Bit Error Concealment For Audio Coding Systems
As a result, the case of bit-error-induced artifacts must still be handled with eSCO channels.  The detection and concealment of clicks in audio signals is not new. As will be discussed in more detail below, re-encoding involves encoding a concealment waveform used to replace a frame of the decoded audio signal so as to synchronize the state memory Jay KuoHindawi Publishing Corporation, 2004 - Technology & Engineering - 252 pages 0 Reviewshttps://books.google.com/books/about/High_fidelity_Multichannel_Audio_Coding.html?id=h3v6ibwgzQ8C Preview this book » What people are saying-Write a reviewWe haven't found any reviews in the usual Wada, and H. http://sovidi.com/bit-error/bit-error-probability-for-coherent-m-ary-psk-systems.php
Thus a click is detected and used to update BER only when BER-based threshold biasing module 202 detects an active region of signal 114 that is quickly followed by an inactive Thus, the threshold K1 advantageously allows other factors to be considered in detecting clicks, such as the bit error frequency rate determined by BER-based threshold biasing module 202, the pitch track However, most prior art techniques deal exclusively with detecting bit errors in memory-less codecs such as the G.711 codec, or in detecting clicks due to degradation of a storage medium. The re-encoding flag is used to enable or disable re-encoding for the current frame.
Concealment techniques generally entail some form of sample replacement/smoothing/interpolation. Using the autocorrelation approach for a three-tap pitch predictor leads to the following system of equations:  [ r xw ( 0 ) r xw ( 1 ) r Interference from these devices can also cause bit errors in the Bluetooth® transmission.  Bluetooth® defines four packet types for transmitting SCO data—namely, HV1, HV2, HV3, and DV packets. Generated Sun, 02 Oct 2016 12:47:44 GMT by s_hv996 (squid/3.5.20) ERROR The requested URL could not be retrieved The following error was encountered while trying to retrieve the URL: http://0.0.0.6/ Connection
There are three codecs defined for SCO channels: A-law PCM, u-law PCM, and CVSD. However, unvoiced regions are not very predictable, and the concealment waveform may not closely match the original speech. The voicing strength vs may be computed in accordance with:  vs = min ( max ( min ( max ( 15 - zc_ave 10 , 0 ) , Threshold when Pitch Tracking Classification is Random  If the pitch track classification, ptc, indicates that the pitch history is random, then the speech signal is not strongly periodic at the
The method of claim 1, wherein the step of decoding the portion of the encoded bit stream is performed by one of: a Continuously Variable Slope Delta Modulation (CVSD) decoder; a FIG. 4 is a block diagram that depicts functional elements of bit error feature set analyzer 314 in accordance with one implementation of the present invention. One important difference that evad attempts to exploit is the fact that bit-errors are frame aligned in Bluetooth®. If the frame preceding the current frame did not contain a bit-error (in other words, if bei(k−1)=0), then AVM calculator 402 calculates avm in accordance with:  avm = ∑ n
For example, if no packets have been lost in the recent past, PLR would be close to zero (or equal to zero). For example, the bit-errors may cause a significant increase in the step-size of the CVSD decoder. In an implementation in which a CVSD encoder block is not available for re-encoding of the PLC output and subsequent state memory update of CVSD decoder 102, this module may be To achieve this...Appears in 5 books from 2000-2004Page 187 - S of sign + can be viewed as a random variable having a binomial distribution with parameters n...Appears in 17 books
Hence,  BER=min(BER,ƒ(PLR)) (1)  BER-based threshold biasing module 202 may determine PLR by tracking a bad frame indicator (BFI) that is associated with each frame and that is received from another click site However, as the threshold for decision K1 increases, the more difficult it will be to detect such a bursty bit error. BER-based threshold biasing module holds BER constant during periods of active speech.  Generally speaking, BER-based threshold biasing module 202 detects a click only if voice activity is observed for a Such embodiments are presented herein for illustrative purposes only.
A particular embodiment of the present invention utilizes a low-complexity design that introduces no added delay and that is particularly well-suited for applications such as Bluetooth® wireless audio devices which have In this case, it would be expected that BER should also be close to zero. LPC Analysis and Filtering Module 306  LPC analysis and filtering module 306 is configured to perform a so-called “LPC analysis” on 8 kHz audio signal 114 to update coefficients of news Re-Encoding Decision Module 408  Re-encoding decision module 408 is configured to set a re-encoding flag, denoted rei, that is used to enable or disable re-encoding for the current frame.
KuoNo preview available - 2007 Bibliographic informationTitleHigh-fidelity Multichannel Audio CodingVolume 1 of EURASIP book series on Signal Processing and Communications: European Association for Speech, Signal and Image ProcessingVolume 1 of EURASIP As mentioned above, CVSD was designed to be robust to random bit errors but is not robust to bursty bit errors. The system of claim 16, wherein the bit error detection module is configured to analyze at least the decoded audio signal to detect whether the decoded audio frame includes the distortion
Murakami, "Reversible Variable Length Codes,Appears in 26 books from 1982-2006Page 87 - The standard deviation is simply the square root of the variance and hence is expressed in the same unit
It has been observed that the pitch track correlates well with the predictability of a current speech signal based on past information. In addition, prior art concealment techniques do not apply to this application because the distortion may be spread across several samples and potentially impact an entire frame (30 samples) or more. Introduction  The following detailed description refers to the accompanying drawings that illustrate exemplary embodiments of the present invention. When packet loss or bit errors occur, the state memory of the encoder and the state memory of the decoder may become out of synchronization, thereby causing degraded performance in the
BRIEF SUMMARY OF THE INVENTION  A bit error concealment (BEC) system and method is described herein that detects and conceals the presence of click-like artifacts in an audio signal caused If the pitch track classification is “tracking,” then it is more likely that if a segment of speech from the current frame does not match well with the past, it is AVM Calculator 402  AVM calculator 402 computes an average magnitude, denoted avm, of a segment within the long-term prediction residual, xwp(n), which is calculated by three-tap prediction analysis and filtering More about the author As shown in FIG. 2, BEC system 110 includes a bit error rate (BER) based threshold biasing module 202, a bit error detection module 204, a packet loss concealment (PLC) module
In particular, using the VAD system, BER-based threshold biasing module 202 continuously updates an estimated click-causing bit error rate, denoted BER, during periods of speech inactivity and uses this rate to The method of claim 1, further comprising: analyzing non-speech segments of the decoded audio signal to estimate a rate at which audible distortions are detected; and adapting a biasing factor based