Convert MKV to AAC Online
Extract audio from MKV files (movies, anime, series) and save as AAC. Ideal for Apple Music, iPhone, iPad, and podcasts. Free, in your browser.
.mkv · up to 100 MB
What you can do
MKV to AAC: movie and anime audio for Apple and podcasting
Apple Music and podcasts
AAC in M4A is the accepted format for Apple Music, iTunes, Apple Podcasts, and Spotify distribution.
100% private
Your MKV never leaves your device. Local processing with FFmpeg.wasm in the browser.
DTS and AC-3 to AAC
Automatic downmix of 5.1/7.1 multichannel audio to high-quality stereo AAC.
Anime and movies
Extract the soundtrack from your favorite MKV files to AAC using the default audio track.
How it works
Three steps, no hassle
Upload your MKV file
Drag or select your .mkv file with DTS, AC-3, FLAC, AAC, or Vorbis audio. Up to 500 MB, no signup.
Extraction to AAC
FFmpeg.wasm selects the default MKV audio track, decodes it, and encodes to AAC-LC in your browser. Automatic downmix if audio is 5.1 or 7.1.
Download your AAC
M4A file ready for iPhone, Apple Music, podcast distributors, or any device. Download with one click.
FAQ
Got questions?
AAC (Advanced Audio Coding) offers better quality than MP3 at the same or lower bitrate. At 128 kbps, AAC offers quality equivalent to MP3 at 192 kbps according to multiple blind listening studies (including Hydrogenaudio Comparison Tests from 2003–2015). This is especially relevant when the source audio in the MKV already has one generation of compression (AC-3, DTS, AAC), because transcoding to AAC adds less loss than transcoding to MP3. Additionally, AAC in M4A is the preferred format for Apple (iPhone, iPad, Apple Music, iTunes), Spotify, and YouTube, which accept it as an upload format. For podcasts, Apple Podcasts and Spotify accept AAC M4A directly.
DTS and AC-3 in movie MKV files are frequently in multichannel configurations: 5.1 (front left, front right, center, LFE, and two surrounds) or 7.1 (those plus two additional surrounds). When converting to stereo AAC, FFmpeg applies a downmix process following ITU-R BS.775 recommendation: the center channel is added to the front left and right channels weighted at -3 dB, surround channels are attenuated and mixed into the stereo channels at -6 dB, and the LFE (subwoofer) is typically omitted (no correlate in headphones or two-channel speakers). The result is a stereo that preserves all dialogue (originally in the center channel) and most of the musical and ambient content. For listening to movie dialogue on mobile devices, the resulting stereo AAC is fully functional.
Yes, if you meet the quality requirements. Apple Music accepts AAC-LC in M4A at 256 kbps bitrate for distribution through accredited distributors (DistroKid, TuneCore, CD Baby). If the source MKV has FLAC audio (lossless), conversion to AAC 256 kbps produces a file with only one generation of loss, technically meeting quality standards for distribution. If the MKV has DTS or AC-3 (already lossy), the AAC will have two generations of loss, though at 256 kbps the difference is imperceptible in practice. Apple Music for Artists accepts direct M4A/AAC uploads via iTunes Producer if you are a registered label, or through distributors for independent artists.
The workflow is: you have a video recording in MKV (a filmed interview, a recorded conference, or a live event) and want to publish only the audio on Apple Podcasts, Spotify, or podcast distribution platforms. Apple Podcasts accepts MP3 and AAC (M4A) as audio formats for podcast episodes. Spotify also accepts M4A/AAC. Extracting the audio from the MKV to AAC using this tool is more efficient than converting to MP3 because AAC produces better quality at the same file size. Recommended bitrate for voice podcast is 96–128 kbps mono AAC (or 128 kbps stereo if there is music). Episode duration, stored in MKV metadata, is transferred to the destination M4A.
AAC works perfectly on Android. Android has natively supported AAC decoding (AAC-LC, AAC-ELD, and HE-AAC) since Android 1.0 (2008). M4A/AAC files play in all Android music apps: YouTube Music, Spotify, VLC, Poweramp, BlackPlayer, etc. The historical limitation was Apple FairPlay DRM-protected AAC (only playable on Apple devices), but the AAC this tool produces is DRM-free, universally compatible. In terms of decoder compatibility, AAC is supported on 99% of devices running Android 4.0 or higher, which represents practically 100% of the active Android device population in 2025.
A 90-minute high-quality movie MKV (Blu-ray rip) occupies 8–25 GB, of which audio represents 500 MB (stereo AAC) to 4 GB (lossless DTS-HD MA 7.1). The stereo AAC extracted at 256 kbps from that same movie will occupy approximately 180 MB for 90 minutes, and at 128 kbps approximately 90 MB. In comparison, MP3 at 320 kbps for the same duration would occupy 216 MB. Thus, AAC at 256 kbps produces a file similar in size to MP3 at 320 kbps but with better perceptual quality. For 24-minute anime episodes, the AAC extracted at 192 kbps occupies approximately 35 MB — manageable for transfer or mobile device storage.
Convert MKV to AAC: extract Matroska audio for Apple Music, iPhone, and podcasting
Converting MKV to AAC allows integrating audio from high-quality Matroska files into the Apple ecosystem (iPhone, iPad, Mac, Apple Music, iTunes, Apple Podcasts) and into podcast production workflows, where AAC dominates as the distribution format. The Matroska (MKV) container stores audio codecs in the TrackEntry element with specific CodecID: A_DTS for DTS and DTS-HD, A_AC3 for Dolby Digital and EAC-3, A_FLAC for lossless FLAC audio, A_AAC for native Advanced Audio Coding, and A_VORBIS for OGG Vorbis. Blu-ray rips in MKV produced with MakeMKV or HandBrake preserve the high-quality audio from the original disc, which may be DTS-HD Master Audio at 24.5 Mbps or Dolby TrueHD with Atmos support. The AAC (Advanced Audio Coding) codec, standardized as MPEG-2 Part 7 (ISO/IEC 13818-7) in 1997 and expanded in MPEG-4 Audio (ISO/IEC 14496-3) in 1999, was designed as the successor to MP3 with the mission of delivering transparent quality at 128 kbps stereo. Over the more than 25 years since its publication, AAC has consolidated as the dominant streaming format: Apple Music uses AAC-LC at 256 kbps, YouTube uses AAC at 128–192 kbps as fallback codec, and Apple podcasts are distributed predominantly in AAC inside M4A. MKV to AAC audio extraction bridges the gap between the high-quality video ecosystem (MKV/Matroska) and the Apple audio distribution ecosystem.
The most frequent workflows for MKV to AAC conversion are four. First, soundtrack extraction for Apple Music: artists and collectors with live performance recordings in high-quality MKV can extract audio to AAC for uploading to DistroKid, TuneCore, or CD Baby as live singles or concert albums, meeting Apple Music's quality requirements (256 kbps AAC-LC in M4A). Second, podcast production from video: conference recordings, filmed interviews, and events in MKV are converted to AAC for publishing as episodes on Apple Podcasts, Spotify, and other platforms, where M4A/AAC is the recommended delivery format. Third, iPhone/iPad sync: personal movies or series stored in MKV that you want to sync to iOS devices via iTunes or Finder for offline playback. iTunes accepts M4A/AAC for syncing directly, while MKV would require additional video conversion. Fourth, corporate archiving: corporate video clips in MKV that need to be preserved as AAC audio only for e-learning repositories compatible with Apple devices.
Convertir.ai runs MKV to AAC conversion entirely in the browser using FFmpeg.wasm. The processing flow begins with analysis of the MKV file's EBML header to identify DocType (matroska or webm) and schema version. In the Segment element, SeekHead provides offsets for Info, Tracks, and Cues elements, allowing FFmpeg to locate track descriptions directly without linearly reading the entire file. The default audio track is identified by inspecting TrackEntry elements in the Tracks block: looking for TrackType=2 (audio) and FlagDefault=1. That track's CodecID determines the FFmpeg decoder: for DTS (A_DTS), the dca decoder is used with DTS Core and DTS-HD support; for AC-3 (A_AC3), the ac3 decoder; for FLAC (A_FLAC), the flac decoder; for native AAC (A_AAC), a direct stream copy to the output M4A container is performed without re-decoding or re-encoding (the fastest and additional-lossless operation). For lossy codecs or PCM, the decoder produces 32-bit float PCM which passes through stereo downmix if needed, and the AAC encoder in libavcodec (AAC-LC profile, native encoder or fdk-aac if available) compresses it to the selected bitrate. The output M4A includes the ilst metadata atom with fields transferred from the MKV: title, artist, duration, and creation_time, for compatibility with iTunes and Apple Music.