ToDoList.txt

Important:

BUG!! When application is playing and is moved back to foreground in few seconds the song jumps to the end or track goes out of sync
Move the open of Audio file from openAudioFile inside FillAudioBuffer to avoid problems and delays.
Stop the Audio Reader when the app is going to background

One or more segments of registered output is kept except when deleted (with undo the last one or with delete all) or overwritten. 

Always play the registered segments at their time

Check for noise when app is back from background (possible conflict with other apps?) or the speaker is plugged/unplugged/re-plugged.

Implement real UI.

Read karaoke data from lyrics
Fix karaoke editor and add list of files
Fix problem with headphone. Put playback channel to minimum when headphone is removed or let the user disable it.
Audio effects (reverber and, if possible, some more). ObjectAL library.

Maintain a list of all registered segments ?
Use flag kAudioUnitRenderAction_OutputIsSilence when a channel is silenced ?