Convert FLV to VOC — Free Online Tool
Convert FLV video files to VOC audio format, extracting the audio stream and encoding it as uncompressed PCM 8-bit unsigned audio — the native format used by Creative Labs Sound Blaster cards in DOS-era multimedia applications. This tool strips the Flash Video container and video stream entirely, delivering a raw PCM audio file compatible with retro gaming engines, DOSBox, and classic multimedia software.
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
FLV files typically carry AAC or MP3 audio alongside an H.264 or Sorenson Spark video stream. During this conversion, FFmpeg discards the video stream entirely and re-encodes the audio into PCM unsigned 8-bit (pcm_u8) — the codec used natively in the VOC format. AAC or MP3 audio, being lossy compressed formats, must be fully decoded and then re-encoded as uncompressed 8-bit PCM samples. This means the VOC output is technically lossless in its own encoding (no further compression is applied), but the audio quality ceiling is constrained by both the original lossy FLV source and the 8-bit depth limitation of the VOC format, which produces a dynamic range of roughly 48 dB. The resulting VOC file contains only raw audio data in a simple block-based container structure designed for the Sound Blaster hardware.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg multimedia processing tool, which handles decoding the FLV container, extracting its audio stream, and encoding the output VOC file entirely within your browser via WebAssembly. |
-i input.flv
|
Specifies the input Flash Video file. FFmpeg will parse the FLV container, identify the embedded video stream (typically H.264) and audio stream (typically AAC or MP3), and make both available for processing — though only the audio will be used in this conversion. |
-c:a pcm_u8
|
Sets the audio codec to PCM unsigned 8-bit, which is the native audio encoding of the VOC format used by Creative Labs Sound Blaster cards. This fully decodes the compressed FLV audio (AAC or MP3) and re-encodes it as raw 8-bit uncompressed samples. |
output.voc
|
Specifies the output filename with the .voc extension, which tells FFmpeg to wrap the pcm_u8 audio data in a Creative Voice File container — the block-based format developed by Creative Labs for Sound Blaster DOS applications and games. |
Common Use Cases
- Extracting audio from FLV video recordings of retro game footage to create sound effects or music files for use in DOSBox-based projects
- Preparing audio assets from online Flash video content for use in classic DOS game modding, where VOC is the required sound format
- Converting narration or dialogue clips saved in FLV format into VOC files for playback through Sound Blaster emulation layers in retro computing environments
- Archiving Flash-era video audio tracks in VOC format for inclusion in retro multimedia collections or CD-ROM recreation projects
- Generating VOC audio files from FLV screen recordings for use in old-school game engine scripting environments that only accept Sound Blaster-compatible audio
- Sampling short audio segments from FLV content to use as sound effects in open-source retro game engines like GZDoom or SDL-based DOS game ports that support VOC playback
Frequently Asked Questions
Yes, some quality degradation is expected. The audio in an FLV file is typically AAC or MP3 — both lossy compressed formats. Converting to VOC requires decoding that compressed audio and re-encoding it as 8-bit unsigned PCM (pcm_u8). The 8-bit depth limits the dynamic range to approximately 48 dB, which is noticeably lower fidelity than the 16-bit audio most people are accustomed to. If preserving maximum quality matters, you can use the pcm_s16le codec in the FFmpeg command instead, though not all VOC players support 16-bit playback.
FLV files contain compressed video and audio, so they are compact relative to their duration. The VOC output contains only raw uncompressed PCM audio with no video, so file size depends purely on the audio duration and sample rate. A one-minute FLV at 128k audio bitrate might be several megabytes including video, while the VOC equivalent will be calculated as: sample_rate × bit_depth/8 × channels × seconds. At 44100 Hz mono 8-bit, that's roughly 2.6 MB per minute — often smaller than the source FLV due to the absence of video, but uncompressed relative to the audio-only data.
Yes. VOC files produced with the pcm_u8 codec are fully compatible with DOSBox's Sound Blaster emulation and with real Sound Blaster cards via DOS utilities like PLAY.EXE or VPLAY. The VOC format was specifically designed for Sound Blaster hardware, and pcm_u8 at standard sample rates (8000, 11025, 22050, or 44100 Hz) is the most widely supported configuration. If targeting very old hardware or DOS programs, consider resampling to 22050 Hz or lower using the -ar flag for maximum compatibility.
No. The VOC format has virtually no metadata support — it is a simple block-based audio container developed in the early 1990s for Sound Blaster hardware. Any title, artist, or timestamp metadata embedded in the FLV file will be dropped during conversion. The VOC file will contain only the raw audio blocks and a basic header. If metadata preservation is important, VOC is not an appropriate target format.
Replace pcm_u8 with pcm_s16le in the command: ffmpeg -i input.flv -c:a pcm_s16le output.voc. This uses signed 16-bit little-endian PCM, which doubles the dynamic range to approximately 96 dB and produces significantly higher-fidelity audio. However, be aware that some older DOS applications and Sound Blaster utilities only support 8-bit VOC playback, so test compatibility with your target software before switching codecs.
Yes, on the command line you can use a shell loop to process multiple files. On Linux or macOS: for f in *.flv; do ffmpeg -i "$f" -c:a pcm_u8 "${f%.flv}.voc"; done. On Windows Command Prompt: for %f in (*.flv) do ffmpeg -i "%f" -c:a pcm_u8 "%~nf.voc". This browser-based tool processes one file at a time, but the displayed FFmpeg command is designed to be copied and run locally for bulk processing, which is especially useful for large batches or files over 1 GB.
Technical Notes
The VOC format stores audio in a chunked block structure with a fixed header identifying it as a Creative Voice File. The pcm_u8 codec stores samples as unsigned 8-bit integers (values 0–255, with 128 representing silence), which was the native data width of the original Sound Blaster hardware's DAC. This differs from most modern PCM formats that use signed integers. Because FLV audio is typically AAC at 44100 Hz stereo, FFmpeg will decode the AAC stream fully before re-encoding it as 8-bit PCM — there is no stream copying possible between these formats. The VOC format does not support multiple audio tracks, chapters, or subtitles, and there is no concept of a video stream. If the source FLV contains only audio (e.g., a Flash audio file disguised as video), the conversion is more straightforward, but the same re-encoding step still applies. Sample rate is preserved from the source by default, but for maximum DOSBox or vintage hardware compatibility, explicitly targeting 22050 Hz mono with -ar 22050 -ac 1 is advisable.