Aec acoustic echo cancellation full#
This is absolutely necessary for clear, full duplex conversation over communication channel. The person at the far end hears only the local talker and not the echoes and reverberation from the far end in the near end space. For example, in the case of a hands-free system or speakerphone, adaptation pauses when a person speaks directly into the microphone. This allows sounds in to be added to the far end out. The filter pauses adaptation when it detects sounds in the acoustic path unrelated to the far end in. The signal is then (optionally) passed through a noise reduction function to produce the output, which is a known as the “Far End Out.” This signal is sent to a Residual Echo Cancellation block (RES) that further recovers the input signal. The AEC block also calculates a residual signal containing nonlinear acoustic artifacts. The output of the filter is then subtracted from the acoustic path signal to produce a “clean” signal output with the linear portion of acoustic echoes largely removed. The algorithm continuously adapts this filter to model the acoustic path. The AEC block is based on an adaptive FIR filter. The acoustic path consists of an amplifier/loudspeaker, an acoustic environment, and a microphone returning the signal to the DSP. As shown in the diagram below, the sound coming from the remote person speaking, known as the Far End In, is sent in parallel to a DSP path and to an acoustic path. The Acoustic Echo Cancellation (AEC) block is designed to remove echoes, reverberation, and unwanted added sounds from a signal that passes through an acoustic space. Public class AecContext extends fm.liveswitch.AecContext fm.liveswitch.Click here to return to the ADI Algorithms page Protected override FM.LiveSwitch.AudioSink CreateOutputMixerSink(FM.LiveSwitch.AudioConfig config) Var tailLength = FM.(config) + FM.(config) Var config = new FM.LiveSwitch.AudioConfig(16000, 1) Protected override FM.LiveSwitch.AecPipe CreateProcessor() public class AecContext : FM.LiveSwitch.AecContext For improved results turn off all enhancements to your virtual audio devices, but for best results you must not run in a VM. Note that in virtual environments DMO can still produce echo. Once you've finished creating an AecContext implementation you have to add it to your local and remote media objects. Generally, you want this to be the combined delay between the sender and receiver. The tail length tells the library how long to keep track of audio data for echo cancellation. Its constructor requires you to specify two things: the audio settings and the tail length to use for echo cancellation.
For this, you should create and return an instance of FM. The next method you must implement is CreateProcessor. In your implementation, instantiate a sink appropriate for your platform, as shown in the example below. Generally, this corresponds to your system speakers. This method creates a sink where the mixed audio output can be played. You must first implement the CreateOutputMixerSink method. There are two methods to implement, CreateOutputMixerSink and CreateProcessor. You need to implement a platform-specific version of this for each of your projects. The FM.LiveSwitch.AecContext class is an abstract class that provides baseline acoustic echo cancellation capability. Similarly, this is not needed on web platforms as each browser has its own implementation. There are no libraries for iOS and macOS because Apple implements their own echo cancellation so there is no need for LiveSwitch to re-invent the wheel. The acoustic echo cancellation implementation can be found in the FM.LiveSwitch.AudioProcessing library and associated native libraries. Here we cover the inclusion of the audio processing libraries specifically, full instructions on setting up project structure are covered in the Starting a New Project section.
Aec acoustic echo cancellation how to#
Read on for information on how to add this to your projects. It is included with the standard LiveSwitch distribution as a separate library. LiveSwitch provides an acoustic echo cancellation implementation. If someone retransmits data that is similar enough to the data you have just sent, it is recognized as an echo and is removed from the audio data before playback. Acoustic Echo Cancellation solves this by keeping track of the audio data you send. The remote peer is playing your audio stream through the speakers, then picking it up with the microphone and streaming it back to you. If you ever hear yourself speaking a few hundred milliseconds after you have spoken, this is most likely because the remote peer does not have Acoustic Echo Cancellation (AEC).
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