MyMediaTools

Convert 3GP to 3G2 — Free Online Tool

Convert 3GP mobile video files to 3G2 format, migrating from GSM-based 3GPP container standards to the CDMA-optimized 3GPP2 format. Both containers share H.264 video and AAC audio codec support, making this a lightweight re-encapsulation with a quality-preserving CRF 23 encode and faststart optimization for mobile streaming.

FFmpeg Command

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Estimated output:

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How It Works

Both 3GP and 3G2 are closely related mobile multimedia containers — 3GP targets GSM/UMTS networks (3GPP standard) while 3G2 targets CDMA networks (3GPP2 standard, used by carriers like Verizon and Sprint). Because both formats support H.264 video and AAC audio, this conversion re-encodes the video stream using libx264 at CRF 23 and encodes audio with AAC at 128k bitrate. The output file receives the -movflags +faststart flag, which relocates the MP4/3G2 metadata atom (moov) to the beginning of the file — essential for streaming over CDMA mobile networks before the full file is downloaded. The input 3GP files are typically encoded at lower bitrates for GSM bandwidth constraints, so the 3G2 output may slightly increase in size due to the higher default audio bitrate (64k in 3GP vs 128k in 3G2).

What Each Flag Does

Flag What it does
ffmpeg Invokes the FFmpeg binary — the open-source multimedia processing engine running here as FFmpeg.wasm compiled to WebAssembly, executing entirely inside your browser without any server upload.
-i input.3gp Specifies the input file in 3GP format — a mobile multimedia container from the 3GPP standard, typically containing H.264 or H.263 video and AAC audio recorded on GSM/UMTS mobile devices.
-c:v libx264 Sets the video encoder to libx264, producing H.264 video in the 3G2 output. H.264 is the standard video codec for 3G2 and ensures compatibility with CDMA mobile devices and modern media players alike.
-c:a aac Sets the audio encoder to AAC (Advanced Audio Coding), the default and most widely supported audio codec in the 3G2 container format, suitable for voice recordings and music common in mobile video files.
-crf 23 Sets the Constant Rate Factor for libx264 to 23, a perceptually transparent quality level well-suited to the low-resolution video typical of 3GP source material, balancing quality and file size for the 3G2 output.
-b:a 128k Sets the AAC audio bitrate to 128 kilobits per second — the standard audio quality target for 3G2, and an improvement over the 64k default commonly used in 3GP source files, resulting in cleaner audio in the output.
-movflags +faststart Moves the moov metadata atom to the beginning of the 3G2 file, enabling progressive playback over CDMA mobile networks before the full file is downloaded — a critical optimization for mobile streaming use cases.
output.3g2 Specifies the output filename with the .3g2 extension, instructing FFmpeg to write a 3GPP2-compliant container file formatted for CDMA network devices and compatible with QuickTime-based players.

Common Use Cases

  • Preparing video recorded on older GSM-based feature phones for playback on CDMA network devices such as legacy Verizon or Sprint handsets that natively parse 3G2 containers.
  • Archiving or re-packaging 3GP video files captured from early Nokia or Sony Ericsson phones into the 3G2 format required by certain CDMA carrier multimedia messaging (MMS) systems.
  • Improving mobile streaming performance by converting 3GP files — which lack faststart metadata positioning — into 3G2 files with moov atom at the front for progressive playback on slow connections.
  • Batch-converting a library of old 3GP mobile video clips into 3G2 for compatibility with legacy multimedia software or CDMA-era video editors that accept 3G2 but not 3GP.
  • Increasing audio fidelity when repurposing 3GP clips recorded at 64k AAC for 3G2 distribution, taking advantage of 3G2's higher standard audio bitrate of 128k for better voice and music quality.
  • Running the equivalent FFmpeg command locally on desktop to convert large collections of 3GP recordings from mobile archives that exceed the 1GB browser processing limit.

Frequently Asked Questions

3GP (3GPP) was developed for GSM and UMTS mobile networks, while 3G2 (3GPP2) was developed for CDMA2000 networks — they are sibling standards with nearly identical codec support. Because both support H.264 and AAC, the video is re-encoded using libx264 at CRF 23 rather than stream-copied, which introduces a small generation of lossy compression. However, CRF 23 is a visually transparent quality level for most mobile video content, and the perceptible quality difference is minimal for typical 3GP source material recorded at low resolutions.
3GP files are optimized for GSM bandwidth constraints and commonly use 64k AAC audio — the default audio bitrate for that format. The 3G2 format targets CDMA networks with slightly more headroom and uses a 128k AAC default, which is reflected in this conversion command with -b:a 128k. This means the output audio will sound noticeably cleaner, especially for voice recordings or music, but the file size will increase relative to the source if the original was encoded at 64k.
The -movflags +faststart flag moves the moov atom (the file's metadata and index table) from the end of the file to the beginning. In the 3G2 and MP4 family of containers, a player must read the moov atom before it can begin playback. Without faststart, a remote player must download the entire file before starting — with it, playback can begin almost immediately over a CDMA mobile network. This flag is particularly critical for 3G2 files intended for streaming or MMS delivery on mobile devices.
Yes — the -crf flag controls video quality in libx264 encoding. CRF 23 (the default used here) is a solid balance between quality and file size for mobile video. For higher quality, lower the value toward CRF 18; for smaller files at the cost of quality, raise it toward CRF 35. For typical 3GP source content recorded at 240p or 320p resolution, CRF values between 20 and 28 are generally indistinguishable from CRF 23, so aggressive compression is often appropriate for this format pair.
On Linux or macOS, you can run a shell loop: `for f in *.3gp; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 128k -movflags +faststart "${f%.3gp}.3g2"; done`. On Windows Command Prompt, use: `for %f in (*.3gp) do ffmpeg -i "%f" -c:v libx264 -c:a aac -crf 23 -b:a 128k -movflags +faststart "%~nf.3g2"`. The browser-based tool processes files one at a time, so the FFmpeg command is the recommended approach for bulk conversions or files larger than 1GB.
Neither 3GP nor 3G2 support subtitles, chapters, or multiple audio tracks as container features, so there is nothing to lose in this conversion. If the 3GP source somehow contains non-standard embedded text or extra streams, FFmpeg will map only the primary video and audio streams by default, which is the correct behavior for 3G2 output. No subtitle or chapter metadata will be silently dropped because these features are outside the scope of both formats.

Technical Notes

3GP and 3G2 are both MPEG-4 Part 12 derivative containers and are structurally very similar to MP4, which is why tools that support one often support the other. The key technical distinction is their target network standard: 3GP aligns with 3GPP Release 4+ (GSM/UMTS) and 3G2 aligns with 3GPP2 (CDMA2000). Both formats share H.264 (libx264) and AAC codec support, but differ in their typical operating bitrate profiles and metadata conventions. One limitation to be aware of: 3GP files produced by early mobile devices sometimes use H.263 or MPEG-4 Part 2 video codecs rather than H.264 — this tool re-encodes everything to H.264, which means those non-H.264 sources will undergo a full transcode rather than a lightweight re-wrap. The scale filter `trunc(iw/2)*2:trunc(ih/2)*2` is applied at the input stage when needed to ensure pixel dimensions are divisible by 2, a requirement of the H.264 encoder that 3GP source material — often recorded at odd pixel dimensions on low-end hardware — may violate. The 3G2 output produced by this tool is compatible with QuickTime, VLC, and most CDMA-era mobile devices, though modern smartphones no longer natively distinguish between 3GP and 3G2 playback.

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