WO2008154852A1 - Procédé et dispositif pour le masquage de trames perdues - Google Patents

Procédé et dispositif pour le masquage de trames perdues Download PDF

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Publication number
WO2008154852A1
WO2008154852A1 PCT/CN2008/071314 CN2008071314W WO2008154852A1 WO 2008154852 A1 WO2008154852 A1 WO 2008154852A1 CN 2008071314 W CN2008071314 W CN 2008071314W WO 2008154852 A1 WO2008154852 A1 WO 2008154852A1
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WO
WIPO (PCT)
Prior art keywords
signal
frame
band
decoding
current frame
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
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PCT/CN2008/071314
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English (en)
French (fr)
Inventor
Wuzhou Zhan
Dongqi Wang
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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Application filed by Huawei Technologies Co Ltd filed Critical Huawei Technologies Co Ltd
Priority to EP08757725A priority Critical patent/EP2159789A4/en
Publication of WO2008154852A1 publication Critical patent/WO2008154852A1/zh
Priority to US12/637,295 priority patent/US8355911B2/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
    • G10L19/00—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
    • G10L19/005—Correction of errors induced by the transmission channel, if related to the coding algorithm
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
    • G10L19/00—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
    • G10L19/02—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis using spectral analysis, e.g. transform vocoders or subband vocoders
    • G10L19/0204—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis using spectral analysis, e.g. transform vocoders or subband vocoders using subband decomposition
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
    • G10L25/00—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00
    • G10L25/03—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00 characterised by the type of extracted parameters
    • G10L25/18—Speech or voice analysis techniques not restricted to a single one of groups G10L15/00 - G10L21/00 characterised by the type of extracted parameters the extracted parameters being spectral information of each sub-band

Definitions

  • the present invention relates to the field of frame dropping concealment, and in particular to a method and device for dropping frames of a speech or audio encoder.
  • packet technology In network communication, packet technology is widely used. Various forms of information—voice, image, or data—are encoded and transmitted over the network using packet technology. Due to the limitation of the transmission capacity of the information sending end, or the packet information frame does not reach the receiving end buffer within the specified delay time, the information is lost, which is a common frame dropping phenomenon in the packet communication. In addition, in packet switched networks, the frame is also caused by network congestion and transmission loss.
  • a frame dropping algorithm is provided in the existing waveform coding technology, but the frame hiding algorithm only supports
  • the narrowband signal sampled by 8khz does not support wideband signals and cannot meet high quality call requirements.
  • embodiments of the present invention provide a frame dropping method and apparatus for supporting band extension, thereby implementing a loss of trust hiding process for broadband information, and satisfying high quality call requirements.
  • the embodiment of the invention discloses a device for implementing frame loss hiding, and the device includes:
  • the lost frame detector is configured to receive voice data, detect whether the voice frame is lost, and generate frame loss information; and the decoding module is configured to decode the received current voice frame, and generate a current frame lowband signal and a current frame piggyback decoding signal;
  • a low-band delay module configured to set a time for the current frame low-band signal delay, generate a pre-frame low-band signal
  • a low-band signal recovery module configured to recover the lost when the frame loss information indicates that the previous frame is lost The previous frame has a low band signal
  • a high-band drop frame hiding module configured to receive the current frame high-band decoding signal and the frame loss information, and generate a front frame high-band signal
  • the QMF synthesis filter is configured to receive the front frame low band signal generated by the low band delay module and the front frame high band signal generated by the frame loss frame hiding module, perform comprehensive filtering, and output the front frame voice signal; or, receive the low band signal
  • the front frame low band signal recovered by the recovery module and the high frame signal generated by the high band drop frame hiding module are used for comprehensive filtering, and the front frame speech signal is output.
  • the embodiment of the invention discloses a method for implementing frame loss hiding, the method comprising: detecting whether a voice frame is lost, and generating frame loss information;
  • the current frame is not lost, decoding the current frame, generating a current frame low-band decoding signal and a current frame high-W decoding signal; generating a previous frame low-band signal for the current frame low-band signal delay setting time, or The true lost information indicates that the lost previous frame low band signal is recovered when the previous frame is lost;
  • the frame dropping device and method described in the embodiments of the present invention utilize the delay of the codec itself, improve the effect of frame dropping of low band and high band signals, and the process of frame dropping concealment does not introduce a nearby delay.
  • Figure 1 is a block diagram of the G.711 wideband extension encoder
  • FIG. 1 is a block diagram of the G.711 wideband extension decoder
  • 3 is a schematic diagram of an overlay window of an MDCT transform
  • Figure 4 is a schematic diagram showing the introduction of a frame delay by the MDCT transform
  • FIG. 5 is a block diagram of an embodiment of an apparatus for implementing frame loss concealment provided by the present invention.
  • FIG. 6 is a flowchart of an embodiment of a high-band drop frame hiding module provided by the present invention.
  • FIG. 7 is a flow chart of another embodiment of a high-band drop frame hiding module provided by the present invention.
  • Figure 8 is a flow chart of a variation of Figure 7;
  • FIG. 9 is a schematic diagram of “recovering the last frame of the last frame of the decoded half window signal” in FIG. 7 and FIG. 8;
  • FIG. 10 is a schematic diagram of the frame missing phase mismatch;
  • FIG. 11 is a schematic diagram of a method for eliminating a lost phase hidden phase mismatch
  • Figure 12 is a waveform diagram after canceling the phase mismatch
  • FIG. 13 is a schematic diagram of the frame loss concealment process when the lost frame is in the clear voice transition segment. Mode for carrying out the invention
  • FIG. 1 is a block diagram of a wideband extended encoder.
  • the QMF (Quadature Mirror Filter) analysis filter 101 receives the 16khz sampled input signal, after analysis and filtering. A low-band signal sampled at 8khz and a piggy-band signal sampled at 8khz are output.
  • the low band signal is input to the core encoder (i.e., the encoder of G.711) 102, and the core bit stream is output after encoding and input to the multiplexing module 108.
  • the core bit stream output from the encoder 102 is also input to the core decoder (i.e., the decoder of G.711) 103, and after decoding, the low band signal is output and input to the adder 105.
  • the low band signal output from the QMF analysis filter 101 is also input to the adder 105, which outputs a residual signal and inputs it to the low band enhancement coder 104.
  • the low band strong encoder 104 encodes the input low band residual signal, outputs a low band enhanced bit stream, and inputs it to the multiplexing module 108.
  • the low-band signal outputted by the QMF analysis filter 101 is also input to the PLC (packet l oss concealment) edge information calculation module 106, which is used to calculate the frame loss hiding (the packet loss hiding and the frame loss hiding concept are similar, In the embodiment of the present invention, unless otherwise specified, the auxiliary information can be exchanged, and by means of these auxiliary functions, the frame dropping performance can be further improved at the decoding end.
  • the PLC side information calculation module 106 outputs PLC side information and inputs it to the multiplexing module 108.
  • the high band signal output from the QF analysis filter 101 is input to the high band encoder 107, and is encoded to output a high band bit stream and input to the multiplexing module 108.
  • the high band encoder 107 is based on an MDCT (Modi fed Di Screte Cosine Transform) transform.
  • FIG. 2 is a block diagram of the wideband extension decoder.
  • the G.711 wideband extension decoder is still taken as an example.
  • the module 201 receives the bit stream, and outputs PLC side information, low-band core bit stream, and low-band enhancement after demultiplexing. Bit stream, ⁇ with bit stream.
  • the core decoder (i.e., the decoder of G.711) 202 receives the low-band core bit stream, and outputs it to the adder 205 after decoding.
  • the low band enhancement decoder 203 receives the low band enhanced bit stream, and outputs it to the adder 205 after decoding.
  • the adder 205 adds the two signals input to generate a low band signal and outputs it to the low band .C module 206.
  • the low band PLC module 206 performs frame loss concealment processing and outputs it to the QMF synthesis filter module 208.
  • the high band decoder (inverse transform based on MDCT) 204 receives the high band bit stream, and after decoding, outputs a high band signal to the high band PLC module 207.
  • the high band PLC module 207 performs high band drop frame hiding processing and outputs it to the QMF integrated filter module 208.
  • the QMP synthesis filter module 208 performs comprehensive filtering on the low-band signal and the high-band signal that have been subjected to frame loss concealment processing, and outputs a signal sampled at 16 kHz.
  • the high-band coder 107 of Fig. 1 and the sniffer decoder 204 of Fig. 2 are based on the "H-transform" and the inverse-transformation of the MDCT transform, respectively, and are closely related to the embodiment of the present invention, and therefore will be described.
  • MDCT uses time domain overlap acknowledgment (Al iasing Cancellation) techniques to reduce the "boundary effect."
  • Al iasing Cancellation time domain overlap acknowledgment
  • h ⁇ n h ⁇ 2N - ⁇ - n)
  • the high-band encoder 107 in FIG. 1 encodes the third frame high-band signal in FIG. 3, and first needs to take 2 samples, and in the embodiment of the present invention, the previous frame (ie, the second frame) ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ ⁇ MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD MD
  • the high-band decoder 204 in Fig. 2 decodes the high-band bit stream of the third frame to obtain an MDCT time-domain signal, and performs an inverse MDCT transform to obtain a signal after the inverse transform.
  • the reconstructed second frame high band signal is output, as shown by the shaded portion in FIG.
  • the MDCT transform introduces an additional frame delay to the codec.
  • FIG. 5 is a schematic diagram of a frame dropping method according to an embodiment of the present invention.
  • the lost frame detector 501 receives the bit stream and detects the voice frame (or IP packet.
  • the embodiment of the present invention assumes that an IP packet contains only one code stream of a linguistic frame, so that in the embodiment of the present invention, one packet is lost and one frame is lost. The concept is equivalent) is lost and remembers the lost state. If the current frame is received, the decoding module 502 decodes the current frame and outputs the current frame low band signal, the current frame high band decoding signal, and the PLC side information.
  • the decoding module 502 corresponds to the demultiplexing module 201, the core decoder 202, the low band enhancement decoder 203, the high band decoder 204, and the adder 205 in FIG.
  • the low band signal input by the decoding module 502 is input to the low band delay module 504, and the low band delay module 504 is delayed by one frame length, and then outputs a frame low band signal to the QMF synthesis filter 506.
  • the QMF synthesis filter 506 corresponds to the QMF synthesis filter 208 in FIG.
  • the lost frame detector 501 outputs the associated frame loss information to the low band signal recovery module 503. If the .h frame is lost, the low band signal recovery module 503 recovers the low of the previous frame by using the low band frame loss concealment algorithm.
  • the low-band signal recovery module 503 also receives the PLC side information output by the decoding module 502, and can always improve by using the PLC side letter. Frame hidden performance, but not required. Since the low-band signal recovery module 503 recovers the low-band signal of the previous frame after delaying one frame, when the current frame is received, the information of the current frame can be used to improve the effect of restoring the low-band number of the previous frame.
  • the low band signal recovery module 503 outputs the low band signal of the previous frame to the QMF synthesis filter 506, and the QMF synthesis module 506 receives the _ frame low band signal output by the low band delay module 504 when the previous frame is not lost.
  • the QMF synthesis filter 506 receives the low band signal of the previous frame.
  • the high-band 3 ⁇ 4 frame hiding module 505 receives the current frame high-band decoding signal, the PLC side information, and the frame loss information output by the lost frame detector output by the decoding module 502, and performs the high-band drop frame hiding process, and outputs the high band of the previous frame.
  • the signal is sent to the QMF synthesis filter 506.
  • the current frame high band decoding after the decoding module 502 outputs the signal '4 is the signal after the MDCT inverse transform, there are two frame lengths, and the high band drop frame hiding module 505 outputs the previous frame height.
  • the band signal has only one frame length, which is the result of superimposing the last half window signal of the previous frame of the MDCT and the first half window signal of the current frame, or the result of restoring by using some frame loss concealment method when the MDCT inverse transform signal is lost.
  • the QMF synthesis filter 506 comprehensively filters the received previous frame low band signal and the previous frame high band signal, and outputs a 6khz 3 ⁇ 4 type of previous frame speech signal.
  • the frame loss concealment scheme employed in the prior art does not utilize the information of the frame following the lost frame when restoring the lost frame, and introduces an additional 3.75 millisecond delay.
  • the Pl £ scheme shown in FIG. 5 fully utilizes the one-frame delay time of the MDCT transform itself, and recovers the lost low-band signal, and can recover the high-band by using the information of the subsequent frame of the lost frame.
  • the latter half of the window signal can also utilize the information of the subsequent frame of the lost frame, and: H. No additional delay is introduced when the frame loss is lost.
  • Step 601 determines whether the current frame high band decoding signal is received according to the frame loss information outputted by the lost frame detector in FIG. 5. If yes, the process proceeds to step 603, otherwise, the process proceeds to step 602.
  • Step 602 recovers the lost current frame high decoding signal by using a frame loss concealment algorithm, and proceeds to step 603 after the processing is completed.
  • the recovered K-band of the current frame high-band decoded signal is 2 frames long.
  • the first half of the high-band decoding signal is the first half window signal, and the second half is the second half window signal.
  • the delay 603 is delayed by 'the last half of the high-band decoded signal.
  • the second half of the frame signal is one frame long, and the upper three frames are superimposed. Decoding the first half window signal and the previous frame high band decoding half window signal to generate the previous frame high band signal. Step 604 outputs the previous frame piggyback signal generated in step 603. Step 605 determines whether it is necessary to continue the frame loss concealment process. If yes, return to step 601, otherwise it is stable.
  • the steps are adjusted in sequence, for example, the operation of "delaying the second half window signal of the current frame high-band decoding signal" in step 603 is moved to step 604, and the algorithm is No substantial change is considered to be within the scope of the invention.
  • the high-band signal is similar to noise and is insensitive to phase. As long as the piggyback signal recovered by the frame loss concealment algorithm and the original piggyback signal have similar energy and zero-crossing rate (reflecting frequency domain characteristics), Can perform better recovery. The characteristics of the adjacent two frames of the banded signal energy and the zero-crossing rate do not change much, so it is considered to use the pre-frame high-band signal instead of the currently lost high-band signal.
  • an effective implementation manner of step 602 is: copying the previous frame high-band decoding signal as the currently lost high-band decoding signal, and the previous frame high-band decoding signal S can be the previous frame received image.
  • the signal output by the decoding module 502 in 5 may also be a signal that is lost in the previous frame.
  • Step 701 determines whether the current frame high band decoding signal is received according to the frame loss information outputted by the lost frame detector in FIG. 5, and if yes, proceeds to step 705, otherwise proceeds to step 702.
  • Step 702 determining whether the high-band decoding signal of the previous frame is received, if yes, proceeding to step 704, otherwise proceeding to step 703.
  • Step 703 restores the high band signal of the previous frame, and after processing, proceeds to step 709.
  • Step 704 recovers the first half window signal of the current frame high band decoding signal, and after processing, enters step 708.
  • Step 705 delays the last half window signal of the current frame high band decoding signal, and after processing, proceeds to step 706.
  • Step 706 determines whether the high band decoding signal of the previous frame is received, and if yes, proceeds to step 708, otherwise proceeds to step 707.
  • Step 707 recovers the last half of the high-band decoded signal of the previous frame, and after processing, proceeds to step 708.
  • Step 708 superimposes the first half window signal of the current frame high band decoded signal and the second half window number of the previous frame high band decoding signal to generate a high band signal of the upper frame.
  • step 709 outputs the previous frame high band signal, but in step 710, it is determined whether it is necessary to continue the frame loss concealment process. If yes, the process returns to step 701, otherwise it ends.
  • step 703 "delay the current frame high-band decoding half-window signal" operation is moved to step 706, 707, 708 or 709, There is no substantial change in the algorithm and it should be considered as falling within the scope of the present invention.
  • Step 801 determines whether the previous frame high band decoding signal is received according to the frame loss information outputted by the lost frame detector in FIG. 5. If yes, the process proceeds to step 806, otherwise, the process proceeds to step 802.
  • Step 802 determines whether the current frame high band decoding signal is received, and if yes, proceeds to step 804, otherwise proceeds to step 803.
  • Step 803 resumes the high band signal of the previous frame, and after processing, proceeds to step 810.
  • Step 804 delays the last half of the current frame to encode the decoded signal, and after processing, proceeds to step 805.
  • Step 805 recovers the last half window signal of the high-band decoding signal of the previous frame, and after processing, proceeds to step 809.
  • Step 806 determines whether the current frame high band decoding signal is received, and if so, proceeds to step 808, otherwise proceeds to step 807.
  • Step 808 delays the second half of the current frame highband decoded signal, and proceeds to step 809 after processing.
  • Step 809 superimposes the first half window signal of the current frame high band decoding signal and the second half window signal of the upper frame high band decoding signal to generate a high band signal of the previous frame.
  • step 810 outputs the previous frame high band signal, and then determines whether it is necessary to continue the frame loss concealment process in step 911. If yes, it returns to step 801, otherwise it ends.
  • Step 704 in Figure 7 and step 807 in Figure 8 "Restoring the current frame high-band decoding first half window signal" have various processing methods, as follows:
  • Method 1 Set the first half window signal of the current frame high-band decoding signal to zero. At this time, step 708 in FIG. 7 and step 809 in FIG. 8 may be omitted, that is, the second half of the high-band decoding signal of the previous frame is directly directly.
  • the window signal is used as the previous frame high band method 2: The first half window signal of the previous frame high band decoding signal is copied as the first half window signal of the current frame high band decoding signal.
  • Step 707 in Fig. 7 and step 805 in Fig. 8 "Restoring the last frame high band decoding half window ⁇ number" have various processing methods, as follows:
  • Method 1 The second half of the high-band decoding signal of the previous frame is set to zero. At this time, the step 708 in FIG. 7 and the step 809 in FIG. 8 may be omitted, that is, the current frame is directly decoded by the high-band signal. The first half of the window signal is used as the L-frame "with signal.
  • Method 2 The last half of the high-band decoded signal of the previous frame of the previous frame is copied as the last half of the frame with the decoded signal.
  • Method 3 Copy the last half window signal of the current frame high band decoding signal as the second half window signal of the previous frame high band decoding signal '.
  • Method 4 As shown in FIG. 9, multiply the rear half window signal of the previous frame high band decoding signal of the previous frame by the h falling window.
  • the first half window signal of the current frame high band decoded signal is multiplied by a rising window, and then superimposed to generate a second half window signal of the previous frame high W decoded signal.
  • the falling window amplitude linearly decreases from 1 to 0, and the rising window amplitude linearly rises from 0 to 1.
  • the rectangular window having a magnitude of 0.5 is also available.
  • Step 703 in Fig. 7 and step 803 in Fig. 8 "Restoring the previous frame high band signal" have various processing methods, as follows:
  • Method 1 recover the first half window signal of the current frame high band decoding signal and the second half window signal of the previous frame high band decoding signal 4, and then perform superposition to generate a previous frame high band signal.
  • the recovery of the first half window signal of the current frame high-band decoding signal may be performed by copying the first half window signal of the high-band decoding signal of the previous frame, and the recovery of the last half window signal of the previous frame of the decoded signal may be performed by copying the previous frame.
  • the method of the last frame high band decoding the second half of the signal may be performed by copying the previous frame.
  • Method 2 Copy the previous frame high band signal of the previous frame as the high band signal of the previous frame.
  • pitch repetition is to fill the missing frame in the last pitch period of the previous frame of the lost frame until the frame is filled.
  • the previous frame is lost.
  • the last pitch period of the previous frame of the previous frame is P.
  • the last pitch period of the previous frame of the previous frame is filled in the lost frame (previous frame).
  • the mountain has not filled the frame, and the frame length is N, then the length to be filled is N-P*2, and the gene cycle starts with *2
  • the samples are filled into the remaining gaps and the entire fill is completed.
  • Step 1101 filling the lost frame: the method of repeating the previous pitch can be used, of course, other methods can also be used;
  • Step 1102 calculating the phase difference: As shown in FIG. 10, it is first necessary to find out that the current frame start point matches the padding data. The point (see Valenzuela's article for the calculation of matching points), and select a best matching point in multiple matching points, and use the phase difference between the best matching point and the starting point of the current frame as the final phase difference.
  • Step 1 103 Interpolation calculation: The linear interpolation calculation is small, and the linear interpolation method is generally used.
  • the calculation formula is as follows:
  • y(n) ⁇ x([a . n + x([_ . n J)
  • N 3 ⁇ 4 frame length " ⁇ '"1 represents the smallest integer greater than "'"
  • - "" represents the largest integer less than or equal to ⁇ ⁇ «
  • X is a sequence that does not consider the phase matching padding, and the length is padded
  • Figure 12 shows the result of this phase elimination mismatch method. Compared with Figure 10, there is no phase mismatch.
  • the lost frame may be in the transition between voiced and unvoiced, and one method of dropping the frame at this time is to fill a part of the voiced and unvoiced frames of the frame before and after the lost frame.
  • one method of dropping the frame at this time is to fill a part of the voiced and unvoiced frames of the frame before and after the lost frame.
  • how long the voiced and unvoiced sounds are filled does not make an accurate judgment.
  • One way to provide judgment accuracy is:
  • the energy and zero-crossing rate of the previous frame are calculated at the encoding end and used as the PLC side information of the current frame.
  • the decoding segment according to the energy and zero-crossing rate of the previous frame (missing frame), it is judged that the component of the voiced sound is more or less clear. If the voiced component is more, the voiced sound is filled longer, otherwise the voiced fill is longer. .

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Description

一种丢帧隐藏的方法和设备
技术领域
本发明涉及丢帧隐藏领域， 具体涉及一种语音或音频编码器丢帧隐藏的 '法和设 备。
发明背景
在网络通信中， 分组技术应用十分广泛。 各种形式的信息——语音、 图像或者数据 经过编码后采用分组技术在网络上传输。 由于信息发送端发送容量的限制， 或在指定延 迟时间内， 分组信息帧没有到达接收端缓冲区， 从而造成信息的丢失， 这就是分组通 中常见的丢帧现象。此外， 在分组交换网络中， 由于网络拥塞、传输损耗也会引起£帧。
目前， 不同的语音编码标准有其相应的丢帧隐藏技术， 以减少因丢帧造成的语音质 量下降。 一些基于码激励线性预测的语音编码器都内嵌了丢帧隐藏算法。
现有所采用的波形编码技术中提供了一种丢帧隐藏算法， 但该 帧隐藏算法只支持
8khz采样的窄带信号， 不支持宽带信号， 不能满足高质量的通话要求。
发明内容 鉴于上述现有技术所存在的问题，本发明的实施例提供一种支持带扩展的丢帧隐藏 方法和设备， 从而实现宽带信息的丢证隐藏处理， 满足高质量的通话要求。
本发明的实施例所采取的技术方案是：
本发明实施例公开了一种实现丢帧隐藏的设备， 该设备包括：
丢失帧检测器， 用于接收语音数据， 检测语音帧是否丢失， 生成帧丢失信息； 解码模块， 用于解码接收到的当前语音帧， 生成当前帧低带信号和当前帧卨带解码 信号；
低带延迟模块， 用于对所述的当前帧低带信号延迟设定时间， 生成前帧低带信 ; 低带信号恢复模块， 用于在所述帧丢失信息表明前帧丢失时， 恢复丢失的前帧低带 信号；
高带丢帧隐藏模块， 用于接收所述的当前帧高带解码信号以及所述的帧丢失信息， 生成前帧高带信号；
QMF综合滤波器， 用于接收低带延迟模块生成的前帧低带信号和 ^带丢帧隐藏模块 生成的前帧高带信号， 进行综合滤波， 输出前帧语音信号； 或者， 接收低带信 恢¾模 块恢复的前帧低带信号和高带丢帧隐藏模块生成的前帧高带信号， 进行综合滤波， 输出 前帧语音信号。 本发明实施例公开了一种实现丢帧隐藏的方法， 该方法包括- 检测语音帧是否丢失， 生成帧丢失信息；
若当前帧没有丢失，解码当前帧，生成当前帧低带解码信号和当前帧高 W解码信号; 对所述的当前帧低带信号延迟设定的时间， 生成前帧低带信号， 或者， 若所述真£ 失信息表明前帧丢失时， 恢复丢失的前帧低带信号；
根据所述帧丢失信息对所述的当前帧高带解码信号进行处理， 生成前帧卨带 ¾ - ; 对所述的前帧低带信号和所述的前帧髙带信号进行综合滤波， 生成前帧语音信号。 本发明的实施例描述的丢帧隐藏设备和方法利用了编解码器本身的延迟， 提^了低 带和高带信号丢帧隐藏的效果， 并且丢帧隐藏的处理没有引入附近的延迟。
附图简要说明 下面通过具体实施方式并结合附图对本发明作进一歩的详细说明。
图 1是 G. 711宽带扩展编码器框图；
图 2是 G. 711宽带扩展解码器框图；
图 3是 MDCT变换的叠加窗示意图；
图 4是 MDCT变换引入一帧延迟的示意图；
图 5是本发明提供的实现丢帧隐藏的装置的实施例的框架图；
6是本发明提供的高带丢帧隐藏模块的一个实施例的流程图；
图 7是本发明提供的高带丢帧隐藏模块的另外一个实施例的流程图；
图 8是图 7的一个变化流程图；
图 9是图 7和图 8中 "恢复上一帧髙带解码后半窗信号" 的一种实现方法； 图 10是丢帧隐藏相位不匹配的示意图；
图 11是消除丢帧隐藏相位不匹配方法的示意图；
图 12是消除相位不匹配后的波形图；
图 13是丢失帧在清迚音过渡段时丢帧隐藏处理后的示意图。 实施本发明的方式
图 1是宽带扩展编码器框图，以 G. 711宽带扩展编码器为例，图中 QMF ( Quadrature Mi rror Fi lter, 正交镜像滤波器） 分析滤波器 101接收 16khz采样的输入信号， 分析 滤波之后输出 8khz采样的低带信号和 8khz采样的髙带信号。低带信号输入给核心编码 器（即 G. 711的编码器） 102， 编码之后输出核心比特流， 并输入给复用模块 108。 核心 编码器 102输出的核心比特流同时也输入给核心解码器 （即 G. 711的解码器） 103, 解 码之后输出低带信号， 并输入给加法器 105。 QMF分析滤波器 101输出的低带信 同时 也输入给加法器 105， 加法器输出残差信号， 并输入给低带增强编码器 104。 低带^强 编码器 104对输入的低带残差信号编码，输出低带增强比特流，并输入给复用模块 108。 QMF分析滤波器 101输出的低带信号同时也输入给 PLC (packet l oss concealment, £ 包隐藏） 边信息计算模块 106， 该模块用于计算丢帧隐藏 （丢包隐藏和丢帧隐藏概念类 似， 在本发明的实施例中如非特殊说明， 可以互换）的辅助信息， 借助于这些辅助^总， 在解码端可以进一歩提高丢帧隐藏性能。 PLC边信息计算模块 106输出 PLC边信息， 并 输入给复用模块 108。 Q F分析滤波器 101输出的高带信号输入给高带编码器 107，编码 后输出高带比特流， 并输入给复用模块 108。 高带编码器 107 是基于 MDCT ( Modi fed Di screte Cosine Transform, 修正的离散余弦变换） 变换。
图 2是宽带扩展解码器框图，仍以 G. 711宽带扩展解码器为例，图屮解¾用模块 201 接收比特流， 解复用之后输出 PLC边信息、 低带核心比特流、 低带增强比特流、 ^带比 特流。 核心解码器 （即 G. 711的解码器） 202接收低带核心比特流， 解码之后输出给加 法器 205。 低带增强解码器 203接收低带增强比特流， 解码之后输出给加法器 205。 加 法器 205对输入的两路信号相加之后产生低带信号， 并输出给低带 .C模块 206。 低带 PLC模块 206进行丢帧隐藏处理之后输出给 QMF综合滤波器模块 208。 高带解码器 （基 于 MDCT的逆变换） 204接收高带比特流， 解码之后输出高带信号给高带 PLC模块 207。 高带 PLC模块 207进行高带的丢帧隐藏处理之后输出给 QMF综合滤波器模块 208。 QMP 综合滤波器模块 208对已经进行丢帧隐藏处理的低带信号和高带信号进行综合滤波， 输 出 16khz采样的信号。
图 1中的高带编码器 107和图 2中的髙带解码器 204分别基于 MDCT变换的」 H变换 和逆变换， ώ于和本发明实施例关系密切， 因此予以说明。
MDCT利用时域的重叠对消（Al iasing Cancellation)技术来降低"边界效应"。 MDCT 的正变换和反变换公式如下：
(" + "。）]
Figure imgf000005_0001
其中 N 是帧长; k = 0，1' . . . , N- l ; n = 0，1, . . .，2N 1 ; "。 = λ"/2+1/2 : 是时 域信号； 是正变换之后的频域信号； 是逆变换之后的信号； 是窗函数， 满足如下关系：
h(n)h{n) + h(n + N)h{n + N) = 1
h{n) = h{2N - \ - n) 重建之后的时域信号 ")可以用下面公式计算- x(n) = Xp (n + N) + X(n) w = 0，l，...N— l 式中 χ Ρ (" + Ν、是前一帧逆变换之后的信号。
下面结合本发明实施例说明。 例如， 图 1中的高带编码器 107准各对图 3中的第 3 帧高带信号进行编码， 首先需要取足 2Ν个样点， 在本发明实施例中取前一帧 （即第 2 帧）的 Ν个样点和当前帧（即第 3帧）的 Ν个样点组成 2Ν个样点， 然后乘 .卜.窗凼数（即 图 3中的虚线所示）， 进行 MDCT正变换。 再对变换之后的 MDCT时域信号进行一定方式 的编码， 例如 huff man编码， 形成高带比特流。 在解码端， 图 2中的高带解码器 204对 第 3帧的高带比特流解码， 获得 MDCT时域信号， 进行 MDCT逆变换， 获得逆变换之后的 信号。 第 2帧逆变换后半窗信号和第 3帧逆变换前半窗信号叠加之后， 就输出重建的第 2帧高带信号， 如图 4中的阴影部分所示。 从图中可以看出， MDCT变换会给编解码器引 入附加的一帧延迟。
图 5是本发明实施例提供的丢帧隐藏方法的框架图。丢失帧检测器 501接收比特流， 检测语音帧 （或 IP包， 本发明实施例假定一个 IP包只包含一个语咅帧的码流， 因此在 本发明实施例中丢失一个包和丢失一个帧的概念是等价的）是否丢失，并记 丢失状态。 如果接收到当前帧， 则解码模块 502解码当前帧， 并输出当前帧低带信 、 当前帧高带 解码信号和 PLC边信息。 解码模块 502和图 2中的解复用模块 201、 核心解码器 202、 低带增强解码器 203、 高带解码器 204、 加法器 205相对应。 解码模块 502输 的低带 信号输入到低带延迟模块 504， 低带延迟模块 504延迟一个帧长， 然后输出 卜.一帧低带 信号给 QMF综合滤波器 506。 QMF综合滤波器 506和图 2中的 QMF综合滤波器 208对应。 丢失帧检测器 501输出相关的帧丢失信息给低带信号恢复模块 503， 如果. h -帧丢火， 则低带信号恢复模块 503釆用低带的丢帧隐藏算法恢复出上一帧的低带信号。低带信号 恢复模块 503同时也接收解码模块 502输出的 PLC边信息， 利用 PLC边信总可以提高 £ 帧隐藏的性能， 但不是必需的。 由于低带信号恢复模块 503是在延迟一帧之后才去恢复 上一帧低带信号， 因此在当前帧收到时， 可以利用当前帧的信息提高恢复上一帧低带^ 号的效果。 低带信号恢复模块 503输出上一帧的低带信号给 QMF综合滤波器 506， 山于 上一帧没有丢失时 QMF综合模块 506会收到低带延迟模块 504输出的 _ 帧低带信号， 这样不论上一帧是否丢失， QMF综合滤波器 506都会收到上一帧的低带信号。 高带¾帧 隐藏模块 505接收解码模块 502输出的当前帧高带解码信号、 PLC边信息以及丢失帧检 测器输出的帧丢失信息， 进行高带丢帧隐藏处理之后， 输出上一帧的高带信 给 QMF综 合滤波器 506。对照图 4可知，当解码模块 502输出的当前帧高带解码之后的信 '4是 MDCT 逆变换之后的信号， 有两个帧长， 而高带丢帧隐藏模块 505输出的上一帧的高带信号只 有一个帧长， 是 MDCT逆变换上一帧后半窗信号和当前帧前半窗信号叠加产^的结果， 或者是 MDCT逆变换信号有丢失时，采用某种丢帧隐藏方法恢复的结果。 QMF综合滤波器 506对接收的上一帧低带信号和上一帧高带信号进行综合滤波， 输出〖6khz ¾样的上一 帧语音信号。
现有技术采用的丢帧隐藏方案在恢复丢失帧时， 没有利用丢失帧后面帧的信息， 并 且会引入附加的 3. 75毫秒延迟。 而本发明实施例提供的， 如图 5所示的 Pl £方案， 充 分利用了 MDCT变换本身的一帧延迟时间， 恢复丢失的低带信号时可以利用丢失帧的后 面帧的信息， 恢复高带后半窗信号时也可以利用丢失帧的后面帧的信息， 并.. H.进行丢帧 隐藏时没有引入附加的延迟。
图 6是图 5中高带丢帧隐藏模块 505的一个实施例。歩骤 601根据图 5中的丢失帧 检测器输出的帧丢失信息， 判断是否收到当前帧高带解码信号， 如果收到则进入 骤 603， 否则进入步骤 602。 步骤 602采用丢帧隐藏算法恢复丢失的当前帧高 解码信号， 处理完毕之后进入步骤 603。 如前面所描述， 恢复的当前帧高带解码信号的 K度为 2个 帧长。 高带解码信号前半部分为前半窗信号， 后半部分为后半窗信号， ^骤 603延迟' 前帧高带解码信号的后半窗信号一个帧长的吋间，并叠加 3前帧高带解码前半窗信号和 上一帧高带解码后半窗信号， 产生上一帧高带信号。 步骤 604输出歩骤 603产生的上一 帧髙带信号。 步骤 605判断是否需要继续进行丢帧隐藏处理， 如果是则回到歩骤 601， 否则结朿。
在图 6所示的高带丢帧隐藏算法中，一些步骤的先后调整，例如将歩骤 603中的"延 迟当前帧高带解码信号的后半窗信号"操作移到步骤 604之后，对算法没有实质的改变， 应认为属于本发明范畴。 高带信号类似于噪声， 对相位不敏感， 只要保证采用丢帧隐藏算法恢 S的卨带信号 和原始的髙带信号有类似的能量、 过零率 （体现了频域特征） 等特征， 则能进行较好的 恢复。 ώ于相邻的两帧髙带信号能量、 过零率等特征变化不大， 因此可以考虑采用前帧 高带信号代替当前丢失的高带信号。 基于以上思想， 步骤 602的一种冇效实现方式是： 复制上一帧高带解码信号作为当前丢失的高带解码信号， 上一帧高带解码信 S既可以是 上一帧收到时图 5中的解码模块 502输出的信号， 也可以是上一帧丢失吋 £帧隐藏产 的信号。
图 7是图 5中高带丢帧隐藏模块 505的另外一个实施例。歩骤 701根据图 5屮的丢 失帧检测器输出的帧丢失信息， 判断是否收到当前帧高带解码信号， 如果收到则进入歩 骤 705， 否则进入步骤 702。 歩骤 702判断是否收到上一帧高带解码信号， 如果收到则 进入歩骤 704， 否则进入步骤 703。 歩骤 703恢复上一帧的高带信号， 处理完之后进入 步骤 709。 歩骤 704恢复当前帧高带解码信号的前半窗信号， 处理完之后迸入^骤 708。 步骤 705延迟当前帧高带解码信号的后半窗信号， 处理完之后进入歩骤 706。 步骤 706 判断是否收到上一帧的高带解码信号， 如果是则进入步骤 708， 否则进入歩骤 707。 歩 骤 707恢复上一帧高带解码信号的后半窗信号， 处理完之后进入歩骤 708。 歩骤 708叠 加当前帧高带解码信号的前半窗信号和上一帧高带解码信号的后半窗 号， 产生上 帧 的高带信号。 步骤 708处理完之后进入歩骤 709。 步骤 709输出上一帧高带信号， 然 在歩骤 710中判断是否需要继续丢帧隐藏处理， 如果是则返回步骤 701， 否则结束。
在图 7所示的高带丢帧隐藏算法中， 一些步骤的先后调整， 例如将步骤 703 "延迟 当前帧高带解码后半窗信号"操作移到步骤 706、 707、 708或 709之后， 对算法没有实 质的改变， 应认为属于本发明范畴。
图 8是图 7的一个变化， 基本思路是一样的， 只是判断当前帧和上一帧足否收到的 先后顺序不一样。 歩骤 801根据图 5中的丢失帧检测器输出的帧丢失信息， 判断是否收 到上一帧高带解码信号， 如果收到则进入步骤 806， 否则进入歩骤 802。 步骤 802判断 是否收到当前帧高带解码信号， 如果收到则进入步骤 804， 否则进入歩骤 803。 骤 803 恢复上一帧的高带信号， 处理完之后进入歩骤 810。 步骤 804延迟当前帧卨带解码信号 的后半窗信号， 处理完之后进入步骤 805。 步骤 805恢复上一帧高带解码信号的后半窗 信号， 处理完之后进入步骤 809。 歩骤 806判断是否收到当前帧高带解码信号， 如果收 到则进入歩骤 808， 否则进入步骤 807。 步骤 808延迟当前帧高带解码信 ¾的后半窗佶 号， 处理完之后进入步骤 809。 歩骤 807恢复当前帧高带解码信号的前半窗信号， 处理 完之后进入步骤 809。 步骤 809叠加当前帧高带解码信号的前半窗信号和上 帧高带解 码信号的后半窗信号， 产生上一帧的高带信号。 步骤 809处理完之后进入步骤 810。 歩 骤 810输出上一帧高带信号， 然后在步骤 911中判断是否需要继续丢帧隐藏处理， 如果 是则返回歩骤 801， 否则结束。
在图 8所示的高带丟帧隐藏算法中， 一些步骤的先后调整， 例如将歩骤 805和 808
"延迟当前帧高带解码后半窗信号"操作移到步骤 809或 810之后， 对算法没有实质的 改变， 应认为属于本发明范畴。
在图 6中， 当发现当前帧丢失时， 立即恢复出当前帧高带解码信号 （包括前半窗信 号和后半窗信号）。 在图 8和图 7中， 发现当前帧丢失时， 只立即恢复 ¾前帧高带解码 信号的前半窗信号， 而后半窗信号的恢复在延迟一帧之后才进行， 即图中的 骤 707和 805 "恢复上一帧高带解码后半窗信号"。 因此图 8和图 7相对于图 6的 -个优点是， 在 恢复上一帧高带解码信号的后半窗信号时， 可以利用当前帧的一些信息， 有利于提高丢 帧隐藏效果。
图 7中的歩骤 704和图 8中的步骤 807 "恢复当前帧高带解码前半窗信号"有多种 处理方法， 举例如下：
方法一： 将当前帧高带解码信号的前半窗信号设为零， 此时图 7中的歩骤 708和图 8中的步骤 809可以省略， 即直接把上一帧高带解码信号的后半窗信号作为上一帧高带 方法二： 复制上一帧高带解码信号的前半窗信号作为当前帧高带解码信兮的前半窗 信号。 相对于方法一的好处是， 可以保持能量的连贯性。
图 7中的步骤 707和图 8中的步骤 805 "恢复上一帧高带解码后半窗 ^号" 有多种 处理方法， 举例如下：
方法一： 将上一帧高带解码信号的后半窗信号设为零， 此时图 7中的歩骤 708和图 8中的歩骤 809可以省略， 即直接把当前帧高带解码信号的前半窗信号作为 L一帧「 带 信号。
方法二： 复制上一帧的上一帧高带解码信号的后半窗信号作为上 帧 带解码信号 的后半窗信号。
方法三： 复制当前帧高带解码信号的后半窗信号作为上一帧高带解码信 ' 的后半窗 信号。
方法四： 如图 9所示， 将上一帧的上一帧高带解码信号的后半窗信号乘 h下降窗， 将当前帧高带解码信号的前半窗信号乘上上升窗， 然后进行叠加， 产生上一帧高 W解码 信号的后半窗信号。 其中下降窗幅值线性的从 1下降到 0， 上升窗幅值线性的从 0 卜.升 到 1。 叠加窗口也可以是其他形状， 例如幅值是 0. 5的矩形窗。 采用该方法的好处足， 在恢复高带解码信号的后半窗信号时， 同时利用了丢失帧前后帧的信息， 能更好的保持 信兮能量的连贯性。
图 7中的歩骤 703和图 8中的步骤 803 "恢复上一帧高带信号"有多种处理方法， 举例如下：
方法一： 分别恢复出当前帧高带解码信号的前半窗信号和上一帧高带解码信 4的后 半窗信号， 然后进行叠加， 产生上一帧高带信号。 当前帧高带解码信兮的前半窗信号的 恢复可采用复制上一帧高带解码信号的前半窗信号的方法， 上一帧髙带解码信号的后半 窗信号的恢复可采用复制上一帧的上一帧高带解码信号的后半窗信号的方法。
方法二： 复制上一帧的上一帧高带信号作为上一帧的高带信号。
图 5中的低带信号恢复模块 503的一种实现方式是基音重复， 即将 £失帧前面一帧 的最后一个基音周期重复的在丢失帧内填充， 直到填充完一帧为止。 例如， 图 10 中， 上一帧丢失， 上一帧的上一帧的最后一个基音周期长度是 P， 首先将上一帧的上一帧的 最后一个基音周期填在丢失帧（上一帧） 的最左边， 紧跟着再填充一个基音周期， 山于 还没有填满- -帧， 令帧长为 N, 则还需填充的长度为 N— P*2， 取基因周期丌始的 *2 个样点填充到剩下的空隙， 则整个填充完毕。
由于基音周期是变化的， 因此采用基音重复的方法进行丢帧隐藏会导致相位不匹 配。 例如， 在图 10中填充的上一帧波形的末尾和当前帧的开始没有吻合， 即相位不 配。为了达到较好的丢帧隐藏效果，需要利用丢失帧后帧的信息消除相位不匹配的影响。 文献 "A New Voice-Packet Reconstruction Technique " (——禾中新的 ϊΐί音包 ίΚ构技术） ( R. A. Valenzuela and C. N. Animalu , IEEE ICASSP— 89， vol. 2, pp. 1334- 1 336, 1989 ) 公开了一种利用丢失帧后帧信息消除相位不匹配的方法， 如图 11所示， 该方法主耍包 括以下一些歩骤：
步骤 1101，填充丢失帧：可以采用前面基音重复的方法，当然也可以采用其他方法； 歩骤 1102， 计算相位差： 如图 10所示， 首先需要找出当前帧起始点和填充的数据 相匹配的点 （寻找匹配点的计算方法参见 Valenzuela的文章）， 并在多个匹配点巾选择 一个最佳匹配点，并以最佳匹配点和当前帧起始点的相位差作为最终的相位差。在图 10 中匹配点有两个， 分别位于当前帧起始点的左边和右边， 到当前帧起始点的距离分别为 de和 dc， 和当前帧起始点之间的相位差分别为一 de和 dc。 如果 de < dc , 则最佳匹配 点是左边的匹配点， 相位差 d = - de , 否则最佳匹配点是右边的匹配点， 相位差 d = dc ;
歩骤 1 103， 插值计算： 线性插值计算量较小， 一般采用线性插值的方法， 计算公式 如下：
y(n) = {x([a . n
Figure imgf000011_0001
+ x([_ . n J) 式中"
Figure imgf000011_0002
， N ¾帧长， 「α'"1表示比" ' "大的最小整数， - "」表示小于 或等于 α · «的最大整数， X是没有考虑相位匹配填充的序列， 长度为填充的起始点到匹 配点， 即等于 W + , 为线性插值之后的序列， " = 1，2···，Λ^。 插值计算完成之^将插 值之后的结果重新填充丢失的帧。
图 12所示的是釆用这种消除相位不匹配方法处理后的结果， 和图 10相比， 已经没 有相位不匹配的问题。
如图 13所示， 丟失帧可能处在浊音和清音的过渡段， 此时丢帧隐藏的一种方法 ：， 用丢失帧前后帧的浊音和清音各填充一部分。但浊音和清音各填充多长并不能做出准确 的判断。 提供判断准确性的一种方法是：
在编码端计算上一帧的能量和过零率， 并作为当前帧的 PLC边信息。 在解码段， 根 据上一帧（丢失帧） 的能量和过零率判断浊音的成分多一些还是清音的多一些， 如果浊 音成分多一些， 则浊音填充的更长一些， 否则清音填充的长一些。
通过以上的实施方式的描述，本领域的技术人员可以清楚地了解到本发明可借助软 件加必需的硬件平台的方式来实现， 当然也可以全部通过硬件来实施， 但很多情况下前 者是更佳的实施方式。基于这样的理解， 本发明的技术方案对背枭技术做出贡献的全部 或者部分可以以软件产品的形式体现出来， 该计算机软件产品可以存储在存储介质巾， 如 R0M/RAM、 磁碟、 光盘等， 包括若干指令用以使得一台计算机设备 （可以足个人计党 机， 服务器， 或者网络设备等）执行本发明各个实施例或者实施例的某些部分所述的方 法。
以上所述， 仅为本发明的较佳实施例而己， 并非用于限定本发明的保护范围， 凡在 本发明的精神和原则之内所做的任何修改、 等同替换、 改进等， 均应包含/本发叨的保 护范围之内。

Claims

权利要求
1、 一种实现丢帧隐藏的设备， 其特征在于， 该设备包括：
丢失帧检测器， 用于接收语音数据， 检测语音帧是否丢失， 生成帧 £火信息； 解码模块， 用于解码接收到的当前语音帧， 生成当前帧低带信号和当前帧高带解码 信号；
低带延迟模块， 用于对所述的当前帧低带信号延迟设定时间， 生成前帧低带信号； 低带信号恢复模块， 用于在所述帧丢失信息表明前帧丢失时， 恢复丢失的前帧低带 信号- 高带丢帧隐藏模块， 用于接收所述的当前帧高带解码信号以及所述的帧丢失 fi, ， 生成前帧高带信号；
QMF综合滤波器， 用于接收低带延迟模块生成的前帧低带信号和高带丢帧隐藏模块 生成的前帧高带信号， 进行综合滤波， 输出前帧语音信号； 或者， 接收低带位号恢 fi模 块恢复的前帧低带信号和高带丢帧隐藏模块生成的前帧高带信号， 进行综合滤波， 输出 前帧语音信号。
2、 如权利要求 1 所述的设备， 其特征在于， 所述高带丢帧隐藏模块具体用十根祸 所述帧丢失信息判断是否收到当前帧高带解码信号； 若收到当前帧高带解码信- ·， 则利 用所述当前帧高带解码信号生成所述前帧高带信号， 若未收到当前帧高带解 ii'i信号， 则 恢复当前帧高带解码信号， 利用所述当前帧高带解码信号生成所述前帧高带信号。
3、 如权利要求 1 所述的设备， 其特征在于， 所述解码模块还用于生成丢帧隐藏边 信息， 所述的丢帧隐藏边信息包括丢失帧的信号能量和过零率。
4、 如权利要求 3所述的设备， 其特征在于， 所述的低带信号恢复模块接收所述 ¾ 帧隐藏边信息，根据所述的丢帧隐藏边信息中的丢失帧的信号能量和过零率判断浊咅成 分和清音成分， 并根据所述浊音和清音成分对所述丢失帧进行恢复。
5、 如权利要求 1所述的设备， 其特征在于， 所述的设定吋间为一帧时间， 所述的 前帧为当前帧的上一帧。
6、 一种实现丢帧隐藏的方法， 其特征在于， 该方法包括：
检测语音帧是否丢失， 生成帧丢失信息；
若当前帧没有丢失，解码当前帧，生成当前帧低带解码信号和当前帧高带解码信 对所述的当前帧低带信号延迟设定的时间， 生成前帧低带信号， 或者， 若所述 A丟 失信息表明前帧丢失时， 恢复丢失的前帧低带信号；
根据所述帧丢失信息对所述的当前帧高带解码信号进行处理， 生成前帧髙带 ^号； 对所述的前帧低带信号和所述的前帧高带信号进行综合滤波， 生成前帧语音信兮。
7、 如权利要求 6所述的设备， 其特征在于， 所述的设定时间为一帧时 1 ， 所述的 前帧为当前帧的上一帧。
8、 如权利要求 7所述的方法， 其特征在于， 所述的生成前帧高带信号的过程为： 根据所述帧丢失信息判断当前帧高带解码信号是否收到， 若收到当前帧高带解码信 号， 则利用所述当前帧高带解码信号生成所述前帧高带信号， 若未收到 前帧高带解码 信号， 则恢复当前帧高带解码信号， 利用所述当前帧高带解码信号生成所述前帧卨带^ 号。
9、 如权利要求 8所述的方法， 其特征在于， 所述利用所述当前帧高带解码信号生 成所述前帧高带信号具体为： 延迟所述当前帧高带解码信号的后半窗信号， 叠加所述 前帧高带解码信号的前半窗信号和前帧高带解码后半窗信号， 生成所述前帧高带信号。
10、 如权利要求 9所述的方法， 其特征在于， 所述的生成前帧高带信号的过程还包 括： 判断是否收到前帧高带解码信号；
且生成前帧高带信号的过程具体还可以包括：
若收到所述当前帧高带解码信号， 以及收到所述前帧高带解码信号， 则延迟所述 前帧高带解码信号的后半窗信号，叠加所述当前帧髙带解码信号的前半窗信号和所述前 帧高带解码后半窗信号， 生成所述前帧高带信号；
若收到所述当前帧高带解码信号， 没有收到所述前帧高带解码信号， 则恢复前帧高 带解码后半窗信号，叠加所述当前帧高带解码信号的前半窗信号和所述前帧卨带解码后 半窗信号， 生成所述前帧高带信号；
若没有收到所述当前帧高带解码信号， 收到所述前帧高带解码信号， 则恢复当前帧 高带解码前半窗信号， 叠加所述当前帧高带解码信号的前半窗信号和所述前帧高带解码 后半窗信号， 生成所述前帧高带信号；
若没有收到所述当前帧高带解码信号， 以及没有收到所述前帧高带解码信号， 则恢 复前帧高带解码信号。
11、 如权利要求 8或 10所述的方法， 其特征在于， 所述的恢复当前帧 ¾带解码 ftl 号具体为： 复制前帧的高带解码信号作为当前帧高带解码信号。
12、 如权利要求 10所述的方法， 其特征在于， 所述的恢复当前帧高带解码信 的 前半窗信号具体为- 将当前帧髙带解码信号的前半窗信号设为零； 或者，
复制前帧高带解码信号的前半窗信号作为当前帧高带解码信号的前半窗信号。
13、 如权利要求 10所述的方法， 其特征在于， 所述的恢复前帧高带解码信兮的后 半窗信号的方法为：
将前帧高带解码信号的后半窗信号设为零； 或者，
复制前帧的上一帧高带解码信号的后半窗信号作为前帧高带解码信号的后半窗佶 号； 或者，
复制当前帧高带解码信号的后半窗信号作为前帧高带解码信 的后半窗信号 ·， 或 者，
将前帧的上一帧高带解码信号的后半窗信号乘以第一半窗， 产生第一信号； 将当前帧高带解码信号的前半窗信号乘以第二半窗， 产生第二信号；
对所述的第一信号和第二信号进行叠加， 生成的信号作为前帧高带解 ϊί' 言号的后半 窗信号；
所述第一半窗和第二半窗组成叠加窗。
14、 如权利要求 10所述的方法， 其特征在于， 所述的恢复前帧高带 号具体为： 恢复前帧高带解码信号的后半窗信号， 产生第一信号， 恢复当前帧! ¾ -带解码信号的 前半窗信号， 产生第二信号， 将所述的第一信号和第二信号进行叠加， 生成的信 作为 所述前帧高带信号； 或者，
复制前帧的上一帧髙带信号作为上一帧的高带信号。
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CN101325537B (zh) 2012-04-04
US8355911B2 (en) 2013-01-15

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