CN100454762C

CN100454762C - Method for shortening coding-decoding synchronous time delay

Info

Publication number: CN100454762C
Application number: CNB03119351XA
Authority: CN
Inventors: 张军
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2003-03-17
Filing date: 2003-03-17
Publication date: 2009-01-21
Anticipated expiration: 2023-03-17
Also published as: CN1531207A

Abstract

The present invention discloses a method for shortening the synchronous time delay of encoding and decoding. The method comprises the following steps that a passage for encoding and decoding is stated; receiving data packets are transmitted after being decoded; the establishing time of the passage for encoding and decoding is stated as 0; the t+(N-1)T time of an N frame data packet arrival is stated as decoding time; the (N-1)T+t+t1 time is stated as time for transmitting decoding data; data packets of all frames are decoded according to the steps. The method reduces the time of the synchronous time delay of the passage. Therefore, the present invention shortens the time delay of the decoding processing of a whole encoding and decoding processing system and enhances the communication quality.

Description

A kind of method that shortens the encoding and decoding synchronization delayed time

Technical field

The present invention relates to the encoding and decoding technique field in voice or the image, particularly a kind of method that shortens the encoding and decoding synchronization delayed time.

Background technology

Along with development of internet technology, utilize group technology to come transmitting multimedia data to become a reality.Group technology is the pulse modulation code stream in the legacy circuit-switched circuit to be compressed into the very little compress coding data stream of occupied bandwidth transmit again.Adopt the network of group technology to be called packet network, because traditional communication network usually combines with packet network multi-medium data is transmitted, so carry out the conversion of the code encoding/decoding mode of multi-medium data between traditional communication network and the packet network by codec.For example, there is the encoding and decoding conversion device in the gateway between landline telephone and the IP phone.In the exchange line of landline telephone, what transmit generally is to restrain the pulse modulation code stream that compresses through A rule or U, its transmission rate is 64k bps, if it is not encoded, directly being translated into grouped data transmits in the network of IP phone and need take very big bandwidth, therefore between the IP packet domain of the circuit domain of landline telephone and IP phone, increase the encoding and decoding speech function, pulse modulated speech data is compressed into the very little compress coding data of occupied bandwidth transmits again.

G.729 the encoding and decoding conversion device generally can support ITU-T, G.723.1, ITU-T waits voice compression algorithm, when being connected, generally should support the encryption algorithms such as AMR of GSM-FR, GSM-HR and 3G (3G (Third Generation) Moblie) with wireless network, when multimedia transmission, also need to support image processing to calculate, insert density in order to improve circuit, usually each encoding and decoding conversion device can be handled the encoding and decoding of many circuits, and every circuit is called an encoding and decoding passage.

For the packetizing process of every kind of encoding and decoding agreement, every kind of coded system all has the frame sign and the frame format of regulation.For example for ITU-T encryption algorithm G.729, be to be transferred to the packet network side after speech data with every 10ms length compresses; For ITU-T encryption algorithm G.723.1, be to be transferred to the packet network side after speech data with every 30ms length compresses.As shown in Figure 1, the flow chart of Fig. 1 for the data of an encoding and decoding passage are encoded, its detailed process is:

Step 100,101, one frame data of reception fixed length carry out encoding process to these frame data in encoder from circuit domain;

Step 102,103, the data of encoded processing send to the purpose packet network, and the decoder in the purpose network is decoded to these data;

Step 104, decoded reduction of data is former data, sends in the circuit domain, this circuit domain is the Time Division Multiplexing network.

Owing to have packet network between encoder and the decoder, therefore there is synchronizing relay between two equipment, as shown in Figure 2, the schematic diagram of Fig. 2 synchronizing relay production process, article one, time shaft is the time shaft that packet arrives, the second time shaft is the time shaft that packet sends, and its detailed process is:

1) sets up the encoding and decoding passage and receive data and send data, be i.e. determine when being engraved in passage during the processing of Code And Decode and setting up and identical to circuit domain from circuit domain;

2) suppose that it is 0 that the encoding and decoding passage is set up constantly, be spaced apart T between each frame data bag, then the moment of the transmission packet of channel coding and decoded data is 0, T, 2T, ..., packet is t by the time that encoder arrives decoder, suppose to decode immediately after passage is received the packet side data, decoded data are placed on circuit domain and send in the buffering area, wait for that delivery time T arrives, just begin to send this frame data, therefore reaching decoder from packet is T-t apart from the time-delay that packet begins to be sent on the circuit-domain network, and this time-delay just is called synchronization delayed time.

The synchronization delayed time that exists in packet network has increased the decoding processing time delay of decoder, and the quality of communication has been caused influence, and is unfavorable to the raising of voice quality.

Summary of the invention

In view of this, the invention provides a kind of method that shortens the encoding and decoding synchronization delayed time, this method has reduced the time of passage synchronization delayed time, thereby has shortened the time delay that whole encoding and decoding treatment system encoding and decoding are handled, and has improved communication quality.

According to above-mentioned purpose, the invention provides a kind of method that shortens the encoding and decoding synchronization delayed time, this method comprises, the encoding and decoding passage is set, and the packet that receives is carried out sending after the encoding and decoding, this method also comprises:

A, the foundation that the encoding and decoding passage is set are 0 constantly, t+ (N-1) T that the arrival of N frame data is set is the decoding moment constantly, (N-1) T+t+t1 is the decoded data delivery time constantly, wherein N is a natural number, T is a clock cycle, t is the decoding moment of first frame, and t1 is the time that packet carries out decoding processing;

B, the Frame that receives is decoded according to steps A.

When network jitter, described step B also comprises:

Whether the data of judging the N frame then receive all data of this frame at the decoded data delivery time, if the packet of N frame is not then also received all data of this frame at the decoded data delivery time, then reset the decoding moment of N frame data; If the packet of N frame is then received all data of this frame at the decoded data delivery time, then all data of this frame are decoded and send decoded data.

This method also comprises, at the decoded data delivery time decoded data is sent to the circuit domain side.

Described circuit domain is a time division multiplex network.

The time of described decoding processing is determined according to decoding algorithm.

By said method as can be seen, the present invention dopes the moment that decoding back data send according to the packet due in, the moment that decoding back data are sent is later than the packet due in, thereby reduce the synchronization delayed time of channel-decoded, shorten the time delay that the whole system encoding and decoding are handled, improved communication quality.

Description of drawings

The flow chart of Fig. 1 for the voice of a passage are encoded.

The schematic diagram of Fig. 2 synchronizing relay production process.

Fig. 3 shortens the schematic diagram of synchronization delayed time method for the present invention.

Fig. 4 shortens the flow chart of synchronization delayed time method when network has shake for the present invention.

Embodiment

In order to make the purpose, technical solutions and advantages of the present invention clearer, by the following examples and with reference to accompanying drawing, the present invention is described in more detail.

Because the generation of synchronization delayed time is former poor because of life period between the moment that is sent to circuit-domain network behind packet due in and the decoded packet data, therefore the timer time that the transmission timer time of setting passage and packet arrive when the encoding and decoding passage is set up is inequality, but dope the timer time that packet sends according to the packet due in, it is more late than the packet due in that this packet sends timer time, reaches the purpose of eliminating synchronization delayed time with this.

This method further describe for: when the encoding and decoding passage is set up, the moment that packet arrival is set is 0 and picks up counting, as t constantly the time, first packet arrives, t is set to pick up counting for decoding constantly constantly, and doping decoded data delivery time is t2=t+t1, and decoded data send timer time and pick up counting behind t2.

When network stabilization or network jitter are very little, the moment that is every frame data bag arrival is even, suppose to arrive after second the packet of a frame every T, article one, time shaft is the time shaft of decoding timer time, the second time shaft is the time shaft of the transmission timer time of decoded data, as shown in Figure 3, Fig. 3 shortens the schematic diagram of synchronization delayed time method for the present invention, and its detailed process is:

Step a, constantly set up the encoding and decoding passage 0, passage begins monitoring network and measures the packet that reaches;

Step b, t constantly first packet arrive, determine that t is the decoding moment constantly, it is the decoded data delivery time that the moment that arrives according to packet is provided with t2=t+t1, it is t1 that the decoded packet data processing time promptly is set, and processing time t1 determines according to code decode algorithm, the processing time t1 difference of different code decode algorithms, as ITU-T G723.1 algorithm is example, the decoding processing time is 5ms, and decoded data send in the circuit domain, and this circuit domain is TDM;

Step c, t+T constantly the packet of second frame arrive, determine t+T constantly for decoding constantly, it is the decoded data delivery time that the moment that arrives according to packet is provided with t+T+t1, decoded data send in the circuit domain, this circuit domain is TDM;

Steps d, the data of n+1 frame are handled according to step c.

When network has some shakes, the moment that every frame data bag arrives is inhomogeneous, be that the time at intervals that every frame data bag arrives is not fixed, so can not determine that decoding constantly according to the packet of first frame, must be by the due in decision decoding moment of every frame data bag, as shown in Figure 4, Fig. 4 is the flow chart of the present invention's shortening synchronization delayed time method when network has shake, and its detailed process is:

Step 400, constantly set up the encoding and decoding passage 0, passage begins the packet that the monitoring network side arrives;

Step 401, t constantly first packet arrive, record t constantly for decoding constantly, it is the decoded data delivery time that the moment that arrives according to packet is provided with t+t1, it is t1 that the decoded packet data processing time promptly is set;

The due in of step 402, setting n frame data bag is t+nT, and this due in is the decoding moment, and the moment that arrives according to packet is provided with the decoded data delivery time, and the due in that this decoded data delivery time is the n frame data adds t1;

Step 403,404,405, judge whether the packet of n frame then receives the packet of this frame at the decoded data delivery time, if the packet of n frame is not then also received this frame data bag at the decoded data delivery time, then reset the due in of n frame data bag, if the packet of n frame is then received this frame data bag at the decoded data delivery time, then this frame data bag is decoded and send decoded data.

As mentioned above, this method has shortened the synchronization delayed time of whole coding/decoding system by prediction decoding constantly, is example with ITU-T G723.1 algorithm, the decoding processing time is 5ms, adopting former dispatching method synchronization delayed time is 5-30ms, adopt this dispatching method after, synchronization delayed time is 5ms, this dispatching method maximum can reduce the 25ms synchronization delayed time, this method decreases the synchronization delayed time of whole passage, has improved communication quality, has obtained good effect.

The above only is preferred embodiment of the present invention, not in order to restriction the present invention, all any modifications of being made within the spirit and principles in the present invention, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.

Claims

1, a kind of method that shortens the encoding and decoding synchronization delayed time, this method comprises, the encoding and decoding passage is set, and sends after the packet that receives is decoded, and it is characterized in that this method also comprises:

B, the packet of all frames is carried out encoding and decoding according to steps A.

2, the method for claim 1 when network jitter, is characterized in that, described step B also comprises:

Whether the packet of judging the N frame then receives the data of this frame at the decoded data delivery time, if the packet of N frame is not then also received these frame data at the decoded data delivery time, the decoding that then resets the N frame data constantly; If the packet of N frame is then received all data of this frame at the decoded data delivery time, then all data of this frame are decoded and send decoded data.

3, the method for claim 1 is characterized in that, this method also comprises, at the decoded data delivery time decoded data is sent to the circuit domain side.

4, method as claimed in claim 3 is characterized in that, described circuit domain is a time division multiplex network.

5, the method for claim 1 is characterized in that, the time of described decoding processing is determined according to encryption algorithm.