Can Audacity open M4A files from iPhone Voice Memos?

Yes — Audacity 3.4 and later bundle FFmpeg, which decodes M4A (AAC), AAC in any container, ALAC, AMR, and most video-container audio tracks. Earlier 3.x versions required a separate FFmpeg download from the Audacity website. If M4A import fails on your install, the fast workaround is converting the file to WAV first with a browser-based [M4A to WAV](/convert/m4a-to-wav) tool, then importing the WAV. The audio content is identical; you just bypass the decoder dependency.

Does Audacity lose quality when I open and save an MP3?

Yes. Opening an MP3 decodes it to 32-bit float PCM internally; exporting as MP3 re-encodes that PCM through LAME, adding one full generation of lossy compression on top of whatever was already in the source. Even without making any edits, the exported MP3 will be perceptibly lower quality than the original. The fix is either keeping the project file (AUP3, 32-bit float, lossless) for future re-exports, or working from a WAV/FLAC source so all your MP3 exports come from a clean lossless master.

What is the best export format for podcast episodes?

For voice-only podcasts, MP3 at 128 kbps CBR mono is the universal default — this is what Apple Podcasts, Spotify for Podcasters, and Buzzsprout recommend, and it works on every podcast app and player. In Audacity: File > Export > Export as MP3 > Bit Rate Mode: Constant > 128 kbps > Channel Mode: Force export to mono. For interview shows with two stereo-panned hosts, 96 kbps CBR stereo is also reasonable. Use VBR only if the host explicitly supports it; some podcast feed validators choke on VBR.

Can Audacity export FLAC?

Yes — FLAC export is built in and works without any additional libraries. File > Export > Export as FLAC opens a dialog with compression level 0 (fastest, largest) through 8 (slowest, smallest), defaulting to level 5 which is the FLAC project's recommended sweet spot. Bit depth defaults to 16-bit; switch to 24-bit for masters destined for streaming services that accept 24-bit lossless. The output is bit-exact with the internal 32-bit float audio after dithering down to the chosen bit depth.

Should I use 32-bit float WAV when exporting from Audacity?

Only when the destination is another DAW that supports 32-bit float, such as Pro Tools, Reaper, Logic, or Premiere. For final delivery to streaming, podcasts, or distribution, export 16-bit (for distribution) or 24-bit (for masters). 32-bit float is twice the file size of 24-bit and offers no benefit on playback because no consumer player decodes float-format WAV. The strength of 32-bit float is preventing clipping during editing, which Audacity already handles internally — it does not need to be preserved on export.

Best Audio Format for Audacity: Import, Edit, and Export

Audacity is the most-installed free audio editor on the planet — over 100 million downloads since 1999, and the active 3.x line is more capable than most people realize. Format handling is the foundation of any Audacity workflow: pick the right import format and you save CPU and avoid quality loss; pick the right export format and your file works on the destination platform without surprises. This guide walks through Audacity's full format pipeline, from project files to delivery.

Audacity's Internal Format: 32-bit Float PCM

Whatever you import into Audacity — MP3, M4A, FLAC, OGG, WMA, WAV, AIFF, Opus — gets decoded to 32-bit floating-point PCM at the project's sample rate the moment it lands on the timeline. This is by design. 32-bit float gives Audacity essentially unlimited headroom (peaks up to roughly +770 dB without clipping) and bit-perfect arithmetic during edits. Every effect, fade, normalization, and gain change happens in 32-bit float.

The practical implication: format quality differences between source files do not affect editing operations. Editing a 128 kbps MP3 in Audacity is no slower or noisier than editing a WAV, because both have already been decoded to identical-precision PCM. The differences appear at export time when you re-encode.

The Project File: AUP3

Audacity 3.0 (released 2021) introduced AUP3, a single SQLite database file that contains the project's audio data, edits, labels, tracks, and settings. Earlier versions used .aup XML files plus an _data folder full of fragmented audio chunks — a notorious source of "missing file" errors when users moved or renamed projects. AUP3 fixes that by bundling everything.

Saved internally as 32-bit float PCM at the project sample rate
Single file, easy to back up or move
Lossless round-trip: close and reopen with no quality change
File size: roughly the same as uncompressed WAV of the same audio length, plus a small SQLite overhead

For long-term archival, export the project to a separate WAV or FLAC file. AUP3 is intended as the live working format, not a delivery format.

Best Format for Importing

Audacity's broad import support comes through two paths: native decoders for WAV, AIFF, FLAC, OGG Vorbis, and MP3 (via the bundled LAME library); and FFmpeg-based decoders for M4A, AAC, OGG Opus, WMA, AC-3, AMR, and most video container audio tracks. The FFmpeg integration is now bundled with Audacity 3.4 and later — older versions required a separate download from the Audacity site.

Recommendations:

WAV or AIFF for editing source. No decode overhead, no compression artifacts, sample-accurate seeking.
FLAC for lossless source you do not want to inflate to WAV size.
MP3, M4A, OGG are fine to import for editing, but if you plan to export back to a lossy format, decode them to WAV first to avoid one extra generation of lossy damage.

If a file fails to import — usually a sign that FFmpeg is missing or out of date — convert it to WAV using a browser-based tool like M4A to WAV or OGG to WAV before importing.

Bit Depth Handling

Audacity's internal 32-bit float means bit depth conversions happen at export time, not during editing. The bit-depth dropdown in File > Export controls the output:

16-bit: CD-quality, standard for distribution (MP3 export is implicitly limited to 16-bit per encoder spec)
24-bit: standard for tracking, mixing, and mastering deliverables
32-bit float: for project-to-project handoff to other DAWs that support it (Pro Tools, Reaper, Logic)

Dithering options appear when downsampling from 32-bit float to 16-bit. Triangular dither is the safe default; shaped dither (TPDF noise-shaped) sounds slightly cleaner on quiet content.

Export Formats by Use Case

| Use case | Format | Settings | |---|---|---| | Personal archive | WAV | 44.1 kHz 16-bit | | Lossless archive (smaller) | FLAC | Level 5 (default) or Level 8 | | Podcast delivery | MP3 | 128 kbps CBR mono | | Audiobook (ACX) | MP3 | 192 kbps CBR mono, -23 to -18 dB RMS | | Music distribution | MP3 | V0 VBR (~245 kbps) or 320 kbps CBR | | Apple Podcasts AAC | M4A | 256 kbps AAC | | YouTube source | WAV or FLAC embedded in video | | Web Opus | OGG Opus | 96 kbps for music, 32 kbps for voice | | Sample for sampler | WAV | 48 kHz 24-bit |

MP3 Export: LAME Bundled

Audacity stopped requiring a separate LAME download in version 2.3.2 (2019). LAME is now bundled and MP3 export works immediately on a fresh install. The export dialog exposes:

Bitrate mode: Constant, Variable, Average
Quality preset: for VBR, q0 (best, ~245 kbps avg) through q9 (worst)
CBR bitrate: 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320 kbps
Channel mode: Joint stereo (default), Stereo, Mono
Force export to mono: required for ACX audiobook compliance

FLAC, OGG Vorbis, and Opus Export

All three are exported via Audacity's bundled libraries. FLAC defaults to compression level 5 (the official sweet spot); level 8 gives 1–3% better compression for ~5x the encoding time. OGG Vorbis quality 5 (~160 kbps) is the recommended setting for music. Opus uses VBR by default with bitrate selectable from 6 to 510 kbps — 96 kbps is transparent for music, 32 kbps for speech.

Recommended Workflow

1. Record or import source as WAV (or FLAC for lossless source) 2. Save the AUP3 project to keep edits non-destructive 3. Apply effects, edits, normalization 4. Export the master to WAV or FLAC for archive 5. From that master, export delivery formats (MP3 for distribution, M4A for Apple, etc.)

Keeping a clean WAV/FLAC master means future deliveries to new platforms encode from a high-quality source rather than compounding lossy generations.

Sample Rate Conversion in Audacity

Audacity 3.x uses libsoxr internally for high-quality sample rate conversion. The default Best Quality preset is essentially transparent for typical audio. Access via Tracks > Resample, or change the project rate at the bottom-left of the window for new tracks.

For collaborative workflows where stems arrive at mixed sample rates: conform on import (Audacity prompts when a clip's rate differs from the project rate), do all editing at the project rate, then export at the destination's required rate. Repeated SRC operations accumulate small artifacts; one well-placed conversion is cleaner than three.

For the broader picture on lossless masters, see PCM audio explained, what is PCM, and fix audio clicks and pops for cleanup workflows in Audacity.