Extract Audio from DVR to AC3 — Free Online Tool
Extract audio from DVR recordings and convert it to AC3 (Dolby Digital) format directly in your browser. This tool strips the video stream and transcodes the AAC or MP3 audio track from your DVR file into AC3 using the ac3 codec — the standard for DVD, Blu-ray, and broadcast audio systems.
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 encoded with H.264 (libx264) and audio encoded with AAC or MP3, wrapped in a proprietary container used by digital video recorders. This tool discards the video stream entirely and re-encodes only the audio track from AAC or MP3 into AC3, Dolby Digital's lossy compression format. Because AAC and AC3 are fundamentally different codecs — different entropy coding, psychoacoustic models, and bitstream structures — a full decode-then-encode transcode is required; there is no possibility of a stream copy here. The output is a raw AC3 bitstream file at 192k bitrate by default, ready for use in authoring environments that demand Dolby Digital audio.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool. In the browser version, this runs via FFmpeg.wasm compiled to WebAssembly, executing the same logic as the desktop FFmpeg binary without sending your DVR file to any server. |
-i input.dvr
|
Specifies the input DVR file. FFmpeg reads and demuxes the proprietary DVR container, making both the H.264 video stream and the AAC or MP3 audio stream available for processing. |
-vn
|
Disables video output entirely. Since the goal is audio extraction, this flag tells FFmpeg to ignore the H.264 video stream from the DVR file and produce an audio-only output — no video frames are decoded or written. |
-c:a ac3
|
Sets the audio codec to ac3, FFmpeg's native Dolby Digital encoder. This triggers a full decode of the DVR's AAC or MP3 audio to PCM, followed by re-encoding into the AC3 bitstream format used in DVDs, Blu-rays, and broadcast television. |
-b:a 192k
|
Sets the AC3 audio bitrate to 192 kilobits per second, a standard Dolby Digital bitrate that balances file size and audio fidelity for stereo content. This is appropriate for dialogue-heavy DVR recordings like broadcast captures or surveillance audio. |
output.ac3
|
Specifies the output filename with the .ac3 extension, producing a raw Dolby Digital bitstream file. This format is directly compatible with DVD authoring tools, Blu-ray encoders, and broadcast systems that ingest AC3 audio streams. |
Common Use Cases
- Archiving surveillance or broadcast DVR footage audio as AC3 for ingestion into DVD or Blu-ray authoring software like DVDStyler or Encore
- Extracting the audio commentary or broadcast dialogue from a DVR-captured TV recording to reuse in a video production project that requires Dolby Digital audio tracks
- Converting DVR security camera audio to AC3 for compatibility with set-top boxes, media players, or AV receivers that decode Dolby Digital but not AAC
- Preparing audio extracted from a DVR recording for use in a home theater system that requires 5.1 AC3 surround sound streams
- Stripping and converting audio from proprietary DVR files for use in broadcast post-production workflows where AC3 is the mandated delivery format
- Getting a locally runnable FFmpeg command to batch-process large collections of DVR recordings over 1GB into AC3 audio files on a desktop workstation
Frequently Asked Questions
Yes, this is a lossy-to-lossy transcode. The AAC or MP3 audio in your DVR file is fully decoded to uncompressed PCM audio first, then re-encoded into AC3. Each generation of lossy compression introduces some degradation compared to the original source. At the default 192k bitrate, AC3 produces very acceptable quality for dialogue-heavy DVR content like surveillance or broadcast recordings, but audiophiles should be aware that the original encoding artifacts from the DVR stage are preserved and new ones are added.
AC3 is an audio-only codec, and a raw .ac3 file is simply a bare Dolby Digital bitstream with no container wrapping it. This is intentional — the tool extracts only the audio and writes it as a standalone AC3 stream. If you need the AC3 audio embedded inside a container like MKV or MP4 for media player compatibility, you would need to mux it into a container using a separate FFmpeg command.
It depends on what the DVR recorded. Most DVR files from broadcast TV or surveillance systems capture stereo (2-channel) audio with AAC or MP3. If the original DVR audio is stereo, the AC3 output will also be stereo — channel layout is preserved during the transcode. AC3 supports up to 5.1 surround, but the converter cannot create surround channels from a stereo source.
Replace the 192k value in the -b:a flag with any bitrate AC3 supports: 96k, 128k, 192k, 256k, 320k, 384k, 448k, or 640k. For example, to get broadcast-quality Dolby Digital at the DVD standard, use -b:a 448k. Lower bitrates like 96k are acceptable for voice-only surveillance recordings but may introduce audible artifacts on music or complex audio from broadcast captures.
Stream copying (-c:a copy) is only possible when the source and destination use the exact same codec. DVR files store audio as AAC or MP3, while the target format is AC3 — these are entirely different codecs with incompatible bitstream formats. FFmpeg must fully decode the DVR's AAC or MP3 audio to raw PCM and then encode it fresh into the AC3 format, which is what the -c:a ac3 flag instructs it to do.
Yes. On Linux or macOS, you can run a shell loop: for f in *.dvr; do ffmpeg -i "$f" -vn -c:a ac3 -b:a 192k "${f%.dvr}.ac3"; done. On Windows Command Prompt, use: for %f in (*.dvr) do ffmpeg -i "%f" -vn -c:a ac3 -b:a 192k "%~nf.ac3". This is especially useful for large DVR archives over 1GB that exceed the browser tool's file size limit.
Technical Notes
DVR files use a proprietary container that FFmpeg can demux in most cases, though compatibility depends on the specific DVR manufacturer's implementation — some highly proprietary formats may require manufacturer-specific software to unwrap before FFmpeg can process them. The audio codec inside DVR files is typically AAC at 128k bitrate, though some DVR systems record MP3 audio instead. When transcoding to AC3, FFmpeg uses its native ac3 encoder, which is a clean Dolby Digital implementation. Metadata such as recording timestamps or channel information stored in DVR container headers is not preserved in the output raw AC3 bitstream, since .ac3 files carry no metadata tags. AC3 enforces specific bitrate constraints tied to its frame structure — only standard Dolby Digital bitrates are valid, so arbitrary values will be rounded to the nearest supported rate. If your DVR audio is mono (common in older surveillance systems), FFmpeg will encode it as mono AC3, which is valid but may cause compatibility issues with some AV receivers that expect stereo or 5.1 streams.