Convert MOV to AC3 — Free Online Tool
Convert MOV files to AC3 (Dolby Digital) audio by extracting and re-encoding the audio stream using the ac3 codec at 192k bitrate by default. This is ideal for extracting professional-grade surround sound audio from QuickTime recordings 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 can contain a variety of audio codecs including AAC, MP3, FLAC, Opus, or Vorbis. During this conversion, FFmpeg discards the video stream entirely and re-encodes the audio stream into Dolby Digital AC3 format. This is a full transcode — not a remux — because AC3 is a distinct codec from anything typically stored in a MOV container. The AC3 encoder applies Dolby Digital's perceptual audio compression, which is lossy, meaning some audio detail is discarded to achieve compact file sizes suited for DVD, Blu-ray, and broadcast delivery. The output is a raw AC3 bitstream file, not wrapped in a container, so it carries no video, subtitles, chapter markers, or metadata beyond what the AC3 format itself supports.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg binary. In the browser tool this runs via FFmpeg.wasm (WebAssembly), while on a desktop it calls the locally installed FFmpeg executable — the command syntax is identical in both environments. |
-i input.mov
|
Specifies the input file, a MOV (QuickTime) container that may contain video, audio, and metadata streams. FFmpeg will read all streams but only the audio will be used in this conversion. |
-c:a ac3
|
Instructs FFmpeg to encode the audio stream using Dolby Digital's AC3 codec. This triggers a full re-encode of whatever audio codec is in the MOV (commonly AAC) into the AC3 format, which is required for DVD, Blu-ray, and broadcast compatibility. |
-b:a 192k
|
Sets the AC3 audio bitrate to 192 kilobits per second. This is a standard bitrate for stereo Dolby Digital audio; for 5.1 surround sound intended for disc authoring, increasing this to 384k or 448k is recommended for better multi-channel fidelity. |
output.ac3
|
Defines the output filename with the .ac3 extension, telling FFmpeg to write a raw Dolby Digital bitstream file. There is no container wrapping the audio — the file is a pure AC3 stream directly consumable by DVD authoring tools and Dolby-compatible playback systems. |
Common Use Cases
- Extracting the audio from a MOV interview or documentary recording to deliver a Dolby Digital AC3 track for DVD authoring software like DVD Studio Pro or Encore
- Preparing a 5.1 surround sound mix exported from Final Cut Pro or DaVinci Resolve as a MOV file for inclusion in a Blu-ray project requiring a separate AC3 audio asset
- Converting a QuickTime audio recording to AC3 for broadcast television delivery where Dolby Digital is mandated by the broadcast specification
- Stripping and re-encoding the audio track from a MOV screen recording or video podcast to a standalone AC3 file for import into a non-linear editing system that requires Dolby Digital audio
- Producing a compatible Dolby Digital audio file from a MOV master to test surround sound playback on AV receivers, home theater systems, or set-top boxes before final disc authoring
Frequently Asked Questions
Yes, provided your MOV file contains a multi-channel audio track (such as a 5.1 AAC or PCM track), FFmpeg will pass those channels through to the AC3 encoder, which natively supports up to 5.1 surround sound. AC3 is one of the standard Dolby Digital formats specifically designed for multi-channel audio, so your channel layout should be preserved. If your MOV contains only stereo audio, the output AC3 will also be stereo.
Yes, this conversion involves two stages of lossy compression. If your MOV already contains AAC audio (the MOV default), transcoding it to AC3 means decoding that lossy AAC audio and re-encoding it into another lossy format. Each generation of lossy encoding introduces additional quality degradation. For the best results, convert from a MOV that contains a lossless or uncompressed audio track (such as PCM or FLAC) rather than an already-lossy AAC source.
192 kbps is a standard AC3 bitrate suitable for stereo audio and acceptable for moderate-quality surround sound. For stereo content, 192k provides good fidelity. However, for 5.1 surround sound intended for DVD or Blu-ray delivery, 384k or 448k is more commonly used to maintain audio quality across all six channels. For maximum AC3 quality, 640k is the format's upper limit, though most DVD players cap support at 448k.
No. The output is a raw AC3 bitstream file, which has no container and therefore no support for metadata tags such as title, artist, album, or chapter information. Any metadata embedded in the MOV file — including chapter markers and multiple audio track labels — will be lost. If you need metadata, consider wrapping the AC3 audio in a container format like MKV or MP4 instead.
Replace the value after -b:a in the command with your desired bitrate. For example, to encode at 448k (common for 5.1 DVD audio), use: ffmpeg -i input.mov -c:a ac3 -b:a 448k output.ac3. Valid AC3 bitrates include 96k, 128k, 192k, 256k, 320k, 384k, 448k, and 640k. Choosing a bitrate that exceeds what the AC3 standard allows for your channel count will cause FFmpeg to automatically clamp it to the nearest valid value.
Yes, on macOS or Linux you can use a shell loop: for f in *.mov; do ffmpeg -i "$f" -c:a ac3 -b:a 192k "${f%.mov}.ac3"; done. On Windows Command Prompt, use: for %f in (*.mov) do ffmpeg -i "%f" -c:a ac3 -b:a 192k "%~nf.ac3". This processes each MOV file in the current directory and outputs a correspondingly named AC3 file. The browser-based tool handles one file at a time, so the command-line approach is recommended for batch workflows.
Technical Notes
AC3 is a lossy codec developed by Dolby Laboratories and is one of the mandatory audio formats for DVD-Video and an optional format for Blu-ray Disc. The raw .ac3 file produced by this conversion is a bare bitstream with no container wrapper, making it directly compatible with DVD authoring tools and broadcast ingest systems that expect a standalone Dolby Digital audio file. MOV files commonly store audio as AAC, which means this conversion will perform a generation-loss transcode from one lossy format to another — for archival or high-fidelity work, source MOV files with FLAC or PCM audio are strongly preferred. The AC3 format supports up to 5.1 channels (3/2 stereo plus LFE), and FFmpeg will automatically detect the channel layout from the MOV source and configure the AC3 encoder accordingly, though you can override this with the -ac flag if needed. Note that MOV-specific features such as chapter markers, multiple audio tracks, subtitles, and video transparency are all discarded because the AC3 format has no mechanism to store them. If your MOV contains multiple audio tracks, FFmpeg will by default encode only the first audio stream; use the -map flag to select a specific track.