Extract Audio from MTS to CAF — Free Online Tool
Extract audio from MTS camcorder footage and save it as a CAF file using 16-bit PCM — Apple's professional-grade lossless audio format. Ideal for importing clean, uncompressed audio from AVCHD recordings directly into Logic Pro, GarageBand, or other macOS audio tools.
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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
MTS files recorded by Sony and Panasonic AVCHD camcorders typically contain AC-3 (Dolby Digital) or AAC audio tracks encoded inside an MPEG-2 Transport Stream container. This tool strips the H.264 video entirely and decodes the compressed audio, then re-encodes it as 16-bit PCM (pcm_s16le) inside Apple's Core Audio Format (CAF) container. Because MTS audio is lossy (AC-3 or AAC) and CAF is being used here in lossless PCM mode, the output is a full-resolution uncompressed representation of whatever audio quality was captured by the camcorder — no further lossy compression is applied. CAF's design overcomes the 4GB file size limit of WAV and AIFF, making it well-suited for long camcorder recordings.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool. In the browser version, this runs via FFmpeg.wasm compiled to WebAssembly, so no files leave your machine — the same command can also be run locally in a terminal for files over 1GB. |
-i input.mts
|
Specifies the input MTS file — an AVCHD recording from a Sony or Panasonic camcorder containing H.264 video and AC-3 or AAC audio inside an MPEG-2 Transport Stream container. |
-vn
|
Disables video output entirely, discarding the H.264 video stream from the MTS file so only the audio is processed. This avoids unnecessary video decoding and keeps the output as a pure audio file. |
-c:a pcm_s16le
|
Encodes the output audio as 16-bit signed little-endian PCM, a lossless uncompressed format. This decodes the lossy AC-3 or AAC audio from the MTS file into raw PCM samples, which is the standard audio format for Apple's Core Audio ecosystem and ensures no further compression artifacts are introduced. |
-b:a 128k
|
Sets a target audio bitrate, but this flag has no practical effect when using a lossless PCM codec — PCM bitrate is fixed by sample rate and bit depth (48 kHz / 16-bit stereo = ~1536 kbps regardless of this setting). It is included for command consistency but can be safely omitted when using pcm_s16le. |
output.caf
|
Defines the output file as a CAF (Core Audio Format) file. FFmpeg infers the container from the .caf extension and wraps the PCM audio stream in Apple's CAF container, which supports large file sizes beyond the 4 GB WAV/AIFF limit and is natively compatible with macOS and iOS audio tools. |
Common Use Cases
- Importing dialogue or ambient audio from AVCHD camcorder footage into Logic Pro or GarageBand for post-production mixing
- Extracting the recorded audio from a Sony or Panasonic camcorder's MTS file to use as a scratch track or sync reference in Final Cut Pro
- Archiving the audio portion of long event recordings (weddings, conferences) captured on AVCHD cameras, where WAV's 4GB size limit would be a concern
- Pulling clean interview audio from MTS footage to hand off to a sound editor working entirely within the Apple ecosystem
- Converting camcorder-recorded music performances stored as MTS files into high-quality PCM CAF files for audio analysis or mastering
Frequently Asked Questions
There is a one-time quality loss if your MTS file uses AC-3 or AAC audio, because those compressed formats must be decoded before being written as PCM. However, once in CAF as pcm_s16le, the audio is uncompressed and will not degrade further through any additional editing or re-exporting within a lossless workflow. The resulting quality is effectively a ceiling set by what the camcorder originally captured — typically 48 kHz / 16-bit, which is broadcast-standard audio.
CAF supports a wide range of codecs, but the default and most universally compatible choice for Apple tools is 16-bit signed little-endian PCM (pcm_s16le). While CAF can technically carry AAC, using PCM ensures the file opens natively in Logic Pro, GarageBand, QuickTime Player, and Core Audio APIs without any decoding overhead. It also avoids a second generation of lossy compression, which would further degrade audio quality.
Because the output uses PCM (lossless), the -b:a 128k bitrate flag has no meaningful effect — PCM bitrate is determined entirely by sample rate and bit depth, not a target bitrate. If you want a smaller file, you can change the codec to AAC or libopus; for example, replace '-c:a pcm_s16le -b:a 128k' with '-c:a aac -b:a 192k' to get a compressed CAF file. Alternatively, adjusting the sample rate with '-ar 44100' will reduce file size while keeping PCM.
On macOS or Linux, you can loop over files in a directory with: for f in *.mts; do ffmpeg -i "$f" -vn -c:a pcm_s16le -b:a 128k "${f%.mts}.caf"; done. On Windows Command Prompt, use: for %f in (*.mts) do ffmpeg -i "%f" -vn -c:a pcm_s16le -b:a 128k "%~nf.caf". This is especially useful for processing a full memory card of AVCHD footage from a camcorder shoot.
Yes. CAF with pcm_s16le audio is a native Apple format and is directly supported in Final Cut Pro, Logic Pro, GarageBand, and any application built on Core Audio. You do not need to install additional codecs or plugins. Logic Pro in particular treats CAF as a first-class audio format and will recognize the 48 kHz sample rate typically found in AVCHD camcorder audio.
MTS files store minimal metadata in the MPEG-2 Transport Stream wrapper, and CAF has limited metadata support compared to formats like BWF or MP4. The FFmpeg conversion will not carry over camcorder-specific tags like recording date, GPS coordinates, or camera model into the CAF file. If preserving this metadata is important, consider extracting it separately using ExifTool before converting, or embedding it manually into the CAF file using Core Audio APIs after conversion.
Technical Notes
MTS is an AVCHD container built on MPEG-2 Transport Stream, and its audio is almost always AC-3 at 48 kHz or, less commonly, AAC — both lossy codecs recorded at camcorder bitrates typically ranging from 192 kbps to 256 kbps. When FFmpeg decodes this stream and writes it as pcm_s16le into CAF, the output file will be substantially larger than the source MTS audio: a one-hour recording with 48 kHz / 16-bit stereo PCM produces roughly 1.2 GB of audio data, well within CAF's design limit but far beyond WAV's 4 GB ceiling for longer recordings. The -vn flag ensures the H.264 video stream is completely ignored, so no video decoding occurs, making this conversion fast even on large MTS files. One notable limitation: MTS files occasionally contain multiple audio tracks (e.g., a main mix plus a secondary mic channel), but CAF does not support multiple audio tracks in a single file — FFmpeg will select the first audio track by default. To extract a secondary track, add '-map 0:a:1' to the command before the output filename.