Any file up to 500 MB. Drop several files and they come back as one ZIP. Many image, audio and video conversions run in your browser; anything else is uploaded and removed within the hour.
Convert MKV video containers into M4A audio files quickly and securely using ConvertX. This tool is essential for users who want to extract sound tracks from Matroska videos to play them on Apple devices or standalone audio players.
MKV is a flexible multimedia container that stores multiple video, audio, and subtitle tracks, whereas M4A is a container dedicated strictly to audio, typically encoded with AAC or ALAC. When converting MKV to M4A, ConvertX performs a data type transition from video to audio by dropping the video stream and extracting or re-encoding the audio track into the M4A wrapper. Because you are discarding the heavy video stream while keeping only the sound, the resulting file size changes insignificantly relative to the original audio payload, yet the visual data is permanently removed.
Audio quality remains virtually identical to the original MKV sound track if the tool performs a direct stream copy, or experiences negligible generation loss if re-encoding to AAC is applied.
We built this project so anyone can convert files without paywalls, accounts, or hidden limits. Here is what that promise means in practice.
Every converter on ConvertX is free to use: no trials, no premium tiers, and no credit packs. We will never put core conversion features behind a subscription. Whether you convert one photo or a hundred files a week, the price stays zero.
Many image, audio, and video conversions run entirely in your browser. Your files never leave your device for those jobs. When server processing is required for documents or specialized formats, uploads are handled securely and removed automatically — typically within one hour.
A quick guide to strengths and trade-offs of popular formats — so you pick the right one before converting.
Clips, streams, screen recordings, and movies.
Common extensions: MP4, WebM, MOV, MKV, AVI, MPEG
Raster and vector graphics for web, print, and photography.
Common extensions: PNG, JPG, WebP, AVIF, GIF, SVG, HEIC, TIFF
Office files, PDFs, ebooks, and plain text.
Common extensions: PDF, DOCX, XLSX, PPTX, ODT, EPUB, TXT
Music, podcasts, voice recordings, and sound effects.
Common extensions: MP3, WAV, FLAC, OGG, AAC, M4A, OPUS
