TWI393431B - Mobile tv system and method for synchronizing the rendering of streaming services thereof - Google Patents

Description

Mobile television system and method for synchronizing the same

The present invention relates to a mobile television system, and more particularly to an Internet Protocol-based (IP-Based) mobile television system, and synchronized in an IP-Based mobile television system. A method of rendering a streaming service in a user terminal.

Currently, the streaming service provided by the IP-Based mobile TV system is based on a broadcast or a multicast method through a Real-time Transport Protocol (RTP) to have a time-based The video stream, interactive service or notification service is transmitted to the mobile TV client device.

Under certain applications, it may be necessary to display the same streaming service in a synchronized manner between mobile TV client devices. For example, when the streaming service includes interactive services (for example, instant callback, instant answer, etc.), in order to ensure the fairness of the interactive service, it is necessary to synchronize the time that the streaming service is presented on different mobile TV users. Or, if the user of the mobile TV user needs to view the same streaming service through the respective client devices and talk to each other to discuss the content of the streaming service, if the presentation of the streaming service can be synchronized between the users, it may be beneficial. The discussion proceeded. Furthermore, many mobile TV client devices may be placed in the store at the same time. If the mobile TV client device can receive and simultaneously present the same streaming service in a synchronized manner, the customer can conveniently compare the mobile TV clients. The difference in display characteristics of the device.

For traditional analog and digital TV sets, it is not a problem to display the same program in a synchronized manner. However, for IP-Based mobile TV systems, for example, DVB-H, 3rd Generation Partnership Project Multimedia Broadcast Multicast Service (3GPP MBMS), microwave access global interoperability group broadcast Worldwide Interoperability for Microwave Access Multicast Broadcast Services (WiMAX MBS), because RTP was originally designed for streaming services for unicast, it is not considered to be different when transmitting by broadcast or multicast. The synchronization problem of the same streaming service is presented on the mobile client device.

FIG. 1 is a schematic diagram showing an example of transmitting a multimedia stream through an RTP according to the prior art, wherein the multimedia stream includes an audio stream, a video stream, and an event stream.

Referring to FIG. 1, timestamps TSa(i), TSv(i), and TSe(i) are RTP timestamps used for audio streams, video streams, and event streams transmitted through RTP, respectively (RTP time). Stamp), the clock rate of the RTP timestamps respectively, the sampling rate of the audio, video and event streams. In addition, the synchronization information required for simultaneously presenting audio streams, video streams, and event streams is carried by a Real-time Transport Control Protocol (RTCP) packet. Specifically, each media stream (ie, audio stream, video stream, and event stream) has a dedicated RTCP channel, which is responsible for periodically transmitting the RTCP transmission required for the corresponding media stream. Sender Report (SR) packet. An RTCP SR packet contains a Network Time Protocol (NTP) time stamp corresponding to an RTP timestamp of a media stream. For example, the NTP timestamp corresponding to the RTP timestamp Vt(1) of the video stream is NTPv(1), and the NTP timestamp corresponding to the RTP timestamp At(1) of the audio stream is NTPa(1). Since the NTP timestamps contained in the RTCP SR packets of each media stream are all from the same wall clock, multiple media streams can be presented on a client device in a synchronized manner.

However, in the IP-Based mobile TV system, the NTP timestamp of the RTCP SR records not the time when the AV multimedia stream is actually broadcast through the IP-Based mobile TV system. In fact, the time recorded by the NTP timestamp is not strictly defined, and is usually the time when multiple media streams are recorded while being synchronized for a multimedia stream. Moreover, in the IP-Based mobile TV system, a standard method is not specified to determine the relative relationship between the time recorded by the NTP timestamp in the RTCP SR packet and the actual broadcast time of the multimedia stream. Therefore, due to the difference in performance of the mobile client device itself, when the same streaming service is received, there is a different initial delay for presentation, which causes the streaming service to be out of synchronization. Taking DVB-H as an example, the Multi-Protocol Encapsulation-Forward Error Correction (MPE-FEC) decoding delay, videoconferencing, and media access control (MAC) layer The initial buffering delay of the decoder (Δ decoder) causes the difference in the presentation start delay of different mobile TV users. Therefore, there is a need to develop a system that can simultaneously stream streaming services in multiple mobile TV user terminals in an IP-Based mobile television system.

The present invention provides a mobile television system in which all mobile terminals are capable of playing an RTP streaming service in a synchronized manner.

The present invention provides a method of synchronizing streaming services in a mobile television system that enables all mobile terminals to play an RTP streaming service in a synchronized manner.

An exemplary embodiment of the present invention provides a mobile television system including an Internet Protocol-based (IP-Based) mobile TV server group, a network device, and a plurality of mobile terminals. An Internet-based Protocol-based (IP-Based) mobile TV server group transmits a streaming service and a network time protocol corresponding to the streaming service through a Real-time Transport Protocol (RTP) (Network Time Protocol, NTP) A sequence of time stamps. The network device provides at least one network to transmit the stream service and the network time stamp time stamp sequence. Each mobile terminal receives the streaming service, the network time stamp time stamp sequence, and a synchronous clock from the network device, wherein each mobile terminal restores the received string according to the synchronization clock and the synchronization time difference. The network service time reference clock of the streaming service plays the received streaming service based on the restored network time protocol reference clock and the received network time stamp timestamp.

An exemplary embodiment of the present invention provides a method for synchronizing a streaming service in a mobile television system, the method comprising using an internet protocol-based (IP-Based) mobile TV server group via a network The device transmits a sequence of a network service and a network time protocol (NTP) time stamp corresponding to the streaming service through a Real-time Transport Protocol (RTP). The method also includes receiving the streaming service, the network time protocol time stamp sequence, and a synchronization clock from the network device using a plurality of mobile terminals. The method further includes restoring, in each mobile terminal, a network time protocol reference clock for presenting the received streaming service based on the synchronization clock and the synchronization time difference, and authenticating in each mobile terminal according to the The network time protocol reference clock and the received network time stamp timestamp play the received streaming service.

Based on the above, exemplary embodiments of the present invention enable all mobile terminals in a mobile television system to play the received RTP streaming service in a synchronized manner.

The above described features and advantages of the present invention will be more apparent from the following description.

The mobile TV system proposed in this exemplary embodiment transmits a streaming service and a streaming service through a network device through a Real-time Transport Protocol (RTP) through an IP-Based mobile TV server group. A corresponding Network Time Protocol (NTP) time stamp sequence is provided to a plurality of mobile terminals, and the mobile terminals are based on a synchronization time difference value and a synchronization clock received from the network device. The network time protocol reference clock used to present the received streaming service is restored, and the received streaming service is played in accordance with the restored network time protocol reference clock and the received network time stamp timestamp.

In detail, when an RTP streaming service is being transmitted by the IP-Based mobile TV server group in a multicast or broadcast manner, the time recorded by the NTP timestamp in the RTCP SR packet transmitted along with the RTP streaming service Has a common clock C _NTP . In addition, on the IP-based mobile TV system, each mobile terminal receives and maintains a synchronous clock C _sync ; that is, the synchronous clock C _sync is transmitted through the out-of-band with the RTP stream service. The technical way is to achieve synchronization of the clocks on multiple mobile terminals. Thereafter, the mobile terminal receiving the streaming service uses the synchronous clock C _sync as a reference clock for presenting the received RTP streaming service.

Specifically, on each mobile terminal, the time value T _NTP originally recorded by the NTP time stamp in the RTCP SR packet is converted to the time based on the synchronous clock C _sync (ie, the time value T _NTP + time difference) dT). Here, if the time difference dT (ie, dT=C _sync -C _NTP ) between the synchronous clock C _sync and the common clock C _NTP on each mobile terminal is adjusted to be consistent, all mobile terminals are rendered. The rendering time of this streaming service can be synchronized.

In addition, another equivalent method is to provide a network time protocol reference clock C _{NTP-R for the} RTP stream service on each mobile terminal, where the network time protocol reference clock C _NTP-R is per mobile terminal. The synchronization clock on C _sync is restored. That is to say, the network time protocol reference clock C _NTP-R is generated according to the synchronous clock C _sync on each mobile terminal (ie, the network time protocol reference clock C _NTP-R = synchronous clock C _sync - time difference dT) And presenting the streaming service according to the time T _NTP originally recorded by the NTP timestamp of the RTCP SR packet and the generated network time protocol reference clock C _NTP-R . Therefore, if the time difference dT on each mobile terminal can be consistent, the network time protocol reference clock C _{NTP-R of} each mobile terminal is also synchronized. Therefore, the time at which each mobile terminal presents this streaming service can be synchronized.

However, it must be noted that the selection of the time difference dT does not advance the presentation time of any mobile terminal (ie, the time value T _NTP + time difference dT) beyond the actual performance limit. That is to say, if the time difference dT is set too small, it may cause the streaming service (for example, the video clip) to be unable to complete decoding when the above presentation time arrives, or cannot be performed on the mobile terminal with poor performance. The decoded video and audio material is presented on the mobile terminal. Therefore, the actual rendering time of this streaming service will be later than the specified rendering time, causing the rendering of the streaming service to remain out of sync.

The invention will be described in more detail below with reference to a number of exemplary embodiments and drawings. It should be noted that in the following exemplary embodiments, the method for determining the synchronized network time protocol reference clock C _NTP-R is taken as an example. However, the exemplary embodiments may also be applied to the above The time value T _NTP originally recorded by the NTP time stamp in an mobile terminal is converted to an example based on the time of the synchronous clock C _sync .

[First Exemplary Embodiment]

2 is a schematic block diagram of a mobile television system according to a first exemplary embodiment of the present invention.

Referring to FIG. 2, the mobile TV system 100 includes an IP-Based Mobile TV Server Set 102, a Broadcast Network Equipment 104, a Mobil Network Equipment 106, and a mobile terminal. 108. The mobile terminal 110 and the mobile terminal 112.

The IP-Based Mobile TV Server Group 102 is a collection of IP-based headend servers required for the operation of the Mobile Television System 100. In the present exemplary embodiment, the IP-Based mobile TV server group 102 can provide streaming services in a broadcast or multicast manner. Here, the streaming service is a scheduled service or an on-demand service requested by a mobile terminal (for example, the mobile terminal 108). Specifically, the IP-Based mobile TV server group 102 transmits the RTP streaming service through the Real-time Transport Protocol (RTP) and transmits the real-time transmission control protocol defined in the RTP standard (RFC 3550) (Real). -time Transport Control Protocol (RTCP) transmits a sequence of Network Time Protocol (NTP) time stamps corresponding to the streaming service.

The IP-Based Mobile TV Server Group 102 includes an RTP Streaming Server 122 and a Service Guide Server 124.

The RTP streaming server 122 is configured to transmit the RTP streaming service to the mobile terminal 108, the mobile terminal 110, and the mobile terminal 112 via a one-way IP channel provided by the broadcast network device 104. In addition, RTP streaming server 122 provides relevant information about the RTP streaming service it transmits to service steering server 124. For example, such related information includes information contained in a Session Description Protocol (SDP) description of the RTP streaming service (shown in FIG. 3). In the present exemplary embodiment, the RTP stream server 122 is an RTP stream server conforming to the DVB-IPDC standard. However, it should be understood that the present invention is not limited thereto. In another exemplary embodiment of the present invention, the RTP stream server 122 may also be an RTP stream server that complies with the OMA BCAST standard or other mobile TV standards.

The service guidance server 124 is configured to transmit the service guidance information to the mobile terminal 108, the mobile terminal 110, and the mobile terminal through the combination of the broadcast network device 104, the mobile network device 106, or the broadcast network device 104 and the mobile network device 106. 112. In the present exemplary embodiment, the service guidance server 124 transmits the suggested time difference dT _def-r to the mobile terminal 108, the mobile terminal 110, and the mobile terminal 112 through the SDP description (as shown in FIG. 3).

In the present exemplary embodiment, the service guidance server 124 is an Electronic Service Guide (ESG) server conforming to the DVB-IPDC standard. However, it should be understood that the present invention is not limited thereto. In another exemplary embodiment of the present invention, the service guidance server 124 may also be a service guidance server conforming to the OMA BCAST standard or other mobile TV standards.

The broadcast network device 104 is a headend device and a wireless signal transmitting station required to constitute a one-way broadcast network. In the mobile television system 100, the broadcast network device 104 is responsible for streaming a unidirectional IP multicast packet from the IP-Based mobile TV server group 102 to the mobile terminal 108, the mobile terminal 110 and the mobile terminal 112, wherein the IP group The packet stream carries the packet of the RTP stream service. In the present exemplary embodiment, the broadcast network device 104 is configured to transmit a sequence of the network time protocol time stamp T _NTP of the streaming service and the corresponding streaming service.

The mobile network device 106 is a network element for receiving wireless signals and performing packet switching. In the IP-based mobile television system 100, the mobile network device 106 is configured to provide a two-way return channel between the mobile terminal and the IP-Based mobile TV server group 102.

The mobile terminal 108, the mobile terminal 110, and the mobile terminal 112 are user equipments for the user to receive and watch the mobile TV streaming service. In the present exemplary embodiment, mobile terminal 108, mobile terminal 110, and mobile terminal 112 receive a sequence of streaming services and corresponding network time protocol timestamps T _NTP from broadcast network device 104. In particular, the mobile terminal 108, the mobile terminal 110, and the mobile terminal 112 receive the synchronization clock _Csync from the broadcast network device 104. Specifically, the mobile terminal 108, the mobile terminal 110, and the mobile terminal 112 acquire and maintain the synchronous clock C _sync via a clock synchronization protocol provided by the mobile TV system broadcast/multicast transmission technology below the IP layer. It is to be noted that, in another exemplary embodiment of the present invention, the mobile terminal 108, the mobile terminal 110, and the mobile terminal 112 can also acquire and maintain the synchronous clock C _sync through the synchronous clock protocol provided by the mobile network device 106.

In the present exemplary embodiment, each mobile terminal (ie, mobile terminal 108, mobile terminal 110, and mobile terminal 112) receives an IP-Based mobile TV server from broadcast network device 104 or mobile network device 106. The suggested time difference dT _{def-r of the} group 102, and the expected time difference dT _{def-r is used to} generate an expected time difference dT _{Exp i} , where i represents the identification code of the mobile terminal. In particular, each mobile terminal is able to successfully play the streaming service at a presentation time that is restored according to the expected time difference dT _{Exp i} generated by itself. In addition, all mobile terminals communicate with each other and coordinate a synchronization time difference dT _sync according to all expected time differences dT _{Exp i} in a decentralized calculation, where the following formula (1):

dT _sync ≧MAX{dT _{Exp i} } (Formula (1))

Furthermore, each mobile terminal generates a network time-based reference clock C _NTP-R (ie, C _NTP-R = C _sync -dT _sync ) according to the synchronization clock C _sync and the synchronization time difference dT _sync and according to the generated The network time protocol reference clock C _NTP-R and the corresponding network time protocol time stamp T _NTP play the received streaming service.

4 is a schematic block diagram showing the mobile terminal of FIG. 2. The configuration and functions of the mobile terminal 108, the mobile terminal 110, and the mobile terminal 112 are the same. Here, the mobile terminal 108 will be described as an example.

Referring to FIG. 4, the mobile terminal 108 includes a DVB-H physical layer module 302, a 3GPP UMTS transmission/reception module 304, an MPEG-2 TS module 306, an IP module 308, a service guiding module 310, and a playback synchronization module. Group 312 and RTP stream play module 314.

The DVB-H physical layer module 302 is configured to receive IP packets from the IP-Based mobile TV server group 102 through the broadcast network device 104. Specifically, the DVB-H physical layer module 302 performs the function of the DVB-H physical layer to transmit MPEG-2 TS received from the DVB-H broadcast network (ie, the broadcast network device 104). The packet is sent to the MPEG-2 TS module 306.

The 3GPP Universal Mobile Telecommunications System (UMTS) transmitting/receiving module 304 is configured to transmit the mobile network device 106 and the IP-Based mobile TV server group 102 or other mobile terminals (eg, the mobile terminal 110 or the mobile terminal). 112) Perform transmission and reception of IP packets.

The MPEG-2 TS module 306 is used to reassemble the MPEG-2 TS packet belonging to the Multi-Protocol Encapsulation (MPE) section carrying the IP packet into a complete DVB-H standard. The IP packet is uploaded to the IP module 308. In addition, the MPEG-2 TS module 306 also restores the IP packet containing the transmission error through the information carried in the Multiple Access Protocol Encapsulation-Forward Error Correction (FEC) segment.

In the present exemplary embodiment, the MPEG-2 TS module 306 includes a Program-Specific Information (PSI)/Service Information (SI) module 322 for receiving and maintaining MPEG-2 transport streams. A PSI/SI table associated with the broadcast network device 104 in (Transport Stream).

Specifically, the PSI/SI table includes a Time and Date Table (TDT) and a Time Offset Table (TOT). The TDT provides a standard clock on the broadcast network device 104, and the time zone of this standard clock is Universal Time (Coordinated, UTC), which is Greenwich Mean Time (GMT). The TOT provides a local time standard clock on the broadcast network device 104. Since the time zone of the regional time is not necessarily UTC, the time difference between the time zone of the regional time and the UTC is recorded in the TOT. In particular, the DVB-H physical layer modules of the mobile terminal 108, the mobile terminal 110 and the mobile terminal 112 all receive the same RTP streaming service, and the RTP streaming service is carried in one or several MPEG-2 transport streams. And the foregoing plurality of MPEG-2 transport streams transmit the RTP service in a closely synchronized manner. At this time, the mobile terminal 108, the mobile terminal 110, and the mobile terminal 112 are clocks restored using TDT or TOT as the synchronous clock C _sync .

In the present exemplary embodiment, the TDT or TOT table is transmitted by the DVB-HIP Encapsulator (IP Encapsulator) in the broadcast network device 104. In this exemplary embodiment, the DVB-H IP encapsulator will transmit a TDT or TOT table for an RTP streaming service in the following manner. For example, the DVB-H IP Encapsulator will transmit a copy of the TDT or TOT table in each transmission burst of the RTP Streaming Service. In addition, in another exemplary embodiment of the present invention, the DVB-H IP encapsulator can also transmit a TDT or TOT table in the transmission spike of an RTP stream service every N RTP stream service transmission spikes. Where N is a natural number. Furthermore, in another exemplary embodiment of the present invention, the DVB-H IP encapsulator may also transmit the transmission peak of the next RTP stream service every M seconds (for example, 10 seconds) for a certain RTP stream service. A TDT or TOT form.

The IP module 308 is used to handle routing between different networks. In the exemplary embodiment, the IP module 308 is configured to receive and process an IP packet from the MPEG-2 TS module 306 and transmit the received IP packet to the service guiding module 310 or the RTP stream playing module. 314.

The service guiding module 310 is configured to receive and maintain service guidance data transmitted from the IP-Based mobile TV server group 102 and transmitted via the broadcast network device 104 or the mobile network device 106. In particular, the service guidance module 310 receives and processes the suggested time difference dT _def-r from the IP-Based mobile TV server group 102. In the present exemplary embodiment, the service guidance server 124 is compliant with the DVB-IPDC standard, so the service guidance module 310 must be compliant with the DVB-IPDC standard.

The play synchronization module 312 is used to determine an expected time difference (eg, the expected time difference dT _{Exp 1 of the} mobile terminal 108). Specifically, when determining the expected time difference dT _{Exp 1} , first, the play synchronization module 312 picks up a test value of the expected time difference dT _{Exp 1} and then sends the value to the RTP stream play module 314. It is judged whether the test value of the expected time difference dT _{Exp 1} exceeds the limit of the performance of the mobile terminal 108 (i.e., the phenomenon that the actual presentation time is later than the specified presentation time). If the test value of the expected time difference dT _{Exp 1} is still within the limit of the performance of the mobile terminal 108, the play synchronization module 312 will use the test value of the expected time difference dT _{Exp 1} as dT _{Exp 1} The final value; otherwise, the playback synchronization module 312 will select another expected time difference dT _{Exp 1} value for testing. In addition, when the test value of the expected time difference dT _{Exp 1} is selected, the play synchronization module 312 refers to the recommended time difference dT _def-r received from the service guide module 310. In particular, in the present exemplary embodiment, the 3GPP UMTS transmission/reception modules of all mobile terminals communicate with each other, and the playback synchronization modules of all mobile terminals use the decentralized algorithm for the determined expected time difference ( For example, a distributed election protocol determines a synchronization time difference dT _sync that satisfies equation (1). This method of dispersion calculation is well known to those skilled in the art and will not be described in detail herein.

The RTP stream play module 314 is configured to receive the synchronization clock C _sync from the PSI/SI module 322, receive the synchronization time difference dT _sync from the play synchronization module 312, and play the received stream service. Specifically, the RTP stream playback module 314 restores the network time protocol reference clock C _NTP-R according to the received synchronization clock C _sync and the synchronization time difference dT _sync , and refers to the restored network time protocol according to the restored network time protocol. The clock C _NTP-R and the corresponding network time protocol time stamp T _NTP play the received streaming service.

Based on the above, in the architecture of the mobile TV system 100, the mobile terminal 108, the mobile terminal 110 and the mobile terminal 112 play the received streaming service with the synchronized network time protocol reference clock C _NTP-R , so the streaming service is The time presented in the mobile terminal 108, the mobile terminal 110, and the mobile terminal 112 will be the same.

FIG. 5 is a flowchart of a method for synchronizing a streaming service according to a first exemplary embodiment of the present invention.

Referring to FIG. 5, each mobile terminal receives a synchronization clock C _sync and a streaming service from the IP-Based mobile TV server group 102, corresponding network time-bound time, from the broadcast network device 104 in step S401. Stamp the sequence of T _NTP with the suggested time difference dT _def-r . Next, in step S403, each mobile terminal refers to the recommended time difference dT _def-r to generate a corresponding expected time difference dT _{Exp i} . Thereafter, all the mobile terminals communicate with each other in step S405 and determine the synchronization time difference dT _sync according to the expected time difference dT _{Exp i} through the distributed algorithm. Finally, in step S407, each mobile terminal restores the network time protocol reference clock C _NTP-R according to the synchronization clock C _sync and the synchronization time difference dT _sync , and each mobile terminal is based on the restored network in step S409. The road time protocol reference clock C _NTP-R and the corresponding network time protocol time stamp T _NTP play the received streaming service.

[Second exemplary embodiment]

FIG. 6 is a schematic block diagram of a mobile television system according to a second exemplary embodiment of the present invention.

Referring to FIG. 6, the mobile TV system 500 includes an IP-Based mobile TV server group 502, a broadcast network device 104, a mobile network device 106, a mobile terminal 108, a mobile terminal 110, and a mobile terminal 112, wherein the broadcast network device 104 The structure and function of the mobile network device 106, the mobile terminal 108, the mobile terminal 110, and the mobile terminal 112 have been described as before, and the description will not be repeated here.

The IP-Based Mobile TV Server Group 502 is a collection of IP-based headend servers required for the operation of the Mobile Television System 500. In the present exemplary embodiment, the IP-Based mobile TV server group 502 transmits the RTP streaming service and the NTP time stamp sequence corresponding to the streaming service through the RTP. The IP-Based mobile TV server group 502 includes an RTP stream server 122, a service steering server 124, and a synchronization server 526, wherein the structure and function of the RTP stream server 122 and the service guidance server 124. It has been explained that the description will not be repeated here as before.

The synchronization server 526 receives the expected time difference dT _{Exp i} transmitted from all mobile terminals (ie, the mobile terminal 108, the mobile terminal 110, and the mobile terminal 112), and recalculates according to the expected time difference dT _{Exp i of} all mobile terminals. A synchronization time difference dT _sync that can be used in all mobile terminals. Next, the synchronization server 526 transmits the synchronization time difference dT _sync back to all mobile terminals via the broadcast network device 104 or the mobile network device 106. Specifically, in the exemplary embodiment, the mobile terminal 108, the mobile terminal 110, and the mobile terminal 112 transmit the expected time difference calculated by the play synchronization module to the synchronization server 526 through the 3GPP UMTS transmission/reception module. And the synchronization time difference dT _{sync is} calculated by the synchronization server 526 and transmitted back to the mobile terminal 108, the mobile terminal 110, and the mobile terminal 112. In particular, the synchronization server 526 must still conform to the above formula (1) when determining the synchronization time difference dT _sync .

FIG. 7 is a flowchart of a method for synchronizing a streaming service according to a second exemplary embodiment of the present invention.

Referring to FIG. 7, each mobile terminal receives the synchronous clock C _sync and the streaming service from the IP-Based mobile TV server group 502 and the corresponding network time protocol time from the broadcast network device 104 in step S601. Stamp the sequence of T _NTP with the suggested time difference dT _def-r . Next, in step S603, each mobile terminal refers to the recommended time difference dT _def-r to generate a corresponding expected time difference dT _{Exp i} . Thereafter, all the mobile terminals transmit the calculated expected time difference dT _{Exp i} to the synchronization server 526 in step S605. Then, in step S607, the synchronization server 526 determines the synchronization time difference dT _sync according to the received expected time difference dT _{Exp i} and transmits the determined synchronization time difference dT _sync back to all mobile terminals. Finally, in step S609, each mobile terminal restores the network time protocol reference clock C _NTP-R according to the synchronization clock C _sync and the synchronization time difference dT _sync , and each mobile terminal according to the restored network in step S611 The road time protocol reference clock C _NTP-R and the corresponding network time protocol time stamp T _NTP play the received streaming service.

It is worth mentioning that in the first exemplary embodiment and the second exemplary embodiment, the service guidance server 124 transmits the suggested time difference dT _def-r to the mobile terminal 108, the mobile terminal 110 and the mobile terminal 112, and The mobile terminal 108, the mobile terminal 110 and the mobile terminal 112 will refer to the suggested time difference dT _def-r to generate a corresponding expected time difference dT _{Exp i} . However, in another exemplary embodiment of the present invention, the service guidance server 124 may also not transmit the recommended time difference dT _def-r to the mobile terminal 108, the mobile terminal 110, and the mobile terminal 112. Specifically, the mobile terminal generates the expected time difference dT _{Exp i} without referring to the suggested time difference dT _def-r . For example, the playback synchronization module of each mobile terminal adjusts the expected time difference dT _{Exp i} based on the time difference between the synchronous clock C _sync and the clock C _{NTP of the} RTP streaming service.

[Third exemplary embodiment]

Figure 8 is a schematic block diagram of a mobile television system in accordance with a third exemplary embodiment of the present invention.

Referring to FIG. 8, the mobile TV system 700 includes an IP-Based mobile TV server group 102, a broadcast network device 104, a mobile network device 106, a mobile terminal 708, a mobile terminal 710, and a mobile terminal 712, wherein the IP-Based mobile TV The structure and function of the server group 102, the broadcast network device 104, and the mobile network device 106 are similar to those described in the first exemplary embodiment, and only the differences will be described below.

The mobile terminal 708, the mobile terminal 710, and the mobile terminal 712 are user equipments for the user to receive and watch the mobile TV streaming service. In the present exemplary embodiment, mobile terminal 708, mobile terminal 710, and mobile terminal 712 receive a sequence of streaming services and corresponding network time protocol timestamps T _NTP from broadcast network device 104. In addition, the mobile terminal 708, the mobile terminal 710, and the mobile terminal 712 receive the synchronization clock _Csync from the broadcast network device 104.

In the present exemplary embodiment, each mobile terminal (ie, mobile terminal 708, mobile terminal 710, and mobile terminal 712) receives an IP-Based mobile TV server from broadcast network device 104 or mobile network device 106. The suggested time difference dT _{def-r of the} group 102, and an expected trim value ddT _{Exp i} is input to fine tune the suggested time difference dT _def-r to generate the expected time difference dT _{Exp i} (ie, the expected time difference dT _{Exp i} = suggested time difference dT _def-r + expected fine adjustment value ddT _{Exp i} ), wherein the mobile terminal is able to successfully play the streaming service at the presentation time restored according to the expected time difference dT _{Exp i} generated by the fine adjustment. In particular, all mobile terminals will confirm and coordinate a common trim value ddT _sync based on each other's expected trim value ddT _{Exp i} , where the common trim value ddT _sync will be greater than or equal to all expected trim values ddT _{Exp i} .

In the present exemplary embodiment, each mobile terminal (ie, mobile terminal 708, mobile terminal 710, and mobile terminal 712) calculates the synchronization time difference dT _sync with the recommended time difference dT _def-r and the common fine adjustment value ddT _sync . (ie, the synchronization time difference dT _sync = suggested time difference dT _def-r + common fine adjustment value ddT _sync ).

FIG. 9 is a schematic block diagram showing the mobile terminal of FIG. 8. The structure and function of the mobile terminal 708, the mobile terminal 710, and the mobile terminal 712 are the same. The mobile terminal 708 will be described as an example.

Referring to FIG. 9, the mobile terminal 708 includes a DVB-H physical layer module 302, a 3GPP UMTS transmission/reception module 304, an MPEG-2 TS module 306, an IP module 308, a service guiding module 310, and a fine adjustment interface 812. And the RTP stream play module 314, wherein the structure of the DVB-H physical layer module 302, the 3GPP UMTS transmit/receive module 304, the MPEG-2 TS module 306, the IP module 308, and the service guide module 310 The function has been described as before, and the description will not be repeated here.

The fine-tuning interface 812 is configured to input an expected fine-tuning value (for example, the expected fine-tuning value ddT _{Exp 1 of the} mobile terminal 708) for coordinating the common fine-tuning value ddT _sync with the fine-tuning interface of the other mobile terminal through the 3GPP UMTS transmission/reception module 304. And transmitting the coordinated common fine adjustment value ddT _sync to the RTP stream playback module 314. Moreover, in another exemplary embodiment of the present invention, the common trim value ddT _sync may be coordinated by other means from the expected trim value ddT _{Exp i} of the fine-tuning interface inputs of all mobile terminals.

It recommends the time difference of the received RTP streaming module 314 will be based on the common dT _def-r trim value calculated ddT _sync synchronization time difference dT _sync.

Thereafter, the RTP stream playback module 314 can restore the network time protocol reference clock C _NTP-R according to the synchronization clock C _sync and the synchronization time difference dT _sync received from the PSI/SI module 322, and according to the restored The network time protocol reference clock C _NTP-R and the corresponding network time protocol time stamp T _NTP play the received streaming service.

FIG. 10 is a flowchart of a method for synchronizing a streaming service according to a third exemplary embodiment of the present invention.

Referring to FIG. 10, in step S901, each mobile terminal receives a synchronous clock C _sync and a streaming service from the IP-Based mobile TV server group 102, corresponding network time protocol time, from the broadcast network device 104. Stamp the sequence of T _NTP with the suggested time difference dT _def-r . Next, in step S903, the expected fine adjustment value ddT _{Exp i} is input in each mobile terminal and in step S905 all mobile terminals coordinate the common fine adjustment value ddT _sync according to the expected fine adjustment value ddT _{Exp i} . Then, in step S907 each terminal operations will be based on common values ddT _sync trimming determine the synchronization time difference dT _sync. Finally, in step S909, each mobile terminal restores the network time protocol reference clock C _NTP-R according to the synchronization clock C _sync and the synchronization time difference dT _sync , and in step S911 each mobile terminal is based on the restored network. The road time protocol reference clock C _NTP-R and the corresponding network time protocol time stamp T _NTP play the received streaming service.

[Fourth exemplary embodiment]

The schematic block diagram of the mobile television system of the fourth exemplary embodiment and the schematic block diagram of the mobile terminal are the same as those of Figs. 8 and 9, respectively, and the fourth exemplary embodiment will be described below using Figs. 8 and 9. In particular, the mobile television system of the fourth exemplary embodiment is essentially the same as the mobile television system of the third exemplary embodiment, and the differences will be described below.

In the third exemplary embodiment, the mobile terminal 708, the mobile terminal 710, and the mobile terminal 712 confirm and coordinate a common fine adjustment value ddT _sync according to each other's expected fine adjustment value ddT _{Exp i} . However, in the present exemplary embodiment, the mobile terminal 708, the mobile terminal 710, and the mobile terminal 712 calculate the synchronization time difference dT _sync according to the recommended time difference dT _def-r and the unified expected fine adjustment value ddT _Exp-c (ie, , synchronization time difference dT _sync = suggested time difference dT _def-r + unified expected fine adjustment value ddT _Exp-c ).

In the present exemplary embodiment, each mobile terminal (ie, mobile terminal 708, mobile terminal 710, and mobile terminal 712) receives an IP-Based mobile TV server from broadcast network device 104 or mobile network device 106. The suggested time difference dT _{def-r of the} group 102, and jointly refers to the suggested time difference dT _def-r and a unified expected trim value ddT _Exp-c to generate an expected time difference dT _{Exp i} , ie each action The expected time difference dT _{Exp i} generated by the terminal is the same. In particular, each mobile terminal will communicate with each other after fine tuning to confirm whether all mobile terminals can successfully play the streaming service at the presentation time restored according to the expected time difference dT _{Exp i} generated by the fine adjustment; if one of the actions The terminal cannot successfully play the streaming service at the presentation time restored according to the expected time difference dT _{Exp i} generated by the fine adjustment, and all the mobile terminals regenerate another expectation with another unified expected trimming value ddT _Exp-c. Time difference dT _{Exp i} ; conversely, when all mobile terminals are able to successfully play the streaming service at the presentation time restored according to the expected time difference dT _{Exp i} generated by the fine adjustment, all mobile terminals will have a final unified expectation The trim value ddT _{Exp-c is} used to calculate the sync time difference dT _sync .

FIG. 11 is a flowchart of a method for synchronizing a streaming service according to a fourth exemplary embodiment of the present invention.

Referring to FIG. 11, each mobile terminal receives the synchronous clock C _sync and the streaming service from the IP-Based mobile TV server group 102 and the corresponding network time protocol time from the broadcast network device 104 in step S1001. Stamp the sequence of T _NTP with the suggested time difference dT _def-r . Next, a unified expected fine adjustment value ddT _Exp-c is input in each mobile terminal in step S1003. Thereafter, in step S1005, all mobile terminals determine the network time protocol reference clock C _NTP-R according to the synchronization clock C _sync , the unified expected trim value ddT _Exp-c and the recommended time difference dT _def-r , after and at the step It is determined in S1007 whether all mobile terminals (ie, mobile terminal 708, mobile terminal 710, and mobile terminal 712) can present the RTP streaming service in a synchronized manner according to the determined network time protocol reference clock C _NTP-R . If all the mobile terminals cannot present the RTP streaming service in a synchronous manner in step S1007, then step S1003 is performed to re-enter another unified expected fine adjustment value ddT _Exp-c ; otherwise, in step S1009, each mobile terminal is restored according to the determined The network time protocol reference clock C _NTP-R and the corresponding network time protocol time stamp T _NTP play the received streaming service.

[Fifth exemplary embodiment]

FIG. 12 is a schematic block diagram of a mobile television system according to a fifth exemplary embodiment of the present invention.

Referring to FIG. 12, the mobile TV system 1100 includes an IP-Based mobile TV server group 102, a broadcast network device 104, a mobile terminal 108, a mobile terminal 110, and a mobile terminal 112, wherein the IP-Based mobile TV server group 102, broadcast The structure and function of the network device 104, the mobile terminal 108, the mobile terminal 110, and the mobile terminal 112 have been described as before, and only the differences are described below.

In the present exemplary embodiment, the service guidance server 124 transmits an SDP description (as shown in FIG. 13) through the broadcast network device 104 to transmit the available time difference dT _def-u to the mobile terminal (ie, the mobile terminal 108). , the mobile terminal 110 and the mobile terminal 112). Here, the available time difference dT _def-u is directly enabling the mobile terminal 108, the mobile terminal 110, and the mobile terminal 112 to successfully play the streaming service at the presentation time restored according to the available time difference dT _def-u . . That is, when the service guiding module of the mobile terminal receives the available time difference dT _def-u from the service guiding server 124, the playback synchronization module 312 of the mobile terminal directly directly synchronizes the synchronization time difference dT _sync. Set to the available time difference dT _def-u (as in formula (2)):

dT _sync =dT _def-u (formula (2))

Thereafter, each mobile terminal generates a network time _- based reference clock C _NTP-R according to the synchronization clock C _sync and the synchronization time difference dT _sync , and according to the generated network time protocol reference clock C _NTP-R and the corresponding network The road time stamp timestamp T _{NTP is} used to play the received streaming service.

In more detail, in the present exemplary embodiment, the available time difference dT _def-u has a mandatory meaning, that is, the network time protocol reference clock generated by each mobile terminal according to the available time difference dT _def-u C _NTP-R , therefore, in the IP-based mobile television system 1100, it is necessary to standardize the standard way in which the IP-Based mobile TV server group 102 calculates the available time difference dT _def-u for a certain RTP streaming service. In addition, the implementation effectiveness of the mobile terminals (ie, the mobile terminal 108, the mobile terminal 110, and the mobile terminal 112) in the IP-based mobile television system 1100 must meet certain specific parameters in order to comply with the IP-based mobile TV. The standard of system 1100. This particular parameter is the parameter required for the IP-Based Mobile TV Server Group 102 to calculate the available time difference dT _def-u . For example, the presentation initiation delay T _{ID of the} mobile terminal implementation must be lower than the specific value specified by an IP-based mobile television system 1100 standard. Specifically, the presentation initiation delay T _ID is that when the mobile terminal receives the first packet of the RTP streaming service without considering the synchronization method proposed in the exemplary embodiment, the mobile terminal starts to display the RTP. The time difference of streaming services. It is assumed here that when the mobile terminal receives any RTP streaming service from the broadcast network device 104, its maximum presentation start delay must be less than or equal to the presentation initiation delay T _ID . Since it is mandatory to present the start delay T _ID value, all mobile terminals must reduce the factors that will cause the start delay, for example, MPE-FEC decoding delay, AV decoder buffer. Start delay, etc., to meet this requirement on the performance side.

The following is an example detailing how to standardize the relationship between the available time difference dT _def-u and the presentation start delay T _ID on a DVB mobile TV system (eg DVB-H). In this example, the available time difference dT _def-u must satisfy the following formula (3) and formula (4):

C _IPE -C _NTP =(C _{RTP Server} -C _NTP )+E _IR +T _ND formula (4)

The C _IPE is used to indicate the clock in the TDT or TOT table in the broadcast network device 104, which is implemented in an IP encapsulator (not shown).

T _ED is the maximum delay time possible between the MPEG-2 transport stream that is received by the RTP packet after being received by the IP encapsulator and that is added to the IP encapsulator.

The C _{RTP Server} is represented in the RTP stream server 122 in the IP-Based mobile TV server group 102, and needs to provide a clock C _{RTP Server} synchronized with the clock C _IPE , wherein the RTP stream server 122 takes the clock C _{RTP The Server} acts as a reference clock to control the start and end of RTP streaming service delivery.

E _IR is a mechanism for clock C _IPE and clock C _{RTP Server} to synchronize with each other through NTP (RFC 1305) or other similar communication protocol. It is assumed here that E _IR is the maximum possible value of the synchronization error between the clock C _IPE and the clock C _{RTP Server} .

T _ND is the maximum network transmission delay time possible when the RTP packet is transmitted from the RTP stream server 122 to the IP encapsulator. Specifically, since the RTP stream transmitted by the RTP stream server 122 is first sent to the IP encapsulator, it is added to the broadcasted MPEG-2 transport stream together with the TDT or TOT, so in the process Network transmission delay time may occur.

In formula (3) (C _IPE -C _NTP ) is the clock of the NTP time stamp of the RTCP SR packet of the RTP stream service, and the time difference from the clock C _IPE observed on the IP encapsulator.

In addition, the presentation start delay T _ID is a constant whose value is independent of the RTP stream service presented by the mobile terminal. Moreover, the presentation start delay T _ID needs to be specified in the relevant standards of the IP-based mobile television system 1100. That is to say, current DVB-H, DVB-IPDC or OMA BCAST related standards need to be expanded to incorporate a presentation initiation delay T _ID to be compatible with the IP-based mobile television system 1100.

In other words, as shown in FIG. 12, the mobile terminal 108, the mobile terminal 110, and the mobile terminal 112 are required to follow the limitation of presenting the start delay T _ID . Conversely, the three parameters of E _IR , T _ND and T _ED are the variables that can be obtained during the implementation or deployment of the IP-Based mobile TV server group 102 and the broadcast network device 104 in FIG. 12 (variable) ). That is, the values of these three parameters will differ depending on the implementation or deployment method when implementing or deploying an IP-Based mobile TV server group or a broadcast network device.

In addition, since the RTCP SR packet in the RTP streaming service is not necessarily transmitted simultaneously when the RTP streaming service starts transmitting, in the formula (4), (C _{RTP Server} -C _NTP ) means The clock of the NTP timestamp of the RTCP SR packet of the RTP stream service, the time difference observed with the clock C _{RTP Server} observed on the RTP stream server 122, as shown in equation (5):

C _{RTP Server} -C _NTP =T _RS -T _FN +T _RD formula (5)

The T _RS is the time when the RTP stream server 122 starts to transmit the RTP stream service, and the time is based on the clock C _{RTP Server} . T _FN is the time value of the NTP timestamp of the first RTCP SR packet in the RTP stream service. T _RD is the relative time difference between the start of the RTP stream transmission and the start of the transmission of the first RTCP SR packet. The T _RD value can be obtained by an estimation method. For example, in the present exemplary embodiment, it is calculated by the following formula:

T _RD value = (the amount of packet data transmitted by the RTP stream service before the first RTCP SR packet is transmitted) / (the bandwidth that the RTP stream server 122 will use to transmit the RTP stream service)

In addition, in another embodiment of the present invention, the T _RD value can also be obtained by a measured method. For example, pre-execution of the pre-run on the RTP stream server 122 before the RTP stream is officially broadcast. The measured method is obtained.

It must be understood that the above formula for calculating the available time difference dT _def-u is only an example, and the present invention is not limited thereto. Furthermore, the formula for calculating the available time difference dT _def-u in the present exemplary embodiment is applicable to calculate the suggested time difference dT _def-r in the first, second, third and fourth exemplary embodiments.

FIG. 14 is a flowchart of a method for synchronizing a streaming service according to a fifth exemplary embodiment of the present invention.

Referring to FIG. 14, each mobile terminal receives the synchronous clock C _sync and the streaming service from the IP-Based mobile TV server group 102 and the corresponding network time protocol time from the broadcast network device 104 in step S1201. Stamp the sequence of T _NTP with the available time difference dT _def-u . Next, in step S1203, each mobile terminal will use the available time difference dT _def-u as the synchronization time difference dT _sync . Finally, in step S1205, each mobile terminal restores the network time protocol reference clock C _NTP-R according to the synchronization clock C _sync and the synchronization time difference dT _sync , and each mobile terminal is based on the restored network in step S1207. The road time protocol reference clock C _NTP-R and the corresponding network time protocol time stamp T _NTP play the received streaming service.

In summary, the exemplary embodiment of the present invention can solve the problem that the RTP streaming service displays synchronization between multiple mobile terminals on the IP-Based mobile TV system. Moreover, the exemplary embodiments of the present invention can avoid the problem of being inapplicable on an IP-Based mobile television system due to the transmission of an in-band reference clock in the RTP band.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

100, 500, 700, 1200. . . Mobile TV system

102. . . IP-Based Mobile TV Server Group

104. . . Broadcast network equipment

106. . . Mobile network equipment

108, 110, 112, 708, 710, 712. . . Mobile terminal

122. . . RTP streaming server

124. . . Service guidance server

302. . . DVB-H physical layer module

304. . . 3GPP UMTS transmit/receive module

306. . . MPEG-2 TS module

308. . . IP module

310. . . Service guidance module

312. . . Play sync module

314. . . RTP streaming module

322. . . Program specific information / service information module

S401, S403, S405, S407, S409. . . Steps to synchronize streaming services

502. . . IP-Based Mobile TV Server Group

526. . . Sync server

S601, S603, S605, S607, S609, S611. . . Steps to synchronize streaming services

812‧‧‧ fine-tuning interface

S901, S903, S905, S907, S909, S911‧‧‧Steps for synchronizing the streaming service

S1001, S1003, S1005, S1007‧‧‧Steps for synchronizing the streaming service

S1201, S1203, S1205, S1207‧‧‧Steps for synchronizing the streaming service

FIG. 1 is a schematic diagram showing an example of transmitting a media stream through an RTP according to the prior art.

2 is a schematic block diagram of a mobile television system according to a first exemplary embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of transmitting a suggested time difference value through a talk description protocol according to a first exemplary embodiment of the present invention.

4 is a schematic block diagram showing the mobile terminal of FIG. 2.

FIG. 5 is a flowchart of a method for synchronizing streaming service playback according to a first exemplary embodiment of the present invention.

FIG. 6 is a schematic block diagram of a mobile television system according to a second exemplary embodiment of the present invention.

FIG. 7 is a flowchart of a method for synchronizing streaming service playback according to a second exemplary embodiment of the present invention.

Figure 8 is a schematic block diagram of a mobile television system in accordance with a third exemplary embodiment of the present invention.

FIG. 9 is a schematic block diagram showing the mobile terminal of FIG. 8.

FIG. 10 is a flowchart of a method for synchronizing streaming service playback according to a third exemplary embodiment of the present invention.

FIG. 11 is a flowchart of a method for synchronizing streaming service playback according to a fourth exemplary embodiment of the present invention.

FIG. 12 is a schematic block diagram of a mobile television system according to a fifth exemplary embodiment of the present invention.

FIG. 13 is a diagram illustrating an example of transmitting a available time difference value through a talk description protocol according to a fifth exemplary embodiment of the present invention.

FIG. 14 is a flowchart of a method for synchronizing streaming service playback according to a fifth exemplary embodiment of the present invention.

100. . . Mobile TV system

102. . . IP-Based Mobile TV Server Group

104. . . Broadcast network equipment

106. . . Mobile network equipment

108, 110, 112, 708, 710, 712. . . Mobile terminal

122. . . RTP streaming server

124. . . Service Guide Server

Claims (27)

A mobile television system comprising: an Internet Protocol-based (IP-Based) mobile TV server group that transmits a stream of services and responds via a Real-time Transport Protocol (RTP) A Network Time Protocol (NTP) time stamp sequence of a streaming service, wherein the network time stamp time stamp sequence records a sequence of time stamps starting at any time; a network device Providing at least one network for transmitting the streaming service and the network time stamp time stamp sequence; and a plurality of mobile terminals, wherein each of the mobile terminals receives the streaming service from the network device, the network a time-scheduled timestamp sequence and a synchronization clock, wherein the Internet Protocol-based mobile TV server group further includes a service guidance server for transmitting a synchronization time difference, the service guidance server It is not necessary to consult the mobile terminal for information about the synchronization time difference before transmitting the synchronization time difference, wherein each of the mobile terminals is based on the synchronization time And synchronizing the time difference to restore a network time protocol reference clock for presenting the received streaming service, and playing the location according to the restored network time protocol reference clock and the received network time stamp timestamp Received streaming service. The mobile television system of claim 1, wherein the Internet Protocol-based mobile TV server group includes a An instant transport protocol stream server for transmitting the stream time service and the network time stamp time stamp sequence corresponding to the streaming service. The mobile television system of claim 2, wherein each of the mobile terminals comprises an instant transmission protocol streaming play module for restoring the network time protocol reference clock and playing the received streaming service . The mobile television system of claim 3, wherein each of the mobile terminals further includes a service guiding module, wherein the service guiding module of each of the mobile terminals is The service guidance server receives an available time difference as the synchronization time difference. The mobile television system of claim 3, wherein each of the mobile terminals further includes a play synchronization module for calculating an expected time difference, wherein the synchronization time difference is based on the expected time The difference is determined, and the synchronization time difference is not less than the expected time difference. The mobile TV system of claim 5, wherein each of the mobile terminals further includes a service guiding module, wherein the service guiding module of each of the mobile terminals is from the network device The service guidance server receives a suggested time difference value, and each of the mobile terminal's play synchronization modules calculates the expected time difference value according to the recommended time difference value. The mobile television system of claim 5, wherein the playback synchronization modules of the mobile terminals are based on a distributed algorithm These expected time differences determine the synchronization time difference. The mobile TV system according to claim 5, wherein the Internet Protocol-based mobile TV server group further comprises a synchronization server, wherein each of the mobile terminal's playback synchronization modules is The network device transmits the calculated expected time difference value to the synchronization server, wherein the synchronization server determines a common time difference value according to the expected time difference values and transmits the common time difference value to the network device The mobile terminal, and the playback synchronization module of each of the mobile terminals uses the common time difference as the synchronization time difference. The mobile television system of claim 3, wherein each of the mobile terminals further includes a service guiding module and a fine adjustment interface, wherein each of the mobile terminal service guiding modules passes through the network The path device receives a recommended time difference from the service guidance server, and the fine adjustment interface of each of the mobile terminals is used to input an expected fine adjustment value, wherein the fine adjustment interfaces of the mobile terminals coordinate a common fine adjustment value. And the instant transmission protocol stream play module determines the synchronization time difference by using the recommended time difference value and the common fine adjustment value, and wherein the common fine adjustment value is not less than the expected fine adjustment values. The mobile television system of claim 3, wherein each of the mobile terminals further includes a service guiding module and a fine adjustment interface, The service guidance module of each of the mobile terminals receives a suggested time difference from the service guidance server via the network device, and the fine adjustment interface of each of the mobile terminals is used to input a unified expected fine adjustment. And a value, wherein the instant transmission protocol stream play module determines the synchronization time difference by using the recommended time difference value and the unified expected fine adjustment value. The mobile television system of claim 2, wherein the instant delivery protocol streaming server conforms to a DVB-IPDC standard or an OMA BCAST standard. The mobile television system of claim 1, wherein the network device comprises at least one of a broadcast network device and a mobile network device. The mobile television system of claim 1, wherein the restored network time protocol reference clock is defined as a value of the synchronous clock, and each received network time stamp time stamp is converted into a A new network time stamp timestamp value, wherein each of the new network time stamp timestamp values is generated by adding the synchronization time difference value to an original value of each received network time stamp timestamp. The mobile television system of claim 1, wherein the restored network time protocol reference clock is defined by the following expression: C _NTP-R = C _sync -dT _sync wherein C _NTP-R indicates the restored The network time protocol reference clock, C _sync represents the synchronous clock and dT _sync represents the synchronization time difference. A method for synchronizing a streaming service in a mobile television system, comprising: Using an Internet Protocol-based (IP-Based) mobile TV server group to transmit a stream of services and corresponding streams via a network device via a Real-time Transport Protocol (RTP) A Network Time Protocol (NTP) time stamp sequence of services, wherein the network time stamp time stamp sequence records a sequence of time stamps starting at any time; using multiple mobile terminals Receiving, by the network device, the streaming service, the network time stamp time stamp sequence and a synchronization clock; using a service guidance server to transmit a synchronization time difference to the mobile terminals, wherein the service guides the servo Before transmitting the synchronization time difference, it is not necessary to consult the mobile terminal for information about the synchronization time difference; in each of the mobile terminals, the synchronization clock and the synchronization time difference are used to restore the received string. a network time protocol reference clock of the streaming service; and in each of the mobile terminals, according to the restored network time protocol reference clock and the received The Network Time Protocol timestamp to play streaming service received. A method for synchronizing a streaming service in a mobile television system as described in claim 15 of the patent application, further comprising: in each of the mobile terminals, the mobile TV server group based on the internet protocol The received time difference is received as the synchronization time difference. The method for synchronizing a streaming service in a mobile television system as described in claim 15 of the patent application, further comprising: calculating an expected time difference value in each of the mobile terminals; The synchronization time difference is determined according to the expected time difference values, wherein the synchronization time difference is not less than the expected time difference values. A method for synchronizing a streaming service in a mobile television system as described in claim 17 wherein the step of calculating the expected time difference in each of the mobile terminals comprises: communicating from the Internet The agreed-based mobile TV server group receives a suggested time difference value and calculates the expected time difference value based on the recommended time difference value. The method for synchronizing a streaming service in a mobile television system as described in claim 17, wherein the step of determining the synchronization time difference according to the expected time difference comprises: transmitting, by using a distributed algorithm The expected time difference values determine the synchronization time difference. A method for synchronizing a streaming service in a mobile television system as described in claim 17 wherein the step of determining the synchronization time difference based on the expected time difference values comprises: in each of the actions The expected time difference values calculated in the terminal are transmitted to the Internet Protocol-based mobile TV server group via the network device; using the Internet Protocol-based mobile TV server group Determining a common time difference value according to the expected time difference values and transmitting the common time difference value to the mobile terminal devices via the network device; and using the common time difference value as the synchronization time in each of the mobile terminal terminals Difference. As described in claim 15 of the scope of the patent for mobile TV systems The method for synchronizing the streaming service includes: receiving a suggested time difference from the service guiding server; inputting an expected trimming value in each of the mobile terminals; and determining, by the mobile terminals The trimming value is expected to coordinate a common trimming value; and the synchronized time difference is determined by the suggested time difference and the common coordination value, wherein the common trimming value is not less than the expected trimming value. The method for synchronizing the streaming service in the mobile TV system as described in claim 15 further includes: receiving a suggested time difference from the service guiding server; and using each of the mobile terminals Entering a unified expected trim value; and determining the synchronization time difference by the recommended time difference and the unified expected trim value. The method for synchronizing a streaming service in a mobile television system as described in claim 15 further includes: defining the restored network time protocol reference clock as a value of the synchronous clock; and receiving The original value of the network time stamp timestamp is added to the synchronization time difference to convert each received network time stamp timestamp into a new network time stamp timestamp value. The method for synchronizing a streaming service in a mobile television system as described in claim 15 of the patent application, further comprising: defining the restored network time protocol reference clock by the following expression: C _NTP-R = C _Sync -dT _sync where C _NTP-R represents the restored network time protocol reference clock, C _sync represents the synchronous clock and dT _sync represents the synchronization time difference. An action terminal for communicating with a network device in a mobile television system to receive a streaming service, the mobile terminal comprising: an internet protocol module for transmitting from the network device through an instant The protocol receives the streaming service and a network time stamp timestamp sequence corresponding to one of the streaming services, wherein the network time stamp timestamp sequence records a sequence of timestamps starting at any time; and an instant transmission protocol string a streaming play module, configured to restore a network time protocol reference clock for presenting the received streaming service according to a synchronization clock and a synchronization time difference from the network device, and according to the restored network The road time protocol reference clock and the received network time stamp timestamp play the received streaming service, wherein the synchronization time difference value is transmitted by a service guidance server, and the service guidance server transmits the It is not necessary to consult the mobile terminal for information about the synchronization time difference before synchronizing the time difference. The mobile terminal according to claim 25, wherein the restored network time protocol reference clock is defined as a value of the synchronous clock, and each received network time stamp time stamp is converted into a new one. A network time stamp timestamp value, wherein each of the new network time stamp timestamp values is generated by adding the synchronization time difference value to an original value of each received network time stamp timestamp. The mobile terminal as claimed in claim 25, wherein the restored network time protocol reference clock is defined by the following expression: C _NTP-R = C _sync -dT _sync where C _NTP-R indicates the restored The network time protocol reference clock, C _sync represents the synchronous clock and dT _sync represents the synchronization time difference.