Extract Audio from AVI to VOC — Free Online Tool
Extract audio from AVI video files and save it as a VOC file — the retro Creative Labs format used in classic DOS games and Sound Blaster applications. The conversion decodes the AVI's audio stream (typically MP3 or AAC) and re-encodes it as uncompressed 8-bit PCM, producing a VOC file compatible with vintage multimedia software and DOS-era tools.
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FFmpeg Command
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Estimated output:
Conversion Complete!
DownloadHow It Works
This conversion strips the video stream entirely from the AVI container and extracts only the audio track. Because VOC is a raw PCM format with no support for compressed codecs like MP3 or AAC (which are common in AVI files), FFmpeg must fully decode the AVI's audio stream and then re-encode it as unsigned 8-bit PCM (pcm_u8). This is a lossy-to-lossless transformation in the sense that the audio is decoded from its compressed form and written out as uncompressed samples — but the 8-bit depth of pcm_u8 is itself a significant quality ceiling. The resulting VOC file carries no video data, no chapters, and no metadata beyond what the basic VOC format header supports.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg program, which handles all media reading, stream processing, codec decoding and encoding, and file writing for this conversion. |
-i input.avi
|
Specifies the input AVI file. FFmpeg reads the AVI container, identifies its interleaved video and audio streams, and makes them available for processing — in this case, the audio stream will be decoded from its original codec (commonly libmp3lame or AAC in AVI files). |
-vn
|
Disables video output entirely, telling FFmpeg to ignore the AVI's video stream. Since VOC is a pure audio format with no capacity to store video data, this flag ensures only the audio track is processed and no errors occur from attempting to mux video into the output. |
-c:a pcm_u8
|
Sets the audio codec to unsigned 8-bit PCM, which is the native and most widely compatible codec for VOC files. This re-encodes the decoded AVI audio — regardless of whether it was MP3, AAC, or Vorbis — into raw 8-bit uncompressed samples matching the original Sound Blaster VOC specification. |
output.voc
|
Specifies the output filename and triggers FFmpeg to use the VOC muxer based on the '.voc' file extension. FFmpeg writes the pcm_u8 encoded audio into a properly structured VOC container with the required Creative Labs header and block format. |
Common Use Cases
- Supplying custom sound effects or music to a DOS game or demoscene project that expects audio in VOC format for Sound Blaster playback
- Extracting dialogue or ambient audio from an old AVI recording of DOS-era software or gameplay footage to use in a retro multimedia presentation
- Creating VOC audio assets for use with DOSBox, where games and applications load sound effects directly from VOC files on a virtual drive
- Converting AVI-sourced audio for use with legacy Creative Labs tools or vintage Sound Blaster hardware that only accepts VOC input
- Archiving the audio track of an AVI file in a historically accurate format for a retro computing or digital preservation project
- Generating VOC format audio clips from modern AVI recordings to test or demonstrate vintage audio playback software and emulators
Frequently Asked Questions
Yes, and it is worth understanding why. The default output codec is pcm_u8 — unsigned 8-bit PCM — which has a dynamic range of only 48 dB, far below the 96 dB of 16-bit audio. If your AVI contains high-quality MP3 or AAC audio, the decoded signal will be quantized down to 8-bit depth during encoding, which introduces audible noise and reduces clarity. This is an inherent limitation of the VOC format's pcm_u8 codec, not a limitation of the tool itself.
Yes. The VOC format also supports signed 16-bit little-endian PCM (pcm_s16le), which provides significantly better audio fidelity with 96 dB of dynamic range. To use it, modify the FFmpeg command to '-c:a pcm_s16le' instead of '-c:a pcm_u8'. Not all VOC players and legacy tools support 16-bit VOC files, so check your target application's compatibility before switching.
The '-vn' flag stands for 'video none' and tells FFmpeg to discard the video stream entirely rather than attempting to include it in the output. VOC is a pure audio container — it has no provision for storing video data — so without '-vn', FFmpeg might throw an error or attempt to process the video stream unnecessarily. Including it makes the command explicit and efficient.
No. The VOC format has an extremely minimal header structure defined by the original Creative Labs specification and does not support embedded metadata tags like artist, title, or album. Any ID3-style or RIFF INFO metadata present in the source AVI file will be lost during this conversion. If metadata preservation is important, consider an alternative audio format like FLAC or WAV.
The displayed command processes a single file, but you can batch process on the command line using a shell loop. On Linux or macOS, you can run: for f in *.avi; do ffmpeg -i "$f" -vn -c:a pcm_u8 "${f%.avi}.voc"; done. On Windows Command Prompt, use: for %f in (*.avi) do ffmpeg -i "%f" -vn -c:a pcm_u8 "%~nf.voc". The browser-based tool processes one file at a time.
AVI technically supports multiple audio streams, though it is uncommon. If your AVI has multiple audio tracks, FFmpeg will by default select the first audio stream (stream index 0) for extraction. To select a different track, add '-map 0:a:1' to the command to pick the second audio track, adjusting the index as needed. Since VOC does not support multiple audio tracks, only one stream can be written to the output.
Technical Notes
VOC is one of the oldest structured audio formats still in practical use within retro computing communities, originally designed by Creative Labs for the Sound Blaster ISA card in the early 1990s. The format encodes audio as a series of typed data blocks, with the actual sample data stored as raw PCM. The default pcm_u8 codec uses unsigned 8-bit samples with a mid-point at 128, which is historically consistent with Sound Blaster hardware but means audio from a modern AVI — likely encoded at 16-bit or higher — will undergo significant bit-depth reduction. There is no audio quality parameter to tune in this conversion because VOC with pcm_u8 has no bitrate control; it is a fixed, uncompressed format determined entirely by the sample rate and bit depth. The sample rate of the output will match the source AVI's audio sample rate unless you explicitly resample with '-ar'. Common Sound Blaster-compatible rates are 8000, 11025, 22050, and 44100 Hz. VOC files do not support stereo in all legacy contexts — some old software and hardware expects mono VOC data — so if stereo compatibility is a concern, add '-ac 1' to the command to downmix to mono.