MyMediaTools

Extract Audio from MTS to ALAC — Free Online Tool

Extract lossless audio from MTS camcorder footage and save it as ALAC (Apple Lossless Audio Codec) in an M4A container. This tool decodes the AC-3 or AAC audio track from your AVCHD recording and re-encodes it into ALAC — a format fully compatible with iTunes, Apple Music, and iOS devices — preserving every detail of the original audio without lossy compression.

FFmpeg Command

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

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Estimated output:

Conversion Complete!

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How It Works

MTS files from Sony or Panasonic camcorders use the MPEG-2 Transport Stream container and typically carry AC-3 (Dolby Digital) or AAC audio alongside H.264 video. This conversion strips the video stream entirely using the -vn flag, then decodes the audio and re-encodes it using Apple's ALAC codec into an MPEG-4 (.m4a) container. Because ALAC is lossless, the output is a bit-for-bit accurate representation of the decoded audio — meaning no additional quality is lost beyond whatever lossy compression existed in the original MTS audio track. If the source used AC-3, the audio is fully decoded and then re-encoded as ALAC; if it used AAC, the same decode-then-lossless-encode path is followed. The output file will be significantly smaller than the original MTS (no video) but larger than a typical AAC or MP3 file of the same duration due to ALAC's lossless nature.

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) — your MTS file never leaves your device.
-i input.mts Specifies the input file — your AVCHD MTS camcorder recording. FFmpeg reads the MPEG-2 Transport Stream container and demuxes the H.264 video and AC-3 or AAC audio streams from it.
-vn Disables video output entirely, telling FFmpeg to ignore the H.264 video stream in the MTS file. Since the goal is audio-only ALAC extraction, this prevents any video data from being processed or included in the output.
-c:a alac Sets the audio codec to ALAC (Apple Lossless Audio Codec). FFmpeg decodes the original AC-3 or AAC audio from the MTS file to raw PCM and then re-encodes it as ALAC — a lossless format that captures the full decoded audio with no further quality loss.
-c:a alac This flag appears twice in the resolved command, which is redundant but harmless — FFmpeg applies the last specified value for each stream type, so ALAC is confirmed as the audio codec. The effective result is identical to specifying it once.
output.m4a Defines the output filename and tells FFmpeg to write the ALAC audio into an MPEG-4 container (.m4a) — the standard Apple container for both AAC and ALAC audio, fully compatible with iTunes, Apple Music, and iOS devices.

Common Use Cases

  • Archiving the audio from a live event or wedding recorded on a Sony or Panasonic camcorder in a lossless format for long-term preservation
  • Extracting narration or dialogue from AVCHD camcorder footage to edit in GarageBand, Logic Pro, or another Apple-ecosystem DAW without any generational quality loss
  • Pulling clean ambient sound recordings made on a camcorder to use as lossless source material for music production or sound design
  • Converting a camcorder's MTS audio track to ALAC so it can be imported directly into an iTunes or Apple Music library and synced to iPhone or iPad
  • Separating the audio from multi-camera MTS footage before a video edit, keeping lossless copies as reference tracks for audio syncing in Final Cut Pro
  • Extracting a lossless ALAC audio file from an MTS interview recording to serve as an archival master before creating compressed delivery formats

Frequently Asked Questions

No — ALAC is lossless, meaning it preserves exactly what it receives during encoding, but it cannot recover detail that was already discarded by the original lossy compression in the MTS file. If your AVCHD camcorder recorded AC-3 audio at 384 kbps or AAC at 128 kbps, the ALAC file will be a perfect lossless copy of that decoded audio. Think of it as a lossless snapshot of a lossy source: no further degradation occurs, but no lost quality is restored.
ALAC uses lossless compression, which means it retains all audio data and cannot achieve the same file size reductions as lossy codecs like AC-3 or AAC. A typical AC-3 track in an MTS file might be around 384 kbps, while a 16-bit stereo ALAC file at 48 kHz will often land between 700 kbps and 1,200 kbps depending on the complexity of the audio. This is the inherent tradeoff of lossless encoding: larger files in exchange for zero additional quality loss.
FFmpeg will decode the AC-3 audio from the MTS file and pass all available channels to the ALAC encoder, so if your camcorder recorded 5.1 surround audio, the ALAC output will contain all six channels. However, many consumer Sony and Panasonic camcorders record AC-3 in stereo (2.0) rather than 5.1, so check your source footage first. ALAC fully supports multi-channel audio, and the M4A container will carry the channel layout metadata correctly.
Yes — ALAC was developed by Apple and is natively supported across the entire Apple ecosystem, including iTunes, Apple Music, iPhone, iPad, iPod, Apple TV, and macOS QuickTime Player. The M4A container used here is the standard file format Apple uses for both AAC and ALAC audio. You can drag the output .m4a file directly into your iTunes or Apple Music library and it will be recognized as a lossless file.
MTS files embed limited metadata in the MPEG-2 Transport Stream container, and FFmpeg will attempt to carry over any compatible tags — such as creation time — into the MPEG-4 M4A container. However, proprietary AVCHD metadata specific to Sony or Panasonic cameras (such as GPS coordinates or camera model information stored in sidecar files) will not be transferred, as this data lives outside the MTS stream itself. If metadata preservation is critical, review the output file's tags in a tool like MP3Tag or Apple Music after conversion.
The command shown extracts audio from a single file, but you can batch process a folder of MTS files on your desktop using a shell loop. On macOS or Linux, run: for f in *.mts; do ffmpeg -i "$f" -vn -c:a alac "${f%.mts}.m4a"; done. On Windows Command Prompt, use: for %f in (*.mts) do ffmpeg -i "%f" -vn -c:a alac "%~nf.m4a". Each MTS file will produce a corresponding ALAC M4A file. Note that the browser-based tool processes one file at a time; the FFmpeg command is what enables bulk processing locally.

Technical Notes

ALAC stores audio in an MPEG-4 container with the .m4a extension, the same container used for AAC audio — the difference is entirely in the codec. Because ALAC is lossless, there are no quality settings to configure; the encoder always captures the full decoded PCM audio data. The source MTS audio is first fully decoded to raw PCM (losing the AC-3 or AAC encoding), then re-encoded by the ALAC encoder — a one-way conversion that cannot be undone to restore the original AC-3 or AAC stream. AVCHD MTS files commonly use 48 kHz sample rates, which ALAC supports natively, so no sample rate conversion is needed. One known limitation: MTS files can contain multiple audio tracks (e.g., a main mix and a secondary track from an external microphone), but FFmpeg's default behavior selects only the first audio stream. If your camcorder recorded a secondary audio track you need, you can specify it with -map 0:a:1 in the command. The ALAC codec in FFmpeg is a mature, well-tested implementation and produces files byte-compatible with those created by Apple's own tools.

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