3G2 to OPUS Converter

3G2 (3GPP2 file format) is a multimedia container developed by the 3rd Generation Partnership Project 2 for use on CDMA2000 mobile networks. Built on the ISO base media file format (MPEG-4 Part 12), it stores video encoded with H.263 or MPEG-4 Visual alongside audio in AMR, EVRC, or AAC codecs. The specification was first published in December 2003 to provide a standardized way for CDMA-based phones and networks to handle multimedia messaging and video playback. 3G2 files are engineered for extremely low-bandwidth conditions, achieving playable video quality at bit rates as low as 30-60 kbps. This makes the format especially efficient for mobile video capture on devices with limited processing power and storage. The container supports multiple tracks, timed text for subtitles, and embedded metadata. One significant benefit is near-universal compatibility with CDMA handsets from the mid-2000s era, ensuring reliable playback across a wide range of mobile devices. Though newer formats like MP4 have superseded 3G2 for most purposes, it remains useful for working with legacy mobile content and for situations where minimal file size is the primary concern.

Opus is a versatile, open audio codec standardized by the IETF as RFC 6716 in 2012. It fuses two coding approaches — SILK for speech and CELT for music — into one algorithm that blends between them based on content type and bitrate. This hybrid design lets Opus outperform virtually every other codec across a wide range of uses: low-latency voice at 6 kbps, high-fidelity music at 128 kbps, and everything in between. It supports bitrates from 6 to 510 kbps, sample rates up to 48 kHz, and frame sizes as small as 2.5 ms, giving it the lowest algorithmic latency of any mainstream audio codec. Three advantages make Opus especially compelling. It is completely royalty-free and open-source, removing licensing barriers that hold back proprietary codecs. It achieves transparent quality at roughly half the bitrate of MP3 and beats AAC at equivalent rates. And its low latency makes it the mandatory codec for WebRTC, so every modern browser ships with an Opus decoder. WhatsApp, Discord, Zoom, and YouTube all rely on Opus for real-time audio.