Extract Audio from MKV to AIFF — Free Online Tool
Extract audio from an MKV file and save it as a lossless AIFF file using uncompressed PCM audio. This tool strips the video stream entirely and outputs a 16-bit big-endian PCM AIFF file — the native uncompressed format favored by macOS and professional audio applications — without any quality loss regardless of the source audio codec.
to
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
MKV containers can hold audio encoded in many codecs — AAC, MP3, Opus, Vorbis, or FLAC. When converting to AIFF, the tool decodes whatever compressed audio codec is present in the MKV and re-encodes it as uncompressed PCM (specifically pcm_s16be: 16-bit signed, big-endian). The video stream is discarded entirely using the -vn flag and is never processed. Because AIFF is an uncompressed format, the output file will be significantly larger than the source MKV audio track, and if the source was lossy (e.g., AAC or Opus), the output will be a lossless-quality PCM representation of that already-decoded audio — no additional lossy compression is applied, but the original lossy artifacts are preserved in the decoded signal.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg program, the open-source multimedia processing engine that handles all decoding, stream selection, encoding, and container writing for this conversion. |
-i input.mkv
|
Specifies the input Matroska (MKV) file. FFmpeg reads and demuxes all available streams — video, audio, and subtitles — from this container, making them available for processing or discarding. |
-vn
|
Disables video output entirely, telling FFmpeg to skip all video streams in the MKV. Since the goal is audio extraction, this prevents any video decoding work and ensures the AIFF output contains only audio data. |
-c:a pcm_s16be
|
Sets the audio codec to 16-bit signed big-endian PCM, which is the standard uncompressed audio encoding used in AIFF files. Regardless of whether the MKV source audio is AAC, FLAC, Opus, or another codec, it will be fully decoded and re-written as raw PCM in this format. |
output.aiff
|
Specifies the output filename and tells FFmpeg to write an AIFF container. The .aiff extension causes FFmpeg to apply the AIFF muxer, which wraps the pcm_s16be audio data in the big-endian chunk structure expected by macOS and Apple audio applications. |
Common Use Cases
- Extract a lossless audio track from an MKV movie or TV episode to import into Apple Logic Pro, GarageBand, or Final Cut Pro, which natively support AIFF
- Pull audio from an MKV lecture recording or documentary and archive it in uncompressed AIFF format for long-term preservation without any generational quality loss from re-compression
- Extract dialogue or sound effects from an MKV source file to use as raw audio material in a professional macOS audio editing workflow
- Convert an MKV music concert recording to AIFF so it can be burned directly to an audio CD via iTunes or other mastering tools that require uncompressed PCM
- Strip audio from an MKV game capture or screen recording to produce an uncompressed AIFF stem for mixing into a video project in DaVinci Resolve or Adobe Premiere on macOS
- Extract FLAC or high-bitrate AAC audio from an MKV and output it as uncompressed AIFF for use in audio restoration or noise reduction tools that require PCM input
Frequently Asked Questions
It depends on the audio codec inside your MKV. If the source track is lossless (e.g., FLAC), the decoded PCM data written to AIFF will be a perfect representation of the original. If the source is lossy (e.g., AAC, Opus, or MP3), the existing compression artifacts are baked into the decoded audio — converting to AIFF does not remove them, but it also introduces no new lossy compression. The AIFF output is always uncompressed PCM, so no additional quality is lost during this conversion step.
AIFF stores audio as raw, uncompressed PCM samples — there is no compression algorithm reducing the file size. A typical MKV might store audio as AAC at 128 kbps or FLAC with lossless compression, both of which are far smaller than uncompressed PCM. A stereo 16-bit PCM AIFF file at 44.1 kHz uses approximately 10 MB per minute of audio, which is many times larger than equivalent AAC or even FLAC. This is expected behavior for an uncompressed format.
FFmpeg selects the first audio stream by default, which is typically the primary language track. If your MKV contains multiple audio tracks (e.g., different languages or a commentary track) and you want to extract a specific one, you can modify the command with a stream specifier such as -map 0:a:1 to select the second audio track. Note that AIFF does not support multiple audio tracks, so only one stream can be written to the output file.
Yes. The default command uses pcm_s16be, which is 16-bit PCM. If your source has higher-quality audio you want to preserve at greater bit depth, you can change the codec flag to -c:a pcm_s24be for 24-bit or -c:a pcm_s32be for 32-bit PCM. To resample to a different sample rate, add -ar 48000 (or your target rate) to the command. For example: ffmpeg -i input.mkv -vn -c:a pcm_s24be -ar 48000 output.aiff.
No. AIFF does not support subtitles, chapters, or structured metadata containers the way MKV does. The subtitle and chapter streams are simply discarded during conversion. Basic metadata such as title or artist tags may be partially written to the AIFF file depending on the source MKV metadata, but AIFF has very limited metadata support compared to MKV.
You can use a shell loop to process multiple files. On macOS or Linux, run: for f in *.mkv; do ffmpeg -i "$f" -vn -c:a pcm_s16be "${f%.mkv}.aiff"; done. On Windows Command Prompt, use: for %f in (*.mkv) do ffmpeg -i "%f" -vn -c:a pcm_s16be "%~nf.aiff". This applies the same extraction and PCM encoding to every MKV in the current directory, producing a matching AIFF file for each.
Technical Notes
AIFF uses big-endian byte ordering inherited from the Motorola 68000 architecture of early Macintosh hardware, which is why the PCM codec is pcm_s16be (signed 16-bit big-endian) rather than the little-endian pcm_s16le used in WAV. Both represent uncompressed PCM audio, but AIFF's big-endian encoding is the canonical choice for macOS compatibility. The output will inherit the sample rate and channel count from the source MKV audio stream — if your source is 44.1 kHz stereo, the AIFF will be 44.1 kHz stereo. If the MKV contains a 5.1 surround track, the AIFF will contain 6 channels of uncompressed PCM, though not all AIFF players handle multi-channel AIFF reliably. Because FFmpeg must fully decode the compressed audio in the MKV before writing PCM, this conversion is computationally heavier than a simple remux — processing time scales with the length of the audio, not just the file size. AIFF does not support the FLAC, Opus, or Vorbis codecs, so lossless passthrough from a FLAC-encoded MKV track is not possible; the FLAC data must be decoded and re-written as PCM, though no quality is lost in that specific case.