CONVERT
W64 → M4A
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Fast, secure W64 to M4A conversion. No registration required.
Why this pair exists — W64 is an audio format with specific trade-offs between file size, bitrate flexibility, and device support. Ergo, the M4A route. Need a M4A version of a W64 recording for a podcast host, audio book platform or DAW that refuses the original container? Drop the file above and our encoder produces a clean M4A you can drag straight into the destination tool. Metadata such as title, artist and cover art travels with the audio. Context: W64 is an audio format with specific trade-offs between file size, bitrate flexibility, and device support. M4A wraps AAC audio in an MP4 container, Apple's default for iTunes and voice memos.
Sony Wave64
Source 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.
M4A Audio
Target 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.
Why convert W64 to M4A
Sony Wave64 is great in its own niche, but M4A Audio is either more universally playable or better suited to the device you are targeting. Converting lets you ship the audio without asking listeners to install a codec. The loss in quality between the two is negligible at sensible bitrates.
HOW TO CONVERT
W64 → M4A
Upload the W64
Drop or select your W64 file. The upload is encrypted and the file is queued for conversion.
Transcode via FFmpeg
FFmpeg decodes the W64 stream to PCM internally, then re-encodes as M4A at the bitrate you select.
Download the M4A
The M4A is delivered as a direct download; metadata and cover art transfer automatically where possible.
Common Use Cases
Share across platforms
Send M4A files to anyone without worrying about whether they have the right software for W64.
Embed in documents
Drop M4A output into Word, Google Docs, PowerPoint, Notion or a website without conversion warnings.
Optimize size
M4A often produces smaller files than W64 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.
W64 vs M4A — Strengths and limitations
What each format does best, and where it falls short.
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.
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 vs M4A — Technical specifications
Side-by-side comparison of the technical details.
W64
- MIME type
- audio/x-w64
- Extension
- .w64
- Max size
- 2^64 bytes
- Relative
- RF64 (EBU 64-bit WAV)
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
| Specification | W64 | M4A |
|---|---|---|
| MIME type | audio/x-w64 | audio/mp4 |
| Extension | .w64 | .m4a (and .m4b for audiobooks, .m4p for legacy DRM) |
| Max size | 2^64 bytes | — |
| Relative | RF64 (EBU 64-bit WAV) | — |
| Container | — | ISO Base Media File Format (ISOBMFF) |
| Codecs | — | AAC-LC, HE-AAC, ALAC |
| Max sample rate | — | 96 kHz |
W64 vs M4A — Typical file sizes
Approximate file sizes for common scenarios.
W64
- 1-hour 24-bit 48 kHz mono ~620 MB
- 48-hour field recording ~30 GB
M4A
- 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
- 4-minute song (Apple Lossless) 25-35 MB
Quality & Compatibility
Lossy-to-lossy transcoding (most cross-format audio jobs) loses a tiny amount of quality on each pass — usually inaudible at our default VBR ~190 kbps for music or 96 kbps for speech. Lossy-to-lossless conversions freeze the existing quality but cannot improve it; lossless-to-lossy is only as good as the target bitrate you choose.
Tips for Best Results
- Pick 128 kbps for podcasts and voice, 192–256 kbps for music, 320 kbps only if the audio will be edited further downstream.
- Keep the W64 master alongside the M4A — re-encoding a lossy format twice accumulates audible artefacts.
- For mono voice content, convert to mono M4A explicitly to halve file size without any quality loss.
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 M4A 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 W64 container to the M4A container automatically where both formats support them. If a tag field has no M4A equivalent, it is dropped silently. Use any tag editor (Mp3tag, MusicBrainz Picard) to fine-tune afterwards.
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Related Guides
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Read guideM4A Files: MPEG-4 Audio Container — AAC, ALAC, and Conversion Guide
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Read guideM4A to MP3 Conversion Guide: Best Methods for Every Platform
Convert M4A audio files from Apple to MP3 with our complete guide. Covers iTunes, FFmpeg, online tools, and batch conversion with quality settings explained.
Read guideSecure & Private Conversion
Your files are encrypted during transfer, processed in isolated containers, and automatically deleted within 60 minutes. We never read, share, or store your data.