Free online MKA to AAC converter

Some phones, editors, media players, and web applications accept standalone AAC but not Matroska Audio containers. Converting an MKA file extracts its selected audio track into .aac for applications that require that extension or for easier file sharing.

What the MKA format is

MKA is the audio-focused Matroska container. Its .mka extension identifies the container, not the codec inside it. An MKA file can contain one or more audio tracks, chapters, tags, cover art, and other Matroska elements, with codecs including AAC, MP3, Opus, Vorbis, FLAC, and AC-3.

MKA files commonly come from MKVToolNix, FFmpeg, MakeMKV, disc-extraction workflows, and audio collections packaged in Matroska. The source may already contain AAC, so conversion is unnecessary when the destination application supports MKA.

What the AAC format is

AAC is a lossy audio codec rather than a container. A standalone .aac file normally stores an AAC elementary stream in ADTS format; AAC is also commonly stored inside MP4 or M4A containers.

AAC generally delivers higher quality than MP3 at the same bitrate and is widely supported in phones, media players, and applications. Raw .aac support is less consistent than AAC in .m4a or .mp4, especially in web browsers and software that expects metadata, artwork, or reliable seeking.

How to convert MKA to AAC

Using 101convert.com

You can convert the file for free on 101convert.com without installing software. Upload the MKA file, select AAC as the output format, start the conversion, and download the result. If the converter exposes stream or bitrate settings, select the required audio track and output bitrate.

Using FFmpeg

FFmpeg supports track selection, re-encoding, and stream copying. First inspect the file to identify its audio streams:

ffmpeg -i input.mka

To encode the first audio stream as standalone AAC at 192 kbps, run:

ffmpeg -i input.mka -map 0:a:0 -c:a aac -b:a 192k output.aac

Change 0:a:0 to the required stream if the file contains multiple languages, commentary tracks, or channel layouts. FFmpeg selects the ADTS AAC output format from the .aac extension. Bitrates such as 128k, 192k, and 256k produce progressively larger files; the suitable value also depends on the source and the intended use.

If the selected MKA stream is already AAC, remove the container without re-encoding:

ffmpeg -i input.mka -map 0:a:0 -c:a copy output.aac

Stream copying avoids another generation of lossy compression, but it works only when the source codec is AAC and FFmpeg can write that stream as ADTS. If FFmpeg reports an incompatible codec or muxing error, use the re-encoding command.

Quality and compatibility limitations

Re-encoding MP3, Opus, AC-3, or already-compressed AAC to AAC cannot restore discarded detail and can add compression artifacts. Keep the original MKA as the archive and avoid re-encoding when the source already contains AAC.

Standalone AAC has limited support for tags, chapters, and embedded artwork. If the receiving application accepts an AAC file inside an MP4-based container, an M4A output is often more compatible:

ffmpeg -i input.mka -map 0:a:0 -c:a aac -b:a 192k output.m4a

Use .m4a when metadata, artwork, seeking, or broader playback compatibility matters; use .aac when the target specifically requires a raw AAC elementary stream.