Convert 3GPP to VOC — Free Online Tool
Convert 3GPP mobile video files to VOC audio format, extracting the audio stream and encoding it as raw 8-bit unsigned PCM — the native format used by Creative Labs Sound Blaster cards in classic DOS applications. This tool strips the video entirely and produces a lossless, uncompressed PCM audio file compatible with retro gaming tools and DOS-era software.
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FFmpeg Command
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Estimated output:
Conversion Complete!
DownloadHow It Works
3GPP files are multimedia containers typically holding H.264 video and AAC-compressed audio, designed for mobile streaming on 3G networks. During this conversion, the video stream is completely discarded and the AAC audio is fully decoded and re-encoded into raw 8-bit unsigned PCM (pcm_u8) — the audio encoding used in the VOC format developed by Creative Labs. Unlike a simple remux, this is a genuine transcode: the AAC audio is decompressed from its lossy compressed state and written out as uncompressed PCM samples at 8-bit depth. The VOC container itself is extremely minimal, with no support for chapters, subtitles, or metadata beyond basic header information. The resulting file will be significantly larger than the audio portion of the original 3GPP on a per-second basis, since PCM stores every sample without compression.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg command-line tool, which handles all decoding, stream selection, transcoding, and muxing for this conversion pipeline. |
-i input.3gp
|
Specifies the input 3GPP file. FFmpeg reads this container, identifies the H.264 video and AAC audio streams inside, and makes them available for processing. |
-c:a pcm_u8
|
Tells FFmpeg to encode the audio stream as 8-bit unsigned PCM — the classic Sound Blaster audio encoding expected by most DOS-era applications and game engines that consume VOC files. The AAC audio from the 3GPP is fully decoded and re-encoded into raw uncompressed PCM samples. |
output.voc
|
Specifies the output filename with the .voc extension, which causes FFmpeg to write a Creative Labs VOC container. Since VOC is audio-only, the video stream from the 3GPP source is automatically excluded from the output. |
Common Use Cases
- Extracting voice recordings or sound effects from 3GPP mobile videos to use as audio assets in a DOS game or retro game mod that requires VOC-format sound files
- Converting field-recorded 3GPP audio clips from an older mobile phone into VOC format for playback in DOSBox or a vintage Sound Blaster-era application
- Preparing audio samples captured on a 3G-era mobile device for use with classic multimedia authoring tools like early versions of Macromedia Director that accept VOC files
- Archiving or cataloguing audio content from 3GPP video clips in a raw PCM format for signal analysis or waveform editing in tools that only accept uncompressed VOC input
- Supplying custom voice lines or sound effects recorded on a mobile phone in 3GPP format to a retro game engine or level editor that loads Sound Blaster VOC assets
- Stripping and converting the spoken audio from a 3GPP video tutorial into an uncompressed VOC file for integration into a DOS-compatible interactive training application
Frequently Asked Questions
The conversion involves one stage of quality loss: the AAC audio inside the 3GPP file is already lossy-compressed, and decoding it back to raw PCM cannot recover the information discarded during that original AAC encoding. However, once decoded, the audio is written to VOC as uncompressed pcm_u8, so no additional compression artifacts are introduced. The main quality constraint of the output is the 8-bit sample depth of pcm_u8, which produces a dynamic range of roughly 48 dB — noticeably lower fidelity than modern 16-bit audio, and consistent with the Sound Blaster hardware these files were designed for.
AAC audio inside 3GPP containers is heavily compressed, often at 64 kbps or lower for mobile use. VOC with pcm_u8 is completely uncompressed, storing every audio sample as a raw byte. A one-minute clip that occupies only a few hundred kilobytes as AAC in a 3GPP file can expand to several megabytes as uncompressed PCM in VOC. This size increase is expected and is a fundamental characteristic of lossless raw PCM storage.
No. The VOC format has an extremely minimal structure with no standardized metadata fields — it was designed purely for storing raw audio samples for Sound Blaster playback, not for tagging or cataloguing. Any metadata present in the 3GPP container (such as recording date, GPS location, title, or artist tags common in mobile-captured video) is discarded entirely during conversion. If preserving metadata matters, you should record it separately before converting.
Yes. FFmpeg supports pcm_s16le (signed 16-bit little-endian PCM) as an alternative codec for VOC files, which doubles the sample depth and gives you a much wider dynamic range — approximately 96 dB versus 48 dB for 8-bit. To use it, change the command to: ffmpeg -i input.3gp -c:a pcm_s16le output.voc. Keep in mind that not all legacy Sound Blaster applications or DOS tools support 16-bit VOC files, so pcm_u8 is the safer default for maximum compatibility with older software.
On Linux or macOS, you can loop over all 3GPP files in a directory with: 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 file is processed sequentially, and the output VOC file takes the same base name as the input 3GPP file. This is especially useful when you have a large collection of mobile video clips to convert for a retro gaming project.
The video stream is silently dropped. The FFmpeg command does not include a video codec flag because VOC is a purely audio-only format with no concept of video data. FFmpeg automatically omits the video when the output container cannot hold it. No explicit -vn flag is required here — the VOC format's own limitations ensure only audio is written. If you need to preserve the video as well, you should choose a different output format.
Technical Notes
The 3GPP container format was defined by the Third Generation Partnership Project to deliver multimedia efficiently over 3G mobile networks, and it typically carries H.264 (libx264) video paired with AAC audio at very low bitrates — commonly 64 kbps or below — optimized for constrained bandwidth. The VOC format sits at the opposite end of the design spectrum: a bare-bones, header-minimal container created by Creative Labs in the early 1990s for the Sound Blaster ISA card, storing raw PCM samples with no compression or rich metadata. The default codec for this conversion is pcm_u8 (8-bit unsigned PCM), which is the historically correct and most widely compatible encoding for VOC files used by DOS games and DOS emulators like DOSBox. Sample rate is preserved from the source audio during conversion — if your 3GPP audio was recorded at 8 kHz (a common mobile telephony rate), the VOC output will also be 8 kHz, which is actually well-suited to the Sound Blaster's expected audio range. Note that VOC does not support multiple audio tracks, so only the first audio stream in the 3GPP file is converted. The format also has no subtitle, chapter, or cover art support. Because the AAC audio in 3GPP is already lossy, the decoded-then-reencoded PCM output will reflect any artifacts present in the original AAC encoding, particularly at the low bitrates typical of mobile 3GPP content.