Extract Audio from MTS to AC3 — Free Online Tool
Extract Dolby Digital AC3 audio directly from AVCHD MTS camcorder footage — no video re-encoding required. This tool strips the H.264 video stream and transcodes the embedded AC-3 or AAC audio into a standalone .ac3 file, preserving the surround sound channel layout ideal for DVD, Blu-ray, and broadcast workflows.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your MTS 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
MTS files from Sony and Panasonic camcorders store audio as either AC-3 (Dolby Digital) or AAC inside an MPEG-2 Transport Stream container. This tool discards the H.264 video stream entirely using the -vn flag, then transcodes the audio track to AC3 using FFmpeg's built-in ac3 encoder. If the source MTS already contains AC-3 audio, the process is a transcode at the target bitrate rather than a stream copy, ensuring a clean, self-contained .ac3 output file. Because no video is processed, conversion is fast even for long recordings. The output AC3 file supports up to 5.1 surround sound, so multichannel audio captured by camcorder microphone arrays or external recorders is preserved in the channel structure.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg command-line tool. In the browser version of this tool, FFmpeg runs locally via WebAssembly (ffmpeg.wasm) — no files leave your device. |
-i input.mts
|
Specifies the input AVCHD MTS file from your Sony or Panasonic camcorder. FFmpeg reads both the H.264 video stream and the embedded audio (AC-3 or AAC) from this MPEG-2 Transport Stream container. |
-vn
|
Disables video output entirely, telling FFmpeg to ignore the H.264 video stream in the MTS file. This is what makes the conversion fast — only the audio track is processed, with no video decoding or encoding overhead. |
-c:a ac3
|
Sets the audio codec to ac3, FFmpeg's Dolby Digital encoder. This transcodes whatever audio format is in the source MTS (AC-3 or AAC) into a standard Dolby Digital elementary stream compatible with DVD, Blu-ray, and broadcast systems. |
-b:a 192k
|
Sets the AC3 audio bitrate to 192 kilobits per second, which is the standard Dolby Digital bitrate for stereo DVD audio. For 5.1 surround sound sources extracted from prosumer camcorders, consider increasing this to 384k or 448k to maintain surround channel quality. |
output.ac3
|
Defines the output as a raw Dolby Digital elementary stream file (.ac3). This format is directly compatible with DVD and Blu-ray authoring tools, broadcast ingest pipelines, and professional video editing software that accepts AC3 as an external audio source. |
Common Use Cases
- Extracting the surround sound audio track from AVCHD wedding or event footage to deliver a standalone Dolby Digital file to a video editor or audio post-production team.
- Preparing audio from camcorder MTS recordings for authoring onto a DVD or Blu-ray disc, where AC3 (Dolby Digital) is the native and often required audio format.
- Isolating the audio from broadcast-quality MTS footage to submit to a television production pipeline that accepts AC3 as the delivery audio codec.
- Stripping audio from large MTS camcorder files for review or transcription without needing to transfer or transcode gigabytes of video data.
- Converting MTS audio to AC3 for use in video editing software like Adobe Premiere or DaVinci Resolve that accepts AC3 as an external audio source for syncing with other footage.
- Archiving the Dolby Digital audio track from MTS recordings separately from the video, reducing storage requirements when only the audio content is needed long-term.
Frequently Asked Questions
Many Sony and Panasonic AVCHD camcorders record audio as AC-3 natively inside the MTS container, but some models use AAC instead. In both cases, this tool transcodes the audio to a new AC3 file at the specified bitrate (default 192k), which means there is a generational quality loss compared to a direct stream copy. If your MTS source already contains AC-3 at 192k or higher, the quality difference will be minimal, but it is not lossless. For the absolute best quality, choose the highest available bitrate (640k) if you have a surround sound source.
Yes, provided your MTS file actually contains multichannel audio. Most consumer AVCHD camcorders record stereo (2.0) audio, but some prosumer models with external microphone inputs or onboard surround capture do record 5.1. FFmpeg's ac3 encoder will preserve the channel layout from the source — if the MTS contains 5.1 audio, the output AC3 will be 5.1. If the source is stereo, the output will be stereo AC3. You can verify your source channel count by inspecting the FFmpeg output log shown on this page.
The .ac3 extension denotes a raw Dolby Digital elementary stream — pure audio data with no container wrapper. This format is directly compatible with DVD and Blu-ray authoring tools, broadcast ingest systems, and professional video editing software. If you need the AC3 audio wrapped inside a container like MKV or MP4 for playback on media players, you would instead mux the ac3 stream into the desired container using FFmpeg, changing the output filename accordingly.
For stereo audio, 192k is a solid default that matches DVD-quality Dolby Digital. For 5.1 surround sound, 384k is the DVD standard and 448k is common for broadcast, with 640k being the AC3 format's maximum and appropriate for Blu-ray authoring. Avoid dropping below 192k for stereo or 320k for 5.1, as AC3 is already a lossy codec and low bitrates can introduce audible artifacts, especially since the MTS source audio has likely already been compressed once.
Modify the -b:a flag in the command to your desired bitrate. For example, to export at 384k for surround sound DVD authoring, change the command to: ffmpeg -i input.mts -vn -c:a ac3 -b:a 384k output.ac3. The AC3 format supports bitrates from 96k up to 640k. The displayed command on this page can be copied and run locally on your desktop — particularly useful for MTS files larger than 1GB that exceed the browser tool's file size limit.
Yes. On Linux or macOS, you can use a shell loop: for f in *.mts; do ffmpeg -i "$f" -vn -c:a ac3 -b:a 192k "${f%.mts}.ac3"; done. On Windows Command Prompt: for %f in (*.mts) do ffmpeg -i "%f" -vn -c:a ac3 -b:a 192k "%~nf.ac3". This is especially practical for processing large batches of AVCHD camcorder clips that exceed what the browser-based tool can handle individually.
Technical Notes
AC3 (Dolby Digital) has a maximum supported channel configuration of 5.1 and a maximum bitrate of 640 kbps — both are format-level ceilings, not FFmpeg limitations. The MTS/AVCHD container does not preserve extensive audio metadata like track titles or language tags in a form that FFmpeg reliably transfers to a raw AC3 elementary stream, so embedded language metadata from the MTS file will not appear in the output. The MPEG-2 Transport Stream container used by MTS can sometimes contain discontinuous timestamps or slight timing anomalies from camcorder recording starts and stops; since this extraction removes video entirely, those issues do not affect the AC3 output. Note that raw .ac3 files are not supported for direct playback in most web browsers or mobile media players — they are primarily intended for professional authoring and broadcast workflows. If broad playback compatibility is needed, consider wrapping the output in an MKV or MP4 container instead. The ac3 encoder in FFmpeg is Dolby Digital compliant and produces files compatible with hardware decoders in AV receivers, DVD/Blu-ray players, and professional broadcast equipment.