Convert WMA to VOC — Free Online Tool
Convert WMA audio files to VOC format using FFmpeg in your browser — decoding Microsoft's wmav2 codec and re-encoding to uncompressed PCM (pcm_u8) for full compatibility with Creative Labs Sound Blaster applications and classic DOS environments. No file uploads required; everything runs locally via WebAssembly.
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FFmpeg Command
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Note: Browser-based encoding uses approximate quality targets. For precise CRF compression, copy the FFmpeg command above and run it on your desktop.
Estimated output:
Conversion Complete!
DownloadHow It Works
WMA files store audio as lossy compressed data using Microsoft's wmav2 (or wmav1) codec, which is decoded in full during this conversion. The resulting raw PCM audio is then encoded into the VOC container format using unsigned 8-bit PCM (pcm_u8) — the native audio encoding of the Creative Labs Sound Blaster standard. Because VOC does not support any form of compressed audio, a full decode-then-encode pipeline is always performed. This means the lossy compression artifacts already present in the WMA source are baked into the final output; the PCM stage does not restore lost audio detail, but it does produce a bit-exact, uncompressed representation of whatever audio information survived the original WMA encoding. The output file will be significantly larger than the WMA source due to the switch from compressed to raw PCM storage.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg multimedia processing tool, which handles the full pipeline of demuxing the WMA container, decoding the wmav2 audio stream, and encoding the output as uncompressed PCM inside a VOC container. |
-i input.wma
|
Specifies the input file — a WMA audio file typically encoded with the wmav2 codec. FFmpeg reads and demuxes the WMA container to extract the compressed audio stream for decoding. |
-c:a pcm_u8
|
Sets the audio codec for the output to unsigned 8-bit PCM, which is the default and most broadly compatible audio encoding supported by the VOC format. This produces raw, uncompressed samples suitable for Sound Blaster playback and DOS-era applications. |
output.voc
|
Defines the output filename with the .voc extension, which signals FFmpeg to use the VOC muxer — the Creative Labs Sound Blaster container format. The file will contain a standard VOC header followed by raw pcm_u8 audio data blocks. |
Common Use Cases
- Preparing audio assets for retro DOS game modding or development, where the game engine only accepts Sound Blaster VOC files natively
- Converting a WMA music or sound effect file to VOC so it can be loaded by classic multimedia authoring tools like early versions of Asymetrix Toolbook or DOS-based presentation software
- Migrating a WMA audio archive to VOC for playback on period-accurate emulators such as DOSBox, which natively supports VOC audio without additional codec configuration
- Extracting and converting WMA voice lines or sound effects into VOC format for use in demoscene productions targeting authentic Sound Blaster hardware
- Providing an uncompressed PCM version of a WMA file in the VOC container for use in embedded or legacy systems that parse the VOC chunk structure but cannot handle modern compressed codecs
- Creating test audio assets in VOC format from existing WMA recordings for QA testing of retro audio playback libraries or emulation software
Frequently Asked Questions
No — the conversion will not recover any audio quality lost during the original WMA encoding. WMA uses lossy compression, meaning certain audio information is permanently discarded when the WMA file is created. When FFmpeg decodes the WMA and writes uncompressed pcm_u8 to a VOC file, it captures exactly what the lossy decoder produces — artifacts and all. The VOC file is a lossless container in the sense that it stores PCM data without further compression, but it cannot undo the losses already introduced by the WMA codec.
WMA files use lossy compression that can reduce file size by a factor of 10 or more compared to raw audio. VOC stores audio as uncompressed 8-bit PCM samples, meaning every sample is written without any compression whatsoever. For example, a 4 MB WMA file at 128 kbps could expand to 40 MB or more as a VOC file, depending on the audio duration and sample rate. This is an inherent consequence of moving from a compressed format to a raw PCM container.
pcm_u8 is unsigned 8-bit pulse-code modulation — each audio sample is represented as a single byte with 256 possible values. WMA files are typically decoded at much higher bit depths (16-bit or 32-bit float internally), so encoding the output as pcm_u8 introduces quantization noise on top of any existing WMA compression artifacts. If fidelity relative to the WMA source matters, you could modify the FFmpeg command to use pcm_s16le instead of pcm_u8, which is the other codec supported by the VOC format and provides 16-bit resolution.
No. The VOC format does not support metadata tags of any kind. WMA files can carry rich metadata including title, artist, album, and DRM information via Windows Media metadata fields, but none of this is transferable to a VOC container. If you need to retain metadata, you should save it separately before converting, as it will be silently dropped during the FFmpeg conversion process.
Replace pcm_u8 with pcm_s16le in the command: ffmpeg -i input.wma -c:a pcm_s16le output.voc. This instructs FFmpeg to encode the VOC file using signed 16-bit little-endian PCM, which is the other audio codec supported by the VOC format. The 16-bit version provides significantly better dynamic range (96 dB vs roughly 48 dB for 8-bit) and will more faithfully represent the decoded WMA audio, at the cost of doubling the output file size.
The single-file command shown on this page processes one file at a time, but you can adapt it for batch conversion using shell scripting. On Linux or macOS, run: for f in *.wma; do ffmpeg -i "$f" -c:a pcm_u8 "${f%.wma}.voc"; done. On Windows Command Prompt, use: for %f in (*.wma) do ffmpeg -i "%f" -c:a pcm_u8 "%~nf.voc". This loops over every WMA file in the current directory and produces a corresponding VOC file for each one.
Technical Notes
The VOC format was designed in the early 1990s specifically for the Creative Labs Sound Blaster ISA card and supports only uncompressed PCM audio — either unsigned 8-bit (pcm_u8) or signed 16-bit little-endian (pcm_s16le). Because WMA carries DRM support as a listed feature, be aware that DRM-protected WMA files cannot be decoded by FFmpeg at all; only DRM-free WMA files will convert successfully. The sample rate of the output VOC file will match the input WMA stream's sample rate, though very high sample rates (above 44100 Hz) may not be supported by all legacy VOC-consuming applications. Stereo audio is technically supported by the VOC format but older playback tools and hardware may only play back mono; if compatibility with real Sound Blaster hardware is required, consider adding -ac 1 to the command to downmix to mono. The VOC file structure uses a simple chunk-based layout with a fixed 26-byte header, making it easy to parse but offering no support for chapters, multiple tracks, or subtitles — all of which are equally absent from the WMA side of this conversion.