Audio Processing Used in Voip Mobile Apps

Question

I am new to VoIP apps and am learning about the various audio processing that are applied in such apps. I have looked at Linphone and CSipSimple apps for Android. I notice that they employ different set of audio processing like echo cancellation, equalization, compression etc.

My questions:

• How would a VoIP app developer decide what audio processing should be used in an app ?
• Is there a list of all processing options somewhere online ?
• Is there a methodology involved in selecting the needed audio processing for an app ?
• If I were to identify the minimum set of audio processing needed for a VoIP app, how would I go about doing it ?

Answer 1

• How would a VoIP app developer decide what audio processing should be used in an app ?

experience, testing, looking at what others do (aka. typical software development).

So, you, for example, know that you need to work in situations where you'll have echos of your speaker in your microphone, so you add echo cancellation.

Do that with all negative effects that you know beforehand.

Then build a prototype, identify problems, find method to solve problem, repeat.

All in all, engineering.

• Is there a list of all processing options somewhere online ?

Sorry, that list would be infinite, so no.

But: You could read a (good) book on speech processing. That would make (somewhat) of an expert on the topic, and experts find solutions to problems by applying their knowledge!

• Is there a methodology involved in selecting the needed audio processing for an app ?

See first point. Engineering.

• If I were to identify the minimum set of audio processing needed for a VoIP app, how would I go about doing it ?

I'd argue that you start with a decoder for the audio codec and call "none" a minimum amount of post-processing that. Then you work up until the application works as intended.