Audio and video development of sound processing technology

In the Instant Messaging application, the need for both sides, or a multi-party real-time voice communication, in the higher requirements of the occasion, usually the use of external speakers to put sound, this will inevitably produce an echo, that is, after one side of the speaker, through the other side of the sound, and then the other side of the mic collected back to themselves. If the echo is not processed, it will affect the call quality and user experience, more serious will also form a concussion, produce a whistle. So how to implement echo cancellation technology!

Echo Cancellation is after the mic acquisition of sound, the local speakers play out of the sound from the mic collected sound data removed, so that the mic recorded sound only local users speak.

Traditional echo cancellation is the use of hardware, in the hardware circuit integrated DSP processing chip, such as our common fixed telephone, mobile phone, etc. have a special echo elimination processing circuit, and the use of software to achieve echo cancellation has been technical difficulties, including the most widely used QQ Super voice, Is the use of foreign gips technology, this shows the general.

Echo cancellation has become a standard method of providing full-duplex voice in instant messaging. Acoustic echo Cancellation is a processing method that prevents the remote sound from returning by eliminating or removing the audio signal from the far end picked up in the local microphone. The removal of this audio is done through digital signal processing. Echo Cancellation technology is one of the typical applications of digital signal processing.

The basic principle of echo cancellation is to establish a voice model of the remote signal based on the correlation of the speaker signal and the multipath echo generated by it, and use it to estimate the Echo and constantly modify the coefficients of the filter, so that the estimate is more approximate to the real echo. The echo estimate is then subtracted from the input signal of the microphone to achieve the purpose of eliminating the echo.

The following is a list of echo cancellation techniques for the Anychat audio and video development system.

Anychat echo Cancellation effect

A user speaks

b User Mic Recording sound (contains A's sound +b sound)

A hear B's voice (echo cancellation, only B's sound is retained)

About noise suppression (ANS)

Anychat Noise suppression Technology is the principle of real-time sampling of digital signal spectrum analysis, so that we can analyze the background noise response intensity and spectral distribution, and then according to this model can design a filter, when someone speaks, at the same time do signal analysis, according to analysis, The ANC can analyze the speaker's spectrum, so based on these background noise and the speaker's spectrum, the filter is changed in real time based on the two-signal contrast, allowing the speaker's voice spectrum to pass through, suppressing the spectrum of background noise, reducing its energy, such as 15 to 20 decibels, It is obvious that the effect of noise suppression can be felt.

Audio and video development of sound processing technology