Extract Audio from MOV to VOC — Free Online Tool
Extract audio from MOV files and save it as VOC format — the classic Sound Blaster audio container used in DOS-era games and multimedia applications. This tool strips the video stream and converts the MOV audio track (typically AAC) to raw PCM data encoded in the 8-bit unsigned format that Creative Labs' VOC standard requires.
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FFmpeg Command
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Estimated output:
Conversion Complete!
DownloadHow It Works
MOV files typically carry AAC-encoded audio alongside a video stream. During this conversion, FFmpeg discards the video entirely using the -vn flag, then decodes the AAC (or whatever audio codec is present in the MOV) and re-encodes it as 8-bit unsigned PCM (pcm_u8) — the native encoding for VOC files. This is a full audio transcode, not a remux, because VOC is a raw PCM container with no support for compressed codecs like AAC or MP3. The output is a headerless-style VOC file with Creative Labs block structure, carrying uncompressed 8-bit audio samples. Be aware that downsampling from AAC (typically 16-bit or higher source quality) to 8-bit unsigned PCM introduces noticeable quantization noise and a reduction in dynamic range — this is inherent to the VOC format's limitations, not a tool deficiency.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg command-line tool. In the browser version of this tool, FFmpeg runs locally via WebAssembly (FFmpeg.wasm) — no files leave your machine. |
-i input.mov
|
Specifies the input file — a MOV container that may carry video (typically H.264/libx264) and audio (typically AAC). FFmpeg reads the container structure and identifies all available streams before processing. |
-vn
|
Disables video output entirely. Since VOC is a pure audio format with no video support, this flag tells FFmpeg to ignore and discard the video stream from the MOV rather than attempt to encode it. |
-c:a pcm_u8
|
Sets the audio codec to 8-bit unsigned PCM — the native and most historically authentic encoding for VOC files. FFmpeg fully decodes the MOV's AAC audio and re-encodes it as raw 8-bit unsigned PCM samples, which is the only format widely compatible with the Creative Labs VOC specification and DOS Sound Blaster playback. |
output.voc
|
Specifies the output filename with the .voc extension, which signals FFmpeg to use its VOC muxer. FFmpeg writes the Creative Labs VOC file header and wraps the pcm_u8 audio data in the correct block structure expected by DOS-era applications and emulators like DOSBox. |
Common Use Cases
- Preparing sound effects or music for a retro DOS game project that requires VOC-format audio assets compatible with Sound Blaster playback routines
- Converting recorded voiceover or dialogue from a MOV screen capture into VOC format for use in a DOSBox-based game mod or fan-made classic game
- Archiving or recreating original Sound Blaster audio assets by converting modern MOV-sourced recordings into period-accurate 8-bit VOC files
- Extracting ambient audio or music from a MOV video clip to use as a sound asset in a retro game engine or demoscene project that mandates VOC input
- Testing or debugging legacy multimedia software that specifically reads VOC files by supplying freshly converted audio from a MOV source
- Generating VOC-format sound bites for use with hardware Sound Blaster cards in vintage PC preservation setups
Frequently Asked Questions
Yes, and substantially so. VOC's pcm_u8 codec stores audio as 8-bit unsigned PCM, which gives only 256 discrete amplitude levels and produces audible quantization noise and a dynamic range of roughly 48 dB. MOV files typically contain AAC audio, which is a high-quality lossy codec designed for modern playback at effectively much higher perceived fidelity. Downconverting to 8-bit unsigned PCM is an irreversible quality reduction that is characteristic of the VOC format itself — it was designed for late-1980s and early-1990s Sound Blaster hardware, not modern audio fidelity requirements.
VOC files are not natively supported by modern operating systems' built-in media players (Windows Media Player, macOS QuickTime, etc.), but they can be played using media players that include legacy format support, such as VLC or Audacity. Their primary practical use today is within DOSBox, vintage PC emulators, or retro game engines that implement the Creative Labs VOC specification. If you need the audio for modern use, formats like WAV or FLAC would be far more appropriate.
Early VOC versions supported only mono audio, though later extensions of the format (VOC block type 9) do support stereo. FFmpeg's VOC muxer has limited stereo support, and pcm_u8 output may default to mono depending on the source channel configuration. If your MOV contains stereo audio and stereo VOC output is critical, you may need to explicitly specify channel parameters. In most retro gaming contexts, mono output is expected and correct.
The AAC audio is fully decoded to raw PCM in memory and then re-encoded as 8-bit unsigned PCM (pcm_u8) for the VOC container. There is no way to copy-paste or remux AAC directly into a VOC file because VOC only supports raw PCM audio — it has no mechanism for compressed codecs. This means the conversion always involves a full decode-and-re-encode cycle for the audio, regardless of the source bitrate or quality.
You can add the -ar flag followed by a sample rate to control the output sample rate — for example, 'ffmpeg -i input.mov -vn -c:a pcm_u8 -ar 22050 output.voc' would resample the audio to 22050 Hz, a common rate for Sound Blaster VOC files in DOS games. Original DOS-era VOC files were frequently recorded at 8000 Hz, 11025 Hz, or 22050 Hz. FFmpeg will default to preserving the source sample rate, which may be 44100 Hz or 48000 Hz from the MOV — higher than many retro systems could handle.
Yes. On Linux or macOS, you can run a shell loop: 'for f in *.mov; do ffmpeg -i "$f" -vn -c:a pcm_u8 "${f%.mov}.voc"; done'. On Windows Command Prompt, use: 'for %f in (*.mov) do ffmpeg -i "%f" -vn -c:a pcm_u8 "%~nf.voc"'. The browser-based tool processes one file at a time, but the FFmpeg command shown can be adapted for bulk processing on your local machine, which is also practical for MOV files larger than the 1 GB browser limit.
Technical Notes
VOC is one of the oldest structured audio file formats still in occasional use, developed by Creative Labs alongside the Sound Blaster ISA card in 1989. It uses a block-based structure with a file header identifying it as a Creative Labs Voice file, followed by typed data blocks carrying PCM samples and metadata. FFmpeg supports writing VOC files with pcm_u8 (8-bit unsigned PCM) and pcm_s16le (16-bit signed PCM) codecs — the default pcm_u8 is the most historically authentic and the most constrained in quality. MOV, by contrast, is a richly featured professional container that can carry multi-track audio, chapter markers, and subtitles; all of this metadata is discarded in the output VOC since the format has no mechanism for storing it. If your MOV contains multiple audio tracks, FFmpeg will by default select the first audio stream; you can use -map 0:a:1 (or another index) to select a specific track before conversion. There is no audio quality parameter to tune for this conversion — VOC with pcm_u8 always stores raw 8-bit samples, so the only meaningful variables are sample rate (-ar) and channel count (-ac). Files will typically be significantly larger per second of audio than AAC-compressed MOV audio, but smaller than lossless 16-bit or 24-bit formats due to the 8-bit depth limitation.