I have a project which, during the first phase of editing in an Audacity project, results in many tracks which will be loaded into subsequent Audacity projects for additional editing and mixing. As the workflow progresses, there may be need for additional exports, and imports of tracks into downstream Audacity projects.
Case 1: (most common)
The source audio file is M4A, with 44100 sampling.
My question is, should I export from the first project as WAV format, or can I export as M4A, without a degradation of quality?
Case 2: (not unusual)
The source file is a WAV file, 24bit, with 48000 sampling.
In this case, do I lose quality if I export as M4A?
As concrete example, most of these WAV files need to be split into pieces – I create a label track and use Export / Multiple for these files. Should I export / multiple as WAV 24bit, 48000 sample, to preserve quality downstream in the workflow, or is M4A okay for the exported “multiple files”?
Case 3: (it happens pretty often)
The source file is an MP3.
So, in summary, are these correct, for best practices?
Starting with M4A:
1a) M4A → WAV → WAV → … → M4A okay
1b) M4A → WAV → WAV → … → WAV not much point
1c) M4A → M4A → M4A → … → M4A bad
Starting with WAV:
2a) WAV → WAV → WAV → … → WAV good
2b) WAV → M4A → M4A → … → M4A bad
2c) WAV → M4A → M4A → … → WAV not much point
Starting with MP3: (the same as M4A, only worse degradation occurs?)
3a) MP3 → WAV → WAV → … → MP3 or M4A okay
3b) MP3 → WAV → WAV → … → WAV not much point
3c) MP3 → MP3 → MP3 → … → MP3 bad
Sorry to be long-winded – hope the question is clear.