CONVERT W64 → GSM (W64 to GSM)
Fast, secure W64 to GSM conversion. No registration required.
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HOW TO CONVERT W64 → GSM
Give us the W64
Select a W64 (or several for batch). We read the header to pick decoder settings automatically.
Re-encode to GSM
The audio is decoded, optionally resampled, and re-encoded as GSM at transparent default bitrate.
Retrieve your GSM
Grab the download as soon as it is ready. Typical jobs finish in seconds for short clips.
Why this pair exists — W64 is an audio format with specific trade-offs between file size, bitrate flexibility, and device support. Ergo, the GSM route. Turn your W64 audio into a widely-supported GSM 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. Keep in mind W64 is an audio format with specific trade-offs between file size, bitrate flexibility, and device support. And remember that GSM is an audio format with specific trade-offs between file size, bitrate flexibility, and device support.
Why convert W64 to GSM
The motivation for a W64 → GSM conversion is almost always practical: a playback device, hosting platform or editing suite that insists on GSM. The audio quality trade-off is controllable via bitrate; the compatibility win is immediate and unambiguous.
W64 vs GSM — 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)
- MIME Type
- audio/x-w64
- Category
- Audio Files
- Full Name
- Sony Wave64
- Conversion Engine
- FFMPEG
GSM
- MIME type
- audio/gsm
- Extension
- .gsm
- MIME Type
- audio/gsm
- Category
- Audio Files
- Full Name
- GSM Audio
- Conversion Engine
- FFMPEG
- Codec
- GSM 06.10 (RPE-LTP)
- Sample rate
- 8 kHz
- Bitrate
- 13 kbps
| Specification | W64 | GSM |
|---|---|---|
| MIME type | audio/x-w64 | audio/gsm |
| Extension | .w64 | .gsm |
| Max size | 2^64 bytes | — |
| Relative | RF64 (EBU 64-bit WAV) | — |
| MIME Type | audio/x-w64 | audio/gsm |
| Category | Audio Files | Audio Files |
| Full Name | Sony Wave64 | GSM Audio |
| Conversion Engine | FFMPEG | FFMPEG |
| Codec | — | GSM 06.10 (RPE-LTP) |
| Sample rate | — | 8 kHz |
| Bitrate | — | 13 kbps |
W64 vs GSM — 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.
GSM Strengths
- Tiny bitrate (13 kbps) — hours of speech in a few MB.
- Speech-optimized — clear voice reproduction.
- Universal cellphone decoder adoption 1991-2015.
- Stable since 1987.
Limitations
- Speech-only — music sounds distorted.
- 8 kHz sampling — narrowband, muffled by modern standards.
- Legacy — LTE VoLTE moved to AMR-WB, Opus, or EVS.
Quality & Compatibility
The GSM output is as good as the W64 source allows. If the W64 was encoded at 96 kbps, the GSM cannot reconstruct detail the encoder already dropped; picking a very high GSM bitrate just produces a larger file. Match GSM bitrate to the W64 quality for the best balance.
Tips for Best Results
- Sample-rate mismatches between W64 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 GSM 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 GSM container automatically where both formats support them. If a tag field has no GSM equivalent, it is dropped silently. Use any tag editor (Mp3tag, MusicBrainz Picard) to fine-tune afterwards.
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.
GSM Audio
Target formatGSM 06.10 is a speech compression standard designed for the Global System for Mobile Communications. It encodes speech at 13 kbps using Regular Pulse Excitation with Long Term Prediction, optimized for voice intelligibility over cellular networks.
Going the other way? Convert GSM back to W64 with the same engine.
Common Use Cases
Share across platforms
Send GSM files to anyone without worrying about whether they have the right software for W64.
Embed in documents
Drop GSM output into Word, Google Docs, PowerPoint, Notion or a website without conversion warnings.
Optimize size
GSM 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 GSM — Typical file sizes
Approximate file sizes for common scenarios.
- 1-hour 24-bit 48 kHz mono ~620 MB
- 48-hour field recording ~30 GB
- 1 min of voice ~100 KB
- 1 hour voicemail archive ~6 MB
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Related comparisons
See these formats side by side to understand which fits your use case best.
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