WO2009036704A1

WO2009036704A1 - The method for resuming the time alignment flag, and the information source encoding method, device and system

Info

Publication number: WO2009036704A1
Application number: PCT/CN2008/072387
Authority: WO
Inventors: Jiang GUO; Ming Li; Guohong Li
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2007-09-17
Filing date: 2008-09-17
Publication date: 2009-03-26
Also published as: CN101394228B; CN101394228A

Abstract

A method for time alignment flag resumption includes the steps: acquiring the data frame from the RTP voice package; if the current frame type is determined to be a silence descriptor frame, and the frame type before the silence descriptor frame is the speech frame in the predetermined time segment, then the time alignment flag of the silence descriptor frame is set to the first value; if the current frame type is determined to be the silence descriptor frame, and the data frame before the silence descriptor is not received in the predetermined time segment, then the time alignment flag of the silence descriptor frame is set to the second value. Methods for simplifying time alignment flag resumption, for simplifying information source decoding, and for information source decoding are also disclosed. A media gateway and system that apply to information source decoding are provided. Use of the invention enables resumption of the time alignment flag in RTP and applies this to information source decoding.

Description

Method for recovering time alignment mark, method, device and system for decoding source code The present application claims to be filed on September 17, 2007 with the Chinese Patent Office, application number 200710154115.6, and the invention name is "method of restoring time alignment mark, source" The priority of the Chinese Patent Application, the entire disclosure of which is incorporated herein by reference. Technical field

The present invention relates to the field of mobile communication technologies, and in particular, to a method for recovering a time alignment flag, a method, apparatus and system for decoding a source.

Background technique

After the A-interface (Internet Protocol) of the GSM (Global System for Mobile Communications), the BSC (base station controller) can directly encapsulate the compressed voice. And transmitted to the core network. The core network is responsible for handling all multi-codec related transactions, including codec negotiation and codec conversion after negotiation failure, and completes the exchange of voice packets. This solution can fully utilize the characteristics of the softswitch core network. By supporting TrFO (Transcoder Free Operation), it can improve voice quality, reduce the use of TC (Transcoder) resources, and save on the A interface. The transmission bandwidth also simplifies the design of the BSS (Base Station Subsystem).

As shown in Figure 1, it is the protocol stack of the user plane of the mobile station base station subsystem-media gateway. The full name of the English abbreviation and its meaning are:

PAYLOAD, indicating the data payload;

Point-to-Point Protocol (PPP), point-to-point protocol;

MAC ( Medium Access Control ), medium access control;

UDP (User Datagram Protocol), User Datagram Protocol;

IP (Internet Protocol), Internet Protocol

RTP (Real-time Transfer Protocol) Real-time transport protocol.

In order to enable smooth communication between network devices produced by different manufacturers, standard RTP (Real Time Transport Protocol) is usually used in these devices to encapsulate voice data. For example, for EFR (Enhanced Full Rate) / FR (FULL RATE) / HR (HALF RATE) voice data, 3GPP TS can be used. The 101 318 protocol is used for encapsulation. In order to align the byte alignment of the encapsulated speech, the protocol specifies that for EFR voice data, 4 bytes of 1100 are added before the payload data; for FR voice data, 4 bytes of 1101 are added before the payload data. For HR voice data, since the data itself is aligned, no extra bytes are added. Since the RTP protocol itself only guarantees the transmission of real-time data, it does not provide a reliable transmission mechanism for transmitting packets in sequence, nor does it provide flow control or congestion control. According to the standard RTP protocol, the standard source codec algorithm specified by the protocol also needs the input parameter TAF (Time Align Flag) to perform source decoding on the SID (Sience Descriptor) frame. There are a variety of algorithms for source decoding of SID frames. Among these different algorithms, the SID frame with a TAF value equal to 1 and the SID frame with a TAF value equal to 0 are different.

However, according to the current standard RTP protocol, the TAF value is not sent from the base station to the media gateway for source decoding. Without the TAF value, the voice decoding process for the mute indication frame is affected, and the MGW (MEDIA GATEWAY, media) is lowered. Gateway) The quality of the call after voice decoding. Summary of the invention

In view of this, it is an object of one or more embodiments of the present invention to provide a method for recovering a time alignment flag, a method, an apparatus, and a system for decoding a source, which enable the RTP protocol to be encapsulated after the UI interface is IP-enabled. The mute indication frame in the voice packet performs time alignment flag recovery.

To solve the above problem, an embodiment of the present invention provides a method for restoring a time alignment flag, including the steps:

Obtaining a data frame from a real-time transport protocol voice packet;

If it is determined that the current data frame type is a mute indication frame, and the data frame type of one frame before the mute indication frame is a speech frame within a predetermined time period, assigning the mute indication frame time alignment flag to the first value, Or,

If it is determined that the current data frame type is a mute indication frame and the data frame is not received before the mute indication frame within a predetermined time period, the mute indication frame time alignment flag is assigned a second value.

The embodiment of the invention further provides a method for restoring a time alignment flag, comprising the steps of: obtaining a data frame from a real-time transport protocol voice packet;

If the current data frame type in the real-time transport protocol voice packet is a mute indication frame, the time alignment flag of the mute indication frame received within a predetermined time period is assigned a value of 0 or 1. The embodiment of the invention further provides a method for decoding a source, comprising the steps of:

Obtaining a data frame from a real-time transport protocol voice packet;

If the current data frame type in the real-time transport protocol voice packet is a mute indication frame, the time alignment flag of the mute indication frame received within a predetermined time period is assigned a value of 0 or 1;

And performing source decoding on the mute indication frame according to the time alignment flag.

The embodiment of the invention further provides a method for decoding a source, comprising the steps of:

Obtaining a data frame from a real-time transport protocol voice packet;

If the current data frame type is a mute indication frame, and the data frame type of one frame before the mute indication frame is a speech frame within a predetermined time period, the mute indication frame time alignment flag is assigned a value of 0,

If the current data frame type is a mute indication frame, and the data frame is not received before the mute indication frame within a predetermined time period, the mute indication frame time alignment flag is assigned a value of 1;

The embodiment of the present invention further provides a media gateway applied to source decoding, comprising: a data frame reading unit, configured to: acquire a data frame from a real-time transport protocol voice packet and send the data frame; And the method is: after receiving the data frame, determining whether the current data frame type is a mute indication frame, and if yes, sending the mute indication frame to the source decoding unit, generating a determination instruction, and sending the determination instruction to the service frame Type determination unit;

a service frame type determining unit, configured to: determine, according to the determining instruction generated by the mute indication frame determining unit, a data frame type received within a predetermined time period,

If the data frame type of one frame before the mute indication frame is a voice frame within a predetermined time period, generating a 0-instruction instruction and sending it to the recovery time alignment flag unit,

If the data frame is not received before the mute indication frame within the predetermined time period, generating an instruction 1 and sending it to the recovery time alignment flag unit;

a recovery time alignment flag unit, configured to: assign a value of 0 to the mute indication frame time alignment flag according to the instruction 0 generated by the service frame type determining unit; or determine an instruction 1 generated by the unit according to the service frame type Setting the mute indication frame time alignment flag to 1 and sending the time alignment flag 0 or 1 to the source decoding unit;

a source decoding unit, configured to: source the mute indication frame according to the time alignment flag Decoding.

An embodiment of the present invention further provides a system for applying source decoding, including:

Media gateway and base station,

The base station is configured to: encapsulate the data sent by the mobile station into a real-time transport protocol voice packet and send the data to the media gateway;

The media gateway is configured to: read a data frame from a real-time transport protocol voice packet, determine whether the current data frame type is a mute indication frame, and if yes, determine a data frame type received within a predetermined time period,

If the data frame type of one frame before the mute indication frame is a speech frame within a predetermined time period, the time alignment flag of the mute indication frame is assigned a value of 0, if there is no previous mute indication frame within a predetermined time period Receiving a data frame, assigning a time alignment flag of the mute indication frame

1,

Source decoding is performed on the mute indication frame according to the time alignment flag 0 or 1.

Compared with the prior art, the embodiment of the invention has the following advantages:

Through the processing of the foregoing technical solution, the mute indication frame time alignment flag that is not sent to the media gateway during the process of transmitting from the mobile station to the base station is recovered, and the subsequent source decoding process can be aligned for different time alignment flags. The mute indication frame is decoded, which reduces the speech damage caused by the inaccurate TAF parameter, and improves the IP-based call quality.

DRAWINGS

1 is a schematic diagram of a protocol stack of a user plane of a mobile station-base station subsystem-media gateway; FIG. 2 is a schematic diagram of data flow from a mobile station to a media gateway through a base station subsystem;

3 is a flow chart of one embodiment of a method for recovering a time alignment flag of the present invention; FIG. 4 is a flow chart of another embodiment of a method for recovering a time alignment flag of the present invention; FIG. 5 is a service received by a media gateway. Timing diagram of the frame;

6 is a flow chart of one embodiment of a method of source decoding of the present invention;

Figure 7 is a block diagram of one embodiment of a source decoding gateway of the present invention;

Figure 8 is a block diagram of one embodiment of a system for source decoding of the present invention;

9 is a block diagram of another embodiment of a system for source decoding of the present invention.

detailed description The specific embodiments of the embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

In various embodiments of the invention and in various portions of the specification of the present application, the service frame includes

The SP frame and the SID frame, the SP frame is the voice frame, the SID frame is the mute indication frame, the TAF is the time alignment flag, and the time alignment flag of the SID frame is 1 and some are 0. The use of Chinese or English abbreviations in different places is required for the convenience of reference and presentation.

As shown in FIG. 2, it is a schematic diagram of data flow from a mobile station to a media gateway through a base station subsystem. According to the 3GPP (Three Generation Partnership Project) 46.031 protocol, in the case where the uplink discontinuous transmission mode is turned on, the mobile station can generate continuous SP frames and SID frames by the source codec module. , but it does not send all of these frames to the air interface, but only sends the following three types of frames:

1) speech frame (all frames marked with SP=1, all frames with the logo "SP = 1", SP frame);

2) The first SID frame after the SP frame, with TAF = 0 (the first one with SP = 0 after one or more frames with SP=1 after the speech frame of one or more identifiers "SP = 1" a mute indication frame of "SP = 0" with a time alignment flag TAF=0);

3) SID frames with TAF=1 (the those marked with SP=0 and aligned with the SACCH multiframe structure as described in 45.008, the identifier "SP = 0" and the frame structure of the slow associated control channel specified in the 45.008 protocol Aligned frame, time-aligned flag TAF=1 mute indication frame), every two time alignment flags with a silence of 1 indicates a frame interval of 480 milliseconds. The period of the S ACCH multiframe is 480 milliseconds as specified in the protocol.

After the above three kinds of data are encapsulated by the real-time transmission protocol of the base station subsystem, the three types of data are encapsulated into an RTP voice packet specified by the real-time transmission protocol standard, and the voice packet includes the above three data frames, that is, the above-mentioned TAF= 1 or a silence indication frame with TAF = 0, and a voice frame, each having a length of 20 milliseconds.

Based on the above features of the data frame transmitted by the mobile station, the present invention discloses the following embodiments: As shown in FIG. 3, it is an embodiment of the method for restoring the time alignment flag of the present invention, including the steps:

S301. The media gateway reads the data frame from the real-time transport protocol voice packet.

S302: The media gateway determines whether the current data frame type in the real-time transport protocol voice packet is a mute indication frame, and if yes, proceeds to step S302, otherwise, ends the process; 5303. The media gateway determines a data frame type received within a predetermined time period. If the data frame type received first in the predetermined time period is a voice frame, the process proceeds to step S304, and the data is not received within the predetermined time period. The frame proceeds to step S305, and the predetermined time period in this step may be set according to the actual operation needs, or may be set according to the characteristics of the length of the voice frame and the mute indication frame data. The length of the two data frames in the existing protocol is 20 milliseconds, and therefore, in the preferred embodiment, 20 milliseconds can be used as the length of the predetermined time period. This will help improve the efficiency and accuracy of judgment. Other lengths are also possible, and such variations do not go beyond the scope of the present invention;

5304, the media gateway assigns the mute indication frame time alignment flag to 0;

S305. The media gateway assigns the mute indication frame time alignment flag to 1.

Through the above steps, the media gateway recovers the time alignment flag of the mute indication frame sent by the real-time transmission protocol from the base station subsystem.

As shown in FIG. 4, a technical solution for obtaining a mute indication frame is disclosed. The present invention provides another embodiment of a method for recovering a time alignment flag, including the steps of:

After receiving the voice frame uploaded by the mobile station, the BSS base station subsystem (the Base Station Subsystem) encapsulates the voice frame uploaded by the mobile station into an RTP voice packet.

After receiving the voice frame sent by the mobile station, the first SID frame after the voice frame, and the SID frame with the TAF=1, the base station subsystem encapsulates the data frames, and the process is: the base station subsystem performs user plane frame format conversion, Converting data in the TRAU format sent by the mobile station into a voice packet in an RTP format;

S402: The base station subsystem transmits the RTP voice packet to the media gateway.

S403. The media gateway determines whether the current data frame type in the real-time transport protocol voice packet is a mute indication frame, and if yes, proceeds to step S404, otherwise, ends the process;

The process of determining whether to mute the frame may be:

The media gateway determines whether the current service frame is an SP frame or a SID frame. In the FR encoding algorithm specified by the GSM standard, the length of the SP frame and the SID frame of each service frame is 260 bits. However, the effective value in the SP frame and the number of valid values in the SID frame are usually different. In an SP frame, its effective value is 260 bits; in a SID frame, its effective value is much less than 260 bits. Therefore, in the SID frame, 0 or 1 is fixed at the invalid value (different encoding methods are different, depending on the encoding method itself). Therefore, the receiving end only needs to detect whether the value at these fixed positions of the current frame is a constant value. If the value of these fixed positions in the current frame is constant at 0, or is constant at 1 (different The encoding method is different, depending on the needs of the encoding method itself. It can be judged that this frame is a SID frame. Conversely, if it is not constantly 0 or is constantly 1 , it can be judged that this frame is an SP frame. Similar to the FR coding algorithm, SP frames and SID frames in the EFR and HR coding algorithms can be distinguished in a similar manner;

S404. The media gateway determines a data frame type received within a predetermined time period. If the data frame type received first in the predetermined time period is a voice frame, the process proceeds to step S405, where no data is received within a predetermined time period. The frame proceeds to step S406. The predetermined time period in this step can be set according to the needs of the actual operation, or can be set according to the characteristics of the length of the voice frame and the mute indication frame data. In the existing protocol, the length of the two data frames is 20 milliseconds, and therefore, in the preferred embodiment, 20 milliseconds can be used as the length of the predetermined time period. This will help improve the efficiency and accuracy of judgment. Other lengths are also possible, and such variations do not go beyond the scope of the present invention;

S405, the media gateway assigns the mute indication frame time alignment flag to 0;

S406, the media gateway assigns the mute indication frame time alignment flag to 1.

Through the processing of the above embodiment, the mute indication frame time alignment flag which is not sent to the media gateway during transmission from the mobile station to the base station is restored. The recovered TAF can be used by the subsequent source decoding process to decode the mute indication frame for different time alignment flags, which reduces the

The speech impairment caused by the inaccurate TAF parameter improves the quality of the call after IP address of the A interface.

As shown in Figure 5, it is the timing diagram of the service frame received by the media gateway. It can be seen that the SP frame with the identifier "SP = 1" and the identifier "SP = 0," according to the time interval specified by the RTP protocol standard. The time interval between the first SID frames is 20 milliseconds, the first SID frame after the SP frame has a TAF = 0, and the interval of each SID frame with a TAF = 1 is 480 milliseconds.

Based on the above-mentioned characteristics of the data distribution in the RTP voice packet, if the predetermined time period is set to 20 milliseconds, step S404 in the embodiment of the present invention may be:

S4041: The media gateway records the data frame received every 20 milliseconds;

S4042: The media gateway determines whether the frame type of the frame is an SP frame or a SID frame.

If the data frame received within the current 20 milliseconds is an SP frame, then the frame is considered to be a SID frame with TAF = 0. If the data frame is not received within the first 20 milliseconds, and the frame is a SID frame, then the frame is considered to be After the SID frame with TAF=1, the media gateway can recover the TAF value of the SID frame that the base station has not sent from the received data. The above method for restoring the time alignment flag of the embodiment fully utilizes the following features of the real-time transport protocol voice packet:

In the Real-Time Transport Protocol voice packet, the first mute indication frame with a time alignment flag of 0 after the SP = 1 speech frame appears 20 ms after the speech frame.

According to the above quantity relationship, the present embodiment obtains the invention of recovering the time alignment flag from the real-time transport protocol voice packet. Accordingly, the media gateway obtains its time alignment flag from the voice packet, which can be used for subsequent source decoding, and the decoding accuracy is greatly improved, and a higher quality voice quality is obtained.

On the basis of the foregoing embodiment, in order to improve the accuracy of the recovery time alignment flag, after the time alignment flag is set to 1 in step S406, the method may further include the following steps:

S407. The media gateway records the service frame received within 20 milliseconds;

S408. The media gateway determines whether the frame type of the service frame is an SP frame or a SID frame:

If the data frame received within the current 20 milliseconds is an SP frame, then the frame is considered to be a SID frame with TAF = 0. If the data frame is not received within the first 20 milliseconds, and the frame is a SID frame, then the frame is considered to be SID frame with TAF = 1.

In step S4042 and in step S408, such a judgment as to the frame type is erroneous because:

If the following special circumstances occur, such as when the mobile station starts to send a service frame to the base station subsystem, after the RTP encapsulation conversion of the base station subsystem, the media gateway receives only a few service frames at this time. If the mobile station transmits the SP frame and the first SID frame immediately after the SP frame according to the protocol, and the SID frame is exactly aligned with the time of the air interface TAF=1, according to the embodiment. The method assigns the time alignment flag of this SID frame to 0, which is inconsistent with the timing of the air interface alignment. The SID frame which is originally TAF=1 is misidentified as the SID frame with TAF=0. In the subsequent decoding process, the SID frame which is originally required to be decoded by using the TAF=1 flag is identified as the SID frame with TAF=0. . However, since the interval of occurrence of the SID frame with TAF = 1 is 480 milliseconds, if the repeated time alignment flag is restored, a periodic relationship of 480 milliseconds for the SID frame of TAF = 1 is established. According to the periodic relationship of 480 milliseconds, it can be checked whether the time alignment flag is restored correctly;

If no data frame is received within the first 20 milliseconds and the frame is a SID frame, then the frame is considered to be a SID frame with TAF = 1. Similarly, in step S4042 and in step S408, such a judgment on the frame type is erroneous because:

If the following special circumstances occur, such as when the mobile station starts to send a service frame to the base station subsystem, after the RTP encapsulation conversion of the base station subsystem, the media gateway receives only a few service frames at this time. If the mobile station transmits the SP frame and one of the SID frames after the SP frame according to the protocol, the SID frame is not sent at the time of the air interface TAF=1, if the frame data is to be sourced. Decode, its TAF value should be equal to zero. However, if the base station subsystem fails to process the closest SP frame in front of the SID frame due to interference from the air interface, the media gateway does not know that the SID frame has an SP frame. According to the foregoing judging method, the media gateway recognizes the SID frame as a SID frame with TAF = 1, thereby causing misjudgment. However, with the rapid establishment of the periodic relationship of 480 milliseconds, this possible recovery error will be quickly reduced, and since this time is short, the number of affected frames will be small, and the quality of decoding will be affected. Very few.

In the actual application process, in order to reduce the judgment error that may exist in the foregoing solution, the foregoing steps S407 and S408 can continuously repeat the detection and identification every 480 milliseconds according to the needs of the technical solution, and the advantage is that the maximum can be maximized. The accuracy of the recovery time alignment flag is increased to a limit, and the number and frequency of repetitions depend on the requirements of the technical solution itself, and the variation does not exceed the protection scope of the present invention.

After the above steps, the media gateway recovers the time alignment flag of the mute indication frame that the base station has not sent from the received data.

Based on the above embodiments, in order to simplify the step of restoring the time alignment flag, the embodiment also provides a simplified method for restoring the time alignment flag, including the steps of:

The media gateway reads the data frame from the real-time transport protocol voice packet;

The media gateway determines whether the current data frame type in the real-time transport protocol voice packet is a mute indication frame, and if so, assigns a time alignment flag of the mute indication frame received within a predetermined time period to 0 or 1.

There are a variety of methods for assigning values, such as: random assignment, cyclic assignment, and the change of a predetermined type of assignment does not exceed the scope of protection of the present invention, and the time is aligned after the assignment of the mute indication frame. Sign. Thus, for the subsequent source decoding process, if the mute indication frame is sent with a fixed value of 0 or 1, if the mute indication frame is inconsistent with the original flag, a decoding error occurs, and the call is lowered. quality. However, the user is acceptable within the limits of the call quality.

In accordance with the method for simplifying the recovery time alignment flag described above, the embodiment of the present invention further discloses a method for simplifying source decoding, including the steps of:

The media gateway determines whether the current data frame type in the real-time transport protocol voice packet is a mute indication frame, and if so, assigns a time alignment flag of the mute indication frame received within a predetermined time period to 0 or 1;

The media gateway performs source decoding on the mute indication frame according to the time alignment flag. There are a variety of methods for assigning values, such as: random assignment, cyclic assignment, and the change of a predetermined type of assignment does not exceed the scope of protection of the present invention, and the time is aligned after the assignment of the mute indication frame. Sign.

With the utility model, the time alignment flag assignment of the mute indication frame and the source decoding are realized in a simpler manner within the limit of the call quality.

As shown in FIG. 6, in order to perform source decoding on the mute indication frame of the recovery time alignment flag, the present invention provides an embodiment of a method for encapsulating speech after source decoding, including the steps of:

S601. The media gateway reads the data frame from the real-time transport protocol voice packet.

S602. The media gateway determines whether the current data frame type in the real-time transport protocol voice packet is a mute indication frame, and if yes, proceeds to step S603, otherwise, ends the process;

S603. The media gateway determines a data frame type received within a predetermined time period. If the data frame type received first in the predetermined time period is a voice frame, the process proceeds to step S604, where no data is received within the predetermined time period. Frame, then proceeds to step S605;

S604, the media gateway assigns the mute indication frame time alignment flag to 0;

S605, the media gateway assigns the mute indication frame time alignment flag to 1;

S606. The media gateway performs source decoding on the mute indication frame according to the restored time alignment flag.

After the processing of the above embodiment, the mobile station is not sent to the medium during the transmission to the base station. The muting of the body gateway indicates that the frame time alignment flag is restored. And according to the time alignment flag, the source decoding can be performed on the mute indication frame in the subsequent source decoding process, which reduces the speech damage caused by the TAF parameter inaccuracy, and improves the call quality of the IP message.

On the basis of the foregoing embodiment, the number of valid values of the voice frame and the mute indication frame in the RTP voice packet is greatly different, and the type of the current data frame can be determined by determining whether the value at the fixed position is constant. The method for specifically determining whether the current data frame type is a mute indication frame may include the following steps:

The media gateway determines whether the value at the fixed position of the current frame is a constant value, and if the value at the fixed position is a constant value, the current frame is a mute indication frame.

Through the embodiment, the recognition of the silence indication frame is implemented according to the difference between the number of valid values of the voice frame and the mute indication frame, and further, the source decoding of the mute indication frame is implemented.

The periodic characteristics of the data distribution in the RTP voice packet analyzed based on the foregoing embodiments are as follows: As shown in FIG. 5, it is a sequence diagram of the service frame received by the media gateway, and it can be seen that According to the time interval specified by the RTP protocol standard, the time interval between the SP frame identifying "SP = 1" and the first SID frame identified by "SP = 0," is 20 milliseconds, the first SID after the SP frame. The TAF of the frame is 0, and the interval of the SID frame of each TAF = 1 is 480 milliseconds, and the following embodiment is obtained:

The predetermined time period has a length of 20 milliseconds. If the current data frame type is a mute indication frame, then:

The media gateway determines the type of the data frame received within 20 milliseconds,

If the service frame type received within 20 milliseconds is a voice frame, the frame is considered to be a mute indication frame with a time alignment flag of 0.

If the service frame is not received within 20 milliseconds, the frame is considered to be a mute indication frame with a time alignment flag of 1.

The media gateway performs source decoding on the mute indication frame with the time alignment flag of 0 and 1.

The above method for restoring the time alignment flag of the present embodiment makes full use of the following features of the real-time transport protocol voice packet:

In the real-time transport protocol voice packet, the first occurrence of the time-aligned target after the SP = 1 speech frame The silence indication frame of 0 = 0 appears 20 ms after the speech frame.

According to the above quantity relationship, the present embodiment obtains the invention of recovering the time alignment flag from the real-time transport protocol voice packet. Accordingly, the media gateway obtains its time alignment flag from the voice packet, and performs source decoding to improve the decoding accuracy and obtain higher quality voice quality.

In addition, on the basis of the foregoing embodiment, in order to improve the accuracy of the recovery time alignment flag and the source decoding, after the time alignment flag is set to 1, the method may further include the following steps:

5606. The media gateway records the service frame received within 20 milliseconds;

5607. The media gateway determines, whether the frame type of the service frame is an SP frame or a SID frame.

If the data frame received within the current 20 milliseconds is an SP frame, then the frame is considered to be a SID frame with TAF = 0.

If no data frame is received within the first 20 milliseconds and the frame is a SID frame, then this frame is considered to be a SID frame with TAF = 1.

The above-mentioned time alignment flag recovery using the data frame length of 20 milliseconds can maximize the accuracy of the recovery time alignment flag, and the number and frequency of repetitions depend on the requirements of the technical solution itself, and the change does not exceed the present invention. The scope of protection.

As shown in FIG. 7, in order to perform source decoding on the mute indication frame of the recovery time alignment flag, the present invention provides an embodiment of a source decoding media gateway, including:

The data frame reading unit 701 is configured to: read a data frame from the real-time transport protocol voice packet and send the signal; the mute indication frame determining unit 702, and the data frame reading unit, the source decoding unit, and the service frame type are determined. The unit is coupled to: determine whether the current data frame type in the real-time transport protocol voice packet is a mute indication frame after receiving the data frame, and if yes, send the mute indication frame to the source decoding unit 705, Generating a determination instruction and sending it to the service frame type determining unit 703;

The service frame type determining unit 703 is coupled to the recovery time alignment flag unit, and configured to: determine, according to the determining instruction, a data frame type received within a predetermined time period,

If the data frame type received first in the predetermined time period is a voice frame, an instruction is given to 0 and sent to the recovery time alignment flag unit 704.

If no data frame is received within the predetermined time period, an instruction is given and sent to the recovery time alignment flag unit 704;

a recovery time alignment flag unit 704, coupled to the source decoding unit, for: The instruction assigns the mute indication frame time alignment flag to 0, assigns the mute indication frame time alignment flag to 1 according to the instruction 1 instruction, and sends the time alignment flag 0 or 1 to the source decoding unit. 705;

The source decoding unit 705 is configured to: perform source decoding on the mute indication frame according to the time alignment flag.

Through the processing of the above embodiment, the mute indication frame time alignment flag that is not sent to the media gateway during transmission from the mobile station to the base station is restored, and according to the time alignment flag, the subsequent source translation can be performed. During the code process, the source decoding of the mute indication frame is performed, which reduces the speech damage caused by the inaccurate TAF parameter, and improves the quality of the IP call.

On the basis of the foregoing embodiment, the number of valid values of the voice frame and the mute indication frame in the RTP voice packet is greatly different. By determining whether the value at the fixed position is a constant value, the following embodiments can be obtained:

The mute indication frame determining unit includes: a mute indication frame determining subunit and a determining instruction transmitting subunit,

The mute indication frame determining subunit is configured to: determine whether a value at a fixed position of a current data frame in a real-time transport protocol voice packet is a constant value, and if yes, send the mute indication frame to a source decoding unit , generating a sending instruction and sending it to the determining instruction sending subunit;

The determining determines a sending subunit, configured to: generate a determining instruction according to the sending instruction, and send the determining instruction to the service frame type determining unit.

The periodic characteristics of the data distribution in the RTP voice packet analyzed based on the foregoing embodiments are as follows: As shown in FIG. 5, it is a sequence diagram of the service frame received by the media gateway, and it can be seen that According to the time interval specified by the RTP protocol standard, the time interval between the SP frame identifying "SP = 1" and the first SID frame identified by "SP = 0," is 20 milliseconds, the first SID after the SP frame. The TAF of the frame is 0, and the length of the SID frame of each TAF = 1 is 480 milliseconds, and the length of the predetermined time period in each of the above embodiments may be 20 milliseconds.

The above method for restoring the time alignment flag of the embodiment fully utilizes the following features of the real-time transport protocol voice packet: In the real-time transport protocol voice packet, the first mute indication frame with the time alignment flag = 0 appearing after the speech frame of SP = 1 appears 20 ms after the speech frame.

As shown in FIG. 8, in order to perform source decoding on the mute indication frame of the recovery time alignment flag, an embodiment of the present invention further provides a system for encapsulating a voice after source decoding, including:

Media gateway 801 and base station 802,

The base station 802 is configured to: encapsulate the data sent by the mobile station into a real-time transport protocol voice packet and send the data packet to the media gateway;

The media gateway 801 is configured to: read a data frame from a real-time transport protocol voice packet, determine whether a current data frame type in the real-time transport protocol voice packet is a mute indication frame, and if yes, determine to receive the data frame within a predetermined time period. Data frame type,

If the data frame type of one frame before the mute indication frame is a speech frame within a predetermined time period, the time alignment flag of the mute indication frame is assigned a value of 0, if there is no previous mute indication frame within a predetermined time period Receiving a data frame, assigning a time alignment flag of the mute indication frame to 1,

Through the processing of the above embodiment, the mute indication frame time alignment flag that is not sent to the media gateway during transmission from the mobile station to the base station is restored, and according to the time alignment flag, the subsequent source translation can be performed. During the code process, the source decoding of the mute indication frame is performed, which reduces the speech damage caused by the inaccurate TAF parameter, and improves the call quality of the IP message.

As shown in FIG. 9, on the basis of the foregoing embodiment, the number of valid values of the voice frame and the mute indication frame in the RTP voice packet is greatly different, and it is determined whether the value at the fixed position is constant by increasing in the media gateway. The value of the mute indicates the frame determining device, and the following embodiments can be obtained:

The media gateway further includes: a mute indication frame determining device 901,

The mute indication frame determining device 901 is configured to: determine whether a value at a fixed position of a current frame in the current real-time transport protocol voice packet is a constant value, and if yes, use the frame as a mute indication frame. After the embodiment, the recognition of the mute indication frame is performed according to the difference between the number of valid values of the voice frame and the mute indication frame, and further, the source decoding of the mute indication frame is implemented.

Due to the time interval specified by the RTP protocol standard, the time interval between the SP frame identifying "SP = 1" and the first SID frame identified by "SP = 0," is 20 milliseconds, the first after the SP frame. The TID of the SID frame is 0, and the length of the SID frame of each TAF=1 is 480 milliseconds, and the length of the predetermined time period in each of the above embodiments may be 20 milliseconds. Of course, if the protocol specifies the respective data. The length of the frame has changed or other needs of the technical solution itself, and the length of the predetermined time period can be adjusted accordingly, and the change does not exceed the protection scope of the present invention.

Through the description of the above embodiments, those skilled in the art can clearly understand that the present invention can be implemented by means of software plus a necessary general hardware platform, and of course, can also be through hardware, but in many cases, the former is a better implementation. the way. Based on such understanding, the technical solution of the present invention, which is essential or contributes to the prior art, may be embodied in the form of a software product stored in a storage medium, including a plurality of instructions for causing a A computer device (which may be a personal computer, server, or network device, etc.) performs the methods described in various embodiments of the present invention.

The embodiments of the present invention described above are not intended to limit the scope of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and scope of the invention are intended to be included within the scope of the invention.

Claims

Rights request

A method for recovering a time alignment flag, comprising the steps of:

Obtaining a data frame from a real-time transport protocol voice packet;

If it is determined that the current data frame type is a mute indication frame, and the data frame type of one frame before the mute indication frame is a speech frame within a predetermined time period, assigning the mute indication frame time alignment flag to a first value; Or,

2. The method of recovering a time alignment flag according to claim 1, wherein the determining that the current data frame type is a mute indication frame comprises:

If the value at the fixed position of the current data frame is a constant value, the current data frame type is a mute indication frame.

3. The method of recovering a time alignment flag according to claim 1, wherein the predetermined time period has a length of 20 milliseconds.

The method of recovering a time alignment flag according to any one of claims 1 to 3, wherein the first value is 0; and the second value is 1.

5. A method for recovering a time alignment flag, comprising:

Obtaining a data frame from a real-time transport protocol voice packet;

If the current data frame type in the real-time transport protocol voice packet is a mute indication frame, the time alignment flag of the mute indication frame received within a predetermined time period is assigned a value of 0 or 1.

6. A method of source decoding, characterized in that it comprises:

Obtaining a data frame from a real-time transport protocol voice packet;

7. A method of source decoding, characterized in that it comprises:

Obtaining a data frame from a real-time transport protocol voice packet;

If the current data frame type is a mute indication frame, and the data frame type of one frame before the mute indication frame is a speech frame within a predetermined time period, the mute indication frame time alignment flag is assigned 0,

The method for decoding a source according to claim 7, wherein the determining that the current data frame type is a mute indication frame comprises:

9. The method of claim 7, wherein the predetermined time period has a length of 20 milliseconds.

10. A media gateway applied to source decoding, characterized in that:

a source decoding unit; a service frame type determining unit; a recovery time alignment flag unit; a data frame reading unit, configured to: obtain a data frame from the real-time transport protocol voice packet and send the data frame; and the mute indication frame determining unit is configured to: receive Determining whether the current data frame type is a mute indication frame after the data frame, if yes, sending the mute indication frame to the source decoding unit, generating a determination instruction, and sending the determination instruction to the service frame type determining unit;

a recovery time alignment flag unit, configured to: assign a value of 0 to the mute indication frame time alignment flag according to the 0-instruction generated by the service frame type determining unit; or

And assigning the mute indication frame time alignment flag to 1 according to the instruction 1 generated by the service frame type determining unit, and sending the time alignment flag 0 or 1 to the source decoding unit;

And a source decoding unit, configured to: perform source decoding on the mute indication frame according to the time alignment flag.

11. The source decoding media gateway of claim 10, wherein said mute The indication frame determining unit includes: a mute indication frame determining subunit and a determining instruction transmitting subunit, the mute indicating frame determining subunit, configured to: determine whether a value at a fixed position of the current data frame is a constant value, if Sending the mute indication frame to the source decoding unit, generating a transmission instruction and sending it to the determination instruction transmission subunit;

The determining instruction sending subunit is configured to: generate a determining instruction according to the sending instruction and send the determining instruction to the service frame type determining unit.

12. A system for source decoding, characterized in that it comprises:

Media gateway and base station,

The source decoding system according to claim 12, wherein the media gateway further comprises: a mute indication frame determining device,

The mute indication frame determining device is configured to: determine whether a value at a fixed position of a current frame in the current real-time transport protocol voice packet is a constant value, and if yes, use the frame as a mute indication frame.