JP4095081B2 - Stream converter - Google Patents

Description

  The present invention relates to a stream conversion apparatus for converting one of data streams generated from the same material and having a different structure, such as a program stream and a transport stream in the MPEG2 standard, which is a compression encoding standard for image information, to the other. Belongs to the technical field.

  In recent years, DVDs, which are optical discs with dramatically improved recording capacities, are becoming popular. When recording image information on these DVDs, the so-called MPEG2 standard (ISO (International Organization for Standardization) standard 13818-1) is used. It is used. At this time, when image information and audio information are combined and recorded on the DVD, a data stream called a program stream (hereinafter referred to as PS) in the MPEG2 standard is generated and recorded on the DVD. To be done.

  On the other hand, in a communication system or transmission system, it is common to use a so-called transport stream (hereinafter referred to as TS) that is also defined in the MPEG2 standard. This TS is also planned to be adopted in ATV (Advanced Television), which is planned for practical use in recent years.

  Here, when image information reproduced from a DVD is transmitted to the outside using the communication system or the transmission system, if conversion from the PS to the TS is not performed, the PS is once decoded and encoded. To generate a TS, or develop a PS into an elementary stream (image or audio data itself) constituting the PS, convert it into information units constituting the TS, and then re-synthesize it. Become.

  Here, in the former case, there is a problem that it is necessary to use an encoder having a complicated configuration and an expensive encoder, and the image quality or sound quality may be deteriorated by re-encoding. It was.

  In the latter case, synthesis is performed while always checking the amount of the elementary stream stored in the buffer in the decoder, and time information indicating the playback time to be reproduced in the PS is newly calculated. There is a problem in that the conversion device requires complicated processing.

  On the other hand, when digital broadcasting becomes common in the future, it is expected that a television apparatus that receives the digital broadcast will be equipped with an MPEG2 decoder for decoding the TS. Here, both PS and TS are used. Is common to the decoding process of image information. Therefore, for example, in the case of reproducing image information by connecting a DVD playback device to a television device, it is economical in terms of the device configuration to include an image decoder only in either the television device or the playback device. In this sense, there is a problem that a stream conversion device that easily converts PS to TS is necessary.

  Accordingly, the present invention has been made in view of the above-described problems, and the problem is to provide a stream conversion apparatus that can efficiently convert PS to TS without requiring complicated processing. There is to do.

In order to solve the above problem, the invention according to claim 1 is the first time information set so that neither overflow nor underflow occurs in the first buffer means such as a video buffer during decoding. A first data stream such as PS including the first data stream decoded while being temporarily stored in the first buffer means based on the first time information. In a stream conversion device for converting into a second data stream to be decoded while being temporarily stored in a second buffer means such as a port buffer, an overflow occurs in the second buffer means when decoding the converted second data stream Or setting of the controller etc. for setting the second time information so that neither underflow occurs Comprising a stage, and a conversion means such as a controller for converting the first data stream and the second time information while multiplexing the set in the second data stream transfer rate of the second data stream is the first The transfer means is higher than the transfer rate of one data stream, and the conversion means is based on the first time information, and the conversion means is provided in the first buffer means when decoding the first data stream using the first time information. First calculation means for predicting and calculating an accumulation amount of the first data stream, and second buffer means for decoding the second data stream using the second time information based on the second time information Second calculation means for predicting and calculating the storage amount of the second data stream, and the storage amount of the first data stream in the first buffer means and the first When the difference from the accumulated amount of the second data stream in the buffer means is equal to or greater than a predetermined threshold value, the first insertion information irrelevant to the first data stream is inserted. Insertion conversion means for converting a data stream into the second data stream, wherein the second buffer means has at least unique buffer means specific to the second data stream, and the threshold value is the second value. The accumulation amount of the second data stream in the buffer means is set to always exceed the accumulation amount of the first data stream in the first buffer means, and is equal to or less than the maximum capacity of the specific buffer means. It is characterized by .

  According to the operation of the first aspect of the present invention, the setting means outputs the second time information so that neither overflow nor underflow occurs in the second buffer means when the converted second data stream is decoded. Set.

Then, the converting means converts the first data stream into the second data stream while multiplexing the set second time information.
In addition, the transfer rate of the second data stream is higher than the transfer rate of the first data stream, and the first calculation unit in the conversion unit uses the first data stream based on the first time information. The amount of accumulation of the first data stream in the first buffer means at the time of decoding is predicted and calculated.
In parallel with this, the second calculating means in the converting means uses the second data stream in the second buffer means when decoding the second data stream using the second time information based on the second time information. Is estimated and calculated.
When the difference between the accumulated amount of the first data stream in the first buffer unit and the accumulated amount of the second data stream in the second buffer unit becomes equal to or greater than a predetermined threshold, The first data stream is converted into the second data stream while inserting irrelevant insertion information into one data stream.
Further, the second buffer means has at least a unique buffer means, and the threshold value is determined so that the accumulated amount of the second data stream in the second buffer means is the accumulated amount of the first data stream in the first buffer means. It is set so as to always exceed the maximum capacity of the unique buffer means.

Therefore, it is possible to convert the second data stream into the second data stream by a simple process while preventing the decoding process of the second data stream from being interrupted and performing the decomposition process on the first data stream.
Further, when the difference between the accumulated amounts of the respective buffer means becomes a predetermined threshold value or more, since conversion is performed while inserting irrelevant insertion information into the first data stream, without changing the data content of the first data stream, In addition, the first data stream can be converted into the second data stream by preventing overflow or underflow in the second buffer means.
Further, it is not necessary to newly provide other buffer means unique to the second data stream, and the first data stream can be converted into the second data stream while reliably preventing overflow or underflow in the unique buffer means. .

In order to solve the above problem, the invention according to claim 2 is the stream conversion device according to claim 1 , wherein the first buffer means stores the first data stream in the first buffer means. The first time information is set so that a preset non-storage area is generated, and the threshold value is set so that the accumulated amount of the second data stream in the unique buffer means is in the first buffer means. It is set to always exceed the accumulation amount of the first data stream, and is configured to be equal to or less than the value obtained by adding the capacity of the unstored area to the maximum capacity of the unique buffer means.

According to the operation of the invention described in claim 2 , in addition to the operation of the invention described in claim 1 , the first time information is stored when the first data stream is stored in the first buffer means. The threshold is set such that the storage amount of the second data stream in the unique buffer means always exceeds the storage amount of the first data stream in the first buffer means. It is set to be equal to or less than the value obtained by adding the capacity of the unstored area to the maximum capacity of the unique buffer means.

  Therefore, it is possible to convert the first data stream into the second data stream while reliably preventing overflow or underflow in the specific buffer means.

In order to solve the above-mentioned problem, the invention according to claim 3 is the stream conversion device according to claim 1 or 2 , wherein the insertion information includes at least the new second time information and the second data. It is configured to be either information of content information indicating the content of data included in the stream or information indicating 0.

According to the operation of the invention described in claim 3 , in addition to the operation of the invention described in claim 1 or 2 , the insertion information includes at least new second time information, content information, or information indicating 0. Therefore, the second data stream can be generated without affecting the decoding of the second data stream.

In order to solve the above-described problem, the invention according to claim 4 is the stream conversion device according to claim 3 , wherein in the second data stream, the second time information and the content are included in the insertion information. When the information insertion frequency is set in advance, the conversion means inserts the second time information and the content information so as to satisfy the insertion frequency, and inserts the second time information and the content information. Information indicating 0 is inserted at a position in the second data stream where the insertion information other than the power position is to be inserted.

According to the operation of the invention described in claim 4 , in addition to the operation of the invention described in claim 3 , the insertion frequency of the second time information and the content information among the insertion information is preset in the second data stream. The conversion means inserts the second time information and the content information so as to satisfy the insertion frequency, and the second data to insert the insertion information other than the position where the second time information and the content information are to be inserted. Since information indicating 0 is inserted at a position in the stream, the first data stream can be efficiently converted into the second data stream.

In order to solve the above-mentioned problem, the invention according to claim 5 is the stream conversion device according to any one of claims 1 to 4 , wherein the first data stream is an MPEG2 standard detected from a DVD. And the second data stream is a transport stream of the MPEG2 standard, and the converting means deletes unnecessary data which is data in the program stream that is unnecessary in the transport stream. It is configured to convert a program stream into the transport stream.

According to the operation of the invention described in claim 5 , in addition to the operation of the invention described in any one of claims 1 to 4 , the first data stream is an MPEG2 standard program stream detected from a DVD. The second data stream is an MPEG2 standard transport stream, and the conversion means converts the program stream into a transport stream while deleting unnecessary data.

  Therefore, the program stream detected from the DVD can be efficiently converted into a transport stream.

In order to solve the above-described problem, according to a sixth aspect of the present invention, in the stream conversion device according to the fifth aspect , the conversion unit prevents underflow in the second buffer unit instead of the unnecessary data. The program stream is converted into the transport stream by inserting dummy data for performing the above.

According to the operation of the invention described in claim 6 , in addition to the operation of the invention described in claim 5 , the conversion means replaces unnecessary data with dummy data for preventing underflow in the second buffer means. Insert and convert program stream to transport stream.

Therefore, the transport stream can be generated while preventing the underflow of the second buffer means without affecting the contents of the transport stream.
In order to solve the above problem, the invention according to claim 7 includes the first time information set so that neither overflow nor underflow occurs in the first buffer means during decoding. A first data stream that is a data stream and is decoded while being temporarily stored in the first buffer means based on the first time information is temporarily stored in the second buffer means based on the second time information. In the stream conversion device for converting into a second data stream to be decoded while being stored, the second buffer means prevents any overflow or underflow from occurring when the converted second data stream is decoded. Setting means for setting second time information; and the first data stream while multiplexing the set second time information. Converting means to convert the second data stream into a second data stream, wherein the transfer rate of the second data stream is higher than the transfer rate of the first data stream, and the conversion means is based on the first time information First calculation means for predicting and calculating an accumulation amount of the first data stream in the first buffer means when the first data stream is decoded using the first time information, and the second time information. A second calculating means for predicting and calculating an accumulation amount of the second data stream in the second buffer means when the second data stream is decoded using the second time information; The difference between the accumulated amount of the first data stream in the buffer means and the accumulated amount of the second data stream in the second buffer means is less than a predetermined threshold value set in advance. And inserting and converting means for converting the first data stream into the second data stream while inserting preset insertion information irrelevant to the first data stream. The information is at least one of the new second time information, the content information indicating the content of the data included in the second data stream, or the information indicating 0.
In order to solve the above-described problem, the invention according to claim 8 is the stream conversion apparatus according to claim 7, wherein in the second data stream, the second time information and the content of the insertion information are included. When the information insertion frequency is set in advance, the conversion means inserts the second time information and the content information so as to satisfy the insertion frequency, and inserts the second time information and the content information. Information indicating 0 is inserted at a position in the second data stream where the insertion information other than the power position is to be inserted.

As described above, according to the first aspect of the present invention, the decoding process of the second data stream is prevented from being interrupted, and the first data stream is simplified without being subjected to a decomposition process or the like. The process can convert the first data stream into a second data stream. Further, when the difference between the accumulated amounts of the respective buffer means becomes a predetermined threshold value or more, since conversion is performed while inserting irrelevant insertion information into the first data stream, without changing the data content of the first data stream, In addition, the first data stream can be converted into the second data stream by preventing overflow or underflow in the second buffer means. Further, the second buffer means has at least a unique buffer means, and the threshold value is always equal to the accumulated amount of the second data stream in the second buffer means. Since it is set so as to exceed the maximum capacity of the unique buffer means, there is no need to newly provide another buffer means unique to the second data stream, and an overflow in the unique buffer means or The first data stream can be converted to the second data stream while reliably preventing underflow.

According to the second aspect of the present invention, in addition to the effect of the first aspect of the invention, the threshold value is determined so that the accumulated amount of the second data stream in the unique buffer means is the first value in the first buffer means. It is set to always exceed the accumulated amount of one data stream, and it is set to a value equal to or less than the maximum capacity of the unique buffer means plus the capacity of the unstored area, so that overflow or underflow in the unique buffer means is ensured. It is possible to convert the first data stream into the second data stream while preventing the above.

According to the invention described in claim 3 , in addition to the effect of the invention described in claim 1 or 2 , the insertion information is at least any of new second time information, content information, or information indicating 0. Therefore, the second data stream can be generated without affecting the decoding of the second data stream.

According to the invention described in claim 4 , in addition to the effect of the invention described in claim 3 , in the second data stream, the insertion frequency of the second time information and the content information among the insertion information is preset. When the second time information and the content information are inserted so as to satisfy the insertion frequency, 0 is added to the position in the second data stream where the insertion information is to be inserted in addition to the position where the second time information and the content information are to be inserted. Therefore, the first data stream can be efficiently converted into the second data stream.

According to the invention described in claim 5 , in addition to the effect of the invention described in any one of claims 1 to 4 , the first data stream is an MPEG2 standard program stream detected from a DVD, The second data stream is an MPEG2 standard transport stream, and the converting means converts the program stream into a transport stream while deleting unnecessary data. Therefore, the program stream detected from the DVD can be efficiently transported. Can be converted to

According to the invention described in claim 6 , in addition to the effect of the invention described in claim 5 , dummy data is inserted in place of unnecessary data to convert a program stream into a transport stream. The transport stream can be generated by preventing underflow of the second buffer means without affecting the contents.

  Next, preferred embodiments of the present invention will be described with reference to the drawings. The embodiment described below is an embodiment in which the present invention is applied to a case where a PS reproduced from a DVD is displayed on a television apparatus configured to display an image using a TS. is there.

(I) Description of Premises First, before describing specific embodiments, basic techniques that serve as a premise for describing the present invention will be described with reference to FIGS.

  First, the structure of a PES (Packetized Elementary Stream) packet (hereinafter simply referred to as a packet) which is a basic unit of a system stream in the MPEG2 standard including PS and TS according to the present invention will be described with reference to FIG. explain.

  As shown in FIG. 1A, a packet PT is a packetized version of the above-described elementary stream, and includes a PES packet header (hereinafter simply referred to as a packet header) 55 and packet data (hereinafter simply referred to as a packet). (Referred to as data) 56.

  Here, the packet data 56 includes image data or audio data to be actually displayed or output.

  The packet header 55 includes a stream ID indicating the type of data included in the packet data 56, a PTS (Presentation Time Stamp), a DTS (Decoding Time Stamp), and the like.

  Here, DTS is time information in units of 90 kHz indicating the time when decoded picture data is output from the buffer in the decoder for decoding the system stream, and PTS is the actual image corresponding to the picture data. Is time information in units of 90 kHz indicating the time displayed on the screen.

  At this time, when the PES packet data 56 is audio data, since PTS and DTS have the same value, only PTS is included as a representative of them.

  PTS and DTS are only when the head of an access unit (that is, each picture in the case of image information and AAU (Audio Access Unit) in the case of audio information) is present in the packet data 56. It is included in the packet header 55.

  Accordingly, the size (number of bits) of the packet header 55 changes depending on the presence / absence of optional information such as the PTS and DTS included therein.

  A plurality of packets PT shown in FIG. 1A are combined, and additional information described later is combined to form the MPEG2 system stream.

  Next, the PS that is one form of the system stream will be generally described with reference to FIG.

  The PS includes a plurality of packs, and one pack P includes one pack header 57, a system header 58, and a plurality of the packets PT, as shown in FIG. It consists of and.

  Among these, the pack header 57 includes an SCR (System Clock Reference) and the like, and needs to be included in the PS at least once in 0.7 msec. This SCR describes the time at which the pack P containing it arrives at the buffer in the decoder in units of 90 kHz.

  The SCR will be described more specifically. The SCR indicates a read start time on the reproduction time axis at which input of data included in each pack P should be started to the buffer in the decoder. .

  The size of the pack header 57 is the number of bytes obtained by adding dummy data to 14 bytes.

  Further, the system header 58 includes information such as the size of the buffer, and it can be arbitrarily set whether or not it is included in one pack P, but if included, it is synthesized immediately after the pack header 57. Is done.

  Next, a physical format on the DVD when a PS including a plurality of packs P shown in FIG. 1B is recorded on the DVD will be described with reference to FIG.

  As shown in FIG. 2, the DVD 1 has a lead-in area LI at its innermost peripheral part and a lead-out area LO at its outermost peripheral part, during which video information and audio information are respectively transmitted. It is divided and recorded in a plurality of VTS (Video Title Set) 3 (VTS # 1 to VTS # n) having ID (identification) numbers. A combination of the plurality of VTSs 3 and a video manager 2 described later corresponds to the PS.

  Here, the VTS is a related title (the number of audio information and sub-picture information included therein, the attributes such as the specification, the corresponding language, etc. are the same) titles (movies etc.) that the producer intends to present to the viewer. It is a set (group) of all the works.

  In addition, the video manager 2 is recorded at the head of the area where the VTS 3 is recorded. The information recorded as the video manager 2 includes, for example, video information and audio recorded on the DVD 1 such as a menu for each title, information for preventing illegal copying, or an access table for accessing each title. Management information related to the entire information is recorded.

  Next, one VTS 3 is divided and recorded into a plurality of VOBs 10 each having an ID number, starting with the control data 11. Here, a portion constituted by a plurality of VOBs 10 is referred to as a VOB set (VOBS). This VOB set is a VOB set for the entity part in order to distinguish between control data 11 which is other data constituting the VTS 3 and a plurality of VOB 10 parts which are entities of video information and audio information. .

  The control data 11 recorded at the head of the VTS 3 includes information such as PGCI (Program Chain Information), which is various information related to the program chain, which is a logical division combining a plurality of cells (cells will be described later). Is recorded. In addition to the control information, each VOB 10 is recorded with video information and audio information entity portions (video or audio itself other than the control information).

  Furthermore, one VOB 10 includes a plurality of cells 20 each having an ID number. Here, one VOB 10 is configured to be completed by a plurality of cells 20, and one cell 20 does not straddle two VOBs 10.

  Next, one cell 20 includes a plurality of VOB units (VOBU) 30 each having an ID number. Here, the VOB unit 30 is an information unit including each of video information, audio information, and sub-video information (referring to sub-video information such as subtitles in a movie).

  One VOB unit 30 includes a navigation pack 41 in which predetermined control information is stored, a video pack 42 that includes video data as video information, an audio pack 43 that includes audio data as audio information, and a sub-packet. The sub picture pack 44 includes sub picture data as video information. Here, only video data is recorded as video data, and only audio data is recorded as audio data. Further, as the sub picture data, a packet PT including graphic data such as characters and figures as a sub video is recorded. The standard stipulates that there are 8 types of audio that can be recorded on the DVD 1 and 32 types of sub-video that can be recorded.

  The playback time corresponding to one VOB unit 30 (playback time corresponding to data recorded between one navigation pack 41 and the navigation pack 41 adjacent to the one navigation pack 41) is 0. It is recorded so as to have a length of 4 seconds or more and 1 second or less.

  Here, the playback time corresponding to one VOB unit 30 is set to 0.4 seconds or more in order to reduce the storage capacity of the PCI buffer in the playback device. This is because the allowable delay time for the decoding process of the video pack 42 defined in the standard is 1 second. Therefore, the navigation pack 41 is always detected once every 0.4 second to 1 second during reproduction.

  Further, in one VOB unit 30, the navigation pack 41 is always present at the head thereof, but each of the video pack 42, the audio pack 43, and the sub-picture pack 44 is not necessarily present in the VOB unit 30, and Even if they exist, their number and order can be arbitrarily set.

  Here, each of the video pack 42, the audio pack 43, and the sub-picture pack 44 shown in FIG. 2 corresponds to the pack P described above.

  For each pack P, video data, audio data, or sub-picture data is normally recorded for each packet PT, which is a recording unit obtained by further subdividing the pack P. In the DVD 1 in the present embodiment, In general, one pack P is composed of one packet PT.

  Furthermore, all the video packs 42 included in one VOB unit 30 are configured by one or a plurality of GOPs (Group Of Pictures).

  Here, the detailed configuration of each of the navigation pack 41, the video pack 42, and the audio pack 43 will be described.

  First, as shown in FIG. 3A, one navigation pack 41 is always included in one VOB unit 30 and is described prior to video data, in order to search for video or audio to be reproduced and displayed. Based on the DSI packet 51, which is a packet PT including the search information (specifically, the address or the like on the DVD 1 in which the video or audio to be reproduced and displayed is recorded) and the data in the DSI packet 51 And a PCI packet 50 which is a packet PT including information related to reproduction display control when displaying video or audio. In these two packets, neither PTS nor DTS is described in the packet header 55.

  At this time, the stream IDs in each packet are both 0xBF (in the case of the private stream 2 standard), and “0x00” and “0x01” are described as substream IDs after the packet header 55, respectively. 50 or DSI packet 51 can be identified.

  This substream ID is not in the MPEG2 standard and is a DVD-specific standard.

  Further, the PCI packet 50 includes highlight information defining a display item and an operation when the item is selected for a selection item selected by the viewer. With this highlight information, for example, in the image (the so-called menu screen) displaying the item to be selected by the viewer, the screen display change with respect to the item selection, the display position to be changed corresponding to the selection, and the selected Settings such as a command for an item (an instruction indicating an operation to be performed on a selected item) are performed.

  Here, image information for displaying a frame, a selection button, and the like necessary for configuring and displaying the menu screen is recorded as sub-picture data which is the sub-picture information.

  Further, the GOP is a minimum image unit that can be reproduced independently in the MPEG2 standard. At the head of each GOP, the reproduction time on the reproduction time axis at which video data included in the GOP is to be displayed. Is recorded.

  Next, the video pack 42 will be described with reference to FIG.

  As shown in FIG. 3B, the video pack 42 includes video data 64 compressed by MPEG2.

  The video data 64 includes only one type of image information in one DVD 1.

  Further, when there is a head of an I (Intra-coded) picture in MPEG2 in the packet PT, the PTS and DTS are included in the packet header 55.

  Furthermore, the stream ID is “0xE0”.

  In FIG. 3B, only one packet PT including the video data 64 exists after the pack header 57, but dummy data (also referred to as a padding packet) is provided after the packet PT in order to adjust the data rate. May be inserted. In this case, the sum of the pack header 57, the packet PT, and the dummy data is 2048 bytes.

  The video data 64 is inserted into the PS so that neither overflow nor underflow occurs in the video data 64 buffer.

  Next, the audio pack 43 will be described with reference to FIG.

  As shown in FIG. 3C, the audio pack 43 includes audio data 65 compressed by a method called AC-3.

  At this time, as described above, there are eight types of audio information that can be recorded on the DVD 1, and when the head of the AAU is in the packet PT, the PTS is described in the packet header 55.

  The stream ID is “0xBD” (in the case of the private stream 1 standard), and the substream ID is “0x80-0x87”. The stream number of the audio information is defined by the lower 3 bits of the substream ID.

  Here, 4 bytes including the substream ID are referred to as a private data area, which is described at the head of the audio data 65 and includes information for reproduction in the AC-3 system. These are not in the MPEG2 standard and are unique to the DVD1.

  Further, in FIG. 3C, only one packet PT including the audio data 65 is included after the pack header 57. However, as in the case of the video pack 42, a dummy is provided after the packet PT in order to adjust the data rate. Data may be inserted. In this case, the sum of the pack header 57, the packet PT, and the dummy data is 2048 bytes.

  In the audio pack 43, the audio data 65 is inserted into the PS so that neither overflow nor underflow occurs in the buffer for the audio data 65.

  Next, the configuration and operation of the decoder used when decoding the above-described PS will be described with reference to FIG.

  As shown in FIG. 4A, the PS decoder D includes a demultiplexer 66, a video buffer 67 as a first buffer means, a video decoder 68, an audio buffer 69, and an audio decoder 70. ing.

  Next, an outline of the operation will be described.

  The data rate of PS input to the demultiplexer 66 is 10.08 Mbps.

  The capacity of the video buffer 67 in which the video pack 42 separated from the PS by the demultiplexer 66 is temporarily stored is 229376 bytes defined by MPEG2-MP @ ML (Main Profile at Main Level) and an additional buffer. This is 237568 bytes, which is the sum of 8192 bytes.

  On the other hand, the capacity of the audio buffer 69 in which the audio pack 43 separated from the PS by the demultiplexer 66 is temporarily stored is 4096 bytes.

  In the PS, the PTS and DTS are managed and synthesized as PS so that the video buffer 67 and the audio buffer 69 do not overflow or underflow.

  Next, FIG. 4B shows an example of the occupied amount of the video buffer 67. Here, in FIG. 4B, Bsvmax indicates the maximum accumulation amount, that is, 237568 bytes.

  As shown in FIG. 4B, data is always input to the video buffer 67 at a constant data rate (10.08 Mbps for DVD1).

  4B shows a period in which the video data 64 is not input to the video buffer 67 due to a reason that there is a packet PT including the audio data 65. Further, the output of the video data 64 from the video buffer 67 is instantaneously output for each picture in units of pictures.

  Next, the TS that is one form of the system stream will be generally described with reference to FIG. 5A shows a state where the TS is generated from the original elementary stream, and FIG. 5B is a block diagram showing a schematic configuration of a decoder used for decoding the TS.

  As shown in FIG. 5A, when a TS is formed from a system stream, the packet PT in the original system stream is broken down into partial packets BPT every 184 bytes, and a 4-byte link header 71 is added to each partial packet BPT. Is added to form one TS packet TPT.

  Then, a 188-byte TS packet TPT is multiplexed as a unit with a TS packet TPT generated from another system stream.

  Here, each link header 71 includes a PID (Packet ID; 13-bit stream identification information indicating the identification number of the individual stream of the corresponding TS packet TPT) and the like.

  Along with these, a plurality of tables unique to TS are multiplexed.

  Note that PS can only transmit a single program (one unit of video data or audio data), whereas TS can transmit a plurality of programs at once.

  Among the plurality of tables described above, the program association table (hereinafter referred to as PAT (Program Association Table)) is referred to as a program map table (hereinafter referred to as PMT (Program Map Table)) corresponding to a certain program number. PID etc.). The PID of the PAT itself is “0x00”.

  On the other hand, the PMT includes PIDs of video, audio, and additional data included in the program.

  When these tables are less than l84 bytes, the necessary number of “0xFF” is inserted after this to make a total of 184 bytes.

  An adaptation field can be inserted after the link header 71, and a PCR (Program Clock Reference) or the like is described in the field. This PCR corresponds to the SCR in the PS, and the time when the TS packet TPT arrives at the decoder buffer is described in units of 90 kHz and 27 MHz.

  Note that the packet PT can be inserted after the adaptation field. In this case, when the length of the packet PT is less than 184 bytes, adjustment is made with dummy data in the adaptation data.

  Moreover, it is prescribed that PCR is inserted at least once within 0.1 seconds.

  Further, a packet indicating “0” (hereinafter referred to as a null packet) is inserted mainly for adjusting the transfer rate, and the payload (actual data other than the link header 71 or the adaptation field in the TS packet TPT) is used. In this case, no meaningful data is inserted into a null packet.

  Next, a system standard in a television apparatus using the TS will be described.

The system standard is basically the TS standard, but there are further restrictions in addition to this. That is,
(I) The PMT must be inserted at least once every 0.4 seconds.

  (Ii) The PAT must be inserted at least once per 0.1 second.

  (Iii) The payload of the packet PT must start at the beginning of the video access unit (picture start code, group start code or sequence header).

  (Iv) The audio data 65 is compressed by the AC-3 system. At this time, the stream ID is “0xBD” (in the case of private stream 1).

  (V) The multiplex rate is about 19.39 Mbps.

  Next, the configuration and operation of the decoder for decoding the TS will be described with reference to FIG.

  As shown in FIG. 5B, the decoder D ′ includes a demultiplexer 72, transport buffers 73 and 76 as second buffer means and unique buffer means, a video buffer 74, a video decoder 75, An audio buffer 77 and an audio decoder 78 are included.

  Next, an outline of the operation will be described.

  The capacity of the video buffer 74 in which the video data separated from the TS by the demultiplexer 72 is temporarily stored is 239376 bytes, which is the sum of 229376 bytes defined by MPEG2-MP @ ML and the additional buffer of 10,000 bytes. .

  On the other hand, the capacity of the audio buffer 77 in which the audio data separated from the TS by the demultiplexer 72 is temporarily stored is 3584 bytes in principle, but is not strictly standardized as a television apparatus.

  In the TS, the PTS and DTS are managed and synthesized as a TS so that the video buffer 74 and the audio buffer 77 do not overflow or underflow.

  Further, the transport buffers 73 and 76 are for compensating for the data bias caused by the link header 71 and the like, and are standardized to 512 bytes.

(II) Embodiment Next, based on the above-mentioned premise, PS reproduced from DVD 1 is converted into TS according to the present invention, and output in a television apparatus configured to display an image or the like using the TS. An embodiment of an information reproducing apparatus will be described with reference to FIGS.

  First, the overall configuration of the information reproducing apparatus according to the embodiment will be described with reference to FIG.

  As shown in FIG. 6, the information reproducing apparatus S of the embodiment converts the PS reproduced from the DVD 1 into a TS and outputs it, and also based on the reproducing apparatus R that outputs the PS to the outside and the generated TS. And a television set TV that outputs an image or sound corresponding to the TS to the outside.

  Further, the reproducing apparatus R irradiates the DVD 1 with a light beam and detects information pits formed on the DVD 1 based on the reflected light, and a signal corresponding to the detected information pits. The demodulating circuit 81 demodulates the demodulated information, the error correcting circuit 82 that performs error correction on the demodulated information and outputs PS, and the PS / TS converter 84 according to the present invention.

  Further, the television device TV is configured to include the decoder D ′ shown in FIG. 5B that decodes the TS reproduced from the reproduction device R and outputs the sound or image corresponding to the TS to the outside. Yes.

  Next, the detailed configuration and operation of the PS / TS converter 84 according to the present invention will be described with reference to FIGS.

  First, the detailed configuration and outline operation of the PS / TS converter 84 will be described with reference to FIG.

  As shown in FIG. 7, the PS / TS converter 84 of the embodiment includes a demodulator 85, a sampling circuit 86, a PLL (Phase Locked Loop) 87, a PES memory 88, a link header memory 89, and a null packet. Memory 90, PCR memory 91, PAT memory 92, PMT memory 93, first calculation means, second calculation means, insertion conversion means, setting means, controller 94 as conversion means, address bus 95, data The bus 96 and the TS memory 97 are configured.

  In this configuration, the demodulator 85 demodulates the input PS, generates the PS clock PCK and outputs it to the sampling circuit 86 and the PLL 87, and generates data PDATA corresponding to the information included in the PS to extract the sampling circuit. 86.

  Then, the sampling circuit 86 extracts unnecessary data from the data PDATA by an operation to be described later and converts the corresponding signals to the controller 94 and generates the internal clock WCK from the PS clock PCK. The data is output to the PES memory 88.

  On the other hand, the PES memory 88, the link header memory 89, the null packet memory 90, the PCR memory 91, the PAT memory 92, and the PMT memory 93 are based on the address information output from the address bus 95 by the operation of the controller 94 described later. Data is temporarily stored and output to the data bus 96.

  At this time, the address bus 95 exchanges addresses between the memories under the control of the controller 94, and the data bus 96 exchanges data between the memories under the control of the controller 94.

  Then, the TS memory 97 temporarily stores the generated TS and outputs data TDATA corresponding to the TS to the television apparatus TV.

  In these operations, the controller 94 controls reading and writing in each memory using the control signal Sc.

  In FIG. 7, the symbol “RD” indicates control for reading the memory contents, and the symbol “WE” indicates control for writing to the memory.

  In parallel with these operations, the PLL 87 generates a TS clock TCK for TS from the PS clock PCK, and outputs the TS clock TCK together with the data TDATA to the television device TV and also to the TS memory 97.

  Next, the detailed operation of the sampling circuit 86 will be described with reference to FIGS.

  As shown in FIG. 8, first, the extraction circuit 86 discards the pack header 57 and the system header 58 from the PS, and extracts only the packet PT.

  In the television apparatus TV of the embodiment, the beginning of the payload of a packet PT (hereinafter simply referred to as a video packet) including the video data 64 must be the beginning of a picture. Since it is only the unit of VOBU30 that the head of the picture is matched with the head of the picture, the other packet headers 55 other than VOBU30 are removed, and one large virtual packet is formed for each VOBU30.

  At this time, since the size of the packet changes, the data indicating the packet length in the packet header is rewritten to “0” (that is, not specified). At this time, PTS and DTS are not rewritten.

  Unnecessary packet PT including data other than video data 64 and audio data 65 is also removed by sampling circuit 86. At this time, if there are a plurality of audio streams, unnecessary streams are also excluded. In this case, an unnecessary stream is selected by a selection circuit (not shown).

  Further, in the case of PS on the DVD 1, the private data area is provided after the packet header 55 in the audio pack 43 including the AC-3 audio data 65, and the substream ID and the like described above are provided in the area. Information of 4 bytes is described, but this is also excluded because it is unnecessary information except for the playback apparatus R.

  However, since the packet length information and the actual length of the packet PT are inconsistent simply by extraction, dummy data is provided in the packet header 55 for adjustment in this case.

  More specifically, after sending the original packet header 55, 4-byte “0xFF” is sent, and “4” is added to the value of the packet length information.

  Next, a specific operation of the sampling circuit 86 will be described using the flowcharts of FIGS.

  In the sampling circuit 86, first, when the power is turned on or reset (step S1), it is determined whether or not the first pack header start code (code indicating that the pack header 57 has been input) has been detected. (Step S2) When it is not detected (Step S2; False (hereinafter simply referred to as F)), it waits until it is detected, and when it is detected (Step S2; True (hereinafter simply referred to as T)). ), The SCR basic part and the SCR extension part are extracted from the pack header 57, rearranged in the correct order, and output to the controller 94 as the SCR signal Sscr. Then, the start code and the remaining 10 bytes in the pack header 57 are discarded (step S3).

  Next, it is detected whether or not the next 4 bytes are a system header start code (a code indicating that the system header 58 has been input. Specifically, “0x000001BB”) (step S4). Step S4; F) The remaining 2030 bytes of data including the start code are discarded (Step S5) and the process returns to the initial state. The steps S1 to S5 so far are processing for searching for the packet PT having the system header 58. By this processing, stream conversion can always be started from the beginning of the GOP.

  On the other hand, when a system header start code is found (step S4; T), a start signal Sst indicating that is sent to the controller 94, and the SCR is sent to the controller 94 as an SCR signal Sscr. Set the flag to “HIGH”.

  Here, the protocol for transmitting the SCR is arbitrary, and the timing for setting the start flag to “LOW” is also arbitrary. For example, the rising edge may be detected by the controller 94 with a fixed pulse width, or may be reset by the controller 94 in a register configuration.

  Next, among the internal registers in the controller 94, the navigation pack detection register is set to “HIGH”, and then the remaining 2030 bytes are discarded (step S6).

  Next, a pack header start code is detected (step S7).

  Here, since the pack header start code must be present at this time (step S7; T), this is passed through as it is, and the SCR is obtained and transmitted to the controller 94 as the SCR signal Sscr. Further, the remaining 10 bytes of information in the pack header 57 are not necessary and are discarded (step S8).

  Next, it is detected whether or not a system header start code has been input (step S9). If it has been input (step S9; T), the pack detected at this time is the navigation pack 41. After the navigation pack detection register is set to “HIGH” (step S10), the remaining 2030 bytes are discarded (step S11), and the process returns to step S7.

  On the other hand, when the system header start code is not detected in step S9 (step S9; F), a video packet start code (a code indicating that the packet PT including the video data 64 has been input) is detected. (Step S12; T), the pack P is sent to the PES memory 88 (step S13), and the process returns to step S7. The detailed processing in step S13 will be described in detail later.

  On the other hand, when the video packet start code is not detected in step S12 (step S12; F), it is next determined whether or not the private stream 1 start code is detected (step S14). Step S14; T) The data is transferred to the PES memory 88 only when this pack handles the AC-3 audio data 43 (Step S15). The detailed processing in step S15 will also be described in detail later.

  Further, when the private stream 1 start code is not detected (step S14; F), the remaining data 2030 bytes in the pack P are discarded (step S16), the process returns to step S7, and the above-described operation is performed while removing dummy data. repeat.

  Next, details of the processing in step S13 will be described with reference to FIG.

  In step S13, first, the navigation pack detection flag is verified (step S20).

  When this is “HIGH” (step S20; T), since it is the first video pack 64 of the VOBU 30, the packet header 55 must also be transmitted to the PES memory 88.

  In this case, the packet start code is first transmitted to the PES memory 88 (step S21), and the remaining packet header 55 is stored in a RAM (not shown) built in the extraction circuit 86 (step S22). At this time, the size of the remaining packet header 55 can be easily calculated from the header length information.

Next, the size of the payload is calculated (step S23). Specifically,
(Equation 1)
Payload size = (value of PES packet length information) -3- (value of header length information)
Can be calculated by The calculated value is stored in a register in the sampling circuit 86.

  Next, after rewriting the packet length information to “0” (step S24), the packet header 55 stored in the RAM built in the sampling circuit 86 is transmitted to the PES memory 88 (step S25).

  Thereafter, the content of the payload is transmitted to the PES memory 88 by the amount calculated in step S23 (step S26).

  When the transmission of each data to the PES memory 88 is completed, the number of transmitted bytes is transferred to the controller 94 as a packet length signal Spdl (step S27). At this time, the number of transmitted bytes may be counted by a counter or the like, or may be calculated in advance based on packet length information.

  Since the predetermined transfer is completed, the navigation pack detection flag is set to “LOW” (step S28), and the packet transfer signal Spdt is output to the controller 94 (step S33), thereby notifying the controller 94 of the end of transfer. Then, the pointer of the RAM built in the sampling circuit 86 is reset (step S34), and the process returns to the original main routine.

  On the other hand, when the navigation pack detection flag is “LOW” in step S20 (step S20; F), only the payload needs to be transmitted. First, the packet header 55 is stored in the RAM built in the extraction circuit 86 (step S29). ), The size of the payload is calculated using this content, and stored in a register built in the sampling circuit 86 (step S30).

  Thereafter, the payload is transferred to the PES memory 88 (step S31), the number of transmitted bytes is transferred to the controller 94 as a packet length signal Spdl (step S32), and the process proceeds to step S33.

  Next, details of the contents of the processing in step S15 will be described with reference to FIG.

  In step S15, it is verified whether the packet is a necessary AC-3 system stream, and if it is the AC-3 system stream, dummy data is added and then transmitted to the PES memory 88.

  First, the private stream 1 start code, the remaining packet header 55, and the subsequent 4-byte data are stored in the RAM built in the sampling circuit 86 (steps S35, S36, S37).

  Next, the substream ID in the private data is verified, and it is determined whether or not it indicates AC-3 audio data 65 (step S38). If it is not AC-3 audio data 65 (step S38; F), since there is no need to transmit it to the PES memory 88, the RAM pointer in the sampling circuit 86 is reset (step S46). Return to.

  On the other hand, if it is determined in step S38 that the AC-3 audio data 65 is indicated (step S38; T), it is verified whether the stream is a desired one of a plurality of streams (step S38; T). Step S39).

  If it is not a desired stream (step S39; F), the internal RAM pointer is reset (step S46) and the process returns to the main routine.

  On the other hand, if it is confirmed in step S39 that the audio data 65 is AC-3 format and that the stream is a desired stream (step S39; T), the private header is information unique to DVD1 and is 4 bytes. The data is rewritten to dummy data, and “4” is added to the value of the packet header length information to rewrite the same (step S40).

  Further, the size of the payload is calculated in the same manner as in the case of the video data 64, and 4 bytes of private data are subtracted and stored in the register in the extraction circuit 86 (step S41).

  Thereafter, the contents and payload of the RAM built in the sampling circuit 86 are transmitted to the PES memory 88 (steps S42 and S43), and the number of transmitted bytes is transferred to the controller 94 as a packet length signal Spdl (step S44).

  Since the predetermined transfer is completed, the packet transfer signal Spdt is output to the controller 94 (step S45), thereby notifying the controller 94 of the end of transfer and resetting the RAM pointer in the sampling circuit 86 (step S46). ) Return to the original main routine.

  Here, the PES memory 88 performs a so-called FIFO (First In First Out) operation.

  Since the PES memory 88 operates in pack units, the capacity may be about 4 kbytes.

  Since the contents of the five types of TS packet TPT of the link header 71, null packet, PCR packet, PAT, and PMT in the TS are almost fixed, once a template is created, each RAM (link header memory 89, null packet memory) 90, the PCR memory 91, the PAT memory 92, and the PMT memory 93), and appropriately change them and multiplex them where necessary. At this time, input and change of each RAM are performed by the controller 94 via the data bus 96.

  Here, an example of the value of the TS packet TPT input to each RAM is specifically shown.

  First, an example of the value of the TS packet TPT including the link header 71 input to the link header memory 89 is shown in the following table.

このリンクヘッダメモリ８９は、ダミーデータに対応するように形成されるので、読み出すバイト数はダミーデータの量に依存する。

Since this link header memory 89 is formed to correspond to dummy data, the number of bytes to be read depends on the amount of dummy data.

  That is, when the payload is 184 bytes and there is no dummy data, only the first 4 bytes are read. In this case, the adaptation field control (Adaptation Field Control) is “01”.

  When the payload is 183 bytes and 1-byte dummy data is required, the first 5 bytes are read. In this case, the adaptation field control is “11”, and the adaptation field length (Adaptation Field Length) is “0x00”.

  Further, when the payload is 182 bytes and 2 bytes of dummy data is required, the first 6 bytes are read. In this case, the adaptation field control is “11”, and the adaptation field length is “0x01”.

  Finally, when the payload is from 1 byte to 181 bytes, only the amount obtained by subtracting the number of bytes of the payload from 188 bytes is read. In this case, the adaptation field control is “11”, and the adaptation field length is a value obtained by subtracting the number of bytes of the payload from 183 bytes.

  The value of PID depends on the type of elementary stream.

  In the case of the television apparatus TV of this embodiment, if the basic PID is defined by shifting the program number to the left by 4 bits, the video is defined as (basic PID + 0x0001) and the audio is defined as (basic PID + 0x0004). Here, a PID is created by a program number selected by a selection circuit (not shown).

  The random access indicator is “1” in the first video packet of the GOP.

  Next, an example of the value of the TS packet TPT including the null packet input to the null packet memory 90 is shown in the following table.

ヌルパケットのＰＩＤは「０ｘ１ＦＦＦ」である。

The PID of the null packet is “0x1FFF”.

  Since any data byte can be entered, the value stored in the RAM by default without being transferred may be used as it is.

  Furthermore, an example of the value of the TS packet TPT including the PCR packet input to the PCR memory 91 is shown in the following table.

実施形態のテレビジョン装置ＴＶでは、ＰＣＲパケットのＰＩＤは、ビデオの場合と同じで、（基礎ＰＩＤ＋０ｘ０００１）とされている。

In the television apparatus TV of the embodiment, the PID of the PCR packet is the same as that of video, and is (basic PID + 0x0001).

  Also, the PCR value is calculated and rewritten on the basis of the SCR immediately before transmitting this packet.

  Furthermore, since this packet is only intended to transmit PCR, it does not have a payload.

  Furthermore, in the first PCR packet, the discontinuity indicator (Discontinuity Indicator) needs to be “1”.

  Further, an example of the value of the TS packet TPT including the PAT input to the PAT memory 92 is shown in the following table.

ＰＡＴのＰＩＤは「０ｘ００００」とされている。

The PID of the PAT is “0x0000”.

  Finally, an example of the value of the TS packet TPT including the PMT input into the PMT memory 93 is shown in the following table.

ＰＭＴのＰＩＤは（基礎ＰＩＤ＋０ｘ００００）とすることが規定されている。

It is specified that the PID of the PMT is (basic PID + 0x0000).

  In addition, descriptors related to program information are program identifiers and program smoothing buffer descriptors, and those related to elementary stream information are data stream assignment descriptors for video and audio elementary for audio. A stream identifier and an AC-3 audio descriptor.

  Next, the operation of the controller 94 in the PS / TS converter 84 will be described in detail with reference to FIGS. The controller 94 mainly performs operations such as appropriately updating the above six memories and switching them to transfer data to the TS memory 97 by DMA (direct memory access).

  In the following description, a case will be described in which processing is completed in units of PS packs P in order to simplify the algorithm.

  Further, PTS and DTS are not replaced, and the SCR is converted to PCR without changing it as much as possible.

  In general, when PS is converted to TS, the transfer rate increases. This is because a 4-byte header is added to a small unit of 184 bytes in TS.

Here, the minimum value of the TS transfer rate is roughly
(Equation 2)
Minimum transfer rate = (PS transfer rate) × (188/184) + (PAT, PMT)
Transfer rate)-(pack header 57 transfer rate)
It becomes.

  In the following description, an algorithm that can cope with any transfer rate higher than the rate calculated by this equation will be described.

  First, FIG. 12A shows an example of the occupation ratio of the video buffer 67 or the audio buffer 69 in pack units of DVD1.

  In this example, each buffer of the decoder D outputs picture data while reading pack P data.

  As described above, picture data is output in an instant.

  In this embodiment, the PTS and the DTS are not changed, and the SCR is converted into the PCR without changing as much as possible. Therefore, the converted TS buffer (the transport buffer 73 or 76 in the decoder D ′, the video buffer 74 or If the accumulated amount of the virtual buffer including the audio buffer 77 is less than the accumulated amount of the PS buffer (the virtual buffer of the video buffer 67 or the audio buffer 69), there is a possibility that underflow may occur in the TS buffer. is there.

  For example, in the example shown in FIG. 12B, an underflow occurs in the TS buffer due to an incorrect TS packet insertion method. That is, there is a possibility of underflow whenever the timing at which each picture in TS and PS is output cannot be grasped.

  Therefore, in the present embodiment, control is performed so that the TS buffer accumulation amount always exceeds the PS buffer accumulation amount.

  As described above, the TS transfer rate is higher than the PS transfer rate, but this is nothing other than inserting the first TS packet TPT before (or simultaneously with) the packet PT in the PS.

  However, if the TS packet TPT is inserted before (or simultaneously with) the packet PT in the PS, there is a possibility that an overflow in the TS buffer will occur as shown in FIG.

  Therefore, in this embodiment, the null packets are inserted into the TS corresponding to the difference between the accumulation amounts of the respective buffers, thereby matching the increase rates of both accumulation amounts. This point will be described with reference to FIG.

  As described above, with respect to the accumulation amount of each buffer, it is necessary to always prevent the TS buffer accumulation amount from being lower than the PS buffer accumulation amount.

  On the other hand, when the TS packet TPT including dummy data is inserted immediately after the inserted null packet, the TS data is not input for a period of almost two packets at the maximum.

In this case as well, in order to satisfy the above condition (so that the TS buffer accumulation amount does not fall below the PS buffer accumulation amount), in FIG.
(Equation 3)
Bx ≧ (Rps / Rts) × (188 × 2) (bytes)
Need to be. However, in the above equation, Bx is the difference in the accumulated amount of each buffer after one packet is transmitted in each stream, and Rps and Rts are the transfer rates of TS and PS, respectively.

  If the null packet is inserted so as to satisfy this condition, the difference between the buffer accumulation amounts of the two streams is always within Bx.

  However, even with such a configuration, the difference in the buffer accumulation amount occurs only up to Bx, so there is still a possibility of overflow.

Here, an overflow does not occur unless the maximum amount Bx of the difference between the buffer accumulation amounts exceeds the capacity of the transport buffers 73 and 74 specific to the TS. Here, since the capacities of the transport buffers 73 and 74 are determined to be 512 bytes as described above, after all,
(Equation 4)
(Rps / Rts) × (188 × 2) (bytes) ≦ Bx ≦ 512 bytes should be satisfied.

Here, considering the case where the playback device R that plays back the DVD 1 in this embodiment is connected to the television device TV, Rps = 10.008 Mbps and Rts = 19.99 Mbps.
(Equation 5)
(10.08 / 19.39) × 188 × 2≈196
Therefore, control should be performed so that 196 bytes ≦ Bx ≦ 512 bytes.

  By the way, when creating PS data, a safety band is often provided for buffer control.

  In this method, a predetermined margin is provided at the upper and lower portions of the buffer, and the buffer occupancy is determined within the range. In this case, the Bx can be set wider as much.

That is, if the upper margin is Bmu and the lower margin is Bml,
(Equation 6)
(Rps / Rts) × (188 × 2) (bytes) −Bml ≦ Bx ≦ 512 bytes + Bmu
Control may be performed so that

That is, in the case of the playback device R and the television device TV,
(Equation 7)
196-Bml ≦ Bx (bytes) ≦ 512 + Bmu
It becomes.

  Here, as described above, in order to complete the processing in units of PS pack P, if the data of packet PT in that unit is not divisible by 184 bytes, dummy data is put in the last TS packet TPT and adjusted. To do.

  When the empty area such as the position where the navigation pack 41 is located has a TS transfer rate of 188 bytes or more, a null packet is inserted to adjust the transfer rate.

  For example, in the case of a variable rate PS such as DVD1, there is a case where a buffer input wait may occur in units of pack P. In this case, too, if it is 184 bytes or more, it is adjusted with a null packet and fixed rate Try to be TS.

  At this time, as described above, since the TS must start to be transmitted in units of packs P rather than PS, when the empty space is within 184 bytes, the TS packet TPT starts to be inserted from there.

  Furthermore, as described above, it is necessary to multiplex various additional information in the TS. For example, in the case of the television apparatus TV of the embodiment, the PAT, PMT, and PCR packets correspond to this. These need to be inserted at a frequency of at least 0.1 seconds, 0.4 seconds, and 0.1 seconds, respectively.

  In order to satisfy this, the null packet is replaced with these pieces of information at a predetermined frequency set in advance. In this case, when inserting a null packet, this and the additional information may be switched and inserted.

  For example, 50 msec from the last insertion for PAT and PCR packets, 200 msec from the previous insertion for PMT, and replace the first null packet after that time with the respective information. That's fine. This time measurement can be easily performed in the process of obtaining the PCR.

  Here, in the decoder D ′, correct decoding cannot be performed until these pieces of information are received. Therefore, when the PS / TS converter 84 of the embodiment starts to operate, it is always necessary to output these before outputting the elementary stream. Information must be inserted.

  On the other hand, the controller 94 includes the following nine registers.

  That is, an SCR1 register, an SCR2 register, a PCR register, a PDLEN (Packet Data Length) register, a PS buffer register, a TS buffer register, a PCR interval register, a PAT interval register, and a PMT interval register are provided. Yes.

  At this time, the SCR value of the PS is stored in the SCR1 register and the SCR2 register.

  The PCR register stores the PCR value of the TS packet TPT next to the TS packet TPT inserted last.

  Furthermore, the length of data to be transmitted in the PS is stored in the PDLEN register.

  The PS buffer register and the TS buffer register store the PS buffer accumulation amount and the TS buffer accumulation amount at that point in time (predicted values based on SCR or PCR, respectively).

  Finally, the PCR interval register, the PAT interval register, and the PMT interval register store the value of the PCR packet, PAT, or PMT inserted last at that time, respectively.

  Next, a specific operation of the controller 94 will be described with reference to the flowcharts of FIGS.

  First, the operation at the time of initialization of the controller 94 will be described using the flowchart shown in FIG.

  As shown in FIG. 14, at the time of initialization of the controller 94, first, after turning on or resetting the power (step S1), all internal registers are initialized (step S51), and the respective RAMs are initialized. The template related to information is recorded (step S52).

  Thereafter, the sampling circuit 84 is reset (step S53), and then it is determined based on the start signal Sst from the sampling circuit 86 whether or not the start code in the navigation pack 41 has been input (step S54). When the start signal Sst is not input (step S54; F), the process waits as it is. When the start signal Sst is input (step S54; T), it is detected that the navigation pack 41 is detected, and the SCR therein is received as the SCR signal Sscr. After the data is input to the register and the PCR register (step S56), the information stored in the PAT memory 92 is DMA-transferred to the TS memory 97, and the PCR at that time is stored in the PAT interval register (step S57). Thereafter, the value of the PCR register is increased by the time Ttsp (step S58).

  Next, the information stored in the PMT memory 93 is DMA-transferred to the TS memory 97, and the PCR at that time is stored in the PMT interval register (step S59). Thereafter, the value of the PCR register is increased by the time Ttsp (step S60).

  Here, the time Ttsp is obtained by measuring the time for transmitting one TS packet TPT at 90 kHz, and is obtained as follows.

(Equation 8)
Ttsp = (188 × 8) × 90000 / Rts
Since this value is not normally divisible, it can be held in, for example, a floating point and rounded off or rounded off each time it is incremented.

  Then, the PCR memory 91 is rewritten with the value of the PCR register at this time (step S61), and the PCR packet is transferred. The PCR at that time is stored in the PCR interval register (step S62). Thereafter, the value of the PCR register is increased by the time Ttsp (step S63), and the process proceeds to the next main routine.

  Next, a main routine of processing in the controller 94 will be described with reference to FIG.

  As shown in FIG. 15, when the above-described initialization ends, the next SCR value is fetched based on the SCR signal Sscr (step S65), and this is fetched into the SCR2 register (step S66).

  At this time, SCR1 roughly represents the start time of the navigation pack 41, and SCR2 generally represents the end time thereof.

  Next, the packet transfer signal Spdt is confirmed (step S69).

  The pack P immediately after the start signal Sst is input is the navigation pack 41, and at this time, the packet transfer signal Spdt is not “HIGH” (step S69; F).

  Therefore, it is next determined whether or not the difference between the value in the PCR register and the value in the SCR2 register is equal to or greater than the time Ttsp (step S82), and when the difference is equal to or greater than the time Ttsp (step S82; T), The information packet is transferred to the TS memory 97 within a range where the value of the PCR register does not exceed the value of the SCR2 register (step S83), the value of the PCR register is incremented by the time Ttsp (step S84), and step S82 is performed again. Return to and repeat the operation so far.

  On the other hand, when the difference between the value of the PCR register and the value of the SCR2 register is less than the time Ttsp in the determination of step S82 (step S82; F), the contents of the SCR2 register are copied to the SCR1 register (step S85). Returning to the original step S65, the above operation is repeated.

  Here, the information packet indicates the PCR packet, PAT, PMT, or null packet.

  On the other hand, if the packet transfer signal Spdt is “HIGH” in the determination in step S67 (step S69; T), the number of bytes in which valid data has been transferred to the PES memory 88 is obtained from the sampling circuit 86 as the packet length signal Spdl. Since it is transmitted, it is stored in the PDLEN register (step S68).

  Next, it is determined whether or not the value of the PDLEN register is 184 bytes or more (step S69). If it is 184 bytes or more (step S69; T), the PS buffer register is first calculated by calculating the PS buffer accumulation amount. (Step S70).

This value is
(Equation 9)
PS buffer register = Rps × (PCR-SCR1) / 90000
Can be calculated as

  Next, the difference between the TS buffer register and the PS buffer register is obtained (step S71). If this difference is larger than the aforementioned threshold value Bx (step S71; T), the information packet is transferred to the TS memory 97 (step S77), and the process proceeds to step S76.

  On the other hand, if it is determined in step S71 that the difference between the TS buffer register and the PS buffer register is not larger than the threshold value Bx (step S71; F), the contents of the link header memory 89 are rewritten so that the link header 71 is transmitted. 4 bytes are transferred (step S72), and the contents of the PES memory 88 are transferred 184 bytes (step S73).

  Thereafter, the value of the TS buffer register is incremented by 184 bytes (step S74), and the value of the PDLEN register is decremented by 184 bytes (step S75).

  Thereafter, the value of the PCR register is incremented by the time Ttsp (step S76), and the process returns to step S69.

  On the other hand, if it is determined in step S69 that the value of the PDLEN register is less than 184 bytes (step S69; F), the contents of the link header memory 89 are rewritten to send dummy data, and then the dummy data is included. Only the number of bytes is transferred (step S78).

The number of bytes transferred at this time is
(Equation 10)
Number of transfer bytes = 4 + 184-(PDLEN register value)
Obtained from

  Thereafter, by transferring the contents of the PES memory 88 by the amount indicated by the PDLEN register (step S79), the 188-byte TS packet TPT can be transferred as a result.

  Thereafter, the PCR register is incremented by the time Ttsp (step S80), and all the valid contents in the pack P have been transferred, so the contents of the TS buffer register are reset (step S81).

  There may be a dummy packet after this. In this case, since the next SCR (SCR2) is sufficiently larger than the PCR at this time, the information packet is inserted by the above-described algorithm.

  Next, transmission of information packets in steps S77 and S83 will be described with reference to FIG. Here, one of the information packets is selected and inserted from the information packet according to the value of the interval calculation register.

That is, in sending information packets in steps S77 and S83, first, the difference between the values of the PCR register and the PCR interval register is detected (step S90), and the difference is 50 msec, that is,
(Equation 11)
90000 × 0.05 = 4500
When the above is reached (step S90; T), the contents of the PCR memory 91 are then rewritten to send one PCR packet (step S95), and the contents of the PCR memory 91 are sent to the TS memory 97 for 188 bytes. Then (step S92), the value of the PCR interval register is rewritten to the value of the PCR register at that time (step S93), and the process returns to the original main routine.

  On the other hand, if it is determined in step S90 that the difference between the PCR register and the PCR interval register is less than “4500”, then the difference between the PCR register and the PAT interval register is detected (step S94). Is 50 msec, that is, “4500” or more (step S94; T), the contents of the PAT memory 92 are then rewritten to send one PAT (step S95), and the contents of the PAT memory 92 are changed. 188 bytes are transmitted to the TS memory 97 (step S96), the value of the PAT interval register is rewritten to the value of the PCR register at that time (step S97), and the process returns to the original main routine.

On the other hand, when the difference between the values of the PCR register and the PAT interval register is less than “4500” in the determination of step S94 (step S94; F), the difference between the values of the PCR register and the PMT interval register is then detected ( Step S98), the difference is 0.2 seconds, that is,
(Equation 12)
90000 × 0.2 = 18000
When the above is reached (step S98; T), the contents of the PMT memory 93 are then rewritten to send one PMT (step S99), and the contents of the PMT memory 93 are sent to the TS memory 97 for 188 bytes. (Step S100), the value of the PMT interval register is rewritten to the value of the PCR register at that time (Step S101), and the process returns to the original main routine.

  Next, when the difference between the values of the PCR register and the PMT interval register is less than “18000” in the determination in step S98 (step S98; F), the content of the null packet memory 90 is transmitted as one null packet. The data is rewritten (step S102), and the null packet is sent to the TS memory 97 for 188 bytes (step S103), and the process returns to the original main routine.

  Next, the form of the TS generated by the above-described algorithm is schematically shown in FIG.

  As shown in FIG. 17, information packets such as PAT and PMT are placed at positions corresponding to the navigation pack 41 in the PS, and actual data or dummy data or null packets as TS are placed in the elementary pack portion. Will be inserted.

  At this time, the accumulation amount in the transport buffer 73 or 74 remains “0” between the information packets, and increases at a timing other than the null packet or the dummy data (see the solid line in FIG. 17). . Further, the accumulation amount of the video buffer 67 gradually increases from the timing when the PS elementary pack is started (see the dashed line in the graph of FIG. 17).

  FIG. 18 shows changes in the accumulation amount of the transport buffers 73 and 74 (solid line) and changes in the accumulation amount of the video buffer 67 (broken line) when the PS / TS conversion of the embodiment is actually performed.

  As is apparent from this graph, the accumulation amount of the transport buffers 73 and 74 always exceeds the accumulation amount of the video buffer 67, and changes without causing overflow or underflow.

  As described above, according to the operation of the PS / TS converter 84 according to the embodiment, the TS decoding process can be prevented from being interrupted, and a simple process can be performed without performing a decomposition process on the PS. PS can be converted to TS.

  Further, when the difference between the accumulated amounts of the buffers becomes equal to or larger than the threshold value Bx, the conversion is performed while inserting dummy data irrelevant to the PS, so that the transport buffer 73 or 74 does not change the data content of the PS. The PS can be converted to TS by preventing overflow or underflow in the.

  Further, the threshold Bx is set so that the accumulated amount of the TS in the transport buffer 73 or 74 always exceeds the accumulated amount of the PS in the video buffer 67, and the maximum of the transport buffer 73 or 74 is set. Since the capacity is less than or equal to the capacity, PS can be converted to TS while reliably preventing overflow or underflow in the transport buffer 73 or 74.

  Furthermore, when the threshold Bx is equal to or less than the maximum capacity of the transport buffer 73 or 74 plus the upper and lower margin capacities, overflow or underflow in the transport buffer 73 or 74 is reliably prevented. PS can be converted to TS.

  Further, since the information packet is at least one of the information of the PCR packet, PAT, PMT, or null packet, the TS can be generated without affecting the decoding of the TS.

  Further, in the TS, when the insertion frequency of the PCR packet, PAT, and PMT is preset in the information packet, the PCR packet, PAT, and PMT are inserted so as to satisfy the insertion frequency, and the PCR packet, PAT, and PMT are also inserted. Since a null packet is inserted at a position in the TS where an information packet is to be inserted in addition to a position where an information packet is to be inserted, PS can be efficiently converted to a TS.

  Further, since dummy data is inserted and PS is converted to TS, underflow of transport buffer 73 or 74 can be prevented and TS can be generated without affecting the contents of TS.

It is a figure which shows the structure of a packet and a pack, (a) is a figure which shows the structure of a packet, (b) is a figure which shows the structure of a pack. It is a figure which shows the physical format of PS on DVD. It is a figure which shows the structure of each pack of PS, (a) is a figure which shows the structure of a navigation pack, (b) is a figure which shows the structure of a video pack, (c) shows the structure of an audio pack. FIG. It is a figure which shows the decoder of PS, (a) is a schematic block diagram, (b) is a graph which shows the change of the accumulation amount of a buffer. It is a figure explaining TS, (a) is a figure which shows the structure of TS, (b) is a general | schematic structure block diagram which shows the decoder of TS. It is a block diagram which shows the schematic structure of the information reproduction apparatus of embodiment. It is a block diagram which shows schematic structure of the PS / TS converter of embodiment. It is a figure which shows the outline | summary of conversion operation | movement. It is a flowchart which shows the whole operation | movement of a sampling circuit. It is a flowchart which shows the process of the video pack in a sampling circuit. It is a flowchart which shows the process of the audio pack in a sampling circuit. FIG. 4A is a diagram illustrating a conversion operation, FIG. 4A is a diagram illustrating a change in the accumulation amount of the video buffer, and FIG. 4B is a diagram illustrating an underflow in the TS buffer. FIG. 11 is a diagram (II) showing a conversion operation, (a) is a diagram showing that an overflow occurs in the TS buffer, and (b) is a diagram showing a change in the accumulated amounts of the TS buffer and the PS buffer according to the present invention. It is. It is a flowchart which shows the initialization process in a controller. It is a flowchart which shows the whole process in a controller. It is a flowchart which shows the information packet transmission process in a controller. It is a figure which shows the relationship between PS and TS by this invention. It is an experimental result which shows the change of the accumulation amount of TS buffer, and the change of the accumulation amount of PS buffer.

Explanation of symbols

1 DVD
2 Video manager 3 VTS
10 VOB
11 Control data 20 cells 30 VOB unit 41 Navi pack 42 Video pack 43 Audio pack 44 Sub picture pack 55 Packet header 56 Packet data 57 Pack header 58 System header 62 PCI packet 63 DSI packet 64 Video data 65 Audio data 66, 72 Demultiplexer 67, 74 Video buffer 68, 75 Video decoder 69, 77 Audio buffer 70, 78 Audio decoder 71 Link header 73, 74 Transport buffer 80 Detection circuit 81 Demodulation circuit 82 Error correction circuit 83, D, D 'decoder 84 PS / TS converter 85 Demodulator 86 Sampling circuit 87 PLL
88 PES memory 89 Link header memory 90 Null packet memory 91 PCR memory 92 PAT memory 93 PMT memory 94 Controller 95 Address bus 96 Data bus 97 TS memory R Playback device TV Television device PS Program stream TS Transport stream P Pack PT Packet LI Lead-in area LO Lead-out area TPT TS packet PCK PS clock PDATA, TDATA Data TCK TS clock Sst Start signal Sscr SCR signal Spdl Packet length signal Spdt Packet transfer signal

Claims (8)

A first data stream including first time information set so that neither overflow nor underflow occurs in the first buffer means during decoding, wherein the first buffer is based on the first time information. A stream conversion device for converting a first data stream decoded while being temporarily stored in the means into a second data stream decoded while being temporarily stored in the second buffer means based on the second time information;
Setting means for setting the second time information so that neither overflow nor underflow occurs in the second buffer means when decoding the converted second data stream;
Conversion means for converting the first data stream into the second data stream while multiplexing the set second time information;
Equipped with a,
The transfer rate of the second data stream is higher than the transfer rate of the first data stream;
The converting means includes
Based on the first time information, first calculation means for predicting and calculating an accumulation amount of the first data stream in the first buffer means when the first data stream is decoded using the first time information. When,
Second calculation means for predicting and calculating an accumulation amount of the second data stream in the second buffer means when decoding the second data stream using the second time information based on the second time information When,
When the difference between the accumulated amount of the first data stream in the first buffer means and the accumulated amount of the second data stream in the second buffer means exceeds a predetermined threshold value, the first Insertion conversion means for converting the first data stream into the second data stream while inserting preset insertion information irrelevant to one data stream;
Composed of
Said second buffer means comprises at least unique buffer means specific to said second data stream;
The threshold is set so that the accumulated amount of the second data stream in the second buffer means always exceeds the accumulated amount of the first data stream in the first buffer means, and the unique buffer means A stream converter characterized in that it is less than the maximum capacity . The stream converter according to claim 1 ,
The first time information is set so that a preset unstored area is generated in the first buffer when the first data stream is stored in the first buffer means, and
The threshold is set so that the accumulated amount of the second data stream in the unique buffer means always exceeds the accumulated amount of the first data stream in the first buffer means, and the unique buffer means The stream conversion apparatus , wherein the maximum capacity is equal to or less than a value obtained by adding the capacity of the unstored area . The stream converter according to claim 1 or 2,
The insertion information is at least one of the new second time information, content information indicating the content of data included in the second data stream, or information indicating 0. Conversion device. The stream converter according to claim 3,
In the second data stream, when the insertion frequency of the second time information and the content information among the insertion information is set in advance, the conversion means sets the second time information so as to satisfy the insertion frequency. And inserting the content information,
The stream conversion apparatus , wherein information indicating the 0 is inserted at a position in the second data stream where the insertion information other than the position where the second time information and the content information are to be inserted is inserted . In the stream converter according to any one of claims 1 to 4 ,
The first data stream is a MPEG-2 (Moving Picture Expert Group 2) standard program stream detected from a DVD, the second data stream is the MPEG2 standard transport stream, and
The stream conversion device, wherein the conversion means converts the program stream into the transport stream while deleting unnecessary data that is unnecessary data in the program stream in the transport stream . The stream converter according to claim 5, wherein
The stream conversion device , wherein the conversion means converts the program stream into the transport stream by inserting dummy data for preventing underflow in the second buffer means in place of the unnecessary data . A first data stream including first time information set so that neither overflow nor underflow occurs in the first buffer means during decoding, wherein the first buffer is based on the first time information. A stream conversion device for converting a first data stream decoded while being temporarily stored in the means into a second data stream decoded while being temporarily stored in the second buffer means based on the second time information;
Setting means for setting the second time information so that neither overflow nor underflow occurs in the second buffer means when decoding the converted second data stream;
Conversion means for converting the first data stream into the second data stream while multiplexing the set second time information;
With
The transfer rate of the second data stream is higher than the transfer rate of the first data stream;
The converting means includes
Based on the first time information, first calculation means for predicting and calculating an accumulation amount of the first data stream in the first buffer means when the first data stream is decoded using the first time information. When,
Second calculation means for predicting and calculating an accumulation amount of the second data stream in the second buffer means when decoding the second data stream using the second time information based on the second time information When,
When the difference between the accumulated amount of the first data stream in the first buffer means and the accumulated amount of the second data stream in the second buffer means exceeds a predetermined threshold value, the first Insertion conversion means for converting the first data stream into the second data stream while inserting preset insertion information irrelevant to one data stream;
Composed of
The insertion information is at least one of the new second time information, content information indicating the content of data included in the second data stream, or information indicating 0. Conversion device. The stream converter according to claim 7,
In the second data stream, when the insertion frequency of the second time information and the content information among the insertion information is set in advance, the conversion means sets the second time information so as to satisfy the insertion frequency. And inserting the content information,
The stream conversion apparatus , wherein information indicating the 0 is inserted at a position in the second data stream where the insertion information other than the position where the second time information and the content information are to be inserted is inserted .

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