Record and send/stream sound from iOS device to a server continuously

Question

I am developing an iOS app that has a button with a microphone on it (along with other features). When the user presses the microphone, it gets highlighted and the app should now start recording sound from the device´s microphone and send to a server (a server dedicated to the app, developed by people that I know, so I can affect its design).

I am looking for the simplest yet sturdiest approach to do this, i.e. I have no need to develop a complicated streaming solution or VoIP functionality, unless it is as simple to do as anything else.

The main problem is that we have no idea for how long the user will be recording sound, but we want to make sure that sounds are sent to the server continuously, we do not wish to wait until the user has finished recording. It is okay if the data arrives to the server in chunks however we do not wish to miss any information that the user may be recording, so one chunk must continue where the previous one ended and so on.

Our first thought was to create "chunks" of sound clips of for example 10 seconds and send them continuously to the server. Is there any streaming solution that is better/simpler that I am missing out on?

My question is, what would be the most simple but still reliable approach on solving this task on iOS?

Is there a way to extract chunks of sound from a running recording by AVAudioRecorder, without actually stopping the recording?

Answer 1

It might actually be easier to have fixed-size chunks, instead of fixed-time. Then you can have two buffers, one that you currently fill with sample data. When the active buffer is full, then switch to fill the other buffer, while sending a signal to a sender-thread that takes the first buffer and sends it to the server.

You can of course use fixed-time instead, but then you need to make sure that the buffer is large enough to keep all samples, or use a dynamic buffer that can increase in size when needed. The double-buffering and sending thread can still be the same though.