JPH11112452A - Information processor, method therefor and transmission medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set new consecutive time bases to a transport stream. SOLUTION: A switch 51 selects a 1st transport stream or a 2nd transport stream in a prescribed timing. An offset detector 52 detects an offset between a time base for the 1st transport stream before the selection and a time base of the 2nd transport stream after the selection, an adder 54 adds the offset from the offset detector 52 to time information detected by a time information detector 53 and provides an output of the sum to a time rewrite device 55 as new time information. The time information rewrite device 55 rewrites the time information of the received transport stream with the sum from the adder 54.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information processing apparatus and method, and a transmission medium. More particularly, the present invention relates to a transport stream having discontinuous time-base time information, and by rewriting time information, a continuous new stream. TECHNICAL FIELD The present invention relates to an information processing apparatus and method, and a transmission medium that set a proper time base.

[0002]

2. Description of the Related Art A video (video) signal, an audio (audio) signal, and the like are recorded or reproduced using a recording medium such as an optical disk or a magnetic tape, or transmitted and received through a predetermined transmission path. When used in a conference system, a videophone system, or the like, these signals are often subjected to A / D conversion and then encoded (encoded) based on an MPEG (Moving Picture Experts Group) method. .

[0003] MPEG is based on ISO / IEC JTC1 / SC29 (International
al Organization for Standardization / International
Electrotechnical Commission, Joint Technical Commi
tee1 / Sub Commitee 29: Abbreviation of the study organization of video coding for storage by the Joint Technical Committee / Specialized Subcommittee 29) of the International Organization for Standardization / International Electrotechnical Commission. For example, ISO11172 as MPEG1 standard and ISO13818 is specified. Also, as these international standards, ISO11172-1 and ISO13818-1 in the system multiplexing item, ISO11172-2 and ISO13818-2 in the video encoding item, and ISO11172-3 and ISO13818 in the audio encoding item -3
Are standardized.

With reference to FIG. 5, transmission of information using a transport stream defined in ISO / IEC13818-1 will be described. In the information transmitting apparatus 1 on the encoding side of the transport stream, the video encoder 11 and the audio encoder 12 encode (packetize) the input video signal and audio signal, respectively, and multiplex them as elementary streams. Output to the converter 13. The multiplexer 13 multiplexes the elementary streams from the video encoder 11 and the audio encoder 12 as one transport stream and transmits the transport stream. The oscillator 14 generates a predetermined clock signal and supplies it to each unit. STC (System Time C
The lock (counter) counter 15 counts the clock signal of the oscillator 14 and counts the count value by PCR (Program Clock Referral).
ence) to the multiplexer 13.

[0005] The video encoder 11 uses, for example, ISO13818-2 as a coding method, and the audio encoder 12 uses, for example, MPEG audio (ISO11172-3 or ISO11172-3) as a coding method.
ISO13818-3) and AC-3 (ATSC standard Doc.A / 52,20 De)
c. 1995) and the like, and each operates in synchronization with a clock signal from the oscillator 14. Therefore, the frame period of the video and the sampling frequency of the audio are synchronized with the clock signal of the oscillator 14.

[0006] As shown in FIG. 6, the multiplexer 13 transports the elementary stream encoded by the video encoder 11 and the elementary stream encoded by the audio encoder 12 (not shown). Packet (18
Time-division multiplexing (hereinafter abbreviated as multiplexing) is performed as an 8-byte fixed-length packet. At this time, the multiplexer 1
Reference numeral 3 denotes a DTS (Decoding) indicating decoding time information of an access unit (a constituent unit of an elementary stream, for example, corresponding to a picture in the case of MPEG video).
Time Stamp), PTS (Presentat) indicating playback output time information
(ion time stamp) or a PCR which is a sample of the count value of the STC counter 15 is added (encoded) to the transport stream. At this time, PTS and DTS are PES (Packetized Elementary Str
eam) Encoded in the packet header and the PCR is encoded in the adaptation field. The PCR, DTS, or PTS enables synchronous reproduction of a video signal and an audio signal.

[0007] The multiplexer 13 performs multiplexing so that a decoding buffer (not shown) incorporated in the video decoder 22 and the audio decoder 23 of the information receiving device 2 is not broken down, and as time reference information. Appropriate addition of PCR, DTS, or PTS is required. These pieces of time reference information are added corresponding to the count value of the STC counter 15 synchronized with the oscillator 14. For example, when the transport stream is output from the multiplexer 13, the PCR
The value is added to the transport stream by latching the count value of the C counter 15. Although omitted in this example, in addition to the video signal and the audio signal,
It is also possible to handle private information such as video subtitles.

[0008] The transport stream transmitted from the multiplexer 13 is transmitted to the information receiving device 2 using a predetermined transmission path (for example, a satellite or a cable).

In the information receiving device 2, the separator 21
The received transport stream is separated into video and audio elementary streams (hereinafter, referred to as a video stream and an audio stream), and supplied to decoding buffers (not shown) of the video decoder 22 and the audio decoder 23, respectively. I do. Further, the separator 21 detects the value of the PCR in the transport stream, and detects a PLL (Phase Locked).
(Loop) circuit 30 to output to the subtractor 31 and the STC counter 34.

The subtractor 31 calculates a difference between the supplied PCR value and the count value output from the STC counter 34,
The difference value is supplied to the low-pass filter 32 (in addition,
Although not shown in the figure, the difference value from the subtractor 31 is supplied from the D / A converter to the low-pass filter 32 after being converted from a digital signal to an analog signal.) The low-pass filter 32 extracts a low-frequency component from the frequency component of the difference value supplied from the subtractor 31,
It is supplied to a VCO (Voltage Controlled Oscillator) 33.

The VCO 33 changes the oscillation frequency according to the applied voltage.
Based on the output from the counter 2, a clock signal is generated so that the difference between the PCR value and the count value of the STC counter 34 becomes 0, and is supplied to each unit. When the value of the PCR initially supplied from the separator 21 is set as an initial value in a register (not shown) incorporated therein,
Thereafter, the count-up is performed in synchronization with the clock signal of the VCO 33. Where the PCR is
Since the count value of the STC counter 15 of the information transmitting device 1 is latched, the VCO 33 operates in synchronization with the clock signal of the information processing device 1.

The video decoder 22 and the audio decoder 23 have a VCO
Each of the decoding buffers is operated at a timing when the value of the DTS encoded in the PES packet header of FIG. 6 and the count value of the STC counter 34 become equal to each other. And decodes and outputs the decoded data as a video signal and an audio signal, respectively, at the timing when the value of the PTS becomes equal to the count value of the STC counter 34. It has been done.

Here, an example of processing in which a plurality of transport streams are connected will be described with reference to FIG. In this example, as shown in FIG. 7A, two transport streams 300-1 and 300-2 are connected. PCR is added to each PES packet header as time information. Normally, the time systems (hereinafter, referred to as time bases) specified for each transport stream are different from each other. Therefore, as shown in FIG. 7B, by connecting these transport streams, The generated transport stream 301 has a portion where the time base becomes discontinuous. In the example of FIG. 7B, the value of PCR increased from 30, 50, 80 to 30, but suddenly decreased to 25. In order to notify the decoding side device of a portion where the time base becomes discontinuous, the Digest is included in the adaptation field of the transport stream 301.
A flag indicating time-base discontinuity called a scontinuity indicator is added.

For example, in the information receiving apparatus 2 shown in FIG.
Transport stream 301 is received and received by separator 2
When this flag is detected by the control of the PLL circuit 30,
Loads a new value of the first PCR whose time base changes to the STC counter 34 when generating a clock signal. Thus, even when a transport stream having a discontinuous time base is received, it can be treated as a transport stream having a continuous time base.

[0015]

However, at present,
Many decoding devices do not assume time-base discontinuities in the transport stream, and thus, for example,
When the transport stream specified by the time base of the second time base and the transport stream specified by the second time base are connected, it takes time until the clocks are synchronized. In a portion where the time base of the port stream is discontinuous, there is a problem that the reproduction output of the decoded data in that portion is interrupted.

The present invention has been made in view of such a situation, and a new continuous time is obtained by rewriting time information for a transport stream having discontinuous time base time information. Set the base.

[0017]

According to a first aspect of the present invention, there is provided an information processing apparatus, comprising: input means for inputting a plurality of data strings; switching means for switching a plurality of data strings from the input means at a predetermined timing; Means for detecting the time base of the data string before switching by the means, the first detection means for detecting the time base offset of the data string switched by the switching means, and the time information of the data string output from the switching means. A second detecting means for detecting, an adding means for adding the offset value detected by the first detecting means to the time information detected by the second detecting means, and a data string output from the switching means. Rewriting means for rewriting the time information as new time information to the addition result of the adding means, and rewriting to new time information by the rewriting means Characterized in that it comprises a and output means for outputting the data string.

In the information processing method according to the fourth aspect, the input step of inputting a plurality of data strings, the switching step of switching the plurality of data strings input in the input step at a predetermined timing, and the switching step. A first detection step for detecting the time base offset of the previous data string and the time base of the data string switched in the switching step, and a second detection for detecting time information of the data string output in the switching step A detection step, an addition step of adding the offset value detected in the first detection step to the time information detected in the second detection step, and a time information of the data string output from the switching step. A rewriting step of rewriting to the addition result in the adding step as new time information; And an outputting step of outputting the data string that has been rewritten to the new time information in step.

According to a fifth aspect of the present invention, in the transmission medium, an input step of inputting a plurality of data strings, a switching step of switching the plurality of data strings input in the input step at a predetermined timing, and a switching step before the switching step. A first detection step of detecting a time base offset of the data string after the switching in the switching step, and a second detection step of detecting time information of the data string output in the switching step. A detection step, an addition step of adding the offset value detected in the first detection step to the time information detected in the second detection step, and a time information of the data string output from the switching step. A rewriting step for rewriting the time information as the addition result in the adding step, and a rewriting step. Characterized by transmitting the computer program and an output step of outputting the data string that has been rewritten to the new time information in the flop.

The information processing apparatus according to claim 1,
And a transmission medium according to claim 5, wherein a plurality of data strings are input, the plurality of data strings are switched at a predetermined timing, and a time base of the data string before being switched, The time base offset and the time information of the switched data string are detected, the offset value is added to the time information, and the time information of the data string is rewritten as the new time information to the addition result, and the new The data string rewritten with the time information is output.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below. In order to clarify the correspondence between each means of the invention described in the claims and the following embodiments, each means is described. When the features of the present invention are described by adding the corresponding embodiment (however, an example) in parentheses after the parentheses, the result is as follows. However, of course, this description does not mean that each means is limited to those described.

An information processing apparatus according to a first aspect of the present invention includes an input means (for example, a switch 51 in FIG. 2) for inputting a plurality of data strings and a switching means for switching the plurality of data strings from the input means at a predetermined timing. (For example, switch 51 in FIG. 2), a first detection unit (for example, a time base of the data string before being switched by the switching unit) and a time base of the data sequence after the switching by the switching unit (for example, , An offset detector 52 in FIG. 2), a second detector (for example, the time information detector 53 in FIG. 2) for detecting time information of a data string output from the switching unit, and a first detector. Adding means for adding the detected offset value to the time information detected by the second detecting means (for example, the adder 5 in FIG. 2)
4), rewriting means (for example, the time information rewriting device 55 in FIG. 2) for rewriting the time information of the data string output from the switching means as new time information to the addition result of the adding means, and a new rewriting means. Output means for outputting a data sequence rewritten to time information (for example, FIG. 2
And a time information rewriter 55).

In the information processing apparatus according to the present invention, the first detecting means detects the time reference information added to the data string (for example, the PC of FIG. 3).
R detector 100), generating means (for example, VCO 104 in FIG. 3) for generating a clock signal corresponding to the time reference information detected by the third detecting means, and a clock signal generated by the generating means. Counting means for counting (for example,
The counter 105) of FIG. 3 and a calculating unit (for example, a subtractor 106 of FIG. 3) for calculating a difference between the time reference information detected by the third detecting unit and the count value of the counting unit are further provided. The difference between the first time reference information calculated by the means and added to the data sequence after the switching by the switching means and the count value of the counting means is set as an offset.

In the information processing apparatus according to the third aspect, the third detecting means (for example, FIG. 3) for detecting a flag indicating the discontinuity of the time base added to the data string inputted from the input means. 4 discontinuous point detectors 71), wherein the first detecting means detects an offset at a timing when the flag is detected by the third detecting means.

FIG. 1 is a block diagram showing a configuration example of an embodiment of an information processing apparatus according to the present invention. In FIG. 1, parts corresponding to those shown in FIG. The description is omitted as appropriate. In this example, the bureau 40
A transport stream encoded, multiplexed and transmitted by the information transmitting apparatus 1 which is the head office is received, a predetermined process is performed on the transport stream, and then the transport stream is transmitted to the information receiving apparatus 2. It has been done.

FIG. 2 is a block diagram showing a configuration example when the branch station 40 in FIG. 1 is, for example, an information processing device as a stream connection device. In this example, the switch 51 switches between and outputs two input transport streams under control of a predetermined timing from the system controller 56. The offset detector 52 determines the time between the two transport streams at the timing when the switch 51 switches the transport stream (ie, the timing when the transport stream 300-1 is switched to the transport stream 300-2 in FIG. 7). The base offset is detected and output to the adder 54.

The time information detector 53 detects various time information (PCR, PTS, or DTS) added to the input transport stream, and outputs the detected time information to the adder 54. The adder 54 adds the offset value detected by the offset detector 52 to each piece of time information detected by the time information detector 53, and adds the addition result to new time information (PCR ', PTS', or DTS). ') Is output to the time information rewriter 55. The time information rewriter 55 sets the new time base by rewriting the time information in the connected transport stream with the new time information from the adder 54,
The transport stream is output. Further, the system controller 56 includes, for example,
It is constituted by a CPU or the like, and controls each section in synchronization with a clock signal from the offset detector 52. Note that, in this example, the case where the transport stream has two inputs has been described, but the present invention can be applied to the case where the transport stream has two or more inputs.

Next, for example, a description will be given assuming that the transport streams 300-1 and 300-2 shown in FIG. Switch 51
First, the input transport stream 300
-1 is output to the offset detector 52. Then, the system controller 56 transmits the transport stream 3
When the stream is switched from 00-1 to the transport stream 300-2, the switch 51 is switched to the lower side in FIG. As a result, the transport stream 300-2 is supplied to the offset detector 52 from this point onward after the transport stream 300-1.

FIG. 3 is a block diagram showing a configuration example of the offset detector 52. In this example,
The PCR detector 100 detects a PCR added to the input transport stream, and detects it by the subtractor 1.
01 and a subtractor 106. The subtracter 101 calculates the supplied PCR value and the STC counter 103
Is calculated, and the difference value is supplied to the low-pass filter 102 (note that the difference value from the subtractor 101 is D /
After being converted from a digital signal to an analog signal by the A converter, it is supplied to the low-pass filter 102). The low-pass filter 102 extracts a low-frequency component from the frequency component of the difference value supplied from the subtractor 101,
104.

The VCO 104 generates a clock signal based on the output from the low-pass filter 102 so that the difference between the PCR value and the count value of the STC counter 34 becomes 0,
The information is supplied to the STC counter 103, the counter 105, or the system controller 56 of FIG. STC counter 10
3 is a register (not shown) built therein.
The value of the PCR supplied from the PCR detector 100 is set as an initial value as needed, and thereafter, the value is counted up in synchronization with the clock signal of the VCO 104. The counter 105 counts the total clock of the device without being reset in synchronization with the clock signal of the VCO 104, and supplies this count value to the subtractor 106.

The subtractor 106 calculates the difference between the PCR value supplied from the PCR detector 100 and the count value from the counter 105, and outputs the difference value as an offset value to the adder 54 in FIG. It has been done.

The offset detector 52 having the above configuration is used for the transport stream 300-1.
To the first PCR value (e.g.,
) Is set as an initial value in the STC counter 103, and the STC counter 103 and the counter 105 count the clock signal. When the switch 51 switches from the transport stream 300-1 to the transport stream 300-2, if the number of clocks per packet is 10 and the count value of the STC counter 103 and the counter 105 is 110 at this time. . At this time, by the PCR detector 100,
The first PCR value (= 25) of the transport stream 300-2 is detected, and the value is newly set as the initial value of the STC counter 103. As a result, a clock signal synchronized with the time base of the transport stream 300-2 is generated by the VCO 104 thereafter.

Further, the offset detector 52 causes the subtractor 106 to calculate the difference between the first PCR value (= 25) of the transport stream 300-2 and the count value (= 110) of the counter 105, and Difference value (= 8
5) is output to the adder 54 as an offset value.

Then, the offset value is added to the value of each time information from the time information detector 53 by the adder 54, and the time information rewriter 5 is added as new time information.
5 is supplied. The time information rewriter 55 rewrites the time information in the input transport stream 301 (transport stream 300-2) with new time information from the adder 54.

As described above, it is possible to set a continuous new time base in a transport stream generated by connecting different transport streams.

Incidentally, this offset value can also be obtained as follows. For example, the value of the last PCR of the transport stream before being switched by the switch 51 is PL, the value of the first PCR of the new transport stream after the switching is PF,
The bit amount of data transmitted during this time is NB. The transport stream rate is TR. Based on the time base of the transport stream before switching, the PCR value of the transport stream after switching can be expressed as follows. PCR = PL + 270,000 × NB / TR (1)

However, the numerical value 270,000 indicates the frequency of occurrence of PCR. Then, at the discontinuous point, the offset value
OFFSET is updated as expressed by the following equation. OFFSET = PF- (PL + 270,000 × NB / TR) + OFFSET (2)

FIG. 4 shows an example of a configuration in which the branch station 40 in FIG. 1 is, for example, an information processing device as a filtering device. Parts corresponding to those in the case shown in FIG. , And a description thereof will be omitted as appropriate. In this example, the transport stream is
The signal is input to the discontinuous point detector 71. When a transport stream whose time base is discontinuous is input, the discontinuity point detector 71 detects a flag indicating discontinuity added thereto and supplies the flag to the system controller 56. It has been made like that.

Then, the system controller 56 controls the offset detector 52 at the timing when the flag is supplied from the discontinuous point detector 71, so that the offset detector 52 sets the initial value of the STC counter 103. In addition, the offset value is detected and the adder 5 detects the offset value.
4 is output. As a result, a continuous new time base can be set even in a transport stream having a discontinuous time base in advance. Other configurations are the same as those shown in FIG.

As a transmission medium for transmitting a computer program for performing the above-described processing, a recording medium such as a magnetic disk, a CD-ROM, and a solid-state memory, as well as a communication medium such as a network and a satellite can be used. it can.

[0041]

As described above, according to the information processing apparatus described in claim 1, the information processing method described in claim 4, and the transmission medium described in claim 5, a plurality of data strings are input. Switching a plurality of data strings at a predetermined timing, detecting a time base offset of the data string before switching and a time base offset of the switched data string and time information, and adding the offset value to the time information. Since the time information of the data string is rewritten as the addition result as new time information and the data string rewritten with the new time information is output, the transport stream having a discontinuous time base is interrupted. It can be played back continuously without the need.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an information processing apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration example when the branch station in FIG. 1 is a stream connection device.

FIG. 3 is a block diagram illustrating a detailed configuration of an offset detector of FIG. 2;

FIG. 4 is a block diagram showing another configuration example of the device in FIG. 2;

FIG. 5 is a block diagram illustrating a configuration example of a conventional information transmitting device and an information receiving device.

FIG. 6 is a diagram illustrating an example of a transport stream.

FIG. 7 is a diagram illustrating a process of connecting two transport streams.

[Explanation of symbols]

40 branch office, 51 switch, 52 offset detector, 53 time information detector, 54 adder, 5
5 time information rewriter, 56 system controller, 71 discontinuity point detector, 100 PCR detection circuit, 101 subtractor, 102 low-pass filter,
103 STC counter, 104 VCO, 105 counter, 106 Subtractor

Claims (5)

[Claims] An input unit for inputting a plurality of data strings; a switching unit for switching the plurality of data strings from the input unit at a predetermined timing; and a time base of the data string before being switched by the switching unit. A first detection unit that detects a time-base offset of a data sequence that has been switched by the switching unit; a second detection unit that detects time information of a data sequence output from the switching unit; Adding means for adding the value of the offset detected by the first detecting means to the time information detected by the second detecting means; and time information of the data string output from the switching means, Rewriting means for rewriting the new time information with the addition result of the adding means; and new time information by the rewriting means. Output means for outputting the rewritten data string. 2. The method according to claim 1, wherein the first detecting means detects time reference information added to the data string, and corresponds to the time reference information detected by the third detecting means. Generating means for generating a clock signal; counting means for counting the clock signal generated by the generating means; time reference information detected by the third detecting means; and a count value of the counting means Calculating means for calculating a difference value of the first time reference information calculated by the calculating means and added to the data string after being switched by the switching means; The information processing apparatus according to claim 1, wherein a difference value of a numerical value is set as the offset. 3. The apparatus according to claim 2, further comprising: third detection means for detecting a flag indicating the discontinuity of the time base, which is added to the data string input from the input means. 2. The information processing apparatus according to claim 1, wherein the offset is detected at a timing when the flag is detected by the third detection unit. 4. An input step of inputting a plurality of data strings, a switching step of switching the plurality of data strings input in the input step at a predetermined timing, and a time of the data string before being switched in the switching step A first detection step of detecting a time base offset of the data string after being switched by the switching step, and a second detection step of detecting time information of the data string output in the switching step. An adding step of adding the value of the offset detected in the first detecting step to the time information detected in the second detecting step; and a time information of the data string output in the switching step. As new time information to the addition result in the addition step. For example step a, an information processing method characterized by comprising an output step of outputting the data string that has been rewritten to the new time information in the rewriting step. 5. An input step of inputting a plurality of data strings, a switching step of switching the plurality of data strings input in the input step at a predetermined timing, and a time of the data string before being switched in the switching step A first detection step of detecting a time base offset of the data string after being switched by the switching step, and a second detection step of detecting time information of the data string output in the switching step. An adding step of adding the value of the offset detected in the first detecting step to the time information detected in the second detecting step; and a time information of the data string output in the switching step. As new time information to the addition result in the addition step. And step e, the transmission medium characterized by transmitting the computer program and an output step of outputting the data string that has been rewritten to the new time information in the rewriting step.