Extract Audio from M2TS to CAF — Free Online Tool
Extract audio from M2TS Blu-ray and AVCHD files and save it as a CAF file using uncompressed PCM audio. This tool demuxes the audio stream from the MPEG-2 Transport Stream container and writes it into Apple's Core Audio Format, making it ideal for further audio editing in Logic Pro or other Apple ecosystem 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
M2TS files are MPEG-2 Transport Stream containers commonly carrying multiple audio tracks encoded in formats like AAC, AC-3, DTS, or TrueHD alongside H.264 or H.265 video. This tool discards the video stream entirely using the -vn flag and extracts the first audio track, re-encoding it to PCM signed 16-bit little-endian (pcm_s16le) — uncompressed linear audio — and wraps it in Apple's Core Audio Format (CAF) container. CAF was designed to overcome the 4GB file size limit of WAV and AIFF, making it a practical choice for long Blu-ray audio extractions. Because the source audio codec (e.g., AC-3 or AAC) is almost certainly different from pcm_s16le, a full decode-and-re-encode is performed rather than a simple stream copy.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg command-line tool, which handles all demuxing, decoding, encoding, and muxing operations in this conversion. In the browser-based version of this tool, FFmpeg runs locally via WebAssembly (FFmpeg.wasm) with no server upload. |
-i input.m2ts
|
Specifies the input M2TS file — a Blu-ray or AVCHD MPEG-2 Transport Stream container that typically contains H.264 or H.265 video alongside one or more compressed audio tracks such as AAC, AC-3, DTS, or TrueHD. |
-vn
|
Disables video output entirely, telling FFmpeg to ignore the H.264 or H.265 video stream in the M2TS file. This is essential for audio-only extraction and prevents FFmpeg from attempting to encode or mux video into the CAF output, which is a pure audio container. |
-c:a pcm_s16le
|
Encodes the extracted audio to PCM signed 16-bit little-endian, which is uncompressed linear audio. Since M2TS audio codecs like AC-3 or DTS are not supported by the CAF container, a full decode-and-re-encode to this uncompressed format is required, and pcm_s16le is the CAF default codec with universal compatibility in Apple applications. |
-b:a 128k
|
Sets a target audio bitrate of 128 kbps. For uncompressed PCM (pcm_s16le), this parameter has no practical effect — the actual bitrate is determined by sample rate and bit depth rather than a configurable target — but it is included as a default parameter that would be meaningful if a lossy codec like AAC or libopus were selected instead. |
output.caf
|
Defines the output file as a CAF (Core Audio Format) container, Apple's audio format designed to support large file sizes beyond the 4GB limit of WAV and AIFF. CAF is natively compatible with Logic Pro, GarageBand, and Core Audio on macOS and iOS. |
Common Use Cases
- Importing clean, uncompressed audio from a Blu-ray rip into Logic Pro or GarageBand for film scoring or sound design work
- Extracting the original audio track from an AVCHD camcorder recording to edit separately from the video in Final Cut Pro on a Mac
- Archiving the audio content of a Blu-ray concert or live performance recording as a high-quality uncompressed CAF file for long-term storage
- Separating dialogue or ambient sound from an M2TS source file before feeding it into speech recognition or transcription software on macOS
- Creating a raw audio master from a Blu-ray rip to use as a reference track when mixing or mastering in a macOS audio workstation
Frequently Asked Questions
The output format itself — pcm_s16le — is uncompressed, so there is no additional lossy compression introduced by the CAF container. However, if the original M2TS audio track is lossy (such as AAC or AC-3), you will be decoding that lossy source and re-encoding it to PCM. The decode step introduces no further generation loss, but you cannot recover information that was discarded by the original lossy codec. If the M2TS source contains lossless audio like TrueHD or DTS-HD MA, the conversion to 16-bit PCM may reduce bit depth from the original 24-bit source.
CAF supports a specific set of codecs, and common M2TS audio codecs like AC-3 (Dolby Digital), DTS, and TrueHD are not among them. Rather than failing silently or producing an incompatible file, the tool transcodes to pcm_s16le, which is a universally compatible uncompressed format fully supported by CAF and every Apple audio application. If your source is AAC or FLAC, those codecs are technically supported by CAF, but pcm_s16le is used as a safe, predictable default.
FFmpeg selects the first audio stream by default, which is typically the primary language track or the main surround mix. M2TS files from Blu-ray discs often contain additional tracks such as director's commentary, secondary language dubs, or descriptive audio. CAF does not support multiple audio tracks in a single file, so only one track can be extracted per conversion. To extract a different track, you can modify the FFmpeg command by adding -map 0:a:1 (for the second audio stream), -map 0:a:2 for the third, and so on.
Because the output codec is pcm_s16le (uncompressed PCM), the -b:a bitrate parameter does not meaningfully control quality — PCM bitrate is determined by sample rate and bit depth, not a configurable bitrate setting. To increase fidelity, you can change the output codec to pcm_s24le for 24-bit audio by replacing -c:a pcm_s16le with -c:a pcm_s24le in the command. You can also add -ar 48000 to explicitly set the sample rate to 48kHz, which matches the native sample rate of most Blu-ray audio tracks.
Yes. On macOS or Linux, you can use a shell loop to process multiple files: for f in *.m2ts; do ffmpeg -i "$f" -vn -c:a pcm_s16le -b:a 128k "${f%.m2ts}.caf"; done. On Windows Command Prompt, use: for %f in (*.m2ts) do ffmpeg -i "%f" -vn -c:a pcm_s16le -b:a 128k "%~nf.caf". This is especially useful for extracting audio from a library of AVCHD camcorder clips, since those are typically stored as many individual short M2TS segments.
Uncompressed PCM audio is significantly larger than the compressed audio codecs found in most M2TS files. For example, a 5.1-channel AC-3 track at 640 kbps in an M2TS will expand to roughly 4.6 Mbps as stereo pcm_s16le at 48kHz, or considerably more if you retain all six channels. A 90-minute Blu-ray audio extraction could easily produce a CAF file exceeding 3GB, which is precisely why CAF's support for files larger than 4GB (unlike WAV or AIFF) makes it a practical container choice for this use case.
Technical Notes
M2TS is a profile of the MPEG-2 Transport Stream format with a 192-byte packet size (adding a 4-byte timestamp prefix to the standard 188-byte TS packet), and it can carry multiple audio streams with different codecs simultaneously — a common Blu-ray structure. FFmpeg handles M2TS demuxing well but may require probing extra packets to identify all streams in files with delayed or non-standard stream headers. The CAF container, developed by Apple, natively supports pcm_s16le and is directly importable into Logic Pro, GarageBand, Audacity (on macOS), and Core Audio APIs without additional codec installation. One notable limitation: CAF does not preserve Blu-ray-specific metadata such as channel mapping descriptors or language tags the way the original M2TS container does. Surround sound from the M2TS source (e.g., 5.1 or 7.1) will be preserved in channel count in the output CAF file, but downstream applications should be verified for correct channel interpretation. If your workflow requires 24-bit or 32-bit float precision, substitute pcm_s24le or pcm_f32le for pcm_s16le in the command — both are fully supported by the CAF container.