Convert 3G2 to MKV — Free Online Converter

MKV (Matroska Video) is the Swiss Army knife of video containers — it supports virtually every video and audio codec ever created, multiple subtitle tracks, chapter markers, and rich metadata. Converting 3G2 to MKV transforms old CDMA phone recordings from the cramped 3GPP2 container into Matroska's flexible and future-proof structure. MKV is the format of choice for media archivists, Kodi/Plex users, and anyone who values container-level flexibility.

While MKV may seem like overkill for tiny phone recordings, the container's ability to carry arbitrary metadata, support any codec without re-encoding, and maintain perfect stream fidelity makes it an excellent archival target. You can remux the original 3G2 streams into MKV without any re-encoding, preserving every bit of the original recording.

MKV's primary advantage is universal codec support without the container-level restrictions found in MP4 or AVI. If you want to preserve the original H.263 or MPEG-4 Part 2 video and AMR audio from your 3G2 files exactly as recorded — without any re-encoding — MKV can hold these streams directly. This is a true archival remux with zero quality change.

Additionally, MKV integrates seamlessly with media server software like Plex, Jellyfin, and Kodi. If you are building a media library that includes old phone recordings alongside movies and TV shows, MKV provides a consistent container format. MKV also supports attaching files (like photos or documents) to the video, which can be useful for contextual archival — embedding the source phone's photo or the original 3G2 file as an attachment.

For remuxing (preserving original codecs), FFmpeg copies the H.263 or MPEG-4 Part 2 video and AMR or AAC audio streams directly into the Matroska container using '-c copy'. This is virtually instantaneous and lossless. For transcoding to modern codecs, FFmpeg can re-encode to H.264/H.265 video with AAC/Opus audio inside MKV. The mkvmerge tool from MKVToolNix can also be used for advanced MKV operations like adding chapters, subtitles, and file attachments.