Extract Audio from MOV to AC3 — Free Online Tool
Extract and convert audio from MOV files to AC3 (Dolby Digital) format, stripping the video stream entirely and encoding the audio track using the ac3 codec at 192kbps by default. Ideal for preparing surround sound audio from professional video projects for use in DVD authoring, Blu-ray production, or broadcast workflows.
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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
MOV files typically carry audio encoded as AAC, but Dolby Digital (AC3) is the mandatory audio format for DVD and a standard for broadcast television. This tool discards the MOV video stream entirely using the -vn flag — no video decoding or encoding takes place — then decodes the existing MOV audio (commonly AAC) and re-encodes it into AC3 using FFmpeg's built-in ac3 encoder. Because AC3 is a lossy format and MOV's default AAC audio is also lossy, this is a lossy-to-lossy transcode, meaning some audio generation loss is unavoidable. The output is a raw .ac3 bitstream file, not wrapped in a container, making it ready for direct import into DVD authoring tools like DVD Studio Pro or Encore.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg binary. In the browser, this runs via FFmpeg.wasm compiled to WebAssembly, executing the identical command logic locally in your browser without any server involvement. |
-i input.mov
|
Specifies the input file — a MOV container which may hold video encoded as H.264 or H.265 and audio encoded as AAC, among other codecs. FFmpeg reads all streams from this file before applying the output flags. |
-vn
|
Disables video output entirely, telling FFmpeg to ignore the video stream in the MOV file. This is essential here because AC3 is a raw audio-only bitstream format and cannot contain video data — without this flag, FFmpeg would error or attempt an incompatible mux. |
-c:a ac3
|
Selects FFmpeg's native AC3 encoder to transcode the MOV audio track into Dolby Digital format. The source audio (typically AAC in a MOV file) is fully decoded and then re-encoded as AC3, which is the mandatory audio codec for DVD Video and a broadcast television standard. |
-b:a 192k
|
Sets the AC3 audio bitrate to 192 kilobits per second, which is the standard for Dolby Digital stereo output and broadly compatible with DVD players and broadcast decoders. For 5.1 surround sound sources, increasing this to 384k or higher is strongly recommended to maintain audio fidelity across all channels. |
output.ac3
|
Specifies the output filename with the .ac3 extension, which tells FFmpeg to write a raw Dolby Digital bitstream file. This containerless format is directly importable into DVD authoring applications and broadcast multiplexers that expect a bare AC3 elementary stream. |
Common Use Cases
- Preparing audio from a Final Cut Pro or DaVinci Resolve MOV export for DVD authoring, where Dolby Digital AC3 is required on the disc
- Extracting a 5.1 surround sound mix recorded in a MOV production file and converting it to AC3 for delivery to a broadcast TV post-production facility
- Stripping and transcoding the audio track from a MOV camera master to AC3 for use as a standalone audio asset in a Blu-ray menu or supplemental feature
- Converting a MOV interview recording's audio to AC3 for import into a DVD multiplexer alongside a separately encoded MPEG-2 video stream
- Pulling the audio from a MOV screener or review copy and encoding it as AC3 to match the deliverable audio spec required by a distributor
- Quickly generating an AC3 audio file from a MOV rough cut to test surround sound mixing in a home theater or A/V receiver before final mastering
Frequently Asked Questions
Yes, this is a lossy-to-lossy transcode. MOV files most commonly store audio as AAC, which is already a compressed lossy format. Re-encoding that AAC audio into AC3 introduces a second generation of lossy compression artifacts, which can degrade quality — particularly in complex high-frequency content. To minimize this, use the highest practical bitrate for the AC3 output (320k or 384k) if transparency is important. If your MOV source contains lossless audio such as FLAC or PCM, the quality loss will be limited to the single AC3 encoding pass.
Yes, provided your MOV file actually contains a multichannel audio track (5.1 or similar). FFmpeg's ac3 encoder supports up to 5.1 channels natively, and if the source MOV audio is already multichannel AAC or another surround format, the channel layout will be preserved in the AC3 output. If your MOV only contains stereo audio, the AC3 file will be stereo — the converter does not upmix channels.
192kbps is the standard minimum for Dolby Digital stereo and is broadly compatible with DVD players and broadcast decoders. However, for 5.1 surround sound, 384kbps is the DVD standard and 640kbps is the maximum AC3 supports. If your MOV source contains a 5.1 mix, you should increase the bitrate to at least 384kbps to maintain acceptable quality across all six channels. The default of 192kbps is a safe starting point for stereo sources.
Replace the value after -b:a in the command. For example, to encode at 384kbps for 5.1 surround sound, use: ffmpeg -i input.mov -vn -c:a ac3 -b:a 384k output.ac3. Supported AC3 bitrates include 96k, 128k, 192k, 256k, 320k, 384k, 448k, and 640k. Choose based on your channel count and the bitrate requirements of your target authoring system or broadcast spec.
Yes. On Linux or macOS, you can use a shell loop: for f in *.mov; do ffmpeg -i "$f" -vn -c:a ac3 -b:a 192k "${f%.mov}.ac3"; done. On Windows Command Prompt: for %f in (*.mov) do ffmpeg -i "%f" -vn -c:a ac3 -b:a 192k "%~nf.ac3". This processes each MOV file in the current directory and outputs a matching .ac3 file. The browser-based tool handles one file at a time, so the FFmpeg command is especially useful for batch workflows.
No. AC3 is a raw audio bitstream format with no container structure, so it cannot store metadata such as track titles, artist tags, chapter markers, or album art. All of that information present in the MOV file will be lost. If you need to preserve metadata alongside Dolby Digital audio, consider wrapping the AC3 stream in a container format like MKV or M2TS instead of outputting a bare .ac3 file.
Technical Notes
The AC3 encoder in FFmpeg (the native ac3 encoder, not the commercial Dolby encoder) is compliant with the ATSC A/52 standard and produces files compatible with virtually all Dolby Digital decoders, DVD players, and A/V receivers. One important limitation is that AC3 supports a maximum of 5.1 channels — if your MOV source contains a 7.1 or ambisonic audio track, FFmpeg will downmix it to fit within AC3's channel ceiling. The -vn flag is critical here: without it, FFmpeg would attempt to include a video stream in the output, which the raw AC3 format cannot accommodate. MOV files support multiple audio tracks, but this command extracts only the first (default) audio stream. To extract a non-default audio track, add -map 0:a:1 (for the second track) before the output filename. Because AC3 does not support chapters or subtitles, any of those assets in the source MOV must be handled separately. File sizes will vary significantly: a 192kbps AC3 file for a one-hour stereo program will be approximately 86MB, while a 384kbps 5.1 file for the same duration will be around 173MB.