So far, I have been able to calculate dB of real time audio stream. On the basis of the highest dB, I have selected the loudest audio stream from multiple audio streams. My problem arises when there is a sudden change in dB level in other audio stream and switching takes place from one stream to another stream. How should I make this switching smooth?
Remember, I have been taking an audio signal or audio stream of 40ms(640 bytes) from various android smartphones.
I am not an acoustic engineer, but will try to guess. You are selecting the stream with highest average |amplitude| or average square of amplitude signal. You can decrease power (average sum of squares) of selected sound stream to the power of previous stream and then increase it slowly. Or just a mix for few seconds? Depends on your purpose.
If your question is how to make the transition smooth, then you could make a crossfade between the current signal and the signal you are going to switch to.
René Erler thanks for the suggestion. I real some papers on crossfading techniques but For real-time VoIP application, I can't use the crossfade technique on the streams as it requires more signal processing and I am out of time bucket i.e 40ms to involve more signal processing. Could you please suggest something else that may help in making the streams switching smooth?
The reason why you may get clicks and pops and the switching may sound abrupt is due to the fact that in most cases you are going to switch the signal in/out in time instances when its amplitude is non-zero. So in order to avoid that you could time your in and out switching of signals exactly so that you always switch when the signal naturally crosses zero.