MyMediaTools

Convert 3G2 to RM — Free Online Tool

Convert 3G2 video files from legacy CDMA mobile devices into RealMedia (RM) format using MJPEG video encoding and AAC audio. This tool re-encodes the H.264 video stream from your 3G2 file into MJPEG frames within the RM container — a format once ubiquitous for early internet streaming — making it accessible for legacy RealPlayer-based workflows.

FFmpeg Command

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Estimated output:

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How It Works

3G2 files typically carry H.264 (libx264) video and AAC audio, optimized for transmission over CDMA mobile networks. During this conversion, the H.264 video stream cannot be carried into the RM container, so it is fully re-encoded into MJPEG — a format that stores each video frame as an independent JPEG image, with no inter-frame compression. The AAC audio stream is passed through or re-encoded to AAC within the RM container. The result is a RealMedia file with frame-by-frame MJPEG video, which is significantly larger than the original H.264 stream and suited for legacy RealPlayer playback or archival workflows rather than modern streaming.

What Each Flag Does

Flag What it does
ffmpeg Invokes the FFmpeg binary, the open-source multimedia processing engine that powers this conversion in the browser via WebAssembly (FFmpeg.wasm).
-i input.3g2 Specifies the input file: a 3G2 container typically holding H.264 video and AAC audio encoded for CDMA mobile network delivery. FFmpeg demuxes this container to access the raw encoded streams.
-c:v mjpeg Re-encodes the video stream using the MJPEG codec, since the RM container cannot carry H.264. MJPEG encodes each video frame independently as a JPEG image, which is the only video codec FFmpeg supports for RM output.
-c:a aac Encodes the audio stream as AAC within the RM container. Since the source 3G2 file also uses AAC, this maintains the same codec family, though the audio is still decoded and re-encoded rather than stream-copied.
-q:v 5 Sets the MJPEG frame quality to 5 on a 1–10 scale (1 = best quality, 10 = most compressed). At the default of 5, each video frame is stored as a mid-quality JPEG, balancing file size against visual fidelity in the RM output.
-b:a 128k Sets the AAC audio bitrate to 128 kilobits per second, a standard quality level for stereo audio. This is unchanged from the 3G2 source's default audio quality, preserving roughly equivalent audio fidelity in the RM file.
output.rm Specifies the output filename with the .rm extension, which tells FFmpeg to mux the MJPEG video and AAC audio into a RealMedia container — the proprietary format developed by RealNetworks for internet streaming.

Common Use Cases

  • Archiving old mobile phone video clips from CDMA-era devices (e.g., early Verizon or Sprint handsets) into RealMedia format for a digital preservation project that catalogs late-1990s to 2000s internet media formats
  • Preparing 3G2 footage for ingestion into legacy video editing or cataloging software that only accepts RealMedia input streams
  • Converting 3G2 clips for playback in a RealPlayer-based kiosk or museum exhibit demonstrating early internet multimedia technology
  • Migrating video content from a CDMA mobile archive to a RealNetworks-based media server for a retro streaming demonstration or educational project
  • Generating MJPEG-encoded video within a RM wrapper from mobile source footage, where downstream tools require frame-independent video encoding for easy random-access scrubbing
  • Producing RM files from 3G2 source material for compatibility testing of legacy media players, codecs, or embedded systems that were built around the RealMedia ecosystem

Frequently Asked Questions

The 3G2 container uses H.264 video, which achieves very small file sizes through inter-frame compression — encoding only what changes between frames. The RM output uses MJPEG, which encodes every frame as a complete JPEG image independently. This means a 10-second 3G2 clip at 30fps re-encodes as 300 separate JPEG frames, dramatically increasing file size. The original 3G2's low-bitrate CDMA-optimized compression simply cannot be matched by MJPEG in terms of size efficiency.
The RM format supports AAC audio, so the audio codec stays the same (AAC at 128k by default). However, because this is a full transcode rather than a stream copy, the audio is decoded and re-encoded, which introduces a small additional generation of lossy compression. For most practical purposes the quality difference is negligible at 128k, but if your original 3G2 has very low-bitrate AAC audio, the re-encode may slightly degrade it further.
VLC has broad support for RM files and MJPEG video, so playback is generally reliable. Windows Media Player dropped native RealMedia support years ago and would require the RealPlayer plugin or codec pack. The RM format is a legacy proprietary format, so modern players treat it as a compatibility edge case. If your goal is broad modern playback, RM is not the right target — but for RealPlayer or VLC specifically, you should be fine.
The -q:v flag sets the MJPEG frame quality on a scale from 1 (highest quality, largest file) to 10 (lowest quality, smallest file), with 5 as the balanced default. Because MJPEG encodes each frame as a JPEG, this directly controls the JPEG compression level applied to every frame. To improve visual fidelity at the cost of file size, lower the value to 2 or 3 in the FFmpeg command: replace '-q:v 5' with '-q:v 2'. To shrink the file further at lower quality, use 7 or 8.
No — neither 3G2 nor RM in this conversion pipeline supports subtitles or chapters, and RealMedia has very limited metadata support compared to modern containers. Basic tags such as title may be carried over depending on the FFmpeg version, but chapter markers, multiple audio tracks, and subtitle streams present in the source will be dropped entirely. The 3G2 format itself rarely carries rich metadata since it was designed for constrained mobile transmission.
You can loop over all 3G2 files in a directory using a shell one-liner. On Linux or macOS: 'for f in *.3g2; do ffmpeg -i "$f" -c:v mjpeg -c:a aac -q:v 5 -b:a 128k "${f%.3g2}.rm"; done'. On Windows Command Prompt: 'for %f in (*.3g2) do ffmpeg -i "%f" -c:v mjpeg -c:a aac -q:v 5 -b:a 128k "%~nf.rm"'. This runs the exact same conversion parameters as the browser tool on every 3G2 file in the current folder.

Technical Notes

The core technical challenge in this conversion is the mandatory full re-encode of the video stream. 3G2 uses H.264 (AVC) as its default video codec — an inter-frame codec with B-frames and P-frames that the RM container cannot carry. The only video codec available for RM output in FFmpeg is MJPEG, which is intra-frame only: every frame is encoded as a discrete JPEG at the quality level set by -q:v. This makes the output file edit-friendly (any frame is independently decodable) but eliminates all the file-size advantages of H.264. Audio fares better: AAC is supported in both formats, though it still undergoes a decode-and-reencode cycle rather than a stream copy. No special flags like -movflags +faststart (used in the 3G2 source format for progressive download) are applicable to RM, as RealMedia uses its own internal indexing for streaming. The RM format does not support transparency, subtitles, chapters, or multiple audio tracks, so any such streams in the source are silently discarded. The resulting RM file is best understood as a legacy compatibility artifact — correct and playable, but not efficient by modern standards.

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