CONVERT M4A → W64 (M4A to W64)
Fast, secure M4A to W64 conversion. No registration required.
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HOW TO CONVERT M4A → W64
Give us the M4A
Select a M4A (or several for batch). We read the header to pick decoder settings automatically.
Re-encode to W64
The audio is decoded, optionally resampled, and re-encoded as W64 at transparent default bitrate.
Retrieve your W64
Grab the download as soon as it is ready. Typical jobs finish in seconds for short clips.
Why this pair exists — M4A wraps AAC audio in an MP4 container, Apple's default for iTunes and voice memos. Ergo, the W64 route. Turn your M4A audio into a widely-supported W64 file. The conversion happens server-side through FFmpeg — the same engine behind every major audio editor — so the output plays cleanly on phones, car stereos, DJ software and streaming tools. Worth knowing: M4A wraps AAC audio in an MP4 container, Apple's default for iTunes and voice memos. Meanwhile W64 is an audio format with specific trade-offs between file size, bitrate flexibility, and device support.
Why convert M4A to W64
The motivation for a M4A → W64 conversion is almost always practical: a playback device, hosting platform or editing suite that insists on W64. The audio quality trade-off is controllable via bitrate; the compatibility win is immediate and unambiguous.
M4A vs W64 — Technical specifications
Side-by-side comparison of the technical details.
M4A
- MIME type
- audio/mp4
- Extension
- .m4a (and .m4b for audiobooks, .m4p for legacy DRM)
- Container
- ISO Base Media File Format (ISOBMFF)
- Codecs
- AAC-LC, HE-AAC, ALAC
- Max sample rate
- 96 kHz
- MIME Type
- audio/mp4
- Category
- Audio Files
- Full Name
- M4A Audio
- Conversion Engine
- FFMPEG
W64
- MIME type
- audio/x-w64
- Extension
- .w64
- MIME Type
- audio/x-w64
- Category
- Audio Files
- Full Name
- Sony Wave64
- Conversion Engine
- FFMPEG
- Max size
- 2^64 bytes
- Relative
- RF64 (EBU 64-bit WAV)
| Specification | M4A | W64 |
|---|---|---|
| MIME type | audio/mp4 | audio/x-w64 |
| Extension | .m4a (and .m4b for audiobooks, .m4p for legacy DRM) | .w64 |
| Container | ISO Base Media File Format (ISOBMFF) | — |
| Codecs | AAC-LC, HE-AAC, ALAC | — |
| Max sample rate | 96 kHz | — |
| MIME Type | audio/mp4 | audio/x-w64 |
| Category | Audio Files | Audio Files |
| Full Name | M4A Audio | Sony Wave64 |
| Conversion Engine | FFMPEG | FFMPEG |
| Max size | — | 2^64 bytes |
| Relative | — | RF64 (EBU 64-bit WAV) |
M4A vs W64 — Strengths and limitations
What each format does best, and where it falls short.
M4A Strengths
- Superior audio quality to MP3 at the same bitrate (AAC codec).
- Native support across Apple, iOS, Android, and Windows.
- Carries rich metadata: album art, chapters, lyrics, podcast bookmarks.
- Same container as MP4 — tooling overlaps with video workflows.
- Lossless variant (ALAC inside M4A) for audiophile archiving.
Limitations
- AAC patents still active in some jurisdictions — licensing fees apply for encoders.
- Seeking in variable-bitrate M4As can drift without an index atom.
- Less universal than MP3 on older hardware (pre-2010 car stereos, cheap MP3 players).
W64 Strengths
- Unlimited file size (64-bit chunks).
- Professional DAW compatibility.
- Bit-exact lossless.
Limitations
- Less universal than WAV.
- Niche — only matters for very large sessions.
- Competes with RF64.
Quality & Compatibility
The W64 output is as good as the M4A source allows. If the M4A was encoded at 96 kbps, the W64 cannot reconstruct detail the encoder already dropped; picking a very high W64 bitrate just produces a larger file. Match W64 bitrate to the M4A quality for the best balance.
Tips for Best Results
- Sample-rate mismatches between M4A and target device (48 kHz phone output from a 44.1 kHz track) are handled automatically; no manual resampling needed.
- For audiobook delivery, match the platform spec exactly — ACX requires 192 kbps CBR 44.1 kHz stereo, for example.
- Batch-convert an album in one job so every track shares identical encoder settings and loudness normalisation.
Frequently Asked Questions
Lossy-to-lossy conversions (most combinations) re-compress the audio, which technically introduces some loss. At a 192 kbps or higher target it is inaudible on normal equipment. Lossy-to-lossless conversions freeze the existing quality but cannot improve it; lossless-to-lossy transcodes are only as good as the target bitrate you choose.
For voice content (podcasts, audiobooks, lectures) 128 kbps is indistinguishable from higher bitrates. For music, 192-256 kbps covers most listening; 320 kbps is the ceiling for W64 and the right choice for audio you plan to edit further. Above that, prefer a lossless target instead.
Yes. Title, artist, album, year and cover art travel from the M4A container to the W64 container automatically where both formats support them. If a tag field has no W64 equivalent, it is dropped silently. Use any tag editor (Mp3tag, MusicBrainz Picard) to fine-tune afterwards.
M4A Audio
Source formatM4A is an MPEG-4 audio container typically containing AAC or ALAC encoded audio. It is the standard format for iTunes purchases and Apple Music downloads.
Sony Wave64
Target formatWave64 (W64) is an extension of the WAV format developed by Sony that breaks the 4 GB file size limit of standard WAV by using 64-bit chunk sizes. It is used in professional audio production for very long or multi-channel recordings.
Going the other way? Convert W64 back to M4A with the same engine.
Common Use Cases
Share across platforms
Send W64 files to anyone without worrying about whether they have the right software for M4A.
Embed in documents
Drop W64 output into Word, Google Docs, PowerPoint, Notion or a website without conversion warnings.
Optimize size
W64 often produces smaller files than M4A for web, email and storage.
Archive & future-proof
Store in a widely-supported format that will still open on future operating systems without legacy plugins.
M4A vs W64 — Typical file sizes
Approximate file sizes for common scenarios.
- 4-minute song (AAC 128 kbps) 4-5 MB
- 4-minute song (AAC 256 kbps) 8-10 MB
- 1-hour podcast (64 kbps) 28 MB
- 1-hour 24-bit 48 kHz mono ~620 MB
- 48-hour field recording ~30 GB
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Related comparisons
See these formats side by side to understand which fits your use case best.
Related Guides
M4A Format: MPEG-4 Audio — Apple Lossless, AAC & iTunes Explained
Learn what M4A files are, the difference between AAC and ALAC inside M4A, why Apple uses M4A instead of MP3, and how to convert M4A to MP3, FLAC, or WAV.
Read guide →M4A Files: MPEG-4 Audio Container — AAC, ALAC, and Conversion Guide
Complete guide to M4A files — AAC-LC vs ALAC content, quality comparison with MP3, gapless playback, FFmpeg conversion to MP3/FLAC/WAV/Opus, metadata...
Read guide →How to Convert M4A to MP3 — The iTunes Audio Format Explained
Convert M4A (AAC) files to MP3 without losing quality. What M4A is, why Apple uses it, differences from MP3, DRM issues, and all conversion methods.
Read guide →
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