MyMediaTools

Convert MTS to AAC — Free Online Tool

Extract and convert the AC-3 or AAC audio track from an AVCHD camcorder MTS file into a standalone AAC (.aac) file. This tool strips the H.264 video stream entirely and re-encodes the audio using FFmpeg's native AAC encoder, producing a lightweight file compatible with iTunes, iOS, and virtually every modern media player.

FFmpeg Command

Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg

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Estimated output:

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How It Works

MTS files from Sony and Panasonic camcorders are MPEG-2 Transport Stream containers that typically carry H.264 video alongside AC-3 (Dolby Digital) or AAC audio. During this conversion, FFmpeg discards the video stream entirely and extracts the audio track. If the source audio is AC-3, it is transcoded (decoded and re-encoded) into AAC using FFmpeg's built-in AAC encoder at 128k bitrate. If the source audio is already AAC, it is still passed through the encoder to produce a clean standalone .aac file stripped of the transport stream wrapper. The output is a raw AAC audio file — no video, no container overhead — ready for playback, editing, or distribution.

What Each Flag Does

Flag What it does
ffmpeg Invokes the FFmpeg tool. In this browser-based tool, FFmpeg runs locally via WebAssembly (FFmpeg.wasm) — no data leaves your device. When running locally on your desktop, this calls your system-installed FFmpeg binary.
-i input.mts Specifies the input AVCHD camcorder file in MPEG-2 Transport Stream format. FFmpeg reads the MTS container and demuxes it into its H.264 video and AC-3 or AAC audio elementary streams for processing.
-c:a aac Sets the audio codec to FFmpeg's built-in AAC encoder. This encodes the demuxed audio — whether it was originally AC-3 or AAC inside the MTS — into the AAC-LC format used in the output .aac file. No video codec is specified because the .aac output format cannot carry video.
-b:a 128k Sets the target audio bitrate to 128 kilobits per second. This is the standard default for AAC and is generally considered transparent quality for speech recordings; for camcorder music or high-quality audio content, increasing this to 192k or 256k will yield noticeably better results.
output.aac Defines the output filename and format. The .aac extension tells FFmpeg to write a raw ADTS AAC stream — a lightweight, widely compatible format recognized by iTunes, iOS, Android, VLC, and most other modern media players and editing tools.

Common Use Cases

  • Extract narrated commentary from camcorder footage to use as a voiceover track in a video editing project without importing the full 4K MTS file
  • Pull the audio from a recorded live event or wedding ceremony MTS clip to create a standalone audio keepsake or share with guests who don't need the video
  • Convert interview or documentary footage audio from MTS to AAC for review and transcription using speech-to-text tools that don't accept video input
  • Extract background music or ambient sound recorded on a camcorder to use as a soundtrack or reference track in a DAW like GarageBand or Logic Pro
  • Reduce file size dramatically for archiving spoken-word camcorder recordings — such as lectures or presentations — where the video content is not needed
  • Prepare camcorder audio for upload to podcast platforms or iTunes by converting from the broadcast-oriented AVCHD container to the widely accepted AAC format

Frequently Asked Questions

It depends on the source audio codec in the MTS file. If your camcorder recorded AC-3 (Dolby Digital) audio, the conversion involves a full decode-and-re-encode cycle, which introduces a small amount of generational quality loss. If the original MTS already contains AAC audio, you are still transcoding rather than copying, so there is minor additional loss. At 128k bitrate, the output AAC is perfectly adequate for speech and most music, but if you need the highest possible fidelity, increase the bitrate to 192k or 256k before converting.
The dramatic size reduction happens because the H.264 video stream — which accounts for the vast majority of an MTS file's data — is completely removed. A typical AVCHD recording at 1080p can consume 15–25 Mbps of video data, while the audio track runs at only 192–448 kbps for AC-3 or lower for AAC. Your output .aac file contains only the audio portion re-encoded at 128k, so a 1GB MTS file might yield an AAC file of just a few megabytes depending on recording duration.
Replace the value after -b:a in the command to set a higher bitrate. For example, use '-b:a 192k' for better quality or '-b:a 256k' for near-transparent audio quality. AAC at 128k is generally considered transparent for speech content, but for music recordings from a camcorder, 192k or higher is recommended. The full command would look like: ffmpeg -i input.mts -c:a aac -b:a 192k output.aac
Yes, if you are running FFmpeg locally and have compiled it with libfdk_aac support, you can substitute '-c:a libfdk_aac' in place of '-c:a aac'. The Fraunhofer FDK AAC encoder is widely regarded as producing slightly better quality than FFmpeg's native AAC encoder at equivalent bitrates, particularly at lower bitrates like 96k or 128k. However, libfdk_aac is not included in most pre-built FFmpeg distributions due to licensing restrictions, so you may need to compile FFmpeg from source or use a third-party build.
The single-file command shown on this page handles one file at a time, but you can batch process on your desktop using a shell loop. On Linux or macOS, run: for f in *.mts; do ffmpeg -i "$f" -c:a aac -b:a 128k "${f%.mts}.aac"; done. On Windows Command Prompt, use: for %f in (*.mts) do ffmpeg -i "%f" -c:a aac -b:a 128k "%~nf.aac". This is particularly useful for camcorder sessions where footage is split across many MTS clips.
MTS transport streams carry limited metadata, and the raw .aac output format supports virtually no embedded metadata tags. FFmpeg may copy some basic timestamp information from the MTS stream, but camcorder-specific metadata such as GPS coordinates, scene modes, or recording device information will not be preserved in the AAC file. If metadata retention is important, consider converting to M4A instead, which is an AAC audio file wrapped in an MP4 container that supports ID3-style tags for artist, title, date, and other fields.

Technical Notes

AVCHD MTS files use the MPEG-2 Transport Stream (M2TS) container with a .mts extension, and the audio is almost always either AC-3 (Dolby Digital) at 192–448 kbps or AAC-LC at 128–256 kbps depending on the camcorder model and settings. Sony cameras (such as the Handycam series) frequently use AC-3 stereo or 5.1 surround, while Panasonic models more often default to AAC. FFmpeg automatically detects the source audio codec and decodes it prior to re-encoding as AAC. The output .aac file is a raw ADTS-framed AAC stream — this is the simplest and most compatible AAC container format but does not support metadata tags or chapter markers. If your source MTS contains multiple audio tracks (some professional AVCHD cameras record dual-channel mono setups), FFmpeg will by default extract only the first audio stream; use '-map 0:a:1' to target a specific track. The -vn flag is not explicitly required in this command because the output format .aac has no video codec defined, so FFmpeg automatically omits the video stream — but adding '-vn' explicitly is harmless and makes the intent clearer when running the command manually.

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