CA2689541A1 - Deterministic program clock reference re-stamping for synchronous bit rate adaptation based on mega-frame initialization packet - Google Patents
Deterministic program clock reference re-stamping for synchronous bit rate adaptation based on mega-frame initialization packet Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
- H04N21/23—Processing of content or additional data; Elementary server operations; Server middleware
- H04N21/236—Assembling of a multiplex stream, e.g. transport stream, by combining a video stream with other content or additional data, e.g. inserting a URL [Uniform Resource Locator] into a video stream, multiplexing software data into a video stream; Remultiplexing of multiplex streams; Insertion of stuffing bits into the multiplex stream, e.g. to obtain a constant bit-rate; Assembling of a packetised elementary stream
- H04N21/23608—Remultiplexing multiplex streams, e.g. involving modifying time stamps or remapping the packet identifiers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04H—BROADCAST COMMUNICATION
- H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
- H04H20/18—Arrangements for synchronising broadcast or distribution via plural systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04H—BROADCAST COMMUNICATION
- H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
- H04H20/65—Arrangements characterised by transmission systems for broadcast
- H04H20/67—Common-wave systems, i.e. using separate transmitters operating on substantially the same frequency
Abstract
A system and processes create a transport stream carrying several encapsulated contents, watermarks, and other ancillary data. The transport stream is re-multiplexed while keeping synchronous and deterministic operation. Synchronous deterministic operation allow each derived transport stream to be broadcasted in Single Frequency Networks, as all re-multiplexers have the same signal at the input and selecting the same content generates exactly the same stream in multiple locations.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority to U.S. Provisional Application No.
60/929,169 titled "Deterministic Program Clock Reference Re-stamping for Synchronous Bit Rate Adaptation based on Mega-frame Initialization Packet" filed on June 15, 2007 in the U.S.
Patent and Trademark Office, and of U.S. Provisional Application No.
60/929,170 titled "Mega-frame Initialization Packet Generation and Synchronous Re-generation with Bit Rate Adaptation for Single Frequency Networks with Multiple Modulation Schemes"
filed on June 15, 2007 in the U.S. Patent and Trademark Office, of which the entire disclosures of both applications are herein incorporated by reference in their entirety for all purposes.
TECHNICAL FIELD
The following description relates generally to a system useful in Single Frequency Networks, and in particular to a system useful in Single Frequency Networks for DVB-T/H complying with European Telecommunications Standards Institute (ETSI) EN
744 and ETS 101 191, and related international standards. The systems and method described herein are also applicable in any other system that requires bit rate adaptation with PCR re-stamping and delivers a deterministic and identical bit stream at all participating equipment.
BACKGROUND
European Telecommunications Standards Institute - European Standard ETSI EN
300 744 describes a broadcasting system for terrestrial distribution based on Orthogonal Frequency-Division Multiplexing COFDM (a digital multi-carrier modulation scheme that uses a large number of closely-spaced orthogonal subcarriers) and MPEG2 (encoding and transport data system, for example, as defined by ISO/IEC 13818-1.MPEG) technologies. Application of the European Telecommunications Standards Institute -Technical Specification ETSI ETS 101 191 extend the user of this system to Single Frequency Networks (SFN), for example, as defined by ETS 101 191 and in Advanced Television Systems Committee (ATSC) A110.
The extension to SFN is accomplished by periodically adding one packet including synchronization time stamps and modulation parameters information to the transport stream (e.g., as defined by ISO 138181-1) of all transmitters broadcasting in a SFN area. The packet that is added to the transport stream is a Mega-frame Initialization Packet (MIP). The MIP is an MPEG2 transport stream compliant packet that carries mega-frame and modulation parameters, for example, as defined by ETS 101 191.
SUMMARY
In one general aspect, a method of providing a fixed and deterministic bit rate adaptation for an output transport stream is described below. The method includes receiving an input transport stream of packets; deriving output timing from the input transport stream; determining an input time stamp for each packet of the input transport stream; determining a corresponding output timestamp for each outgoing packet of the output transport stream; determining the difference between the input timestamp and the output timestamp; extracting a program clock reference (PCR) for the output transport stream; adding the determined difference to the PCR; and adding the PCR to the output transport stream.
The method also may includes receiving the input stream of packets includes a time mark packet; determining a period from the time mark; determining the input time stamp and output time stamp for each packet within the period; and resetting the timestamps at the end of each period.
The time mark may be a mega-frame initialization packet (MIP) and the period is a mega-frame. The time mark also may be a mega-frame initialization packet (MIP) and the period is an extra long mega-frame.
The method may further include the output transport stream from the input transport stream packets by inserting or eliminating null packets to perform rate adaptation based on the output timing.
The time base sampling frequency may be 34,292,160 MHz for a reference clock of 27MHz and the difference is divided by 1,270,080.
The time base sampling frequency may be 5,670 MHz for a reference clock of 8MHz and the difference is divided by 210.
In another general aspect, a system for providing a fixed and deterministic bit rate adaptation for an output transport stream is described below. The system may include an input to receive an input transport stream of packets; a timer to provide output timing derived from the input transport stream; a counter to determine an input time stamp for each packet of the input transport stream; a counter to determine a corresponding output
This application claims priority to U.S. Provisional Application No.
60/929,169 titled "Deterministic Program Clock Reference Re-stamping for Synchronous Bit Rate Adaptation based on Mega-frame Initialization Packet" filed on June 15, 2007 in the U.S.
Patent and Trademark Office, and of U.S. Provisional Application No.
60/929,170 titled "Mega-frame Initialization Packet Generation and Synchronous Re-generation with Bit Rate Adaptation for Single Frequency Networks with Multiple Modulation Schemes"
filed on June 15, 2007 in the U.S. Patent and Trademark Office, of which the entire disclosures of both applications are herein incorporated by reference in their entirety for all purposes.
TECHNICAL FIELD
The following description relates generally to a system useful in Single Frequency Networks, and in particular to a system useful in Single Frequency Networks for DVB-T/H complying with European Telecommunications Standards Institute (ETSI) EN
744 and ETS 101 191, and related international standards. The systems and method described herein are also applicable in any other system that requires bit rate adaptation with PCR re-stamping and delivers a deterministic and identical bit stream at all participating equipment.
BACKGROUND
European Telecommunications Standards Institute - European Standard ETSI EN
300 744 describes a broadcasting system for terrestrial distribution based on Orthogonal Frequency-Division Multiplexing COFDM (a digital multi-carrier modulation scheme that uses a large number of closely-spaced orthogonal subcarriers) and MPEG2 (encoding and transport data system, for example, as defined by ISO/IEC 13818-1.MPEG) technologies. Application of the European Telecommunications Standards Institute -Technical Specification ETSI ETS 101 191 extend the user of this system to Single Frequency Networks (SFN), for example, as defined by ETS 101 191 and in Advanced Television Systems Committee (ATSC) A110.
The extension to SFN is accomplished by periodically adding one packet including synchronization time stamps and modulation parameters information to the transport stream (e.g., as defined by ISO 138181-1) of all transmitters broadcasting in a SFN area. The packet that is added to the transport stream is a Mega-frame Initialization Packet (MIP). The MIP is an MPEG2 transport stream compliant packet that carries mega-frame and modulation parameters, for example, as defined by ETS 101 191.
SUMMARY
In one general aspect, a method of providing a fixed and deterministic bit rate adaptation for an output transport stream is described below. The method includes receiving an input transport stream of packets; deriving output timing from the input transport stream; determining an input time stamp for each packet of the input transport stream; determining a corresponding output timestamp for each outgoing packet of the output transport stream; determining the difference between the input timestamp and the output timestamp; extracting a program clock reference (PCR) for the output transport stream; adding the determined difference to the PCR; and adding the PCR to the output transport stream.
The method also may includes receiving the input stream of packets includes a time mark packet; determining a period from the time mark; determining the input time stamp and output time stamp for each packet within the period; and resetting the timestamps at the end of each period.
The time mark may be a mega-frame initialization packet (MIP) and the period is a mega-frame. The time mark also may be a mega-frame initialization packet (MIP) and the period is an extra long mega-frame.
The method may further include the output transport stream from the input transport stream packets by inserting or eliminating null packets to perform rate adaptation based on the output timing.
The time base sampling frequency may be 34,292,160 MHz for a reference clock of 27MHz and the difference is divided by 1,270,080.
The time base sampling frequency may be 5,670 MHz for a reference clock of 8MHz and the difference is divided by 210.
In another general aspect, a system for providing a fixed and deterministic bit rate adaptation for an output transport stream is described below. The system may include an input to receive an input transport stream of packets; a timer to provide output timing derived from the input transport stream; a counter to determine an input time stamp for each packet of the input transport stream; a counter to determine a corresponding output
2 timestamp for each outgoing packet of the output transport stream; a processor to determine the difference between the input timestamp and the output timestamp, extract a program clock reference (PCR) for the output transport stream; add the determined difference to the PCR; and add the PCR to the output transport stream; and an output to output the transport stream according to the derived output timing.
The input stream may include a time mark packet used to determine a period, the input time stamp and output time stamp are determined for each packet within the period;
and the timestamps are reset at the end of each period. The time mark may be a mega-frame initialization packet (MIP) and the period is a mega-frame. The time mark also may be a mega-frame initialization packet (MIP) and the period is an extra long mega-frame.
The system also may include a composer to create the output transport stream from the input transport stream packets by inserting or eliminating null packets to perform rate adaptation based on the output timing.
The time base sampling frequency may be 34,292,160 MHz for a reference clock of 27MHz and the difference is divided by 1,270,080. The time base sampling frequency also may be 5,670 MHz for a reference clock of 8MHz and the difference is divided by 210. Other features will be apparent from the detailed description, drawings, and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exemplary block diagram of a system for single frequency networks.
DETAILED DESCRIPTION
Transport streams suitable for DVB SFN systems are defined by ETSI standard.
The standard defines a bit rate and a synchronization packet (MIP) for each set of four parameters: channel Band Width (BW), Guard Time interval (GT), Constellation (CON), and Forward Error Correction ratio (FEC). The SFN transport stream must be the same (i.e., all bits in the stream must be equal bit after bit) at all transmitters broadcasting in an SFN area. However, some examples where the parameters require changing are as follows:
= receiving an 8MHz BW incoming signal which must be broadcast to an area where a 7MHz channel is required (e.g., often the case in Italy and Germany where channels have mixed BW);
The input stream may include a time mark packet used to determine a period, the input time stamp and output time stamp are determined for each packet within the period;
and the timestamps are reset at the end of each period. The time mark may be a mega-frame initialization packet (MIP) and the period is a mega-frame. The time mark also may be a mega-frame initialization packet (MIP) and the period is an extra long mega-frame.
The system also may include a composer to create the output transport stream from the input transport stream packets by inserting or eliminating null packets to perform rate adaptation based on the output timing.
The time base sampling frequency may be 34,292,160 MHz for a reference clock of 27MHz and the difference is divided by 1,270,080. The time base sampling frequency also may be 5,670 MHz for a reference clock of 8MHz and the difference is divided by 210. Other features will be apparent from the detailed description, drawings, and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exemplary block diagram of a system for single frequency networks.
DETAILED DESCRIPTION
Transport streams suitable for DVB SFN systems are defined by ETSI standard.
The standard defines a bit rate and a synchronization packet (MIP) for each set of four parameters: channel Band Width (BW), Guard Time interval (GT), Constellation (CON), and Forward Error Correction ratio (FEC). The SFN transport stream must be the same (i.e., all bits in the stream must be equal bit after bit) at all transmitters broadcasting in an SFN area. However, some examples where the parameters require changing are as follows:
= receiving an 8MHz BW incoming signal which must be broadcast to an area where a 7MHz channel is required (e.g., often the case in Italy and Germany where channels have mixed BW);
3 = receiving an 1/4GT + x/xFEC incoming signal (e.g., where 1/4GT is used in a main transmitter for optimum SFN performance) which must be broadcast to an area where a smaller GT (e.g., 1/32GT, used in small area coverage) may be used and a more robust y/yFEC provides increased signal protection for a lower power transmitter; and = receiving a 1/32GT + x/xFEC incoming signal (e.g., 1/32GT is used in main transmitter where SFN operation is not required) which must be broadcast to SFN
mode where an improved GT (e.g., 1/8GT, used in medium area SFN coverage) may be used and a less robust y/yFEC provides a similar payload.
In these examples, when the transport stream changes from one set of parameters to another, the change in the transport stream bit rate, MIP, and PCR
information must be determined. In a conventional system, the change in bit rate is made in a random way by inserting or subtracting null packets from an incoming transport stream and inserting a new MIP packet in a new random position. However, this random process does not guarantee that the bit stream at two different locations will be exactly the same in each bit (i.e., bit exact). In addition, the PCR re-stamping is typically made by modifying PCR
information based on time-of-arrival and time-of-departure difference of transport stream packets. However; within the network there may be small differences due to jitter and equipment delays. Even the time-of-arrival itself is not a finite quantity.
Furthermore, these small differences in PCR correction values are normally made between different locations. As a result, different systems are not able to generate the same bit sequence.
The following description provides a process and system for determining PCR re-stamping that produces a bit stream that is bit exact at any participating system, even in two different locations.
Fig. 1 shows an example 100 of a basic block diagram of a system 100 for deterministic program clock reference re-stamping for synchronous bit rate adaptation using an MIP. The input signal may be any a transport stream 101, for example, as provided for in the ISO/IEC 13818-1 standard. The transport stream may include packets include packets grouped into a mega-frame, which is a group of a integer number of TS
packets, for example, as specified by ETS-101 191. The transport stream 101 is supplied to detector 105, time stamp generator I10, and memory 115.
The detector 105 processes the transport stream 101 to extract received mega frame information, such as the MIP parameters and related transport stream parameters, mega frame time boundaries, and, when available, extra-long mega frame time
mode where an improved GT (e.g., 1/8GT, used in medium area SFN coverage) may be used and a less robust y/yFEC provides a similar payload.
In these examples, when the transport stream changes from one set of parameters to another, the change in the transport stream bit rate, MIP, and PCR
information must be determined. In a conventional system, the change in bit rate is made in a random way by inserting or subtracting null packets from an incoming transport stream and inserting a new MIP packet in a new random position. However, this random process does not guarantee that the bit stream at two different locations will be exactly the same in each bit (i.e., bit exact). In addition, the PCR re-stamping is typically made by modifying PCR
information based on time-of-arrival and time-of-departure difference of transport stream packets. However; within the network there may be small differences due to jitter and equipment delays. Even the time-of-arrival itself is not a finite quantity.
Furthermore, these small differences in PCR correction values are normally made between different locations. As a result, different systems are not able to generate the same bit sequence.
The following description provides a process and system for determining PCR re-stamping that produces a bit stream that is bit exact at any participating system, even in two different locations.
Fig. 1 shows an example 100 of a basic block diagram of a system 100 for deterministic program clock reference re-stamping for synchronous bit rate adaptation using an MIP. The input signal may be any a transport stream 101, for example, as provided for in the ISO/IEC 13818-1 standard. The transport stream may include packets include packets grouped into a mega-frame, which is a group of a integer number of TS
packets, for example, as specified by ETS-101 191. The transport stream 101 is supplied to detector 105, time stamp generator I10, and memory 115.
The detector 105 processes the transport stream 101 to extract received mega frame information, such as the MIP parameters and related transport stream parameters, mega frame time boundaries, and, when available, extra-long mega frame time
4 boundaries of the received tr. The detector 105 provides the receive time frame boundaries to detector 107.
The time stamp generator 110 computes input time stamps or an input time base for each incoming packet of the transport stream. The time base count is incremented linearly at every input packet. The count is reset by the signal Reset TB 108 provided every time at the end of a Mega Frame or of an Extra-Long Mega Frame.
The memory 115 stores each input transport stream packet with a related time stamp computed by the time stamp generator 110. In one example, the memory may be implemented using a First In - First Out (FIFO) memory, where the first data written in are the first data read.
The transport stream also is provided to output timing generator 120. The output timing generator 120 generates an output timing signal based on the input transport stream bit rate. Since input and output transport streams are linked by a fixed ratio, all pulses and timing signals required to build the output transport stream are derived from the input transport stream bit rate, as is known to those skilled in the art.
Processing block 125 computes the transmit mega-frame information for the outgoing transport stream, such as the mega frame time boundaries, and, when available, extra-long mega frame time boundaries. The transmit time frame boundaries are provided to detector 107.
The Detector 107 detects the end/start of each mega frame in the transport steam, or, in the case that the input and the output mega frame do not have the same length, detects the end of an extra-long mega frame. When the detector 107 detects the end of a mega frame or extra-long mega frame, the detector generates the signal reset TB 108.
The output time stamp generator 130 computes the output time stamps or time base for each outgoing packet. The output time base count is incremented linearly at every output packet. The base count is reset by the signal reset TB 108 provided at the end of every mega frame or extra-long mega frame.
Block 135 determines the difference between the output time stamp provided by generator 130 and the input time stamp TS_TB 137 computed by the input time stamp generator 110 that is stored with each associated packet in the FIFO memory 115. The received packets are output from the FIFO memory 115 to the transport stream composer 140. The transport stream composer 140 is provided with the output timing and performs bit rate adaptation of the transport stream by determining whether to eliminate or insert null packets in the transport stream. The transport stream is provided to the extractor 145.
The time stamp generator 110 computes input time stamps or an input time base for each incoming packet of the transport stream. The time base count is incremented linearly at every input packet. The count is reset by the signal Reset TB 108 provided every time at the end of a Mega Frame or of an Extra-Long Mega Frame.
The memory 115 stores each input transport stream packet with a related time stamp computed by the time stamp generator 110. In one example, the memory may be implemented using a First In - First Out (FIFO) memory, where the first data written in are the first data read.
The transport stream also is provided to output timing generator 120. The output timing generator 120 generates an output timing signal based on the input transport stream bit rate. Since input and output transport streams are linked by a fixed ratio, all pulses and timing signals required to build the output transport stream are derived from the input transport stream bit rate, as is known to those skilled in the art.
Processing block 125 computes the transmit mega-frame information for the outgoing transport stream, such as the mega frame time boundaries, and, when available, extra-long mega frame time boundaries. The transmit time frame boundaries are provided to detector 107.
The Detector 107 detects the end/start of each mega frame in the transport steam, or, in the case that the input and the output mega frame do not have the same length, detects the end of an extra-long mega frame. When the detector 107 detects the end of a mega frame or extra-long mega frame, the detector generates the signal reset TB 108.
The output time stamp generator 130 computes the output time stamps or time base for each outgoing packet. The output time base count is incremented linearly at every output packet. The base count is reset by the signal reset TB 108 provided at the end of every mega frame or extra-long mega frame.
Block 135 determines the difference between the output time stamp provided by generator 130 and the input time stamp TS_TB 137 computed by the input time stamp generator 110 that is stored with each associated packet in the FIFO memory 115. The received packets are output from the FIFO memory 115 to the transport stream composer 140. The transport stream composer 140 is provided with the output timing and performs bit rate adaptation of the transport stream by determining whether to eliminate or insert null packets in the transport stream. The transport stream is provided to the extractor 145.
5 Extractor 145 detects if any of the packets of the transport stream have an adaptation field with a PCR. If a PCR is detected, the extractor 145 extracts the PCR and sets a flag EN_PCR_INSERT 147. Any extracted PCR is provided to adder 150 which adds the time difference generated by block 135 to the extracted PCR to provide the recalibrated PCR. Inserter 155 re-inserts any recalibrated PCR into the transport stream when EN_PCR_INSERT flag is set. The adapted transport stream is delivered to output connector TS OUTPUT 160.
According to the systems and methods described herein, the input and output transport streams have a fixed and deterministic bit rate, even if ruled by a fractional ratio, and an input transport stream carries a time mark, such as the MIP
packet, which may be used to identify a time period. The time period allows determination of a periodical starting point common to input and output transport streams by indicating where to reset the PCR adaptation process. To have comparable exact input and output time stamps at any possible input and output transport stream rate identified in EN 300 744, the time base sampling frequency of 34,292,160 MHz may be used as a virtual reference clock.
Table 1 shows a packets period expressed in cycles of time base sampling frequency for every combination of guard time (e.g. as defined by EN 300 744), constellation, Forward Error Correction (FER) in an 8 MHz channel. It may be noted that all values are integers and exact.
t.:P'S K '114 16 1:32 ~
.:~ {~ t..,~,.~~,~~~Ta?8Er2ry~~r`'.~,':!u ~ 9327467520 8t31 ~~t. ~ y~t L:"?.4_. _:D r=,.J- J f c':ZL
f't,__,~J '~:t -r. 7772889600 6995600640 t E06956 1 f~0 64 ~3392i, ~{ `r' 3% =r 6909235200 2=,u~=t..~.~~.+,a i;='^ 587284992D `~ V . ; :_ ` ,.:
iy ~ e ' ..
51~13 15218311580 5596480h1.2 5285531492851 13 0:0t`1,1~~'.
T8 +922201600 :5329981440 5033871360 CRR5q'~[~`1~~~~..~.'r ~a.... .:.z`
1~;~ QA~N`1 1>4 -1;8 1 : 1G 1a'32 .1{i 5181926400 4..+6t7 3 3TuJ0 4 40 4 f+3 7 4~F 0''~~`i.Y 5, 03 9 :d`?`,2 "tJ:3 3886444800 C7i?~..3=L`. r'~~u'~~ ~~ ~,.~,.?~..._~ l ir~~.^=C~..1t v.~Ii~n .~ ~ .~~r"q v ~ ~;..r Z =J .~ k ^S '. f..'~~,?~r=r'.'~.`v ~ ~,Qt1 ~ C`~:,Q G 0 = '"a .r5 Vti:.;2;' :'~'=?.~ ..3 34 ''~~
it r7~~0 4~ G#, FuFi~ r 1 5:`?:~ 31G .:-11-51-5.u =r:.~
~=~~? 271-8240256 26427824C-4 ~54''5~'~53-5:6 ~ ~#~#!. L` ~~,~i L> ~c-c `r ~3 8~'tr 8 2961100800 ~L ~1= '~~ ~ ti.t rV~V ~'1~ ` ~ "~~
64 QA.M 114 1PS '1s'1Ã'F 1a132 l'`.-" 3 4 5 4 6 176 Q.~.` 00 10 9 : `1 5 45 4 i: 29E6424960 z8'a!s`!1',~:9't-a'20, 213 2590963200 233. ti668fi0 2 2023'1 fi720 21 375-44:640 3;4 2303078400 207:2770560 1~-~57f_:16640 1 ?'00396tii:
`a>`?v 20727705601 1865493504 1761854976 17100357,12 1...~' +1~~40`~"}N'~:liaa 1776660480, ~ , k1?; ,~~i7'`~,:.. 14628605440 . 6 Stamping with an exact value each input or output packet inside the reference period, the period of one Mega Frame or one Extra-Long Mega Frame allows the difference between the arrival time and the departure time of the transport stream to be determined. In addition, the computation is independent of any eventual jitter found in an incoming transport stream.
MPEG2 systems are based on an MPEG reference clock (a reference clock is used by transport stream system target decoder, for example, as defined by ISO/IEC
13818-1).
The MPEG reference clock has a frequency of 27MHz. To express a computed delay in the number of the reference clock, the difference is divided by 1,270,080, which is the ratio between the time base reference clock and the MPEG reference Clock.
Addition of the computed time difference to the PCR value is performed using dual modulus arithmetic, as described in IS013818-1. The time base sampling frequency is only one example, and that many others may be computed according to the teachings herein.
For example, much lower frequencies my be found if only a subset of possible combinations is required like that shown in Table 2, which is base on the time base sampling frequency of 5,670 MHz. In this example, the flexibility is reduced compared to that of the first value, but for applications dealing with channel bandwidth of only 8MHz it is sufficient. For this table and time base sampling frequency, the computed delay difference is divided by 210 to get the value added to the PCR.
T'a1AT1e 2 QPSK 1,4 ; ty 1a'1as V'i,i '1,2 a 13G' 1542240 1456~~60 1413720 211 12S5200 I 5G680 1092420 106 029,7.~
3M 1,142400 1028160 971040 942480 '~ ~ ~ . ~~ 925344 . ar u . ~. ~~ ;= C~ 873936 848232 7:8 ~a+' 9''~0O 88,1280 8:32320' 8078;:L
16 O.'.N-1 1,4 ; r1~i 1' 1 C, 1132 1,12 ~~568LG 77 1'@tG ? z828CI: 7 0 6,13 60 =
`~,=: r ~] ` ~ ~ C 't r h ~' ' ', >.-aG L 2 ` ; .< ~3 t! , ~; ~.~~~ I `:_:1:_ ': ::
3s'.4 571200 5I408~.``i 485520 47124:0 a.Ã~,.~e 5,14080 4}.2:I?i2 '~36 u`=.~``~C '-F 2'=~i~1Z,:
T`8 459:600 ~ 40:Lt0 41 f, -60 4Vtii~-~2L
~."v'Y
.-''" fl'} i':, :i ~ f~:R ~ ~:is:~:.~./6 ivL
1>2 5712030 ,1408G 418515-20: 471240 2'3 4.2840C, 38 5 5~S G 3 5 :=10353I3:0 i7:;;
516 342720 > n ~ ~:~ 29 ~t ~~., ~ 282744 ~
718 ..i2'64r`t~i 29f,1;:V 27744E' 2 6- -9 2 5D
This process gives examples of a way to implement a deterministic program clock reference re-stamping in Digital Video Broadcasting for Handheld Mobile/Terrestrial Television DVB-T/H (e.g., as defined in EN 300 744 and in TR 102 377DVB-T/H) systems where mega-frame initialization packet or extra-long mega frame watermarking is present. The processes described above guarantee that any equipment having the same signal at the input and having the same output bit rate, and generates exactly the same stream (bit exact) in multiple locations. As a result, the system and methods described herein allow the use of the embedded Mega-frame Initialization Packet to achieve a high precision and deterministic PCR re-stamping that can be applied at the input of each transmitter of an SFN network, thereby maintaining the SFN requirements of identical bit stream at every transmitter and being fully compliant with above-mentioned standards.
A number of exemplary implementations have been described. Nevertheless, it will be understood that various modifications may be made. For example, suitable results may be achieved if the steps of described techniques are performed in a different order and/or if components in a described components, architecture, or devices are combined in a different manner and/or replaced or supplemented by other components.
Accordingly, other implementations are within the scope of the following claims.
According to the systems and methods described herein, the input and output transport streams have a fixed and deterministic bit rate, even if ruled by a fractional ratio, and an input transport stream carries a time mark, such as the MIP
packet, which may be used to identify a time period. The time period allows determination of a periodical starting point common to input and output transport streams by indicating where to reset the PCR adaptation process. To have comparable exact input and output time stamps at any possible input and output transport stream rate identified in EN 300 744, the time base sampling frequency of 34,292,160 MHz may be used as a virtual reference clock.
Table 1 shows a packets period expressed in cycles of time base sampling frequency for every combination of guard time (e.g. as defined by EN 300 744), constellation, Forward Error Correction (FER) in an 8 MHz channel. It may be noted that all values are integers and exact.
t.:P'S K '114 16 1:32 ~
.:~ {~ t..,~,.~~,~~~Ta?8Er2ry~~r`'.~,':!u ~ 9327467520 8t31 ~~t. ~ y~t L:"?.4_. _:D r=,.J- J f c':ZL
f't,__,~J '~:t -r. 7772889600 6995600640 t E06956 1 f~0 64 ~3392i, ~{ `r' 3% =r 6909235200 2=,u~=t..~.~~.+,a i;='^ 587284992D `~ V . ; :_ ` ,.:
iy ~ e ' ..
51~13 15218311580 5596480h1.2 5285531492851 13 0:0t`1,1~~'.
T8 +922201600 :5329981440 5033871360 CRR5q'~[~`1~~~~..~.'r ~a.... .:.z`
1~;~ QA~N`1 1>4 -1;8 1 : 1G 1a'32 .1{i 5181926400 4..+6t7 3 3TuJ0 4 40 4 f+3 7 4~F 0''~~`i.Y 5, 03 9 :d`?`,2 "tJ:3 3886444800 C7i?~..3=L`. r'~~u'~~ ~~ ~,.~,.?~..._~ l ir~~.^=C~..1t v.~Ii~n .~ ~ .~~r"q v ~ ~;..r Z =J .~ k ^S '. f..'~~,?~r=r'.'~.`v ~ ~,Qt1 ~ C`~:,Q G 0 = '"a .r5 Vti:.;2;' :'~'=?.~ ..3 34 ''~~
it r7~~0 4~ G#, FuFi~ r 1 5:`?:~ 31G .:-11-51-5.u =r:.~
~=~~? 271-8240256 26427824C-4 ~54''5~'~53-5:6 ~ ~#~#!. L` ~~,~i L> ~c-c `r ~3 8~'tr 8 2961100800 ~L ~1= '~~ ~ ti.t rV~V ~'1~ ` ~ "~~
64 QA.M 114 1PS '1s'1Ã'F 1a132 l'`.-" 3 4 5 4 6 176 Q.~.` 00 10 9 : `1 5 45 4 i: 29E6424960 z8'a!s`!1',~:9't-a'20, 213 2590963200 233. ti668fi0 2 2023'1 fi720 21 375-44:640 3;4 2303078400 207:2770560 1~-~57f_:16640 1 ?'00396tii:
`a>`?v 20727705601 1865493504 1761854976 17100357,12 1...~' +1~~40`~"}N'~:liaa 1776660480, ~ , k1?; ,~~i7'`~,:.. 14628605440 . 6 Stamping with an exact value each input or output packet inside the reference period, the period of one Mega Frame or one Extra-Long Mega Frame allows the difference between the arrival time and the departure time of the transport stream to be determined. In addition, the computation is independent of any eventual jitter found in an incoming transport stream.
MPEG2 systems are based on an MPEG reference clock (a reference clock is used by transport stream system target decoder, for example, as defined by ISO/IEC
13818-1).
The MPEG reference clock has a frequency of 27MHz. To express a computed delay in the number of the reference clock, the difference is divided by 1,270,080, which is the ratio between the time base reference clock and the MPEG reference Clock.
Addition of the computed time difference to the PCR value is performed using dual modulus arithmetic, as described in IS013818-1. The time base sampling frequency is only one example, and that many others may be computed according to the teachings herein.
For example, much lower frequencies my be found if only a subset of possible combinations is required like that shown in Table 2, which is base on the time base sampling frequency of 5,670 MHz. In this example, the flexibility is reduced compared to that of the first value, but for applications dealing with channel bandwidth of only 8MHz it is sufficient. For this table and time base sampling frequency, the computed delay difference is divided by 210 to get the value added to the PCR.
T'a1AT1e 2 QPSK 1,4 ; ty 1a'1as V'i,i '1,2 a 13G' 1542240 1456~~60 1413720 211 12S5200 I 5G680 1092420 106 029,7.~
3M 1,142400 1028160 971040 942480 '~ ~ ~ . ~~ 925344 . ar u . ~. ~~ ;= C~ 873936 848232 7:8 ~a+' 9''~0O 88,1280 8:32320' 8078;:L
16 O.'.N-1 1,4 ; r1~i 1' 1 C, 1132 1,12 ~~568LG 77 1'@tG ? z828CI: 7 0 6,13 60 =
`~,=: r ~] ` ~ ~ C 't r h ~' ' ', >.-aG L 2 ` ; .< ~3 t! , ~; ~.~~~ I `:_:1:_ ': ::
3s'.4 571200 5I408~.``i 485520 47124:0 a.Ã~,.~e 5,14080 4}.2:I?i2 '~36 u`=.~``~C '-F 2'=~i~1Z,:
T`8 459:600 ~ 40:Lt0 41 f, -60 4Vtii~-~2L
~."v'Y
.-''" fl'} i':, :i ~ f~:R ~ ~:is:~:.~./6 ivL
1>2 5712030 ,1408G 418515-20: 471240 2'3 4.2840C, 38 5 5~S G 3 5 :=10353I3:0 i7:;;
516 342720 > n ~ ~:~ 29 ~t ~~., ~ 282744 ~
718 ..i2'64r`t~i 29f,1;:V 27744E' 2 6- -9 2 5D
This process gives examples of a way to implement a deterministic program clock reference re-stamping in Digital Video Broadcasting for Handheld Mobile/Terrestrial Television DVB-T/H (e.g., as defined in EN 300 744 and in TR 102 377DVB-T/H) systems where mega-frame initialization packet or extra-long mega frame watermarking is present. The processes described above guarantee that any equipment having the same signal at the input and having the same output bit rate, and generates exactly the same stream (bit exact) in multiple locations. As a result, the system and methods described herein allow the use of the embedded Mega-frame Initialization Packet to achieve a high precision and deterministic PCR re-stamping that can be applied at the input of each transmitter of an SFN network, thereby maintaining the SFN requirements of identical bit stream at every transmitter and being fully compliant with above-mentioned standards.
A number of exemplary implementations have been described. Nevertheless, it will be understood that various modifications may be made. For example, suitable results may be achieved if the steps of described techniques are performed in a different order and/or if components in a described components, architecture, or devices are combined in a different manner and/or replaced or supplemented by other components.
Accordingly, other implementations are within the scope of the following claims.
Claims (14)
1. A method of providing a fixed and deterministic bit rate adaptation for an output transport stream, the method comprising:
receiving an input transport stream of packets;
deriving output timing from the input transport stream;
determining an input time stamp for each packet of the input transport stream;
determining a corresponding output timestamp for each outgoing packet of the output transport stream;
determining the difference between the input timestamp and the output timestamp;
extracting a program clock reference (PCR) for the output transport stream;
adding the determined difference to the PCR; and adding the PCR to the output transport stream.
receiving an input transport stream of packets;
deriving output timing from the input transport stream;
determining an input time stamp for each packet of the input transport stream;
determining a corresponding output timestamp for each outgoing packet of the output transport stream;
determining the difference between the input timestamp and the output timestamp;
extracting a program clock reference (PCR) for the output transport stream;
adding the determined difference to the PCR; and adding the PCR to the output transport stream.
2. The method of claim 1 further comprising:
receiving the input stream of packets includes a time mark packet;
determining a period from the time mark;
determining the input time stamp and output time stamp for each packet within the period; and resetting the timestamps at the end of each period.
receiving the input stream of packets includes a time mark packet;
determining a period from the time mark;
determining the input time stamp and output time stamp for each packet within the period; and resetting the timestamps at the end of each period.
3. The method of claim 2 wherein the time mark is a mega-frame initialization packet (MIP) and the period is a mega-frame.
4. The method of claim 2 wherein the time mark is a mega-frame initialization packet (MIP) and the period is an extra long mega-frame.
5. The method of claim 1 further comprising composing the output transport stream from the input transport stream packets by inserting or eliminating null packets to perform rate adaptation based on the output timing.
6. The method of claim 2 wherein the time base sampling frequency is 34,292,160 MHz for a reference clock of 27MHz and the difference is divided by 1,270,080.
7. The method of claim 2 wherein the time base sampling frequency is 5,670 MHz for a reference clock of 8MHz and the difference is divided by 210.
8. A system for providing a fixed and deterministic bit rate adaptation for an output transport stream, the system comprising:
an input to receive an input transport stream of packets;
a timer to provide output timing derived from the input transport stream;
a counter to determine an input time stamp for each packet of the input transport stream;
a counter to determine a corresponding output timestamp for each outgoing packet of the output transport stream;
a processor to determine the difference between the input timestamp and the output timestamp, extract a program clock reference (PCR) for the output transport stream; add the determined difference to the PCR; and add the PCR to the output transport stream; and an output to output the transport stream according to the derived output timing.
an input to receive an input transport stream of packets;
a timer to provide output timing derived from the input transport stream;
a counter to determine an input time stamp for each packet of the input transport stream;
a counter to determine a corresponding output timestamp for each outgoing packet of the output transport stream;
a processor to determine the difference between the input timestamp and the output timestamp, extract a program clock reference (PCR) for the output transport stream; add the determined difference to the PCR; and add the PCR to the output transport stream; and an output to output the transport stream according to the derived output timing.
9. The system claim 8 wherein the input stream includes a time mark packet used to determine a period, the input time stamp and output time stamp are determined for each packet within the period; and the timestamps are reset at the end of each period.
10. The system of claim 9 wherein the time mark is a mega-frame initialization packet (MIP) and the period is a mega-frame.
11. The system of claim 9 wherein the time mark is a mega-frame initialization packet (MIP) and the period is an extra long mega-frame.
12. The system of claim 8 further comprising a composer to create the output transport stream from the input transport stream packets by inserting or eliminating null packets to perform rate adaptation based on the output timing.
13. The system of claim 9 wherein the time base sampling frequency is 34,292,160 MHz for a reference clock of 27MHz and the difference is divided by 1,270,080.
14. The system of claim 9 wherein the time base sampling frequency is 5,670 MHz for a reference clock of 8MHz and the difference is divided by 210.
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| US60/929,170 | 2007-06-15 | ||
| PCT/IB2008/003587 WO2009040680A2 (en) | 2007-06-15 | 2008-06-16 | Deterministic program clock reference re-stamping for synchronous bit rate adaptation based on mega-frame initialization packet |
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| CA002689541A Abandoned CA2689541A1 (en) | 2007-06-15 | 2008-06-16 | Deterministic program clock reference re-stamping for synchronous bit rate adaptation based on mega-frame initialization packet |
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| US7937618B2 (en) * | 2007-04-26 | 2011-05-03 | International Business Machines Corporation | Distributed, fault-tolerant and highly available computing system |
| EP2165442B1 (en) * | 2007-06-15 | 2011-09-21 | Michele Bargauan | Mega-frame initialization packet generation and synchronous re-generation with bit rate adaptation for single frequency networks with multiple modulation schemes |
| US8493853B2 (en) | 2007-12-13 | 2013-07-23 | Arris Solutions, Inc. | Flow control in a network device |
| JP5380862B2 (en) * | 2008-03-05 | 2014-01-08 | 日本電気株式会社 | IP stream transmission / reception system, IP stream reception apparatus, and reception processing timing synchronization method used therefor |
| US20100042866A1 (en) * | 2008-08-15 | 2010-02-18 | Mediatek Inc. | Method and Apparatus for Adjusting a System Timer of a Mobile Station |
| EP2368365A1 (en) * | 2008-12-19 | 2011-09-28 | Thomson Licensing | Method for transport stream synchronizing in a multiplexer comprising an external coprocessor |
| CN102215144B (en) * | 2011-05-17 | 2016-06-29 | 中兴通讯股份有限公司 | The measuring method of packet loss and system |
| JP6232870B2 (en) * | 2013-09-11 | 2017-11-22 | 株式会社リコー | Wireless communication system, wireless communication method, program, and recording medium |
| FR3015739B1 (en) * | 2013-12-19 | 2017-05-26 | Enensys Tech | METHOD FOR GENERATING TEMPORAL MARKING FOR SYNCHRONOUS TERRESTRIAL DIFFUSION |
| US11095535B2 (en) * | 2017-08-15 | 2021-08-17 | Gigamon Inc. | Adaptive and flexible packet sampling |
| US11115294B2 (en) | 2019-05-07 | 2021-09-07 | Gigamon Inc. | Automatic dynamic determination of data traffic sampling policy in a network visibility appliance |
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| GB9921261D0 (en) | 1999-09-09 | 1999-11-10 | Nds Ltd | Method and apparatus for processing a digital bitstream |
| CA2394923A1 (en) * | 1999-12-14 | 2001-06-21 | General Instrument Corporation | Hardware filtering of input packet identifiers for an mpeg re-multiplexer |
| FR2803459B1 (en) * | 1999-12-30 | 2002-02-15 | Itis | TRANSMISSION SYSTEM WITH SPATIAL, TEMPORAL AND FREQUENTIAL DIVERSITY |
| CA2352398C (en) | 2000-07-06 | 2005-07-26 | Unique Broadband Systems, Inc. | Low phase noise frequency converter |
| US20030112883A1 (en) * | 2001-12-13 | 2003-06-19 | Ihrie David Wayne | Method and apparatus for bi-directional communication in systems broadcasting multi-carrier signals |
| JP2005051633A (en) | 2003-07-30 | 2005-02-24 | Sony Corp | Edit device, bit rate control method, and bit rate control program |
| KR100584381B1 (en) * | 2004-02-04 | 2006-05-26 | 삼성전자주식회사 | Method for adjusting transmission rate of mpeg-2 data and apparatus therefor |
| KR100526189B1 (en) * | 2004-02-14 | 2005-11-03 | 삼성전자주식회사 | Transcoding system and method for keeping timing parameters constant after transcoding |
| US7336646B2 (en) * | 2004-10-26 | 2008-02-26 | Nokia Corporation | System and method for synchronizing a transport stream in a single frequency network |
| WO2006084361A1 (en) | 2005-02-09 | 2006-08-17 | Alex Dolgonos | System and method for implementing a transmit diversity single frequency network without gps receivers |
| JP4308178B2 (en) * | 2005-09-02 | 2009-08-05 | リーダー電子株式会社 | Device for correcting part of broadcast TS |
| EP1768285A1 (en) | 2005-09-23 | 2007-03-28 | Udcast | Method and device for processing a DVB-H (Digital Video Broadcasting - Handheld) compliant transport stream |
| US8275003B2 (en) * | 2005-10-24 | 2012-09-25 | General Instrument Corporation | Method and apparatus for generating multiplexed signals |
| JP2007274607A (en) | 2006-03-31 | 2007-10-18 | Toshiba Corp | Digital signal processor and data stream processing method |
| US20080107099A1 (en) * | 2006-11-03 | 2008-05-08 | Alex Dolgonos | System and method for adapting a transport stream for transmission |
| EP2165442B1 (en) * | 2007-06-15 | 2011-09-21 | Michele Bargauan | Mega-frame initialization packet generation and synchronous re-generation with bit rate adaptation for single frequency networks with multiple modulation schemes |
| EP2158707A2 (en) * | 2007-06-15 | 2010-03-03 | Michele Bargauan | Communications system to feed multiple single frequency networks with multiple content |
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| WO2009037597A3 (en) | 2009-08-20 |
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| US7924886B2 (en) | 2011-04-12 |
| BRPI0813506A2 (en) | 2015-12-15 |
| WO2009037597A2 (en) | 2009-03-26 |
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