JP3787411B2 - Information processing apparatus and method, and computer-readable recording medium on which information processing program is recorded - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an information processing apparatus and method for separating and decoding signals transmitted by encoding and multiplexing information signals of a plurality of programs, and a computer-readable recording medium on which an information processing program is recorded.
[0002]
[Prior art]
Recently, digital processing systems compliant with MPEG (Moving Picture Experts Group) 2 standards (ISO / IEC (International Organization for Standardization / International Electrotechnical Commission) 13818-1-3) It is becoming the standard. It becomes possible to transmit video / audio data and the like with high quality within a limited transmission band by a device conforming to the MPEG2 standard. In MPEG2, video and audio are digitally compressed and multiplexed by an encoding device, and the video and audio signals multiplexed by a decoding device are separated and decoded.
[0003]
FIG. 6 is a block diagram showing the configuration of a digital information transmission system using MPEG2.
[0004]
In FIG. 6, reference numerals 100 and 102 denote digital video signal input terminals, 101 and 103 denote video encoding circuits for compressing the digital video signal, 104 and 106 denote digital audio signal input terminals, and 105 and 107 denote digital audio signal compression. An audio encoding circuit, 108 is a video encoding circuit 101, 103, a multiplexing circuit that multiplexes the signals output from the audio encoding circuits 105, 107, and 109 converts the multiplexed signal into a transmission format and modulates it. Transmission line encoding / modulation circuit.
[0005]
110 is a transmission path decoding / demodulation circuit that demodulates the transmitted signal and cancels the transmission format, 111 is a separation circuit that separates the multiplexed video / audio signals, and 112 is the original video signal that has been separated. Decompressing video decoding circuit, 113 is a video output terminal for outputting the decompressed video signal, 114 is an audio decoding circuit for decompressing the separated audio signal to the original signal, and 115 outputs the decompressed audio signal. Audio output terminal.
[0006]
The operation of the digital information transmission system configured as described above will be described.
[0007]
The video signals input from the digital video signal input terminals 100 and 102 are compressed and packetized by the video encoding circuits 101 and 103 so as to conform to the syntax of MPEG2 video (ISO / IEC13818-2). Are output to the circuit 108 respectively.
[0008]
Audio signals input from digital audio signal input terminals 104 and 106 are compressed and packetized by audio encoding circuits 105 and 107 so as to conform to the syntax of MPEG audio (ISO / IEC11172-3), and multiplexed. Are output to the circuit 108 respectively.
[0009]
The multiplexing circuit 108 multiplexes a plurality of video / audio packet signals into one packet signal in a transport stream format for multiplexing a plurality of programs in the MPEG2 system (ISO / IEC13818-1).
[0010]
Since information such as which program is selected from a plurality of programs, which packet is extracted and how to be decoded is necessary on the receiving side, the program specification information (PSI: Program Specific) is required in the MPEG2 system. Information) is specified.
[0011]
Therefore, the multiplexing circuit 108 also multiplexes these PSIs. The multiplexing circuit 108 outputs a transport stream obtained by multiplexing each program and PSI to the transmission path encoding / modulation circuit 109.
[0012]
FIG. 7 shows an example of multiplexing of transport streams.
[0013]
The transport stream is composed of 188-byte fixed-length packets, and a 4-byte packet header is multiplexed on 188-byte packets. In this packet header, a packet identifier (PID: Packet Identification) for identifying the type of payload (data such as video, audio and PSI) after the packet header is multiplexed.
[0014]
The PSI is composed of four tables. In this one program association table (PAT), this table indicates each program number constituting the transport stream and the PID of the program map table (PMT) for transmitting information of packets constituting the program. The PMT indicates the PID of a packet in which a stream of video, audio, additional data, etc. constituting the program is transmitted for each program number. Since the remaining two tables are not related to the present invention, description thereof will be omitted.
[0015]
The transmission path encoding / modulation circuit 109 adds an error correction signal for transmission, performs interleaving processing, etc., digitally modulates and sends it to the transmission path.
[0016]
The transmission path decoding / demodulation circuit 110 digitally demodulates a signal from the transmission path, performs deinterleave processing, error correction decoding, and the like, and outputs the result to the separation circuit 111.
[0017]
The separation circuit 111 separates the video / audio stream from the transport stream based on the PSI described above, and outputs it to the video decoding circuit 112 and the audio decoding circuit 114.
[0018]
Specifically, the received data separation processing in the separation circuit 111 will be described with reference to FIG.
[0019]
FIG. 8 is a flowchart for explaining video / audio stream separation processing from the received transport stream.
[0020]
First, the program number received by the receiving side is selected. In this example, it is assumed that program number 2 is selected.
[0021]
In step S101, it is determined whether or not a PAT transmitted in a packet with PID = 0 is received. If received, the process proceeds to step S102. If not received, the current state is maintained and reception is awaited.
[0022]
In step S102, the PAT is written into the memory. In step S103, a program map PID corresponding to program number 2 is detected (in this example, PID = XX).
[0023]
Next, in step S104, it is determined whether or not a PMT transmitted in a packet of PID = XX has been received. If received, the process proceeds to step S105, and if not received, the current state is maintained and reception is awaited.
[0024]
In step S106, an elementary PID for each stream type (video, audio) corresponding to program number 2 is detected in the PMT (in this example, video: PID = XV, audio: PID = XA).
[0025]
In step S107, it is determined whether a transport stream packet having PID = XV has been received. If received, the process proceeds to step S108. If not received, the process proceeds to step S109.
[0026]
In step S108, the video stream of the transport stream packet having PID = XV is output to the video decoding circuit 112.
[0027]
In step S109, it is determined whether or not a transport stream packet having PID = XA has been received. If received, the process proceeds to step S108. If not received, the process returns to step S107.
[0028]
In step S110, the audio stream of the transport stream packet having PID = XA is output to the audio decoding circuit 114.
[0029]
The video / audio stream is separated from the transport stream by the above process.
[0030]
[Problems to be solved by the invention]
However, in the case of a device that multiplex-transmits a plurality of programs and has a decoding circuit for a plurality of programs, in the worst case, a received PID, an elementary PID for the decoding circuits of the plurality of programs, and a program map PID describing the elementary PID And PAT of PAT need to be compared and separated. The worst case is when the received PID and the PID just described do not match to the end.
[0031]
For example, when 8 programs are transmitted and 8 programs are received and each program is video and audio, the worst case is 25 (= PAT (1) + PMT (8) + elementary (8 × 2)) Comparison processing with PID is required.
[0032]
Further, when the comparison process with the PID is performed using the CPU, generally one search / comparison process requires a processing cycle number of about several cycles to several tens of cycles. When a syntax check of the transport stream is performed, the number of processing cycles is further required.
[0033]
For this reason, there are problems that the number of programs to be received can be limited and that comparison processing needs to be performed at high speed.
[0034]
In view of the above-described background, the present invention solves the above-described problems and can reduce the processing time required for search comparison processing for identification of transmitted packets, and a computer-readable recording medium recording an information processing program The purpose is to provide.
[0035]
[Means for Solving the Problems]
An information processing apparatus according to the present invention includes: an input unit that inputs a multiplexed stream signal in which a plurality of programs transmitted in units of packets to which a packet identification signal for identifying each packet is added; and the input unit Extraction means for extracting the program specification information for recognizing the packet corresponding to each program from the multiplex stream signal input from, and in association with each program specification based on the program specification information extracted by the extraction means, Generating means for making a table of at least a packet identification signal, an attribute flag, and output address information; and distributing means for distributing and outputting the multiplexed stream signal input by the input means based on the table generated by the generating means It is characterized by having.
[0036]
The information processing method according to the present invention includes an input step of inputting a multiplexed stream signal in which a plurality of programs transmitted in packet units to which a packet identification signal for identifying each packet is added is multiplexed, An extraction step for extracting program specification information for recognizing a packet corresponding to each program from the multiplexed stream signal input in the input step, and correspondence to each program specification based on the program specification information extracted by the extraction step A generation step of tabulating at least a packet identification signal, an attribute flag, and output address information, and a distribution step of distributing and outputting the input multiplexed stream signal based on the table generated by the generation step. It is characterized by having.
[0037]
A computer-readable recording medium in which an information processing program according to the present invention is recorded, and a multiplexed stream in which a plurality of programs transmitted in packet units to which a packet identification signal for identifying each packet is added are multiplexed Input a signal, extract program specification information for recognizing a packet corresponding to each program from the multiplex stream signal, and each program specification based on the program specification information extracted by the extraction step Correspondingly, at least a packet identification signal, a flag indicating an attribute, and a code of a generation process that forms a table of output address information, and the input multiplexed stream signal are distributed and output based on the table generated by the generation process Characterized by having a distribution step with a code
[0038]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing the configuration of a digital information transmission system as an embodiment of the present invention.
[0039]
In FIG. 1, 10, 12, 14, and 16 are input terminals for digital video signals, 11, 13, 15, and 17 are video encoding circuits that compress the digital video signals, and 18, 20, 22, and 24 are digital audio signals. Input terminals 19, 21, 23, 25 are audio encoding circuits for compressing digital audio signals, and 26 is output from the video encoding circuits 11, 13, 15, 17 and audio encoding circuits 19, 21, 23, 25. And a multiplexing circuit for multiplexing the signals.
[0040]
27 is a transmission path encoding / modulation circuit that converts and modulates a multiplexed signal into a transmission format, 28 is a transmission path decoding circuit that demodulates the transmitted signal and cancels the transmission format, and 29 is a multiplexed video / audio signal. Separating circuit 30, 32, 34, 36 is a video decoding circuit for decompressing the separated video signal to the original signal, and 31, 33, 35, 37 are video output terminals for outputting the decompressed video signal , 38, 40, 42, and 44 are audio decoding circuits that expand the separated audio signal to the original signal, and 39, 41, 43, and 45 are audio output terminals that output the expanded audio signal.
[0041]
Next, the operation of the digital information transmission system configured as described above will be described.
[0042]
The video signals input from the digital video signal input terminals 10, 12, 14, and 16 are matched with the MPEG2 video (ISO / IEC13818-2) syntax by the video encoding circuits 11, 13, 15, and 17, The data is compressed and packetized and output to the multiplexing circuit 26.
[0043]
The audio signals input from the digital audio signal input terminals 18, 20, 22, and 24 follow the syntax of MPEG audio (ISO / IEC11172-3) by the audio encoding circuits 19, 21, 23, and 25. The data is compressed and packetized and output to the multiplexing circuit 26.
[0044]
The multiplexing circuit 26 outputs a transport stream obtained by multiplexing each program and PSI to the transmission path encoding / modulation circuit 27.
[0045]
FIG. 2 shows the status of each program and PSI.
[0046]
As shown in FIG. 2, the PAT is transmitted in a packet of PID = 0x000, and each program map PID assigns the outputs of the video encoding circuits 11, 13, 15, and 17 to 0x100, 0x200, 0x300, and 0x400, respectively. The program numbers are designated as programs 0x10, 0x20, 0x30, and 0x40, respectively.
[0047]
Also, the video elementary PIDs of the program map PID of 0x100, 0x200, 0x300, and 0x400 are assumed to be 0x101, 0x201, 0x301, and 0x401.
[0048]
The audio elementary PIDs of the program map PID of 0x100, 0x200, 0x300, and 0x400 are assumed to be 0x102, 0x202, 0x302, and 0x402.
[0049]
The transmission encoding / modulation circuit 27 adds an error correction signal for transmission, performs interleaving processing, etc., digitally modulates and sends it to the transmission line.
[0050]
The transmission path decoding / demodulation circuit 28 digitally demodulates the signal from the transmission path, performs deinterleaving processing, error correction decoding, and the like, and outputs the result to the separation circuit 29.
[0051]
The separation circuit 29 separates the video / audio stream from the transport stream based on the aforementioned PSI, and outputs it to the video decoding circuits 30, 32, 34, 36 and the audio decoding circuits 38, 40, 42, 44.
[0052]
Next, details of the separation circuit 29 will be described with reference to FIG.
[0053]
FIG. 3 is a block diagram showing details of the separation circuit 29.
[0054]
In FIG. 3, 50 is a transport stream input terminal of the separation circuit 29, 51 is a buffer for holding the data of the transport stream, 52 is a PID search circuit for searching and comparing PIDs of transport packets (flexibility of search comparison result) For example, a CPU is used), 53 is a PID list table in which PIDs for reception are arranged in order of magnitude, 54 is a PSI table for storing PSI transmitted in a transport stream, and 56 is a buffer output. Is a switch for outputting to each decoding.
[0055]
As shown in FIG. 2, the program numbers received by the video decoding circuits 30, 32, 34, and 36 and the audio decoding circuits 38, 40, 42, and 44 are 0x10, 0x20, 0x30, and 0x40, respectively.
[0056]
A signal input to the input terminal 50 of the separation circuit 29 is input to the PID search circuit 52 and the buffer 51.
[0057]
The PID search circuit 52 detects 0x0 that is the PID of the PAT. When this packet is detected, PAT program map PIDs 0x100, 0x200, 0x300, and 0x400 are written into the PSI table 54.
[0058]
Next, the PID search circuit 52 detects PMTs of 0x100, 0x200, 0x300, and 0x400 that are program maps PID.
[0059]
When a packet with PID = 0x100 is detected, 0x101 (video) and 0x102 (audio), which are 0x100 elementary PIDs, are written in the PSI table 54. Similarly, elementary PIDs of 0x201 (video), 0x202 (sound) that are elementary PIDs of PID = 0x200, 0x301 (video), 0x302 (sound) of elementary PIDs of PID = 0x300, and PID = 0x400. 0x401 (video) and 0x402 (audio) are written in the PSI table 54.
[0060]
When the PSI table 54 is created, a PID list table 53 is created from the PSI table 54 in the order of PID values.
[0061]
This will be described with reference to FIG.
[0062]
FIG. 4 is a diagram for explaining the contents of the PID list table of the present embodiment.
[0063]
In addition to the PID necessary for decoding, a flag indicating whether the PID indicates a program map PID or an elementary PID and an output destination address of the elementary PID are written in the PID list table 53. Further, when the program being transmitted is changed halfway, the PID list table 53 is also updated.
[0064]
Based on the PID list table 53, a PID search / comparison process of the transport packet received is performed.
[0065]
Next, the PID search comparison process will be described with reference to FIG.
[0066]
FIG. 5 is a flowchart showing the PID search comparison process of the present embodiment.
[0067]
First, in this embodiment, the PIDs of the PID list table arranged as described above are divided into three so as to be approximately equally divided, and the PID of the division point (middle point) is stored in advance.
[0068]
For example, three midpoints are set as shown in FIG.
[0069]
In FIG. 5, in step S <b> 1, the received PID is compared with the first midpoint PID of the PID list table 53. If the received PID is larger than the first midpoint PID, the process proceeds to step S3, and if not larger, the process proceeds to step S2.
[0070]
In step S2, the received PID and the second midpoint PID of the PID list table 53 are compared. If the received PID is larger than the second midpoint PID, the process proceeds to step S4. If not, the process proceeds to step S5.
[0071]
In step S3, the third midpoint within the search range of the remaining PID list table 53 is compared with the received PID. If the received PID is larger than the third midpoint PID, the process proceeds to step S4. If not, the process proceeds to step S5.
[0072]
In step S4, a comparison process is performed between the PID whose level is higher by one than the PID used immediately before the PID list table 53 and the received PID. If they match, the PID search process ends. Then, the loop process of step S4 is performed until they match.
[0073]
In step S5, the PID used immediately before the PID list table 53 is compared with the received PID. If they match, the PID search process ends. If they do not match, the process proceeds to step S6, where the PID used by the PID level just before the PID list table 53 is substituted by 1 and returns to step S5.
[0074]
If there is no matching PID in steps S4 and S5, the process is terminated with the midpoint PID used in the processes of steps S1, S2, and S3.
[0075]
Next, a specific example will be described. For example, a case where a transport stream packet as shown in FIG. 4 is received and the PID search circuit 52 searches for a transport stream packet with PID = 0x402 will be described.
[0076]
First, the PID search circuit 52 compares 0x202, which is the first midpoint of the PID list table 53, with the received PID0x402.
[0077]
Since the received PID 0x402 is large, the received PID 0x402 is compared with 0x400, which is the third midpoint between the first midpoint (0x202) and 0x402 of the PID list table 53. The received PID 0x402 is larger.
[0078]
Next, the PID list table 53 is compared with a PID one level higher from 0x400 sequentially. The PID 0x401 that is one level higher than 0x400 in the PID list table 53 is compared with the received PID 0x402. Since they do not match, the PID 0x402 that is one level higher than 0x401 in the PID list table 53 is compared with the received PID0x402. Since the PID matches, the received transport packet is output from the buffer 51 to the switch 56 according to the flag of the matched PID and the elementary output address.
[0079]
The switch 56 is connected to the speech decoding circuit 44 based on the PID search result, and a transport packet having PID = 0x402 is output to the speech decoding circuit 44.
[0080]
The buffer 51 holds data until a PID search result is obtained.
[0081]
In this example, the PID can be searched by performing the comparison process four times. In this embodiment, the worst case of the search / comparison process is six times.
[0082]
If this is searched from the small values of PAT, PMT, and elementary PID as in the conventional case, 13 times of comparison processing is required in the worst case, and the worst case comparison processing time can be reduced by this embodiment.
[0083]
The audio decoding circuit 44 decompresses the compressed audio stream and decodes the digital audio signal. The decoded audio signal is output to the audio output terminal 45.
[0084]
In this embodiment, the PID list table is divided into three midpoints for search comparison processing. However, the present invention is not limited to this, and the same effect can be obtained even if the number of midpoints is changed according to the number of received programs. Is obtained.
[0085]
In the present embodiment, the encoding / decoding of video / audio is described in the MPEG format, but other encoding / decoding formats may be used.
[0086]
In the present embodiment, it has been described that video / audio is multiplexed / separated in the MPEG format. However, other multiplexing / separation formats may be used as long as the packet identification signal is multiplexed for each packet in a fixed-length packet. But it doesn't matter.
[0087]
In this way, by newly providing a PID list table in which the PIDs necessary for reception are sorted in order of magnitude, the search for the PID of the transport packet can be quickly terminated. As a result, the number of multiple programs can be increased.
[0088]
Alternatively, the PID search process for receiving a plurality of programs can be performed without increasing the operation speed of the search process.
[0089]
<Other Embodiments of the Present Invention>
The present invention may be applied to a system composed of a plurality of devices (for example, a host computer, interface device, reader, printer, etc.) or to an apparatus composed of a single device (for example, a digital VTR).
[0090]
In addition, a program code of software for realizing the functions of the embodiment is provided to an apparatus or a computer in the system connected to the various devices so as to operate the various devices so as to realize the functions of the above-described embodiments. What is implemented by operating the various devices in accordance with a program stored in the computer (CPU or MPU) of the system or apparatus supplied is also included in the scope of the present invention.
[0091]
In this case, the software program code itself realizes the functions of the above-described embodiments, and the program code itself and means for supplying the program code to the computer, for example, the program code are stored. This storage medium constitutes the present invention.
[0092]
As a storage medium for storing the program code, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.
[0093]
Further, by executing the program code supplied by the computer, not only the functions of the above-described embodiments are realized, but also the OS (operating system) in which the program code is running on the computer, or other application software, etc. Needless to say, the program code is also included in the embodiment of the present invention even when the functions of the above-described embodiment are realized in cooperation with the embodiment.
[0094]
Further, after the supplied program code is stored in the memory provided in the function expansion board of the computer or the function expansion unit connected to the computer, the CPU provided in the function expansion board or function storage unit based on the instruction of the program code However, it is needless to say that the present invention also includes a case where the function of the above-described embodiment is realized by performing part or all of the actual processing.
[0095]
【The invention's effect】
As described above, according to the present invention, program specification information is extracted from the input multiple stream signal to recognize a packet corresponding to each program, and each program specification is supported based on the extracted program specification information. In addition, the packet identification signal is converted into a table, and the multiplexed stream signal input using the table is distributed and output, so the search processing time for the received packet identification signal can be reduced compared to the conventional method, and multiple programs can be received. It has the effect of becoming.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a digital information transmission system as an embodiment of the present invention.
FIG. 2 is a diagram illustrating a state of each program and PSI in the present embodiment.
FIG. 3 is a block diagram showing details of a separation circuit 29;
FIG. 4 is a diagram illustrating the contents of a PID list table according to the present embodiment.
FIG. 5 is a flowchart illustrating PID search comparison processing according to the present exemplary embodiment.
FIG. 6 is a block diagram showing a configuration of a digital information transmission system using MPEG2.
FIG. 7 is a diagram illustrating an example of multiplexing of transport streams.
FIG. 8 is a flowchart for explaining video / audio stream separation processing from a received transport stream;

Claims (8)

Input means for inputting a multiplexed stream signal in which a plurality of programs transmitted in packet units to which a packet identification signal for identifying each packet is added is multiplexed;
Extraction means for extracting program specification information for recognizing a packet corresponding to each program from the multiplex stream signal input from the input means;
Generation means for making a table of at least a packet identification signal, a flag indicating an attribute, and output address information in association with each program specification based on the program specification information extracted by the extraction means;
An information processing apparatus comprising: distribution means for distributing and outputting the multiplexed stream signal input by the input means based on the table generated by the generation means.   2. The information processing apparatus according to claim 1, wherein the generation unit rearranges the packet identification signal, the flag, and the output address information into a table by rearranging the packet identification signal based on the value of the packet identification signal.   3. The information processing method according to claim 2, wherein the distribution unit starts searching for the input packet identification signal from the midpoint of the values using a series of tabulated packet identification signal values. apparatus. Input means for inputting a multiplexed stream signal in which a plurality of programs transmitted in packet units to which a packet identification signal for identifying each packet is added is multiplexed;
Search means for searching for a packet identification signal for recognizing a packet from the multiple stream signal input from the input means;
First generation means for detecting program specification information corresponding to each program from the search result of the search means and tabulating the program specification information;
A second generation unit that tabulates at least a packet identification signal, a flag indicating an attribute, and output address information in association with each program specification based on the program specification information from the inspection result of the search unit;
Distribution means for distributing and outputting the multiplexed stream signal input by the input means based on the table information generated by the first and second generation means;
The second generation means rearranges the packet identification signal, the flag, and the output address information based on the value of the packet identification signal into a table,
A packet identification signal by the table of the second generator is searched from the program specification information by the table of the first generator, the output address information in the same table corresponding to the search result is output, and the output An information processing apparatus that controls the distribution means based on a result.   5. The information processing apparatus according to claim 1, wherein each program includes at least video and audio information.   6. The information processing apparatus according to claim 1, wherein the multiplexed stream is multiplexed in an MPEG2 transport format. An input step of inputting a multiplex stream signal in which a plurality of programs transmitted in packet units to which a packet identification signal for identifying each packet is added is multiplexed;
An extraction step of extracting program specification information for recognizing a packet corresponding to each program from the multiplex stream signal input in the input step;
A generation step of making a table of at least a packet identification signal, a flag indicating an attribute, and output address information in association with each program specification based on the program specification information extracted by the extraction step;
A distribution step of distributing and outputting the input multiplexed stream signal based on the table generated by the generation step. A computer-readable recording medium on which an information processing program is recorded,
To input a multiplexed stream signal obtained by multiplexing a plurality of programs transmitted in packet units to which a packet identification signal for identifying each packet is added, and to recognize a packet corresponding to each program from the multiplexed stream signal Extraction process code to extract the program specification information of
A code of a generation step that tabulates at least a packet identification signal, a flag indicating an attribute, and output address information in association with each program specification based on the program specification information extracted by the extraction step;
A computer-readable recording medium on which an information processing program is recorded, comprising: a distribution step of distributing and outputting the input multiplex stream signal based on the table generated by the generation step.

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