG. 7 described later).

However, retrieving the pack header start code means that a new pack has begun, so both the variables compared and merge are set to FALSE.

FIG. 6 embodies the system header process (step 70) of FIG. In the MPEG-1 bit stream, the system header is an option that can be included in the pack. The system header contains information about the entire bit string. In particular, information is provided for all individual bit strings included in the system bit strings, for example, bit string identifiers, standard buffer size limits, etc. (see the system bit string form in FIG. 1).

Therefore, if a system header is present in a particular pack of MPEG-1 bitstreams, this information for the multiplexed text bitstreams must be added. Figure 6 shows the processing of the system header containing this task.

First, the system header start code already read in step 710 is stored in an internal buffer. In operation 720, the existing system header is read and stored. Specifically, the system length of 2 bytes is first read and 3 is added to the internal buffer. The header length is increased by 3 bytes because 3 bytes are needed later to add the text bit string information. Next, it reads bytes of the original header length, that is, existing system header information, and stores them in an internal buffer. When the processing of the existing system header is completed as described above, in step 730, text bit string information having a length of 3 bytes is added. The first byte indicates the identifier of the text bit string to be added and the remaining two bytes are used to indicate the standard buffer size limit.

In the present invention, 1011 1101 defined as a private bitstream in the MPEG-1 standard is used as an identifier of a text bit string. Private bit strings allow the addition of bit strings not defined in the standard, such as text bit strings of the present invention, to MPEG-1 system bit strings. By using the private bit stream, the text-synchronized MPEG-1 bit stream can also be reproduced by the reference MPEG-1 player. The synchronization part is ignored.

FIG. 7 embodies the packet processing (step 80) of FIG. 3 as a key part of the multiplexing process in the present invention.

The packet processing basically reads the next packet, extracts the PTS, and compares it with the PTS of the current slide to determine which one is multiplexed, that is, output. As described above, in the present invention, since multiplexing occurs in units of packs, the above decision affects all packets in the pack to which the packet belongs.

In detail, as shown in the drawing, packet processing performed when the retrieved start code is a packet header includes: reading a packet header start code and a packet and storing the packet in an internal buffer; Checking a value of a variable indicating whether a PTS of a pack to which a current packet belongs is compared with a PTS of a slide; If the comparison between the PTS of the pack to which the current packet belongs and the PTS of the slide has already been completed (compared = TRUE), the current packet is output only when the multiplexing order of the current packet is ahead of the current slide (merge = TRUE) and the MPEG-1 bit string Transitioning to retrieving a next start code in a; And if the PTS comparison decision of the pack to which the current packet belongs is not completed (compared = FALSE), determining and multiplexing the multiplexing order of the current packet and the current slide.

First, in step 810, the packet header start code is stored in the internal buffer, and the packet is read and stored in the internal buffer according to the bit string format (see FIG. 1).

Then check the value of the variable compared (step 811).

If the value of the variable compared is TRUE, the PTS comparison decision of the pack to which the current packet belongs is already completed. Therefore, the current packet is stored or output in the internal buffer according to the value of the variable merge in step 820. If the merge value is TRUE, the previous PTS comparison determined that the current pack should be multiplexed before the current slide.

Therefore, in step 821, the packet stored in the internal buffer is outputted, and the process returns to step 30 (junction point J1 of FIG. 3) for searching the next start code in the MPEG-1 bit sequence for processing the next packet or pack. If the merge value is FALSE in step 820, the process returns to step 30 (junction point J1 of FIG. 3) which immediately retrieves the next start code from the MPEG-1 bit stream without output of the internal buffer.

If the compared value is FALSE under the condition of step 811, this means that the PTS of the current or future packet and the PTS of the slide must be compared since the multiplexing order has not yet been determined.

Therefore, it is first checked in step 830 whether the PTS is included in the current packet. For reference, in MPEG-1, PTS is a packet option. Therefore, not all packets need to have PTS information.

If no PTS information is included, the PTS comparison shall be made in the next packet or, in some cases, in the next pack. Therefore, the process returns to step 30 (junction point J1 in FIG. 3) of searching for the next start code in the MPEG-1 bit stream.

However, if the current packet contains the PTS, then the PTS information is extracted from the packet header already read and stored in the internal buffer (step 831), and the compared variable is set to true (step 832).

In step 833, the PTS of the current slide is compared with the PTS of the current packet. If the PTS of the packet is smaller than the PTS of the slide, this means that the pack to which the current packet belongs is preceded by a new MPEG-1 bit string that is output than the current slide. Therefore, after first setting merge to true in step 840, the internal buffer is output (step 821), and then step 30 for retrieving the next start code from the MPEG-1 bit stream for processing the next packet (junction J1 of FIG. 3). Back to

Setting the value of the variable merge to true at step 840 indicates that all packets after being included in the current pack must also precede the current slide.

If in step 833 the PTS of the current packet is greater than the PTS of the current slide, this means that the current slide must precede in the new MPEG-1 bit string that is output than the pack to which the current packet belongs. Therefore, in step 850, the current slide is packetized and packed. After reading the next slide in step 851, it is checked in step 852 whether the end of the slide bit string has been reached. If the processing is completed up to the last slide, the process branches to step 90 (junction J2 in FIG. 3) of processing the MPEG-1 bit stream and multiplexes the MPEG-1 bit stream still remaining. If not, the multiplexing continues using the newly read slide by branching to step 833.

FIG. 8 is an embodiment of the MPEG-1 bit string processing (step 90) of FIG. 3, and is a flowchart for multiplexing a pack of MPEG-1 bit strings not yet processed after all slides of the text bit string are multiplexed.

Basically, all bits of the MPEG-1 bit string are read and output.

However, in the case of a system header, information about a text bit string added as in the system header process described above is attached.

First, if there is an internal buffer not yet output in step 910, it is output. Next, in step 920, a search is made until the next start code. At this time, the retrieved bits are not stored in the internal buffer but are output immediately.

In steps 930 to 950, if the found start code is a system header start code, information of a text bit string multiplexed to the system header is added and output in the same manner as in FIG.

If it is not the system header start code, it is checked in step 960 if it is an MPEG-1 end code. As a result of the check in step 960, if the start code is the MPEG-1 end code, all the multiplexing is completed. However, if the retrieved start code is not an MPEG-1 end code, branch to the bit string output and start code search of step 920 to continue processing the remaining MPEG-1 packs.

9 is an exemplary view for explaining the multiplexing process of the present invention described above.

I in slide Si in the input text bit string represents the PTS of the slide. For example, the first four slides must be played in 1, 4, 5, and 7 seconds respectively. In the input MPEG-1 bit stream, V and A represent video and audio packets, respectively. The number after the alphabetic characters in the text bit string indicates the PTS. As illustrated, some packets do not have a PTS. In some cases, as in the third pack, not all packets in the pack may have a PTS.

The PTS of the first packet V1 of the first pack is compared with the slide S1 by the multiplexing algorithm. Since 1 ≦ 1, the first pack is multiplexed first. Next, S1 is multiplexed by comparing the slide S1 with the second packet V3 of the second pack. The next slide, S4, has a larger PTS than packet V3, so the second pack containing packet V3 is multiplexed.

The third pack does not include the PTS, so it is not compared, and audio packets A5 and slide S4 of the fourth pack are compared. In this case, since slide S4 is small, it is multiplexed first. Finally, packet A5 and slide S5 are compared, and the third and fourth packs are multiplexed so that all MPEG-1 bit strings are processed, and slides S5 and S7 of the remaining text bit strings are output to complete all the multiplexing.

10 is an MPEG-1 decoder supporting text synchronization according to the present invention.

In the input system stream, individual bit strings such as video, audio, and text are multiplexed. Therefore, the MPEG-1 decoder first separates the received multiple bit strings into individual bit strings such as video, audio, and text, and decodes them into individual bit string units and outputs them to the corresponding output device. Compared to the conventional MPEG-1 decoder in the present invention, the added part is a text decoder and a text buffer for reproducing a text bit string.

That is, the MPEG-1 decoder of the present invention is an input buffer for storing the received multiple bit strings, a system decoder for separating the multiple bit strings received through the input buffer into individual bit strings and transmitting the result to each individual decoder. An audio decoder for decoding and outputting the MPEG-1 audio bit stream separated by a system decoder, an audio buffer for storing the output of the audio decoder, and a video for decoding and outputting the MPEG-1 video bit stream separated by the system decoder. A MPEG-1 decoder comprising a decoder, a video buffer for storing the output of the video decoder, and a clock controller for controlling the clock of the audio / video decoder, the MPEG-1 decoder for decoding and outputting a text bit string separated by the system decoder. And a text buffer that stores the text decoder and the output of the text decoder. .

Each function and operation are as follows. First, the system decoder 2 separates the received multiple bit streams input from the input buffer 1 into individual bit streams such as video, audio, and text, and transmits them to each individual decoders 4, 6, and 8. . It also manages the system time clock (STC) for decoding the individual bit streams and synchronizing the playback times.

The audio decoder 4 decodes the separated MPEG-1 audio bit string and outputs it to the audio buffer 5. The contents of the audio buffer 5 are then output to the corresponding output device (eg, speaker). The timestamp is referenced for synchronization of the decoded audio signal output.

The video decoder 6 decodes the MPEG-1 video bit stream separated by the system decoder 2 and outputs it to the video buffer 6. The content of the video buffer 7 is then output to the output device (eg screen). The video decoder 6 references the time stamps included in the STC and the bit stream for temporal synchronization. That is, each video picture is decoded at the time of DTS and output at the time of PTS.

Finally, the text decoder 8 decodes, if necessary, additional text data added to the MPEG-1 video and audio and outputs it to the text buffer 9. The contents of the text buffer 9 are then output to the corresponding output device (eg screen). Refer to the time stamps included in the STC and text bit strings for synchronization with video and audio signals during playback of added text data.

As described above, the present invention makes it possible to add not only audio and video but also text data synchronized with the MPEG-1 multimedia stream established as an international standard.

In the present invention, since the text is synchronized in units of variable length called slides, the text can be synchronized in various forms and precisions according to the application field and purpose, and by multiplexing the text in an MPEG-1 system stream where audio and video are synchronized. Since existing MPEG-1 streams can be used without regeneration, it is possible to economically and effectively synchronize text information.

In addition, since text information does not exist separately and is merged into an MPEG-1 system stream, the stream is easy to maintain and the multiplexing method complies with the MPEG-1 standard. 1 It has the advantage that it is played perfectly by the player (except sync text).

The technical spirit of the present invention has been described above with reference to the accompanying drawings, but this is by way of illustration of a preferred embodiment of the present invention by way of example and not by way of limitation. In addition, it is obvious that any person skilled in the art can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

Claims (10)

In a method of synchronizing text data into an MPEG-1 multimedia stream, The process of dividing text data into slides, which is a unit of synchronization, assigning each time slide a time stamp indicating the time at which the slide should be played, and encoding each slide in a predetermined bit form (slide frame) to form a text bit string. and; Multiplexing to generate a text-synchronized MPEG-1 system bit string by packetizing the slide bit string of the text bit string and inserting each packet at a predetermined position of the MPEG-1 system bit string according to the playback time stamp of the slide included in the packet. And text data synchronization to the MPEG-1 multimedia stream. The method of claim 1, And a slide frame forming the text bit string comprises a slide start code, slide length, playback time information, slide data, and additional data fields. The method according to claim 1 or 2, The multiplexing process may include: receiving a slide from a text bit string, extracting a PTS of a corresponding slide, and checking whether the input slide is the last slide; Processing the remaining MPEG-1 bit stream if the input slide is the last; And searching for a next start code in an MPEG-1 bit string if the input slide is not the last, and selectively performing any one of end code processing, pack header processing, system header processing, or packet processing according to the type of the found start code. Text data synchronization method to the MPEG-1 multimedia stream comprising a. The method of claim 3, End code processing is characterized by packetizing the current slide, packing it, outputting it, recursively multiplexing all the remaining unprocessed slides in the text bit stream, and then outputting an MPEG-1 bit string end code. How to synchronize text data into a multimedia stream. The method of claim 3, Pack header processing outputs and initializes an internal buffer that stores the contents of a previous pack that has not yet been output, and then stores the pack header start code in an internal buffer, and internalizes the contents of the system header from the MPEG-1 bit stream. A method of synchronizing text data into an MPEG-1 multimedia stream after storing it in a buffer and initializing internal variables used for multiplexing packets such as compared and merge. The method of claim 3, The system header process saves the read system header start code in the internal buffer, reads the header length from the existing system header information, changes the number of bytes required to add the text bit string information, and then changes the system header information. A method of synchronizing text data into an MPEG-1 multimedia stream, characterized by storing in an internal buffer and adding text bit string information (such as an identifier of the text bit string and a standard buffer size limit). The method of claim 3, The packet processing may include reading a packet header start code and a packet, storing the packet in an internal buffer, and checking a value of a variable indicating whether or not the PTS of the pack to which the current packet belongs is compared with the PTS of the slide; If the comparison of the PTS of the pack to which the current packet belongs to the PTS of the slide has already been completed (compared = TRUE), the multiplexing order of the current packet is earlier than the current slide (merge = TRUE). Outputting only the current packet and retrieving the next start code from the MPEG-1 bit stream; And if the PTS comparison of the pack to which the current packet belongs is not completed (compared = FALSE), determining and multiplexing the multiplexing order of the current packet and the current slide. A method of synchronizing text data into an MPEG-1 multimedia stream. The method of claim 7, wherein The multiplexing order determination and multiplexing step of the current packet and the current slide may include a substep of branching to retrieving a next start code from an MPEG-1 bit string if the current packet does not include a PTS; If the current packet contains the PTS, extract it, change the variable value indicating whether or not to compare the PTS of the pack to which the current packet belongs to the slide PTS (compared = TRUE), and extract the PTS of the extracted current packet and the current slide PTS. Comparing substeps; As a result of the PTS comparison, if the PTS of the current packet is less than or equal to the slide PTS, the variable value indicating the packet multiplexing order is changed because the current packet and all packets of the pack including the current packet must be multiplexed before the current slide (merge = TRUE). Sub-multiplexing the current packet and then searching for the next start code in the MPEG-1 bit stream; If the PTS of the current packet is larger than the slide PTS, the current slide needs to be multiplexed before the current packet. Branching to a substep of comparing the PTS of the extracted current packet with the current slide PTS; otherwise, the substep of branching to a step for processing the MPEG-1 bit stream. How to sync data. The method of claim 3, The remaining MPEG-1 bit string processing step may include: outputting a bit string of an internal buffer not yet output; Retrieving a start code while outputting a bit string; If the retrieved start code is a system header start code, adding and outputting information of a text bit string multiplexed in the system header, and then branching to a bit string output and start code search step; If the found start code is not the system header start code, it is checked whether it is an MPEG-1 end code, and if it is an MPEG-1 end code, the multiplexing is terminated. And processing the text data into the MPEG-1 multimedia stream. An input buffer (1) for storing the received multiple bit streams, a system decoder (2) for separating the multiple bit streams received through the input buffer into individual bit streams, and transmitting the result to each individual decoder; The audio decoder 4 which decodes and outputs the MPEG-1 audio bit stream separated by the "), the audio buffer 5 which stores the output of the audio decoder 4, and the MPEG separated by the system decoder 2 A video decoder 6 decoding and outputting a video bit string, a video buffer 6 storing an output of the video decoder 6, and a clock controller controlling a clock of the audio / video decoders 4 and 6. In the MPEG-1 decoder comprising (3), A text decoder 8 for decoding and outputting a text bit string separated by a system decoder 2 and having a clock controlled by the clock controller 3, and a text buffer for storing an output of the text decoder 8 ( 9), wherein the MPEG-1 decoder is characterized by decoding a text-synchronized MPEG-1 system bit string.