Patent application number | Description | Published |
20080247535 | Method and apparatus for mitigating impact of nonlinear effects on the quality of audio echo cancellation - A method is provided for reducing the adverse impact of echo on audio quality in a two-communication system. The method includes two parts. The first part begins by detecting non-linear effects (e.g. clippings and audio glitches). If a non-linear effect is detected, the system temporarily disables adaptation of the adaptive filter. In this way, filter coefficients obtained before the non-linear effect happens will not be corrupted, so the AEC can quickly recover from the non-linear effects. The second part begins by monitoring a parameter reflecting signal quality (e.g., ERLE). If the signal quality parameter falls below a given value the system switches from a full-duplex mode of operation to a half-duplex mode of operation. In this way, when a non-linear effect that is undetectable or occurs repeatedly (e.g., speaker volume changes) and which can corrupt an acoustic echo canceller (AEC) for a relatively long period of time, the system switches from full-duplex operation to half-duplex operation. In half-duplex operation, communication can only happen in one direction at a time, and thus the echo path is broken, effectively eliminating echoes. When the non-linear effect is no longer present and the quality parameter rises to a normal level, communication returns to a full-duplex mode of operation and the AEC once again removes the echoes. | 10-09-2008 |
20080253553 | Filter bank optimization for acoustic echo cancellation - A communications device is presented for providing bi-directional audio communications between a near-end user and a far-end user via a bidirectional communications channel. The communications device includes an adaptive echo canceller receiving a near-end audio signal and a far-end audio signal and providing an echo-canceled near-end audio signal for transmission to the far-end user via the communications channel. The adaptive echo canceller includes a first bank of analysis filters for filtering the near-end audio signal, a second bank of analysis filters for filtering the far-end audio signal, and a bank of synthesis filters for filtering sub-band echo-canceled signals generated within the adaptive echo canceller. The first and second filter banks have a frequency response optimized to reduce echo residual gain. | 10-16-2008 |
20080259828 | Method and apparatus for reducing timestamp noise in audio echo cancellation - A communication end device of a two-way communication system is shown. The device includes an audio signal capture device for capturing local audio to be transmitted to another end device, an audio signal rendering device for playing remote audio received from the other end device, and buffers for buffering the captured and rendered audio signals. The device also includes an audio echo canceller operating to predict echo from the rendered audio signal at a calculated relative offset in the captured audio signal based on an adaptive filter, and subtract the predicted echo from the signal transmitted to the other end device The calculated relative offset that is used by the audio echo canceller for a current signal sample is adjusted if a difference between it and an adjusted relative offset of a preceding sample exceeds a threshold value. | 10-23-2008 |
20090006103 | BITSTREAM SYNTAX FOR MULTI-PROCESS AUDIO DECODING - An audio decoder provides a combination of decoding components including components implementing base band decoding, spectral peak decoding, frequency extension decoding and channel extension decoding techniques. The audio decoder decodes a compressed bitstream structured by a bitstream syntax scheme to permit the various decoding components to extract the appropriate parameters for their respective decoding technique. | 01-01-2009 |
20090207763 | VOICE SWITCHING FOR VOICE COMMUNICATION ON COMPUTERS - A voice communication end device performs quality checks to determine whether acoustic echo cancellation would be ineffective, such as due to noise or clock drift or discontinuities between incoming and outgoing voice channels. In the case where echo cancellation would prove ineffective, the device falls back on a tri-state voice switching operation that includes a bi-direction state in which both channels are on in full duplex operation, which provides a smoother transition switching between active channels. The tri-state voice switching supports both voluntary transitions where the active user voluntarily stops to yield the active channel, and forced transitions where the active user is forcedly interrupted by the other user speaking more loudly. | 08-20-2009 |
20090210222 | Multi-Channel Hole-Filling For Audio Compression - Multi-channel hole-filling for audio compression is disclosed. Channel dependency groups (CDGs) are explicitly extracted based on channel transform information. Holes are detected within each CDG for each bark, and a CDG hole is identified as requiring filling as a particular section of frequency bandwidth larger than a predetermined hole bandwidth threshold and with all zero-value coefficients in all channels after quantizing. Bark weights are adjusted by multiplying the original bark weights with one calculated scalar so as to remove each detected CDG hole. | 08-20-2009 |
20090316881 | TIMESTAMP QUALITY ASSESSMENT FOR ASSURING ACOUSTIC ECHO CANCELLER OPERABILITY - A voice communication end device provides echo reduction when operating in a full duplex mode using acoustic echo cancellation, which includes periodic audio queue adjustments to account for drift. The end device performs a quality assessment by calculating consistency statistics for the queue adjustments to determine whether acoustic echo cancellation would be ineffective, and if so falls back to a half duplex mode using voice switching. | 12-24-2009 |
20090316924 | ACCOUSTIC ECHO CANCELLATION AND ADAPTIVE FILTERS - In one embodiment, a two-way telecommunication device may perform acoustic echo cancellation on incoming signals. An audio decoding module may produce an audio render signal. An audio capture interface may receive an audio capture signal. A short length adaptive filter may determine a time delay between the audio render signal and the audio capture signal by adaptively predicting a sub-band of the audio capture signal using a corresponding sub-band of the audio render signal. | 12-24-2009 |
20090319589 | USING FRACTIONAL EXPONENTS TO REDUCE THE COMPUTATIONAL COMPLEXITY OF NUMERICAL OPERATIONS - Technologies are described herein for using efficient log-linear transformations to reduce the complexity of numerical computations. Efficient transforms can convert between linear fixed point values and log space values in about ten processor cycles per sample. A fractional exponent and an integer exponent may be combined together into a log domain variable representation. Log domain arithmetic operations may be performed on the combined variable as a whole. A fractional exponent representation of log domain numerical values can support automatic bit carries from the fractional exponent into the integer exponent. If an intermediate result of a calculation in the log domain causes the fractional portion of the exponent to exceed one, a bit carry can occur over to the integer component of the exponent. This carry can occur automatically due to the conjoined placement of the integer and fractional components of the exponent in the log domain combined variable. | 12-24-2009 |
20100145689 | KEYSTROKE SOUND SUPPRESSION - An audio signal is received that might include keyboard noise and speech. The audio signal is digitized and transformed from a time domain to a frequency domain. The transformed audio is analyzed to determine whether there is likelihood that keystroke noise is present. If it is determined there is high likelihood that the audio signal contains keystroke noise, a determination is made as to whether a keyboard event occurred around the time of the likely keystroke noise. If it is determined that a keyboard event occurred around the time of the likely keystroke noise, a determination is made as to whether speech is present in the audio signal around the time of the likely keystroke noise. If no speech is present, the keystroke noise is suppressed in the audio signal. If speech is detected in the audio signal or if the keystroke noise abates, the suppression gain is removed from the audio signal. | 06-10-2010 |
20100177884 | ECHO PRESENCE DETERMINATION IN VOICE CONVERSATIONS - Presence of echo in a conversation is determined through a search performed in the sub-band domain using independent short length adaptive filters across a range of sub-band and maximum expected echo delay values. The adaptive filters attempt to predict and cancel the echo in the microphone signal based on the content in the speaker signal. If substantial cancelation is achieved in any of the sub-band filters, echo presence in the microphone signal is determined. | 07-15-2010 |
20100246804 | MITIGATION OF ECHO IN VOICE COMMUNICATION USING ECHO DETECTION AND ADAPTIVE NON-LINEAR PROCESSOR - Architecture that mitigates echo in voice communications using echo detection and adaptive management of attenuation by a non-linear processor (NLP). Suppression values provided by the NLP are determined based on echo detection and retained on a case-by-case basis to automatically increase or decrease the attenuation as needed. Feedback is incorporated that where the controls for the NLP attenuation is given by the amount of echo that remains, and this in turn affects the amount of echo that remains. | 09-30-2010 |
20110196684 | BITSTREAM SYNTAX FOR MULTI-PROCESS AUDIO DECODING - An audio decoder provides a combination of decoding components including components implementing base band decoding, spectral peak decoding, frequency extension decoding and channel extension decoding techniques. The audio decoder decodes a compressed bitstream structured by a bitstream syntax scheme to permit the various decoding components to extract the appropriate parameters for their respective decoding technique. | 08-11-2011 |
20120128162 | MIXED LOSSLESS AUDIO COMPRESSION - A mixed lossless audio compression has application to a unified lossy and lossless audio compression scheme that combines lossy and lossless audio compression within a same audio signal. The mixed lossless compression codes a transition frame between lossy and lossless coding frames to produce seamless transitions. The mixed lossless coding performs a lapped transform and inverse lapped transform to produce an appropriately windowed and folded pseudo-time domain frame, which can then be losslessly coded. The mixed lossless coding also can be applied for frames that exhibit poor lossy compression performance. | 05-24-2012 |
20120163615 | FILTER BANK OPTIMIZATION FOR ACOUSTIC ECHO CANCELLATION - A communications device is presented for providing bi-directional audio communications between a near-end user and a far-end user via a bidirectional communications channel. The communications device includes an adaptive echo canceller receiving a near-end audio signal and a far-end audio signal and providing an echo-canceled near-end audio signal for transmission to the far-end user via the communications channel. The adaptive echo canceller includes a first bank of analysis filters for filtering the near-end audio signal, a second bank of analysis filters for filtering the far-end audio signal, and a bank of synthesis filters for filtering sub-band echo-canceled signals generated within the adaptive echo canceller. The first and second filter banks have a frequency response optimized to reduce echo residual gain. | 06-28-2012 |
20120323584 | BITSTREAM SYNTAX FOR MULTI-PROCESS AUDIO DECODING - An audio decoder provides a combination of decoding components including components implementing base band decoding, spectral peak decoding, frequency extension decoding and channel extension decoding techniques. The audio decoder decodes a compressed bitstream structured by a bitstream syntax scheme to permit the various decoding components to extract the appropriate parameters for their respective decoding technique. | 12-20-2012 |
20130148801 | VOICE SWITCHING FOR VOICE COMMUNICATION ON COMPUTERS - A voice communication end device performs quality checks to determine whether acoustic echo cancellation would be ineffective, such as due to noise or clock drift or discontinuities between incoming and outgoing voice channels. In the case where echo cancellation would prove ineffective, the device falls back on a tri-state voice switching operation that includes a bi-direction state in which both channels are on in full duplex operation, which provides a smoother transition switching between active channels. The tri-state voice switching supports both voluntary transitions where the active user voluntarily stops to yield the active channel, and forced transitions where the active user is forcedly interrupted by the other user speaking more loudly. | 06-13-2013 |
20140156287 | BITSTREAM SYNTAX FOR MULTI-PROCESS AUDIO DECODING - An audio decoder provides a combination of decoding components including components implementing base band decoding, spectral peak decoding, frequency extension decoding and channel extension decoding techniques. The audio decoder decodes a compressed bitstream structured by a bitstream syntax scheme to permit the various decoding components to extract the appropriate parameters for their respective decoding technique. | 06-05-2014 |