CN101394228B - Method for restoring time alignment note, signal source decoding method, apparatus and system - Google Patents

Abstract

The embodiment of the present invention discloses a method for recovering a time alignment mark, comprising the steps of: reading a data frame from a real-time transport protocol voice packet; The data frame type of a frame before the indication frame is a voice frame, then the mute indication frame time alignment flag is assigned a value of 0, if it is determined that the current data frame type is a silence indication frame, and within a predetermined period of time in the silence indication frame If no data frame has been received before, the time alignment flag of the silence indication frame is assigned a value of 1. Also disclosed are a simplified method for recovering time alignment marks, a method for simplifying information source decoding, and a method for information source decoding. Also provided are a media gateway and system for source decoding. The embodiment of the present invention can realize the recovery of the time alignment mark in the real-time transport protocol and use it for information source decoding.

Description

Method for recovering time alignment mark, method, device and system for source decoding

technical field

The invention relates to the technical field of mobile communication, in particular to a method for recovering a time alignment mark, a method, a device and a system for information source decoding.

Background technique

After GSM (Global System for Mobile Communications, Global System for Mobile Communications) A interface (Ainterface) IP (Internet Protocol, Internet Protocol), BSC (base station controller, base station controller) can directly perform IP encapsulation and sent to the core network. The core network is responsible for handling all multi-codec-related affairs, including codec negotiation and codec conversion after negotiation failure, and completing the exchange of voice packets. This solution can make full use of the characteristics of the softswitch core network. By supporting TrFO (Transcoder FreeOperation, free code conversion operation), it can improve voice quality, reduce the use of TC (Transcoder, code converter) resources, and save transmission on the A interface. bandwidth, and also simplifies the design of BSS (BaseStation Subsystem, base station subsystem).

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

PAYLOAD, indicating the data load;

PPP (Point-to-Point Protocol), 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 transmission protocol.

In order to enable smooth intercommunication between network devices produced by different manufacturers, standard RTP (Real Time Transport Protocol, Real Time Transport Protocol) is usually used in these devices to encapsulate voice data. For example, for EFR (Enhanced Full Rate, enhanced full rate)/FR (FULLRATE, full rate)/HR (HALF RATE, half rate) voice data, the 3GPPTS 101318 protocol can be used for encapsulation. In order to align the bytes of the encapsulated voice, the protocol stipulates: 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 ; As 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 cannot provide a reliable transmission mechanism for sequentially transmitting data packets, nor does it provide flow control or congestion control. According to the provisions of the standard RTP protocol, the standard source codec algorithm stipulated in the protocol also needs to input the parameter TAF (Time Align Flag) to perform source decoding on the SID (Silence Descriptor, mute indication) frame. There are many algorithms for source decoding of SID frames. Among these different algorithms, the processing methods for SID frames with TAF value equal to 1 and SID frames with 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 will be affected, reducing the MGW (MEDIA GATEWAY, media Gateway) call quality after voice decoding.

Contents of the invention

In view of this, the purpose of one or more embodiments of the present invention is to provide a method for recovering the time alignment flag, a method, a device and a system for source decoding, so that after the A interface is converted to IP, the speech encapsulated by the RTP protocol can be processed Silence in the packet indicates that the frame undergoes time alignment marker recovery.

In order to solve the above problems, an embodiment of the present invention provides a method for restoring a time alignment flag, including steps:

Read data frames from real-time transport protocol voice packets;

If it is determined that the current data frame type is a silence indication frame, and the data frame type of a frame preceding the silence indication frame within a predetermined period of time is a voice frame, then the silence indication frame time alignment flag is assigned a value of 0,

If it is determined that the current data frame type is a silence indication frame, and no data frame is received before the silence indication frame within a predetermined period of time, the time alignment flag of the silence indication frame is assigned a value of 1.

The embodiment of the present invention also provides a simplified method for restoring the time alignment mark, including steps:

Read data frames from real-time transport protocol voice packets;

If it is determined that the current data frame type in the real-time transport protocol voice packet is a silence indication frame, and the data frame type of a frame before the silence indication frame within a predetermined period of time is a voice frame, then the silence indication frame time alignment flag The assignment is 0, if it is determined that the current data frame type in the real-time transport protocol voice packet is a silence indication frame, and no data frame is received before the silence indication frame within a predetermined period of time, then the silence indication frame time alignment flag is assigned a value is 1.

The embodiment of the present invention also provides a method for simplifying information source decoding, including steps:

Read data frames from real-time transport protocol voice packets;

If it is determined that the current data frame type in the real-time transport protocol voice packet is a silence indication frame, and the data frame type of a frame before the silence indication frame within a predetermined period of time is a voice frame, then the silence indication frame time alignment flag The assignment is 0, if it is determined that the current data frame type in the real-time transport protocol voice packet is a silence indication frame, and no data frame is received before the silence indication frame within a predetermined period of time, then the silence indication frame time alignment flag is assigned a value is 1;

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

The embodiment of the present invention also provides a method for information source decoding, including steps:

Read data frames from real-time transport protocol voice packets;

If the current data frame type is a silence indication frame, and the data frame type of a frame preceding the silence indication frame within a predetermined period of time is a voice frame, then the silence indication frame time alignment flag is assigned a value of 0,

If the current data frame type is a silence indication frame, and no data frame is received before the silence indication frame within a predetermined period of time, then the silence indication frame time alignment flag is assigned a value of 1;

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

Embodiments of the present invention also provide a media gateway for source decoding, including:

The data frame reading unit is used to: read the data frame from the real-time transport protocol voice packet and send it;

The mute indication frame determination unit is coupled with the data frame reading unit, the source decoding unit and the service frame type determination unit, and is used to determine whether the current data frame type is a mute indication frame after receiving the data frame, if Yes, sending the mute instruction frame to the source decoding unit, generating a determination instruction and sending it to the service frame type determination unit;

A service frame type determination unit, coupled to the recovery time alignment flag unit, configured to: determine the type of data frame received within a predetermined time period according to the determination instruction,

If the data frame type of a frame before the silence indication frame is a speech frame within a predetermined period of time, generate a 0 command and send it to the recovery time alignment flag unit,

If no data frame is received before the mute indication frame within a predetermined period of time, generate a 1 command and send it to the recovery time alignment flag unit;

A recovery time alignment flag unit, coupled with the source decoding unit, configured to: assign a value of 0 to the silence indication frame time alignment flag according to an assignment of 0 instruction, and assign a value to the silence indication frame time alignment flag according to an assignment of 1 instruction is 1, and the time alignment flag 0 or 1 is sent to the source decoding unit;

A source decoding unit, configured to: perform source decoding on the silence indication frame according to the time alignment flag.

Embodiments of the present invention also provide a source decoding system, including:

media gateways and base stations,

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

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

If the data frame type of a frame before the silence indication frame is a voice frame within a predetermined period of time, the time alignment flag of the silence indication frame is assigned a value of 0, if there is no before the silence indication frame within a predetermined period of time After receiving the data frame, the time alignment flag of the silence indication frame is assigned a value of 1,

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

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

After the processing of the above technical solution, the time alignment flag of the mute indication frame that was not sent to the media gateway during the transmission from the mobile station to the base station is restored, and can be used for the subsequent information source decoding process for different time alignment flag pairs Mute indication frame is decoded, which reduces voice damage caused by inaccurate TAF parameters and improves IP-based call quality.

Description of drawings

FIG. 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 the mobile station to the media gateway via the base station subsystem;

Fig. 3 is a flow chart of an embodiment of the method for recovering the time alignment mark of the present invention;

Fig. 4 is a flow chart of another embodiment of the method for restoring the time alignment mark of the present invention;

Fig. 5 is the sequence diagram of the business frame that media gateway receives;

Fig. 6 is a flowchart of an embodiment of the method for source decoding of the present invention;

Fig. 7 is the block diagram of an embodiment of the gateway of the information source decoding of the present invention;

Fig. 8 is a block diagram of an embodiment of the source decoding system of the present invention;

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

Detailed ways

The specific implementation manners of the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings.

In each embodiment of the present invention and in each part of the description of this application, the service frame includes an SP frame and a SID frame, the SP frame is a voice frame, the SID frame is a mute indication frame, and the TAF is a time alignment flag. Some flags are 1 and some are 0. The use of Chinese or English abbreviations in different places is required for the convenience of reference and expression.

As shown in Fig. 2, it is a schematic diagram of data flow from the mobile station to the media gateway via the base station subsystem. According to the 3GPP (Three Generation Partnership Project, the third generation mobile communication cooperation project) 46.031 agreement, when the uplink discontinuous transmission mode is turned on, although the mobile station can generate continuous SP frames and SID frames by the source codec module , but instead of sending all these frames to the air interface, it only sends the following three types of frames:

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

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

3) SID frame with TAF=1 (th se marked with SP=0 and aligned with the SACCH multiframe structure as described in 45.008, marked with "SP=0" and aligned with the slow-speed associated control channel multiframe structure specified in the 45.008 protocol frame, time alignment flag TAF = 1 mute indication frame), and every two silence indication frames with time alignment flag TAF = 1 are separated by 480 milliseconds. The period of the SACCH multiframe is 480 milliseconds according to the agreement.

After the above-mentioned three kinds of data are encapsulated by the real-time transmission protocol of the base station subsystem, these three kinds of data are encapsulated into the RTP voice packet stipulated in the real-time transmission protocol standard, and the voice packet includes the above-mentioned three kinds of data frames, that is, the above-mentioned TAF= The mute indication frame of 1 or TAF=0, and the speech frame, both have a length of 20 milliseconds.

Based on the above characteristics of the data frame sent by the mobile station, the present invention discloses the following embodiments:

As shown in Figure 3, it is an embodiment of the method for recovering the time alignment mark of the present invention, including steps:

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

S302, the media gateway judges whether the current data frame type in the real-time transport protocol voice packet is a mute indication frame, if yes, enters step S302, otherwise, ends the process;

S303, the media gateway judges the type of data frame received within the predetermined time period, if the type of data frame received first within the predetermined time period is a voice frame, then enter step S304, and no data is received within the predetermined time period frame, then enter step S305, the predetermined period of time in this step can be set according to the needs of actual use, and can also be set according to the characteristics of the length of the speech frame and silence indication frame data. In the existing protocol, the lengths of these two data frames are both 20 milliseconds, therefore, in a preferred embodiment, 20 milliseconds may be used as the length of the predetermined time period. Doing so helps to improve the efficiency and accuracy of judgment. Other lengths are also possible, and this change does not exceed the protection scope of the present invention;

S304. The media gateway assigns the mute indication frame time alignment flag to 0;

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

Through the above steps, the media gateway restores the time alignment mark of the silence indication frame that the real-time transport protocol has not sent from the base station subsystem.

As shown in Figure 4, a technical solution for obtaining a mute indication frame is disclosed, and the present invention provides another embodiment of a method for restoring a time alignment mark, including steps:

S401, BSS base station subsystem (Base Station Subsystem), after receiving the voice frame uploaded by the mobile station, 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 TAF=1, the base station subsystem encapsulates these data frames. The process is: the base station subsystem performs user plane frame format conversion, Converting the data in TRAU format sent by the mobile station into voice packets in RTP format;

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

S403, the media gateway judges whether the current data frame type in the real-time transport protocol voice packet is a mute indication frame, if yes, enters step S404, otherwise, ends the process;

The process of judging whether it is a mute indication frame can be:

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

S404. The media gateway judges the type of the data frame received within the predetermined time period. If the type of the data frame received first within the predetermined time period is a voice frame, then enter step S405, and no data is received within the predetermined time period. frame, go to step S406. The predetermined period of time in this step can be set according to the needs of actual use, or can be set according to the characteristics of the length of the voice frame and the silence indication frame data. In the existing protocol, the lengths of these two data frames are both 20 milliseconds, therefore, in a preferred embodiment, 20 milliseconds may be used as the length of the predetermined time period. Doing so helps to improve the efficiency and accuracy of judgment. Other lengths are also possible, and this change does not exceed the protection scope of the present invention;

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

S406. The media gateway assigns a value of 1 to the time alignment flag of the mute indication frame.

Through the process of the above embodiment, the time alignment flag of the mute indication frame that is not sent to the media gateway during the transmission from the mobile station to the base station is restored. The recovered TAF can be used for the subsequent source decoding process to decode the mute indication frame according to different time alignment marks, which reduces the voice damage caused by inaccurate TAF parameters and improves the call quality of the A interface after IP .

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

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

S4041. The media gateway records the data frames 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 this frame is considered to be a SID frame with TAF=0; if no data frame is received within the previous 20 milliseconds, and this frame is a SID frame, then this frame is considered to be a SID frame For the SID frame with TAF=1, after the above steps, the media gateway can recover the TAF value of the SID frame not sent by the base station from the received data.

The above-mentioned method for recovering the time alignment mark of the present embodiment fully utilizes the following characteristics of the real-time transport protocol voice packet:

In the real-time transport protocol voice packet, the silence indication frame that appears first after the voice frame with SP=1 and whose time alignment flag=0 appears 20 milliseconds after the voice frame.

According to the above quantitative relationship, this embodiment obtains the invention of recovering the time alignment flag from the real-time transport protocol voice packet. Accordingly, the media gateway obtains the time alignment mark from the voice packet, which can be used for subsequent information source decoding, and the accuracy of decoding is greatly improved, resulting in higher voice quality.

Wherein, on the basis of the above-mentioned embodiments, in order to improve the accuracy of recovering the time alignment flag, after step S406 assigns the time alignment flag to 1, further steps may be included:

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

S408. The media gateway judges 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 this frame is considered to be a SID frame with TAF=0; if no data frame is received within the previous 20 milliseconds, and this frame is a SID frame, then this frame is considered to be a SID frame SID frame with TAF=1.

In step S4042 and step S408, there is an error in the judgment of the frame type, because:

If the following special circumstances occur, for example, when the mobile station starts to send service frames to the base station subsystem, after the RTP encapsulation and conversion of the base station subsystem, the media gateway only receives a few service frames at this time. If the mobile station sends the SP frame and the first SID frame immediately after the SP frame according to the protocol at this time, and this SID frame is just aligned with the time when TAF=1 of the air interface, according to the The method will assign the time alignment flags of these SID frames to 0, so that the time alignment with the air interface is inconsistent. Misidentify the SID frame with TAF=1 as the SID frame with TAF=0, and identify the SID frame that needs to be decoded with the TAF=1 flag as the SID frame with TAF=0 in the subsequent decoding process . However, since the occurrence interval of the SID frame with TAF=1 is 480 milliseconds, if repeated time alignment mark recovery is performed, a periodic relationship of 480 milliseconds with the SID frame with TAF=1 will be established. According to this 480 millisecond cycle relationship, it can be checked whether the restoration of the time alignment flag is correct;

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

In the same way, it can be seen that in step S4042 and step S408, there is an error in the judgment of the frame type, because:

If the following special circumstances occur, for example, when the mobile station starts to send service frames to the base station subsystem, after the RTP encapsulation and conversion of the base station subsystem, the media gateway only receives a few service frames at this time. If the mobile station sends the SP frame and a certain SID frame after the SP frame according to the protocol at this time, and this SID frame is not sent at the time of TAF=1 of the air interface, if the frame data is to be sourced Decoding, its TAF value should be equal to 0. However, if the base station subsystem happens to fail to process the closest SP frame preceding the SID frame due to air interface interference, the media gateway does not know that the SID frame has an SP frame. According to the aforementioned judging method, the media gateway will recognize the SID frame as a SID frame with TAF=1, thus causing misjudgment. However, with the rapid establishment of the subsequent 480 ms periodic relationship, this possible recovery error will soon be reduced, and because this time is very short, the number of affected frames will be very small, and the impact on the decoding quality will be small. Very few.

Among them, in the actual application process, in order to reduce the judgment error that may exist in the above-mentioned scheme, the judgment process of the above-mentioned steps S407 and S408 can continuously repeat the detection and identification every 480 milliseconds according to the needs of the technical scheme. The advantage of this is that it can maximize To maximize the accuracy of recovering the time alignment mark, the number and frequency of repetitions depend on the requirements of the technical solution itself, and this change does not exceed the protection scope of the present invention.

Through the above steps, the media gateway restores the time alignment flag of the mute indication frame not sent by the base station from the received data.

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

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

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

There are many methods of assignment, for example: random assignment, cyclic assignment, cyclic assignment with a preset period, or different random assignment methods combined with different cyclic assignment methods, and so on. Changes in various assignment methods do not exceed the scope of protection of the present invention, and it is all about determining the time alignment flag after assigning a value to the silence indication frame.

In this way, for the subsequent information source decoding process, if the mute indication frame is sent with a fixed value of 0 or 1, if the assigned value of the mute indication frame is inconsistent with the original flag, a decoding error will occur, reducing the call quality. However, within the limit allowed by the call quality, it is acceptable to the user.

Compatible with the above simplified method for recovering the time alignment flag, the embodiment of the present invention also discloses a method for simplifying source decoding, including steps:

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

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

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

There are many methods of assignment, for example: random assignment, cyclic assignment, cyclic assignment with a preset period, or different random assignment methods combined with different cyclic assignment methods, and so on. Changes in various assignment methods do not exceed the scope of protection of the present invention, and it is all about determining the time alignment flag after assigning a value to the silence indication frame.

Utilizing this practical example, within the limit allowed by the call quality, the time alignment flag assignment and source decoding for the silence indication frame are realized in a simpler solution.

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

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, if yes, enters step S603, otherwise, ends the process;

S603, the media gateway determines the type of data frame received within the predetermined time period, if the type of data frame received first within the predetermined time period is a voice frame, then enters step S604, and no data is received within the predetermined time period frame, enter step S605;

S604. The media gateway assigns the time alignment flag of the mute indication frame to 0;

S605. The media gateway assigns the time alignment flag of the mute indication frame to 1;

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

Through the process of the above embodiment, the time alignment flag of the mute indication frame that is not sent to the media gateway during the transmission from the mobile station to the base station is restored. And according to the time alignment flag, the mute indication frame can be source decoded in the subsequent source decoding process, which reduces the voice damage caused by inaccurate TAF parameters and improves the call quality of the IP call.

Wherein, on the basis of the above-mentioned embodiment, according to the effective value quantity difference of the voice frame in the RTP voice packet and the mute indication frame, by judging whether the value on its fixed position is constant, the type of the current data frame can be judged, The method for specifically determining whether the current data frame type is a silence 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 this embodiment, the recognition of the silence indication frame is realized according to the difference in the number of effective values of the speech frame and the silence indication frame, and further, information source decoding of the silence indication frame is realized.

Wherein, on the basis of the above-described embodiments, based on the periodic characteristics of the data distribution in the RTP voice packet analyzed in the aforementioned relevant embodiments: as shown in Figure 5, it is a sequence diagram of the business frame received by the media gateway, as can be seen, According to the time interval stipulated in the RTP protocol standard, the time interval between the SP frame marked "SP=1" and the first SID frame marked "SP=0" is 20 milliseconds, and the first SID frame after the SP frame TAF=0, and the interval of each SID frame of TAF=1 is 480 milliseconds, just obtain following embodiment:

The length of the predetermined time period is 20 milliseconds, if the current data frame type is a silence indication frame, then:

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

If the service frame type received within 20 milliseconds is a voice frame, it is considered that this frame is a mute indication frame with a time alignment flag of 0,

If no service frame is 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 frames whose time alignment flags are 0 and 1.

The above-mentioned method for recovering the time alignment mark of the present embodiment fully utilizes the following characteristics of the real-time transport protocol voice packet:

In the real-time transport protocol voice packet, the silence indication frame that appears first after the voice frame with SP=1 and whose time alignment flag=0 appears 20 milliseconds after the voice frame.

According to the above quantitative relationship, this embodiment obtains the invention of recovering the time alignment flag from the real-time transport protocol voice packet. Accordingly, the media gateway obtains the time alignment mark from the voice packet, and uses it to decode the information source, thereby improving the decoding accuracy and obtaining higher voice quality.

Wherein, on the basis of the above-mentioned embodiments, in order to improve the accuracy of recovering the time alignment flag and the source decoding, after assigning the time alignment flag to 1, further steps may be included:

S606. The media gateway records the service frames received within 20 milliseconds;

S607. 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 this frame is considered to be a SID frame with TAF=0,

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

The above-mentioned recovery of the repeated time alignment mark using a data frame length of 20 milliseconds can maximize the accuracy of recovering the time alignment mark. The number and frequency of repetitions depend on the requirements of the technical solution itself, and this change does not exceed the requirements of the present invention. 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 media gateway for source decoding, including:

The data frame reading unit 701 is used to: read the data frame from the real-time transport protocol voice packet and send it;

The mute indication frame determination unit 702 is coupled with the data frame reading unit, the source decoding unit and the service frame type determination unit, and is used to: determine the current data frame type in the real-time transport protocol voice packet after receiving the data frame Whether it is a mute instruction frame, if yes, send the mute instruction frame to the source decoding unit 705, generate a determination instruction and send it to the service frame type determination unit 703;

A service frame type determination unit 703, coupled to the recovery time alignment flag unit, configured to: determine the type of data frame received within a predetermined time period according to the determination instruction,

If the data frame type received earlier in the predetermined period of time is a voice frame, generate a 0 command and send it to the recovery time alignment flag unit 704,

If the data frame is not received within the predetermined period of time, a 1 command is generated and sent to the recovery time alignment flag unit 704;

Restoring the time alignment flag unit 704, coupled with the source decoding unit, for: assigning the silence indication frame time alignment flag to 0 according to the assignment instruction, and assigning the silence indication frame time alignment flag to 0 according to the assignment instruction Assign a value of 1, and send the time alignment flag 0 or 1 to the source decoding unit 705;

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

After the process of the above embodiment, the time alignment flag of the mute indication frame that was not sent to the media gateway during the transmission from the mobile station to the base station is restored, and according to the time alignment flag, it can be translated in the subsequent information source In the encoding process, source decoding is performed on the mute indication frame, which reduces the voice damage caused by inaccurate TAF parameters and improves the quality of IP-based calls.

Wherein, on the basis of above-described embodiment, according to the voice frame in the RTP voice packet and the mute indication frame effective value quantity difference is very big, by judging whether the value on its fixed position is constant value, can obtain following embodiment:

The mute indication frame determination unit includes: a mute indication frame determination subunit and a determination instruction sending subunit,

The mute indication frame determination subunit is used for: judging whether the value at the fixed position of the current data frame in the real-time transport protocol voice packet is a constant value, if yes, then sending the mute indication frame to the source decoding unit , generating a sending instruction and sending it to the confirming instruction sending subunit;

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

Through this embodiment, the recognition of the silence indication frame is realized according to the difference in the number of effective values of the speech frame and the silence indication frame, and further, information source decoding of the silence indication frame is realized.

Wherein, on the basis of the above-described embodiments, based on the periodic characteristics of the data distribution in the RTP voice packet analyzed in the aforementioned relevant embodiments: as shown in Figure 5, it is a sequence diagram of the business frame received by the media gateway, as can be seen, According to the time interval stipulated in the RTP protocol standard, the time interval between the SP frame marked "SP=1" and the first SID frame marked "SP=0" is 20 milliseconds, and the first SID frame after the SP frame TAF=0, and the length of each SID frame with TAF=1 is 480 milliseconds, the length of the predetermined time period in each of the foregoing embodiments may be 20 milliseconds.

The above-mentioned method for recovering the time alignment mark of the present embodiment fully utilizes the following characteristics of the real-time transport protocol voice packet:

In the real-time transport protocol voice packet, the silence indication frame that appears first after the voice frame with SP=1 and whose time alignment flag=0 appears 20 milliseconds after the voice frame.

According to the above quantitative relationship, this embodiment obtains the invention of recovering the time alignment flag from the real-time transport protocol voice packet. Accordingly, the media gateway obtains the time alignment mark from the voice packet, and uses it to decode the information source, thereby improving the decoding accuracy and obtaining higher voice quality.

As shown in FIG. 8 , in order to perform source decoding on the mute indication frame for recovering the time alignment flag, an embodiment of the present invention also provides a system for source decoding after encapsulating speech, 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 it to the media gateway;

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

If the data frame type of a frame before the silence indication frame is a voice frame within a predetermined period of time, the time alignment flag of the silence indication frame is assigned a value of 0, if there is no before the silence indication frame within a predetermined period of time After receiving the data frame, the time alignment flag of the silence indication frame is assigned a value of 1,

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

After the process of the above embodiment, the time alignment flag of the mute indication frame that was not sent to the media gateway during the transmission from the mobile station to the base station is restored, and according to the time alignment flag, it can be translated in the subsequent information source Source decoding is performed on the mute indication frame during the decoding process, which reduces the voice damage caused by inaccurate TAF parameters and improves the call quality of the IP call.

Wherein, as shown in Figure 9, on the basis of the above-mentioned embodiment, according to the voice frame in the RTP voice packet and the effective value quantity of the silence indication frame are very different, by adding in the media gateway to judge whether the value at its fixed position is constant The value of mute indicates that the frame determines the device, the following embodiments can be obtained:

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

The mute indication frame determining device 901 is configured to: determine whether the value at the fixed position of the 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.

Through this embodiment, the recognition of the silence indication frame is realized according to the difference in the number of effective values of the speech frame and the silence indication frame, and further, information source decoding of the silence indication frame is realized.

Because according to the time interval stipulated in the RTP protocol standard, the time interval between the SP frame of the mark "SP=1" and the first SID frame of the mark "SP=0" is 20 milliseconds, the first SID after the SP frame The TAF=0 of the frame, and the length of each SID frame with TAF=1 is 480 milliseconds, and the length of the predetermined time period in each of the above-mentioned embodiments may be 20 milliseconds. Of course, if the length of each data frame stipulated in the protocol changes or other needs of the technical solution itself, the length of the predetermined time period can be adjusted accordingly, and this 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-purpose hardware platform, and of course also by hardware, but in many cases the former is a better implementation Way. Based on this understanding, the essence of the technical solution of the present invention or the part that contributes to the prior art can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions to make a A computer device (which may be a personal computer, a server, or a network device, etc.) executes the methods described in various embodiments of the present invention.

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

Claims (13)

1. One kind recovery time alignment mark method, it is characterized in that, comprise step:

   Read data frame from the RTP voice packet;

   If determine that the current data frame type is quiet indication frame, and the data frame type of the frame before described quiet indication frame is speech frame within a predetermined period of time, is 0 with described quiet indication frame time alignment mark assignment then,

   If determine that the current data frame type is quiet indication frame, and before described quiet indication frame, do not receive Frame within a predetermined period of time, be 1 with described quiet indication frame time alignment mark assignment then.
2. Recovery time as claimed in claim 1 alignment mark method, it is characterized in that described definite current data frame type is that quiet indication frame is specially:

   If the value on the fixed position of described current data frame is constant, then described current data frame type is quiet indication frame.
3. Recovery time as claimed in claim 1 alignment mark method, it is characterized in that the length of described predetermined amount of time is 20 milliseconds.
4. Recovery time as claimed in claim 1 alignment mark method, it is characterized in that, also comprise step:

   After complete to described quiet indication frame assignment, re-execute described from the RTP voice packet read data frame step.
5. 5. the method for a source decoding is characterized in that, comprises step:

   Read data frame from the RTP voice packet;

   If the current data frame type is quiet indication frame, and the data frame type of the frame before described quiet indication frame is speech frame within a predetermined period of time, is 0 with described quiet indication frame time alignment mark assignment then,

   If the current data frame type is quiet indication frame, and not receiving Frame within a predetermined period of time before described quiet indication frame, is 1 with described quiet indication frame time alignment mark assignment then;

   According to described time unifying sign described quiet indication frame is carried out source decoding.
6. 6. the method for source decoding as claimed in claim 5 is characterized in that, described definite current data frame type is that quiet indication frame is specially:

   If the value on the fixed position of described current data frame is constant, then described current data frame type is quiet indication frame.
7. 7. the method for source decoding as claimed in claim 5 is characterized in that, the length of described predetermined amount of time is 20 milliseconds.
8. 8. the media gateway of a source decoding is characterized in that, comprising:

   The Frame reading unit is used for: from RTP voice packet read data frame and transmission;

   Quiet indication frame determining unit, with described Frame reading unit, source decoding unit and the coupling of traffic frame type determining unit, be used for: determine whether the current data frame type is quiet indication frame after receiving described Frame, if, described quiet indication frame is delivered to described source decoding unit, generate and determine instruction and deliver to described traffic frame type determining unit;

   Traffic frame type determining unit with alignment mark element coupling recovery time, is used for: according to the definite data frame type of receiving within a predetermined period of time of described definite instruction,

   If the data frame type of the frame before described quiet indication frame is speech frame within a predetermined period of time, generate and compose 0 instruction and deliver to alignment mark unit recovery time,

   If before described quiet indication frame, do not receive Frame within a predetermined period of time, generate and compose 1 instruction and deliver to alignment mark unit recovery time;

   Recovery time the alignment mark unit, with described source decoding element coupling, be used for: be 0 according to composing 0 instruction with described quiet indication frame time alignment mark assignment, be 1 according to composing 1 instruction with described quiet indication frame time alignment mark assignment, and described time unifying sign 0 or 1 is delivered to described source decoding unit;

   The source decoding unit is used for: according to described time unifying sign described quiet indication frame is carried out source decoding.
9. 9. the media gateway of source decoding as claimed in claim 8 is characterized in that, described quiet indication frame determining unit comprises: quiet indication frame determines that subelement and definite instruction send subelement,

   Described quiet indication frame is determined subelement, is used for: determine the value constant whether on the fixed position of described current data frame, if so, then described quiet indication frame is delivered to the source decoding unit, generate and send instruction and also deliver to and determine that instruction sends subelement;

   Described definite instruction sends subelement, is used for: generate according to described transmission instruction and determine instruction and deliver to traffic frame type determining unit.
10. 10. the media gateway of source decoding as claimed in claim 8 is characterized in that, the length of described predetermined amount of time is 20 milliseconds.
11. 11. the system of a source decoding is characterized in that, comprising:

    Such as claim 8 to 10 each described media gateway and base station,

    Described base station is used for: the data encapsulation that travelling carriage is sent is the RTP voice packet and delivers to described media gateway;

    Described media gateway is used for: from RTP voice packet read data frame, determines whether the current data frame type is quiet indication frame, if so, then determines the data frame type receive within a predetermined period of time,

    If the data frame type of the frame before described quiet indication frame is speech frame within a predetermined period of time, be 0 with the time unifying sign assignment of described quiet indication frame, if before described quiet indication frame, do not receive Frame within a predetermined period of time, be 1 with the time unifying sign assignment of described quiet indication frame

    Carry out source decoding according to described time unifying sign 0 or 1 pair of described quiet indication frame.
12. 12. source decoding as claimed in claim 11 system, it is characterized in that described media gateway also comprises: quiet indication frame is determined equipment,

    Described quiet indication frame is determined equipment, is used for: determine the value constant whether on the fixed position of current described RTP voice packet present frame, if so, then with described frame as quiet indication frame.
13. 13. source decoding as claimed in claim 11 system is characterized in that the length of described predetermined amount of time is 20 milliseconds.

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