Convert DVR to VOC — Free Online Tool
Convert DVR surveillance or broadcast recordings to VOC audio format, extracting the AAC or MP3 audio track and encoding it as uncompressed 8-bit PCM — the native format of Creative Labs Sound Blaster cards. This tool runs entirely in your browser using FFmpeg.wasm, with no server uploads required.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your DVR file here
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Settings
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
DVR files typically store video and audio together in a proprietary container, with audio encoded in AAC or MP3. During this conversion, FFmpeg discards the video stream entirely and decodes the audio track, then re-encodes it as unsigned 8-bit PCM (pcm_u8) wrapped in the VOC container format. VOC is a simple, lossless raw audio format with no compression — it stores audio as a direct stream of 8-bit PCM samples at whatever sample rate the source audio provides. Because 8-bit audio has a dynamic range of only 48dB, some quality degradation from the original AAC or MP3 source is expected, particularly in quiet passages or high-frequency detail. The VOC format does not support stereo in all implementations, so the output may be mono depending on the encoder path.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool, which handles the demuxing of the proprietary DVR container, decoding of the compressed audio track, and encoding to the VOC output format. |
-i input.dvr
|
Specifies the input DVR file. FFmpeg reads the proprietary DVR container and identifies the available audio stream (typically AAC or MP3) and video stream, which will be discarded in this conversion. |
-c:a pcm_u8
|
Sets the audio codec to unsigned 8-bit PCM, the standard and most compatible codec for the VOC format. This decodes the DVR's compressed AAC or MP3 audio and re-encodes it as raw 8-bit uncompressed samples, matching the native Sound Blaster VOC specification. |
output.voc
|
Specifies the output filename with the .voc extension, which tells FFmpeg to wrap the pcm_u8 audio stream in the Creative Labs VOC container format, including the required VOC file header and block structure. |
Common Use Cases
- Extracting audio from DVR surveillance footage to use as a sound effect or ambient noise clip in a retro-style DOS game or demo scene production
- Converting captured broadcast audio stored in DVR format into VOC files for playback on vintage Sound Blaster hardware or DOSBox emulator environments
- Archiving spoken-word content from DVR recordings — such as announcements or interviews — into the VOC format for use in legacy multimedia kiosk systems that only support Sound Blaster audio
- Preparing audio samples from DVR-recorded footage for integration into classic game modding projects that require VOC-formatted sound assets
- Extracting and downsampling audio from DVR security camera recordings into lightweight 8-bit PCM VOC files for low-bandwidth or embedded system playback
Frequently Asked Questions
Yes, some quality loss is expected. The DVR's audio is typically stored as AAC or MP3, both of which are lossy formats with relatively high fidelity. VOC uses unsigned 8-bit PCM (pcm_u8), which provides only 256 amplitude levels and a dynamic range of roughly 48dB — significantly less than the original. High-frequency detail and subtle audio nuances will be noticeably reduced, especially compared to the 16-bit audio most modern listeners are used to. If fidelity matters, consider using pcm_s16le instead for 16-bit output, which you can specify by modifying the FFmpeg command.
No. VOC is a purely audio-only format developed by Creative Labs — it has no capacity to store video data. FFmpeg automatically drops the video stream during this conversion and only processes the audio track. If you need to preserve the video, you would need to convert to a different output format that supports both video and audio.
Yes. The VOC format supports both pcm_u8 (8-bit unsigned) and pcm_s16le (16-bit signed little-endian). To get higher quality 16-bit audio, change the command to: ffmpeg -i input.dvr -c:a pcm_s16le output.voc. This doubles the file size compared to 8-bit output but preserves significantly more dynamic range and is a better choice if you are archiving speech or music.
VOC stores audio as uncompressed PCM — there is no compression applied to the audio samples. In contrast, the DVR file's audio was compressed using AAC or MP3, which can achieve 10:1 or greater compression ratios. When that compressed audio is decoded and stored as raw 8-bit PCM in VOC, the audio-only output can be larger than the compressed audio portion of the source file. However, since the video stream is discarded, the VOC file will still typically be much smaller than the original DVR recording overall.
Generally yes. The pcm_u8 codec is the most widely compatible VOC encoding and is natively supported by DOSBox, vintage Sound Blaster cards, and most DOS-era software that reads the VOC format. However, playback success depends on the sample rate of your source audio — some older Sound Blaster cards and DOS programs only support specific sample rates such as 8000Hz, 11025Hz, or 22050Hz. If playback is incorrect, you may need to add a sample rate flag to the command, for example: -ar 22050.
Yes. On Linux or macOS, you can use a shell loop: for f in *.dvr; do ffmpeg -i "$f" -c:a pcm_u8 "${f%.dvr}.voc"; done. On Windows Command Prompt, use: for %f in (*.dvr) do ffmpeg -i "%f" -c:a pcm_u8 "%~nf.voc". The browser-based tool processes one file at a time, so the FFmpeg command is especially useful for batch workflows involving large collections of DVR recordings.
Technical Notes
The VOC format was designed in the early 1990s specifically for Creative Labs Sound Blaster cards and carries a fixed file header with the ASCII signature 'Creative Voice File'. It supports a block-based internal structure, though FFmpeg writes it as a simple linear stream. The pcm_u8 codec uses unsigned 8-bit samples, meaning silence is represented at amplitude value 128 rather than 0 — this is an important distinction from signed PCM formats. DVR recordings may contain multiple audio tracks or streams depending on the capture device; FFmpeg will default to the first audio stream if multiple are present. The VOC format does not preserve metadata such as timestamps, channel names, or any surveillance-specific tagging that may exist in the DVR container. Sample rate is inherited from the source audio unless explicitly resampled, and since VOC has no built-in resampling constraints, the output file will embed whatever rate the DVR audio used — which may not always be compatible with target playback systems without additional processing.