Convert M2TS to CAF — Free Online Tool
Extract and convert audio from Blu-ray M2TS files into Apple's Core Audio Format (CAF), encoding the audio stream as uncompressed PCM (pcm_s16le) — ideal for high-fidelity archival or professional audio workflows on macOS. The video stream is discarded entirely, producing a pure audio file that preserves the full dynamic range of the original Blu-ray soundtrack.
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FFmpeg Command
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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 used on Blu-ray discs, typically carrying video (H.264 or HEVC) alongside audio encoded in formats like Dolby TrueHD, DTS-HD, or AAC. During this conversion, FFmpeg strips the video stream entirely and extracts the audio, transcoding it to 16-bit signed little-endian PCM (pcm_s16le) inside a Core Audio Format container. CAF is Apple's modern replacement for AIFF and WAV, capable of holding very large uncompressed audio files without the 4GB size limit that WAV imposes. The result is a lossless, uncompressed audio file that is natively compatible with macOS and iOS audio tools.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg binary — the open-source multimedia processing engine that this tool runs entirely in your browser via WebAssembly (FFmpeg.wasm), with no server upload required. |
-i input.m2ts
|
Specifies the input file as an M2TS container, the BDAV transport stream format used by Blu-ray discs and AVCHD camcorders. FFmpeg will parse all streams inside it, including video, audio, and any subtitle tracks. |
-c:a pcm_s16le
|
Sets the audio codec to 16-bit signed PCM in little-endian byte order, producing uncompressed audio suitable for the CAF container. This decodes whatever compressed audio format (AAC, AC-3, DTS, TrueHD) was in the M2TS and outputs raw PCM samples — no further compression is applied. |
-b:a 128k
|
Specifies a target audio bitrate of 128 kbps, though this flag is effectively inert for pcm_s16le since uncompressed PCM audio has a fixed bitrate determined by sample rate and channel count, not a user-configurable compression target. |
output.caf
|
Defines the output file as a Core Audio Format (.caf) container — Apple's audio container designed to handle large uncompressed files without the 4GB size restriction of WAV, and natively supported across macOS and iOS audio tools. |
Common Use Cases
- Extracting the uncompressed audio soundtrack from a Blu-ray rip to use as a high-quality source for audio mastering or post-production in Logic Pro on macOS.
- Archiving the audio layer of an AVCHD camcorder recording (stored as M2TS) into a stable, lossless CAF file for long-term preservation on Apple systems.
- Pulling the audio track from a Blu-ray concert film M2TS for use in a macOS-based music production environment where CAF is the native working format.
- Preparing a clean, uncompressed audio stem from a Blu-ray source for synchronization with video in Final Cut Pro, which natively handles CAF files.
- Converting AVCHD M2TS recordings from a Sony or Panasonic camcorder into CAF for editing in GarageBand or other Apple audio applications without re-encoding artifacts.
- Stripping audio from a large Blu-ray M2TS backup file to create a lightweight audio-only reference track for dialogue editing or subtitle alignment workflows.
Frequently Asked Questions
If the original M2TS contains a lossless audio track (such as Dolby TrueHD or DTS-HD MA), the conversion to pcm_s16le will be a lossless transcode — the PCM output accurately represents the decoded audio with no perceptible quality loss at 16-bit depth. If the source audio is lossy (e.g., Dolby Digital AC-3 or AAC), the quality ceiling is already set by that original encoding, and the PCM output simply preserves whatever quality exists without introducing additional compression artifacts.
CAF does not support multiple audio tracks within a single container, unlike M2TS which can carry several audio streams simultaneously (e.g., different language dubs or commentary tracks). FFmpeg will default to selecting the first or highest-priority audio stream from the M2TS file. If you need a specific track, you can add the flag '-map 0:a:1' (for the second audio stream) to the command before the output filename to target a particular stream explicitly.
Both subtitles and chapters are dropped during this conversion. CAF is a pure audio container and has no mechanism to store subtitle streams or chapter markers. The conversion is audio-only by design — the M2TS video, subtitle, and chapter data are all discarded. If you need to preserve those elements, you would need a different output format such as MKV or MP4.
Because pcm_s16le is an uncompressed PCM codec, the '-b:a 128k' flag in the command has no effect on output quality — the bitrate of uncompressed audio is determined purely by sample rate and bit depth, not a compression target. If you want a smaller compressed output, you could swap the codec by replacing '-c:a pcm_s16le' with '-c:a aac' and then '-b:a 192k' will meaningfully control the output quality. For uncompressed PCM output, the file size is fixed by the audio duration and sample rate.
Yes. On macOS or Linux, you can wrap the command in a shell loop: 'for f in *.m2ts; do ffmpeg -i "$f" -c:a pcm_s16le "${f%.m2ts}.caf"; done'. On Windows Command Prompt, use 'for %f in (*.m2ts) do ffmpeg -i "%f" -c:a pcm_s16le "%~nf.caf"'. This processes each M2TS file in the current directory and produces a corresponding CAF file with the same base name.
M2TS files store audio in compressed formats like Dolby Digital (AC-3), AAC, or DTS, which are many times smaller than uncompressed audio. Converting to pcm_s16le in CAF removes all audio compression, so the output size reflects the raw uncompressed audio data. As a rough guide, uncompressed 16-bit stereo audio at 48kHz (standard for Blu-ray) produces about 5.5 MB per minute, and multi-channel surround audio scales proportionally with the number of channels.
Technical Notes
M2TS files sourced from Blu-ray discs commonly carry multi-channel audio (5.1 or 7.1 surround) encoded in Dolby TrueHD, Dolby Digital Plus (E-AC-3), DTS-HD Master Audio, or standard AAC. FFmpeg decodes whichever stream is selected and re-encodes it into pcm_s16le, which represents audio as 16-bit signed integers in little-endian byte order — the same bit depth used on audio CDs. If the source contains high-resolution audio at 24-bit depth (common on Blu-ray), using pcm_s16le will downsample the bit depth from 24 to 16 bits; consider switching to '-c:a pcm_s24le' in the command to preserve the full 24-bit resolution. CAF natively supports pcm_s24le and is one of the few widely supported containers that handles this cleanly on macOS. Multi-channel layouts (e.g., 5.1 surround) are carried through to the CAF output, though playback compatibility for surround CAF files is more limited than stereo. No metadata from the M2TS container (track titles, language tags) is guaranteed to transfer into the CAF output, as the two containers use incompatible metadata schemes.