Convert MKV to AIFF — Free Online Tool
Extract and convert audio from an MKV video file into a high-quality, uncompressed AIFF file using PCM 16-bit big-endian encoding. AIFF is Apple's native lossless audio format, making this conversion ideal for bringing video audio into macOS audio workflows, Logic Pro, or GarageBand without any quality degradation.
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FFmpeg Command
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Estimated output:
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DownloadHow It Works
MKV files typically carry compressed audio streams — most commonly AAC, MP3, Opus, or Vorbis. During this conversion, FFmpeg discards all video streams entirely and decodes the compressed audio track into raw PCM samples, then re-encodes those samples as 16-bit big-endian PCM (pcm_s16be), which is the standard codec inside an AIFF container. This is a full audio transcode: the compressed audio is fully decoded and then written as uncompressed data. If the source MKV audio was 16-bit or lower, no quality is lost beyond what was already lost during the original compression. If the MKV contained a lossy codec like AAC or MP3, the conversion to AIFF preserves exactly the quality present in that lossy stream — it does not restore frequencies that were discarded during earlier compression.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg program, the open-source multimedia processing engine that handles all decoding, transcoding, and muxing operations in this conversion. |
-i input.mkv
|
Specifies the input file — an MKV container which may contain video, one or more audio tracks (commonly AAC, MP3, Opus, or FLAC), subtitles, and chapter data. |
-c:a pcm_s16be
|
Sets the audio codec to PCM 16-bit big-endian, which is the standard uncompressed audio encoding required by the AIFF format. Any compressed audio from the MKV (such as AAC or Vorbis) is fully decoded and written as raw PCM samples in big-endian byte order, matching AIFF's Apple-originated specification. |
output.aiff
|
Specifies the output filename and container format. The .aiff extension tells FFmpeg to wrap the pcm_s16be audio stream in an AIFF container, which is Apple's native lossless audio format widely supported by macOS, Logic Pro, GarageBand, and other professional audio tools. |
Common Use Cases
- Import a film's audio track from an MKV file into Logic Pro or GarageBand on macOS for music scoring or sound design work
- Extract a recorded lecture or podcast from an MKV container to deliver to a client or broadcaster who requires uncompressed AIFF masters
- Bring dialogue audio from an MKV video project into Final Cut Pro for professional audio post-production using a format with native Apple compatibility
- Archive the audio track of a home video or documentary stored in MKV as an uncompressed AIFF for long-term preservation without codec dependency
- Extract the stereo music track from an MKV music video to import into Ableton Live or Pro Tools on a Mac for remixing or mastering
- Convert the audio from an MKV screen recording or tutorial video into AIFF for use in an e-learning platform that requires uncompressed audio assets
Frequently Asked Questions
No — if the audio track inside the MKV was encoded with a lossy codec like AAC, MP3, Opus, or Vorbis, that compression has already permanently removed certain audio data. Converting to AIFF does not recover that lost information; it simply stores what remains in an uncompressed format. However, the resulting AIFF will not undergo any additional quality loss and will be an exact uncompressed representation of the audio as it exists in the MKV source.
AIFF is an Apple-originated format and uses big-endian byte ordering, which is why the codec is pcm_s16be: PCM (uncompressed audio), 16-bit sample depth, big-endian byte order. This contrasts with WAV, which uses little-endian PCM (pcm_s16le). The 16-bit depth means up to 65,536 amplitude levels per sample, which is the standard for CD-quality audio. Big-endian ordering is a historical artifact of the Motorola 68000 processors used in early Macintosh hardware.
By default, FFmpeg selects the first audio track in the MKV file, which is typically the primary or default-flagged track. AIFF does not support multiple audio tracks in a single file, so only one track can be exported. If you need a specific audio track other than the first — for example, a director's commentary or an alternate language track — you can modify the command with the -map flag, such as adding '-map 0:a:1' to select the second audio track.
Significantly larger, because AIFF stores audio as raw, uncompressed PCM data. For example, a stereo 44.1kHz 16-bit audio stream uses approximately 10MB per minute uncompressed. If the MKV contained AAC audio at 128k, the original compressed audio might use only about 1MB per minute — meaning the AIFF could be roughly 10 times larger for the same duration. The exact ratio depends on the source bitrate and sample rate of the MKV audio.
No. The AIFF format is a pure audio container and does not support chapters, subtitles, video, or rich metadata structures. All of these elements present in the MKV — including chapter markers, subtitle tracks, video streams, and extended metadata — are discarded during conversion. Only the audio content and basic tags like title or artist (if compatible) carry over.
Replace '-c:a pcm_s16be' with '-c:a pcm_s24be' to produce a 24-bit big-endian AIFF file. The full command would be: ffmpeg -i input.mkv -c:a pcm_s24be output.aiff. A 24-bit AIFF provides greater dynamic range (144dB versus 96dB for 16-bit) and is the professional standard for studio audio work. This is especially worthwhile if the source MKV audio was encoded at a high bitrate or if the AIFF will undergo further processing in a DAW.
Technical Notes
AIFF uses big-endian PCM encoding, which differentiates it from the functionally similar WAV format that uses little-endian PCM. This byte-order distinction matters when working with low-level audio tools or legacy Apple hardware, but is completely transparent on modern macOS and in standard DAW software. The default output of this tool uses pcm_s16be (16-bit, 44.1kHz or whatever sample rate the source carries), which is CD-quality and compatible with virtually all macOS audio software. AIFF does not support any form of audio compression — there is no 'quality' slider because the output is always lossless and uncompressed. The output file size is determined entirely by sample rate, bit depth, number of channels, and duration. One notable limitation: AIFF supports only a single audio stream, so if the MKV contains multiple audio tracks, only the default track is extracted. Additionally, MKV's subtitle tracks, chapter data, and video streams are all silently dropped since AIFF has no mechanism to carry them. If the source MKV audio is already in a lossless format such as FLAC, the conversion to AIFF pcm_s16be is fully lossless end-to-end provided the FLAC was encoded at 16-bit depth; FLAC encoded at 24-bit will be truncated to 16-bit unless you explicitly select pcm_s24be.