Convert 3GPP Audio (.3ga) to Matroska Video (.mkv) online for free. Fast, secure audio conversion with no watermarks or registration.
Upload your .3ga file by dragging it into the upload area or clicking to browse.
Choose your output settings. The default settings work great for most files.
Click Convert and download your .mkv file when it's ready.
MKV (Matroska Video) is the most flexible open-source multimedia container, capable of holding virtually any combination of audio, video, subtitle, and metadata streams. While MKV is primarily known as a video format popular in the media enthusiast community, it can also serve as a powerful audio container when you need features that simpler formats lack — such as multiple audio tracks, embedded subtitles for transcription, chapter markers, and extensive metadata tagging.
Converting 3GA audio from old Samsung or LG phones to MKV is an unusual but technically sound operation. The AMR audio is transcoded to a universally supported codec like AAC or Opus and wrapped in the MKV container. This is relevant for media library managers like Plex, Jellyfin, and Kodi that are configured to work with MKV files, or for users who want to embed transcription subtitles alongside their converted voice recordings in a single container file.
MKV's standout feature is its ability to carry multiple streams in one file. If you have old phone recordings that you want to pair with text transcriptions, translations, or chapter markers for navigation, MKV is the only common container format that supports all of these features simultaneously. A single MKV file can contain the converted audio plus an SRT subtitle track with the transcription, making it a self-contained audio-with-text document.
MKV is also the preferred format for media server software. Plex, Jellyfin, Emby, and Kodi all handle MKV files as first-class citizens with full metadata scraping, chapter navigation, and subtitle support. If you maintain a home media server and want to add converted voice recordings from old 3G-era phones to your library alongside your music and video collection, MKV integrates naturally with your existing infrastructure.
FFmpeg decodes the AMR audio from the 3GA container and re-encodes it as AAC (192 kbps) or Opus (128 kbps) inside the MKV (Matroska) container. MKV does not natively support AMR, so transcoding is required. The Matroska container supports an unlimited number of audio, video, and subtitle tracks with chapter navigation and rich metadata. The output uses WebM-compatible codecs by default for maximum player support. MKV files use EBML (Extensible Binary Meta Language) structure for efficient seeking and streaming.
The transcoding from AMR to AAC or Opus introduces one generation of lossy re-encoding. At 192 kbps AAC or 128 kbps Opus, the quality is completely transparent for AMR source material from 3G-era phones. The original narrowband recording quality (3.4 kHz bandwidth for AMR-NB) is the bottleneck, not the output encoding. The MKV container itself adds no quality impact — it is purely a wrapper for the encoded audio stream.
| Device | 3GA | MKV |
|---|---|---|
| Windows PC | Partial | Partial |
| macOS | Partial | Partial |
| iPhone/iPad | Partial | Partial |
| Android | Partial | Partial |
| Linux | Partial | Partial |
| Web Browser | No |
Resolution: N/A
Bitrate: 320 kbps
OGG Vorbis preferred
Resolution: N/A
Bitrate: 256 kbps
AAC format required
Resolution: N/A
Bitrate: 128 kbps
Lossless FLAC/WAV for best quality
Resolution: N/A
Bitrate: 128 kbps
MP3 mono for spoken word
Converting 3GA to MKV is ideal for users who need the advanced container features that simpler audio formats lack — multiple tracks, embedded subtitles, chapter navigation, and rich metadata. It integrates seamlessly with media server software and provides the most flexible archival option for voice recordings.
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| No |
| Tính năng | 3GA | MKV |
|---|---|---|
| Tên đầy đủ | 3GPP Audio | Matroska Video |
| Phần mở rộng | .3ga | .mkv |
| Phù hợp nhất cho | Mobile recording | Multiple audio tracks |