Extract Audio from VOB to VOC — Free Online Tool
Extract audio from DVD VOB files and save it as a VOC file — the retro PCM audio format developed by Creative Labs for Sound Blaster cards. This tool decodes the AC3 (Dolby Digital) audio stream from your VOB file and converts it to raw unsigned 8-bit PCM, which is the native format for VOC files used in classic DOS games and multimedia applications.
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FFmpeg Command
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Estimated output:
Conversion Complete!
DownloadHow It Works
VOB files from DVD discs typically carry AC3 (Dolby Digital) audio encoded at 192–448 kbps, multiplexed alongside MPEG-2 video and subtitle streams. During this conversion, FFmpeg discards the video and subtitle streams entirely using the -vn flag, then decodes the AC3 audio to raw PCM and re-encodes it as unsigned 8-bit PCM (pcm_u8) — the default and most widely compatible codec for the VOC container. The VOC format, designed in the early 1990s for Creative Labs Sound Blaster cards, is a simple chunk-based container that stores raw PCM audio with a basic header. Because pcm_u8 operates at 8-bit depth, this is a significant downgrade in bit depth from the 16-bit or 24-bit fidelity in the original AC3 stream, though the sample rate is preserved. The output file will be substantially smaller than the original VOB, but audio quality will reflect the 8-bit limitation inherent to the VOC format.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool, which handles the full pipeline of demuxing the VOB container, decoding the AC3 audio stream, and encoding the output to VOC format. |
-i input.vob
|
Specifies the input VOB file — a DVD Video Object that typically contains multiplexed MPEG-2 video, AC3 Dolby Digital audio, and optional subtitle streams. FFmpeg's VOB demuxer handles the MPEG program stream structure used in this format. |
-vn
|
Disables all video output streams, ensuring that the MPEG-2 video data from the VOB is completely discarded and only the audio stream is processed into the output VOC file. |
-c:a pcm_u8
|
Encodes the decoded audio as unsigned 8-bit PCM — the default and most historically authentic codec for the VOC format, matching the original Sound Blaster hardware capabilities that the VOC format was designed for. |
output.voc
|
Specifies the output file in VOC format. FFmpeg infers the VOC container from the .voc file extension and writes the chunk-based VOC structure with a pcm_u8 audio data block, compatible with Sound Blaster-era playback software and modern retro emulators. |
Common Use Cases
- Extracting DVD audio to load into a retro DOS game engine or emulator that requires VOC sound assets, such as DOSBox-based projects or ScummVM custom asset replacements
- Converting DVD commentary tracks or dialogue recordings into VOC files for use in vintage Sound Blaster-compatible hardware or period-accurate multimedia demos
- Archiving or restoring classic multimedia CD-ROM titles that originally shipped with VOC audio, by sourcing replacement audio from DVD-quality VOB files
- Preparing audio samples from DVD concert footage or film scores for use in retro tracker music software (like MOD/XM composers) that supports VOC sample import
- Extracting a specific audio track from a multi-track DVD VOB for integration into a legacy game modding project that expects 8-bit unsigned PCM VOC assets
- Testing FFmpeg's VOC muxer output against a reference Sound Blaster playback environment to validate audio pipeline compatibility in retro computing development
Frequently Asked Questions
Yes, and it is significant. The original AC3 audio in a VOB file typically operates at 16-bit depth or higher with full Dolby Digital encoding. VOC files using the pcm_u8 codec store audio at only 8 bits per sample, which means a theoretical dynamic range of about 48 dB — far below the ~96 dB of 16-bit audio. You will likely notice a reduction in clarity, increased background noise (quantization noise), and a flattening of dynamic range compared to the source. If you need higher fidelity, consider whether your target application can accept a WAV or AIFF file instead, as those support 16-bit PCM without the VOC format's historical constraints.
Yes. DVD VOB files often contain multiple audio streams — for example, separate tracks for different languages or a director's commentary. By default, FFmpeg selects the first detected audio stream. To choose a specific stream, add the flag -map 0:a:1 to select the second audio track (zero-indexed), or -map 0:a:2 for the third, and so on. The full command would look like: ffmpeg -i input.vob -vn -map 0:a:1 -c:a pcm_u8 output.voc. Use ffmpeg -i input.vob to inspect all available streams before deciding which to extract.
Yes, FFmpeg supports the pcm_s16le codec for VOC output, which stores audio as signed 16-bit little-endian PCM — significantly better quality than the default 8-bit unsigned PCM. To use it, change the command to: ffmpeg -i input.vob -vn -c:a pcm_s16le output.voc. However, be aware that not all VOC players or legacy applications support 16-bit VOC files, as many Sound Blaster-era tools were designed specifically around 8-bit unsigned PCM. If your target environment is a modern retro emulator, 16-bit support is usually fine; for authentic vintage hardware, stick with pcm_u8.
No. The VOC format has virtually no metadata support — it is a minimal chunk-based container designed purely for raw PCM audio playback on Sound Blaster hardware, with no provision for embedded tags like title, artist, language, or chapter markers. Any metadata present in the VOB file (such as Dolby Digital stream language labels or DVD chapter information) will be completely discarded during conversion. If metadata preservation matters, VOC is not an appropriate target format.
You can resample the audio by adding the -ar flag followed by your desired sample rate in Hz. For example, to output at 22050 Hz (a common rate for retro Sound Blaster audio): ffmpeg -i input.vob -vn -c:a pcm_u8 -ar 22050 output.voc. Classic VOC files commonly used sample rates of 8000, 11025, or 22050 Hz — rates matching Sound Blaster hardware capabilities. The source AC3 audio in a DVD VOB is typically at 48000 Hz, so downsampling will reduce file size and may improve compatibility with older playback software at the cost of some high-frequency detail.
Yes, with a simple shell loop. On Linux or macOS, you can run: for f in *.vob; do ffmpeg -i "$f" -vn -c:a pcm_u8 "${f%.vob}.voc"; done. On Windows Command Prompt, use: for %f in (*.vob) do ffmpeg -i "%f" -vn -c:a pcm_u8 "%~nf.voc". This is particularly useful for DVD rips that are split across multiple VOB files (e.g., VTS_01_1.VOB, VTS_01_2.VOB). Note that if you want to treat a full DVD title as a single stream, you should concatenate the VOB files first using FFmpeg's concat demuxer before extracting audio.
Technical Notes
The VOC format was introduced by Creative Labs in 1989 and was the dominant PC audio format through the DOS era, tightly coupled to the Sound Blaster ISA card family. Its structure consists of a fixed 26-byte file header followed by typed data blocks (chunks), with the most common block being the raw PCM audio data block. The format natively supports only mono and stereo audio, and when using pcm_u8, audio samples are represented as unsigned 8-bit integers centered around 128 (silence). DVD VOB files, by contrast, carry AC3 audio that is multi-channel (commonly 5.1 surround), 16-bit or higher, at 48 kHz — so the conversion to VOC involves channel downmixing (FFmpeg will automatically downmix 5.1 to stereo by default), sample rate conversion if needed, and severe bit-depth reduction from typically 16-bit to 8-bit. There is no quality parameter for VOC output in FFmpeg because pcm_u8 is fixed-depth with no variable quality setting. File sizes will be much smaller than the source VOB video container, but the audio data itself will be uncompressed raw PCM, so a long audio track at 48 kHz stereo pcm_u8 can still reach tens of megabytes. No subtitle streams, chapter markers, or video data from the VOB will survive in the output.