When software asks for WAV
M4A is a great format for storing and sharing, but many tools that process audio still prefer WAV. Typical cases include transcription and subtitling software, speech recognition services, academic research tools, audio editors that do not import M4A, older video editors, and CD burning programs. Journalists and students often convert M4A to WAV after recording interviews on an iPhone, because the next tool in their workflow wants uncompressed audio.
AAC or ALAC inside makes a difference
An M4A file can contain one of two codecs, and the converter shows you which:
- AAC (lossy): the usual case. The WAV contains exactly the decoded AAC audio. No new loss is added, and nothing lost during AAC encoding comes back.
- ALAC (Apple Lossless): the WAV is a perfect, bit-identical copy of the original recording.
Choosing the WAV settings
| Purpose | Sample rate | Channels | Size per minute |
|---|---|---|---|
| Speech recognition, transcription | 16 kHz | mono | about 1.9 MB |
| Audio editing, podcasts | original (44.1 or 48 kHz) | original | 5.3 to 11.5 MB |
| Video projects | 48 kHz | stereo | about 11.5 MB |
| Audio CD | 44.1 kHz | stereo | about 10.6 MB |
Use 16-bit unless your project requires 24-bit. For an AAC source, 24-bit stores no extra detail. For a 24-bit ALAC file, choose 24-bit to keep it lossless.
Voice memos and interviews
iPhone voice memos are mono AAC at around 64 kbps or, with the lossless setting enabled, ALAC. Either way, mono WAV is the right output: a stereo WAV would just duplicate the same channel and double the size. Before sending a recording to transcription, it can help to reduce background noise with noise reduction and to bring quiet speakers up with normalize. Long interviews can be divided into parts with the split tool if a service limits file length.
WAV has poor support for tags: title, artist and album are saved in a basic INFO chunk, but many programs do not show them. Name the files clearly. If you need a lossless file with tags, convert to FLAC instead.