Convert 3GP to VOC — Free Online Tool
Convert 3GP mobile video files to VOC audio format, extracting the audio stream and encoding it as raw unsigned 8-bit PCM — the native format used by Creative Labs Sound Blaster cards in DOS-era applications. This tool strips the 3GP video container entirely and outputs a VOC file ready for retro game engines, DOS emulators, or legacy multimedia projects.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
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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
3GP files typically contain an AAC or AMR audio stream wrapped in a mobile-optimized container alongside a video track. During this conversion, FFmpeg discards the video stream entirely and decodes the audio from its compressed 3GP container. The decoded audio is then re-encoded as unsigned 8-bit PCM (pcm_u8) and wrapped in the VOC container format. VOC is a headerized raw PCM format, so no lossy compression is applied to the output — the audio fidelity is limited only by the 8-bit sample depth, which is inherently lower resolution than the original AAC source. The result is a mono or stereo VOC file compatible with Sound Blaster hardware emulation and DOS-era tools.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg command-line tool, which handles all demuxing, decoding, encoding, and muxing steps needed to convert the 3GP file into a VOC file entirely within your browser via WebAssembly. |
-i input.3gp
|
Specifies the input file — a 3GP container, typically containing a compressed video track and an AAC or AMR audio track as used by 3G mobile phones. FFmpeg reads and demuxes both streams from this file. |
-c:a pcm_u8
|
Sets the audio codec to unsigned 8-bit PCM, the native and most compatible audio encoding for the VOC format used by Creative Labs Sound Blaster cards. The AAC audio from the 3GP file is fully decoded and re-encoded at 8-bit depth, which reduces dynamic range but ensures compatibility with DOS-era tools and emulators. |
output.voc
|
Specifies the output file with the .voc extension, which tells FFmpeg to wrap the pcm_u8 audio in the VOC container format. The video stream from the 3GP input is silently discarded because VOC is an audio-only format. |
Common Use Cases
- Preparing voice recordings or sound effects captured on an older 3G mobile phone for use in a DOS game mod or retro game engine that requires VOC audio assets.
- Extracting dialogue or ambient audio from 3GP video clips recorded on early mobile devices to use as sound samples in a Sound Blaster emulation project.
- Converting 3GP audio content into VOC files for playback inside DOSBox or other DOS emulators that use the Sound Blaster VOC format for custom sound effects.
- Creating period-authentic audio assets for a demoscene or retro computing project by sourcing modern recordings from a mobile device and converting them to the classic VOC format.
- Archiving or cataloguing 3GP multimedia content from early 3G-era mobile phones into a stripped-down, format-documented audio file for long-term retro software preservation.
- Supplying custom VOC sound files to legacy multimedia applications or CD-ROM titles that load Sound Blaster audio from VOC files at runtime.
Frequently Asked Questions
Yes, some quality loss is inherent due to the 8-bit sample depth of the default pcm_u8 codec used in VOC files. The original 3GP audio is typically AAC-encoded at moderate bitrates suited for mobile streaming, which already involves lossy compression. Decoding that AAC audio and re-encoding it as unsigned 8-bit PCM reduces the dynamic range significantly — 8-bit audio has only 256 possible amplitude levels compared to 65,536 for 16-bit. If your target application supports it, you can use pcm_s16le instead for better fidelity (see the FFmpeg command FAQ below).
No. The VOC format was designed for Sound Blaster hardware in the early 1990s and has essentially no support for metadata tags. Any title, artist, or date information stored in the 3GP container is discarded during conversion. If metadata preservation is important, you should archive the original 3GP file alongside the converted VOC.
This is expected. 3GP files use AAC audio compression, which can achieve very compact file sizes by discarding audio data the ear is less sensitive to. VOC with pcm_u8 is uncompressed raw PCM audio — every sample is stored as-is with no compression. A 1-minute AAC track at 64 kbps in a 3GP file might be around 480 KB, while the same audio as 8-bit PCM at 8 kHz mono in a VOC file could be a similar size, but at higher sample rates the uncompressed VOC will be substantially larger.
Yes. Replacing pcm_u8 with pcm_s16le in the command — running 'ffmpeg -i input.3gp -c:a pcm_s16le output.voc' — will encode the audio as signed 16-bit PCM, which gives 65,536 amplitude levels versus 256 for 8-bit. The resulting VOC file will be larger but will sound significantly cleaner, with less quantization noise. Not all legacy applications that consume VOC files support 16-bit samples, so check your target software's requirements before switching.
No. The VOC format is audio-only and has no mechanism to store video data. FFmpeg automatically drops the video stream when writing to a VOC output file. If you need to preserve the video, you should convert to a different output format such as MP4 or MKV instead.
On Linux or macOS, you can use a shell loop: 'for f in *.3gp; do ffmpeg -i "$f" -c:a pcm_u8 "${f%.3gp}.voc"; done'. On Windows Command Prompt, use: 'for %f in (*.3gp) do ffmpeg -i "%f" -c:a pcm_u8 "%~nf.voc"'. Each 3GP file in the directory will be processed individually, producing a matching VOC file with the same base filename.
Technical Notes
The VOC format stores audio as headerized raw PCM blocks and was originally designed for the Creative Labs Sound Blaster ISA card, introduced in 1989. It supports 8-bit unsigned PCM (pcm_u8) and 16-bit signed PCM (pcm_s16le), with mono or stereo channels, and sample rates typically ranging from 8 kHz to 44.1 kHz. The pcm_u8 default used by this tool is the most historically authentic and universally compatible option for DOS software, but it introduces audible quantization noise on audio that was originally recorded or compressed at higher bit depths. The 3GP container's AAC audio will be fully decoded before being written as PCM, meaning there is a full decode-and-encode cycle — not a stream copy. No subtitles, chapters, or secondary audio tracks can be carried into the VOC output, and the VOC format does not support metadata fields. The converted file will reflect whatever sample rate was present in the 3GP audio stream unless you explicitly resample using FFmpeg's '-ar' flag.