Convert VOB to VOC — Free Online Tool
Convert VOB files from DVD-Video discs to VOC audio format, extracting the AC3/MPEG audio stream and encoding it as raw PCM (8-bit unsigned) compatible with the classic Creative Labs Sound Blaster format. Useful for pulling audio from DVD sources into retro DOS game toolchains or legacy multimedia applications.
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FFmpeg Command
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DownloadHow It Works
A VOB file is a multiplexed container holding MPEG-2 video, AC3 (Dolby Digital) audio, subtitle streams, and DVD navigation data. Converting to VOC is an audio-only extraction process: FFmpeg demuxes the VOB container, discards the video and subtitle streams entirely, decodes the AC3 audio, and re-encodes it as raw 8-bit unsigned PCM (pcm_u8) wrapped in the VOC container format developed by Creative Labs. The VOC format supports no metadata, no chapters, and only a single audio track — so all but the first audio stream are dropped. The output is a simple, headerless-style PCM audio file suitable for the Sound Blaster hardware ecosystem. Because VOC uses uncompressed PCM, there is no further lossy compression applied after the AC3 decode step, though the downconversion from AC3 (typically 16-bit or 24-bit) to 8-bit unsigned PCM does reduce dynamic range and audio fidelity significantly.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg command-line tool, which handles all demuxing, decoding, encoding, and muxing steps for this VOB-to-VOC conversion entirely within a single pass. |
-i input.vob
|
Specifies the input VOB file. FFmpeg will demux the DVD Video Object container, identifying the multiplexed MPEG-2 video, AC3 audio, and subtitle streams contained within it. |
-c:a pcm_u8
|
Sets the audio codec to 8-bit unsigned PCM, which is the native and default audio encoding for the VOC format. FFmpeg will decode the source AC3 audio from the VOB and re-encode it as raw uncompressed 8-bit PCM samples for the Sound Blaster-compatible VOC output. |
output.voc
|
Specifies the output filename with the .voc extension, which tells FFmpeg to use the Creative Labs VOC muxer. The output will contain only the single PCM audio stream; the video and subtitle streams from the VOB are automatically dropped because the VOC format is audio-only. |
Common Use Cases
- Extracting spoken dialogue or music from a DVD movie VOB file to use as a sound effect or voice sample in a retro DOS game or demoscene project
- Preparing audio assets from DVD-sourced VOB files for playback on vintage Sound Blaster hardware or DOSBox emulator environments that expect VOC files
- Converting DVD bonus disc audio commentary or narration tracks into VOC format for use in legacy interactive CD-ROM authoring tools that only accept VOC input
- Archiving audio content from personal home DVD recordings into the VOC format as part of a retro computing preservation workflow
- Testing or debugging Sound Blaster audio pipelines by supplying real-world DVD audio content in VOC format rather than synthetic test tones
Frequently Asked Questions
Yes, and it is significant. AC3 audio on DVDs is typically encoded at 16-bit depth, while pcm_u8 (8-bit unsigned PCM) provides only 256 discrete amplitude levels compared to 65,536 in 16-bit audio. This reduction in bit depth introduces audible quantization noise, reduced dynamic range, and a general 'lo-fi' quality. If fidelity matters, consider using the pcm_s16le codec option instead, which stores 16-bit signed PCM in the VOC file and preserves significantly more audio detail.
No. The VOC format supports only a single mono or stereo audio track with no provision for multichannel surround sound. FFmpeg will automatically downmix the AC3 stream (which may be 5.1 surround) to stereo or mono as required when encoding to pcm_u8. All secondary audio tracks present in the VOB file (e.g., dubbed language tracks) are also discarded — only the default first audio stream is used.
Both are silently discarded. FFmpeg extracts only the first audio stream from the VOB and encodes it to PCM for the VOC output. The MPEG-2 video stream, DVD subtitle/subpicture streams, and any menu navigation data present in the VOB are not processed or preserved in any form. The resulting VOC file is audio-only.
Replace the codec flag in the command: run 'ffmpeg -i input.vob -c:a pcm_s16le output.voc'. The pcm_s16le codec encodes 16-bit signed little-endian PCM, which matches the native bit depth of most DVD audio and avoids the severe quality degradation of 8-bit encoding. Note that not all legacy applications expecting VOC files will handle 16-bit VOC correctly, so test compatibility with your target software or hardware.
Yes, using a shell loop. On Linux or macOS: 'for f in *.vob; do ffmpeg -i "$f" -c:a pcm_u8 "${f%.vob}.voc"; done'. On Windows Command Prompt: 'for %f in (*.vob) do ffmpeg -i "%f" -c:a pcm_u8 "%~nf.voc"'. Each VOB file is processed independently, and FFmpeg will extract and convert the first audio stream from each. This is particularly useful for processing individual chapter VOB files from a ripped DVD (e.g., VTS_01_1.vob, VTS_01_2.vob).
VOB files are highly compressed — the MPEG-2 video typically dominates file size, and AC3 audio is also a compressed lossy format. When you extract only the audio and store it as uncompressed PCM in VOC, you are removing the large video stream entirely, which dramatically reduces file size. However, the audio portion itself may actually grow because raw PCM is uncompressed compared to AC3. A typical DVD chapter VOB of 1GB might yield a VOC file of only a few hundred megabytes representing just the audio duration.
Technical Notes
The VOC format was designed by Creative Labs in the early 1990s for the Sound Blaster ISA card and has hard limitations that make it a poor general-purpose archive format but an appropriate target for retro computing workflows. It supports only PCM audio (pcm_u8 or pcm_s16le in FFmpeg), has no support for metadata tags, chapters, or multiple tracks, and its sample rate support is limited to values compatible with the original Sound Blaster hardware (commonly 8000, 11025, 22050, or 44100 Hz). FFmpeg will pass through whatever sample rate the source AC3 stream uses (typically 48000 Hz for DVD), which may cause compatibility issues with older VOC players or DOS software expecting lower sample rates — you can add '-ar 22050' or '-ar 44100' to the command to resample. The VOB source format uses the special '-f vob' demux flag internally to handle DVD sector alignment correctly. Because VOB files on a DVD disc are split into 1GB chunks (VTS_01_1.vob, VTS_01_2.vob, etc.), for full-length audio extraction you may need to concatenate them first using FFmpeg's concat demuxer before running this conversion.