Convert 3G2 to WebM — Free Online Tool
Convert 3G2 video files — originally encoded for CDMA mobile networks using H.264 and AAC — into WebM format with VP9 video and Opus audio, optimized for modern HTML5 web playback. This conversion trades legacy mobile-network efficiency for open, royalty-free web streaming with superior compression at equivalent quality.
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FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
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Settings
Note: Browser-based encoding uses approximate quality targets. For precise CRF compression, copy the FFmpeg command above and run it on your desktop.
Estimated output:
Conversion Complete!
DownloadHow It Works
3G2 files use an MPEG-4-derived container with H.264 (libx264) video and AAC audio, originally designed to minimize bandwidth over CDMA networks like Verizon and Sprint. Converting to WebM requires full transcoding of both streams: the H.264 video is decoded and re-encoded into VP9 using libvpx-vp9, and the AAC audio is decoded and re-encoded into Opus using libopus. Neither stream can be copied directly because WebM only accepts VP9 (or VP8/AV1) video and Opus or Vorbis audio — none of which are compatible with the 3G2 container's codec set. The special flag -b:v 0 forces VP9 into constant-quality mode governed entirely by the -crf 33 value, rather than targeting a specific bitrate. Because 3G2 files were often recorded at low resolutions and bitrates for mobile transmission, the output WebM may not gain visual quality — the transcoder can only preserve what was captured, not recover compressed detail.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg multimedia processing tool. In this browser-based tool, FFmpeg runs entirely via WebAssembly (ffmpeg.wasm) inside your browser — no file data leaves your device. |
-i input.3g2
|
Specifies the input file in 3G2 format — a mobile container from the 3GPP2/CDMA standard, typically containing H.264 video and AAC audio recorded on CDMA network devices. |
-c:v libvpx-vp9
|
Selects the VP9 video encoder (libvpx-vp9) to transcode the H.264 video stream from the 3G2 source, since WebM requires VP9 (or VP8/AV1) and cannot carry H.264. |
-c:a libopus
|
Selects the Opus audio encoder (libopus) to transcode the AAC audio from the 3G2 file into Opus, the only royalty-free codec permitted alongside VP9 in the WebM container. |
-crf 33
|
Sets the Constant Rate Factor for VP9 encoding to 33, controlling perceptual video quality on a scale of 0 (near-lossless) to 63 (heavy compression). A value of 33 is VP9's recommended default for web delivery and will typically produce a WebM of equal or better quality than a typical low-bitrate 3G2 source. |
-b:a 128k
|
Sets the Opus audio output bitrate to 128 kilobits per second. This is well above what most 3G2 audio tracks were encoded at originally, so the Opus audio will be limited in quality by the source AAC rather than this bitrate ceiling. |
-b:v 0
|
Sets the target video bitrate to zero, which is required to activate VP9's pure constant-quality mode driven by -crf 33. Without this flag, VP9 would fall back to a constrained variable-bitrate mode and the CRF value would be ignored. |
output.webm
|
Specifies the output filename with the .webm extension, which tells FFmpeg to use the WebM container — an open, Matroska-based format natively supported in HTML5 browsers for royalty-free video streaming. |
Common Use Cases
- Uploading old video MMS messages or CDMA phone recordings to a website or web app that requires HTML5-native WebM playback without JavaScript video polyfills.
- Archiving a collection of early 2000s–2010s CDMA phone videos (from devices like early Verizon feature phones) into a more modern, open-standard container that doesn't depend on proprietary MPEG-LA licensing.
- Embedding legacy mobile footage into a web-based documentary or multimedia project where WebM's broad HTML5 support across Chrome, Firefox, and Edge is required.
- Preparing 3G2 clips from older Android or flip-phone recordings for use in a WebM-only video pipeline or CMS that rejects MP4 and MOV inputs.
- Converting 3G2 files captured on CDMA network devices into WebM so they can be streamed via a self-hosted video platform that relies on open, royalty-free codecs to avoid licensing overhead.
- Batch-converting a library of 3G2 sports clips or event recordings from a CDMA-era camcorder accessory for use in a browser-based video editor that only accepts WebM input.
Frequently Asked Questions
No — transcoding from 3G2 to WebM cannot recover detail that was already discarded by the original H.264 encoding on the mobile device. The VP9 encoder in WebM is a more efficient codec than H.264, meaning it can represent the same quality at a smaller file size, but it cannot reconstruct information that no longer exists in the 3G2 source. If your 3G2 was recorded at 240p or 320p with a low bitrate (common for CDMA MMS video), the WebM output will look identical or potentially marginally different due to re-encoding generation loss.
3G2 files were aggressively compressed for transmission over slow CDMA data networks, sometimes at bitrates as low as 64–128 kbps, making them extremely small. When re-encoded to WebM with a default CRF of 33 targeting a general-purpose quality level, the VP9 encoder may produce a larger file because the default quality setting assumes a higher acceptable bitrate than the original mobile encoding allowed. You can increase the CRF value (e.g., to 40 or higher) in the FFmpeg command to reduce the WebM output size closer to the 3G2 source size, though this trades off visual quality.
3G2 files can embed metadata such as creation timestamps, GPS coordinates, and device information in their MPEG-4-derived container atoms. WebM, based on the Matroska container, supports metadata tags but uses a completely different schema. During this FFmpeg conversion, most 3G2-specific metadata atoms are not automatically mapped to WebM tags, meaning GPS data and device info are likely lost. If preserving recording metadata is important, extract it separately from the 3G2 file before conversion using a tool like ExifTool.
The WebM container specification only supports Opus and Vorbis as audio codecs — AAC is not permitted inside a WebM file. This is by design: WebM is an open, royalty-free format, and AAC carries licensing requirements from MPEG-LA that conflict with that goal. Opus is actually a superior codec to AAC at most bitrates, offering better quality per kilobit especially at the 128k default used here, so the audio quality in your WebM output should be comparable to or better than the original 3G2 AAC track.
The -crf 33 flag controls VP9 video quality in constant-quality mode. Lower values produce higher quality and larger files (0 is mathematically lossless), while higher values compress more aggressively with smaller file sizes (63 is the maximum). For a 3G2 source with already-limited quality, a CRF between 36 and 45 is often a practical range that avoids generating a WebM larger than the source. The -b:a 128k flag controls Opus audio bitrate — for voice-heavy or low-quality mobile recordings, 64k or 96k is usually indistinguishable and reduces file size further.
Yes. On Linux or macOS, you can run: for f in *.3g2; do ffmpeg -i "$f" -c:v libvpx-vp9 -c:a libopus -crf 33 -b:a 128k -b:v 0 "${f%.3g2}.webm"; done — this loops over every 3G2 file in the current directory and converts each one. On Windows Command Prompt, use: for %f in (*.3g2) do ffmpeg -i "%f" -c:v libvpx-vp9 -c:a libopus -crf 33 -b:a 128k -b:v 0 "%~nf.webm". The browser-based tool processes one file at a time, so the FFmpeg command is especially valuable for batch jobs or files over 1GB.
Technical Notes
3G2 is a close relative of MP4/MOV, sharing the ISO Base Media File Format lineage, but it was specifically profiled for 3GPP2 (CDMA) mobile deployments with constraints on resolution, bitrate, and codec profiles designed for over-the-air transmission. Most 3G2 files in the wild contain Baseline Profile H.264 video at low resolutions (QCIF 176×144, QVGA 320×240) and AAC-LC audio at 8–44.1 kHz. Converting to WebM requires full transcoding of both streams since there is zero codec overlap between the two containers. VP9's two-pass encoding mode is not invoked by this command — it uses single-pass constant-quality mode (-crf 33 with -b:v 0), which is efficient for browser-based processing but means the encoder cannot optimize bitrate distribution across the entire file as it would in a two-pass job. The Opus encoder at 128k will comfortably exceed the audio quality of most 3G2 source files, which were often encoded at 12.2 kbps (AMR) or low-bitrate AAC. WebM supports transparency (alpha channel in VP9), multiple audio tracks, chapters, and subtitles — none of which are present in a 3G2 source, so these capabilities remain unused in this conversion. The resulting WebM file will play natively in Chrome, Firefox, and Edge without plugins, but Safari has historically had limited WebM support and may require a fallback.