Extract Audio from MTS to AAC — Free Online Tool
Extract audio from AVCHD camcorder footage (.mts files) and save it as an AAC file. This tool strips the H.264 video stream and re-encodes the AC-3 or AAC audio track from the MPEG-2 Transport Stream container into a standalone .aac file, giving you clean, portable audio from your Sony or Panasonic camcorder recordings.
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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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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 use the MPEG-2 Transport Stream (M2TS) container, which typically carries H.264 video alongside AC-3 (Dolby Digital) or AAC audio. This conversion discards the video stream entirely and re-encodes the audio into a standalone AAC (.aac) file. If the source audio is already AAC, the re-encoding step introduces a small amount of additional generation loss — it is not a lossless copy — because the audio must be decoded from the transport stream and re-encoded into an elementary AAC bitstream at the target bitrate. If the source audio is AC-3, the transcoding converts Dolby Digital audio into the more universally compatible AAC format. The output is a raw AAC elementary stream file, which is playable on virtually all modern devices and platforms.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg program. In the browser-based version of this tool, FFmpeg runs locally via WebAssembly (FFmpeg.wasm) — no data leaves your device. |
-i input.mts
|
Specifies the input file — your AVCHD camcorder recording in the MPEG-2 Transport Stream format. FFmpeg will demux the H.264 video and AC-3/AAC audio streams from this container for processing. |
-vn
|
Disables video output entirely, telling FFmpeg to ignore the H.264 video stream in the MTS file. This is the key flag that makes this an audio extraction rather than a full video conversion, and it significantly speeds up processing since no video decoding or encoding occurs. |
-c:a aac
|
Sets the audio codec to AAC using FFmpeg's built-in AAC encoder. This encodes the audio stream — whether it was originally AC-3 or AAC inside the MTS — into a standard AAC bitstream suitable for the .aac output file. |
-b:a 128k
|
Sets the audio bitrate to 128 kilobits per second, which is the default for this tool. At 128k, AAC provides good quality for speech and acceptable quality for music. Increase this value (e.g., 192k or 256k) in the FFmpeg command if you need higher fidelity audio from your camcorder recording. |
output.aac
|
The output filename with the .aac extension, which tells FFmpeg to write a raw AAC elementary stream file. This format is broadly compatible with modern devices and software, including all Apple platforms, Android, and web browsers. |
Common Use Cases
- Extracting interview audio from AVCHD camcorder footage to use in a podcast or radio production without carrying the large video file
- Pulling ambient sound recordings or location audio from Sony or Panasonic camcorder clips for use in a film or video project's sound design
- Converting the AC-3 audio track from MTS footage into AAC for compatibility with Apple devices, iTunes, or iOS apps that do not support Dolby Digital
- Archiving just the audio from family event recordings (weddings, graduations) stored on old AVCHD camcorder memory cards to save storage space
- Extracting narration or speech recorded via a camcorder microphone into AAC for use in e-learning or presentation software that accepts AAC but not MTS
- Creating a lightweight AAC audio preview of camcorder footage for a client to approve dialogue or timing before the full video is edited and delivered
Frequently Asked Questions
Yes, there is some quality loss. Even if the original MTS file already contains AAC audio, the conversion re-encodes the audio rather than copying it losslessly, because it must be extracted from the MPEG-2 Transport Stream and written as a standalone AAC elementary stream. If the source MTS has AC-3 (Dolby Digital) audio — common on Panasonic and Sony camcorders — the conversion also changes the codec, adding transcoding loss. At the default 128k bitrate the quality is generally transparent for speech and acceptable for music, but for critical audio work you should raise the bitrate to 192k or 256k.
AC-3 (Dolby Digital) audio cannot be placed inside a raw .aac file — the formats are fundamentally incompatible. AAC and AC-3 are two different codecs with different bitstream structures. To produce a valid .aac output file, the AC-3 audio must be fully decoded and then re-encoded as AAC. If you want to avoid re-encoding entirely, you could instead extract the audio to an .ac3 file or use an MKV container that can hold AC-3 audio natively.
Change the value after the -b:a flag. For example, replace 128k with 192k or 256k for higher quality: ffmpeg -i input.mts -vn -c:a aac -b:a 192k output.aac. Higher bitrates produce larger files but preserve more audio detail. The AAC codec typically reaches transparent quality for most listeners at 192k, making 256k or 320k more useful for archival or professional audio work than for casual listening.
Yes, with a small modification. On Linux or macOS, you can loop over all MTS files in a folder with: for f in *.mts; do ffmpeg -i "$f" -vn -c:a aac -b:a 128k "${f%.mts}.aac"; done. On Windows Command Prompt, use: for %f in (*.mts) do ffmpeg -i "%f" -vn -c:a aac -b:a 128k "%~nf.aac". This processes each file individually and names the output after the original file.
Yes. AAC is Apple's preferred audio format and has been natively supported on every iPhone, iPad, and Mac for well over a decade. The output .aac file will play directly in Apple Music, iOS Files, QuickTime Player, and can be imported into iMovie, Final Cut Pro, and GarageBand without any additional conversion. MTS files, by contrast, are not natively supported on most Apple software, so extracting to AAC significantly broadens compatibility.
Generally no. AVCHD MTS files store metadata — such as recording timestamps, GPS coordinates, and camera model information — in the transport stream container or in sidecar files on the memory card, not embedded in the audio track itself. When the audio is extracted and written to a raw AAC elementary stream, this container-level metadata is not transferred. If preserving recording metadata matters, consider wrapping the output in an MP4 or M4A container instead, and manually copying relevant tags using FFmpeg's -metadata flag.
Technical Notes
MTS (AVCHD) files are recorded using the MPEG-2 Transport Stream container, which is designed for broadcast and streaming robustness rather than file-based editing. The audio inside is typically either AC-3 at 192–256 kbps (common on Panasonic camcorders) or AAC-LC at 128–256 kbps (common on Sony camcorders). The FFmpeg command uses the native aac encoder built into FFmpeg, which is a solid general-purpose AAC encoder. If you have access to the libfdk_aac encoder (available in some FFmpeg builds), replacing -c:a aac with -c:a libfdk_aac typically yields marginally better quality at the same bitrate, particularly for stereo content. The output is a raw AAC elementary stream (.aac), not an M4A file — both contain AAC audio, but M4A wraps it in an MPEG-4 container and supports richer metadata. If you need iTunes library compatibility or ID3-style tags, consider changing the output extension to .m4a, which FFmpeg will handle automatically by switching to the MP4 container while keeping the same AAC audio encoding settings. Files with multiple audio tracks (some AVCHD recordings include a second audio channel) will default to the first audio track; use -map 0:a:1 to select a specific track.