MyMediaTools

Convert 3G2 to RMVB — Free Online Tool

Convert 3G2 files — the CDMA-era mobile container format — to RMVB using H.264 video and AAC audio. This tool re-encodes your 3G2 content into RealNetworks' variable bitrate container, making legacy mobile clips compatible with classic RMVB-oriented media players and archives.

FFmpeg Command

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Estimated output:

Conversion Complete!

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How It Works

3G2 files typically carry H.264 or MJPEG video alongside AAC or MP3 audio in a container derived from the MPEG-4 Part 12 base format. RMVB, despite its RealMedia branding, is handled here by wrapping H.264 video and AAC audio inside the RMVB container using FFmpeg's libx264 encoder. Because 3G2's default video codec is already libx264-compatible, the video stream is re-encoded with a CRF of 23 — a perceptually transparent quality level for most content — rather than simply remuxed, since the RMVB container requires its own stream framing. Audio is similarly transcoded to AAC at 128k. Neither format supports subtitles, chapters, or multiple audio tracks, so there is no metadata loss on those dimensions; however, any mobile-specific 3GPP2 metadata atoms embedded in the 3G2 container will be dropped during the conversion.

What Each Flag Does

Flag What it does
ffmpeg Invokes the FFmpeg binary — the underlying engine that performs all demuxing, decoding, encoding, and muxing for this 3G2-to-RMVB conversion.
-i input.3g2 Specifies the input file in 3G2 format. FFmpeg reads the 3G2 container, which is an MPEG-4 Part 12-derived format used for CDMA mobile video, and demuxes the video and audio streams for processing.
-c:v libx264 Re-encodes the video stream using the libx264 H.264 encoder. Since the source 3G2 may contain H.264 or MJPEG video, this ensures the RMVB output always receives a properly framed H.264 stream regardless of the input codec.
-c:a aac Transcodes the audio stream to AAC, which is the default audio codec for this RMVB output. Whether the 3G2 source carried AAC or MP3 audio, the output will be standardized to AAC.
-crf 23 Sets the Constant Rate Factor for the libx264 encoder to 23, the default quality level. For typical low-resolution 3G2 mobile footage, CRF 23 provides a good balance between file size and visual fidelity without over-compressing the already limited source detail.
-b:a 128k Sets the AAC audio bitrate to 128 kilobits per second. This is a standard quality level appropriate for the speech and ambient audio typically found in 3G2 mobile recordings, and matches the default audio quality of the source format.
output.rmvb Defines the output filename and signals FFmpeg to mux the encoded H.264 video and AAC audio into the RMVB container format, as determined by the .rmvb file extension.

Common Use Cases

  • Archiving old camera phone videos originally recorded in 3G2 format into RMVB for storage alongside an existing RealMedia library from the early 2000s
  • Preparing CDMA-era 3G2 clips for playback in legacy media players like RealPlayer that have strong RMVB support but limited 3G2 compatibility
  • Converting a collection of 3G2 videos captured on vintage Verizon or Sprint handsets into RMVB so they can be catalogued and played in RMVB-centric media center software
  • Re-packaging low-bitrate 3G2 mobile footage into RMVB's variable bitrate container to take advantage of more efficient bit allocation during complex motion scenes
  • Migrating 3G2 content from a mobile backup archive into RMVB format to share with users in regions where RMVB distribution was historically dominant
  • Testing RMVB output compatibility on a specific set-top box or media streamer that reads RMVB but does not recognize the 3G2 container

Frequently Asked Questions

No — because 3G2 is a lossy format, re-encoding it to RMVB with libx264 at CRF 23 introduces a second generation of lossy compression on top of what already existed. The output quality will be equal to or slightly lower than the source. If your 3G2 was recorded at a very low mobile bitrate (common on CDMA handsets), the RMVB output will reflect that original quality ceiling, not exceed it.
3G2 files from mobile devices were often encoded at very low bitrates — sometimes under 100 kbps total — optimized for CDMA network transmission. Re-encoding to RMVB with CRF 23 and 128k AAC audio targets a higher quality level than the original, which can produce a larger file. If you want a smaller output, you can increase the CRF value (e.g., to 28 or 35) or reduce the audio bitrate to 64k or 96k in the FFmpeg command.
Strictly speaking, the classic RealMedia/RMVB ecosystem was built around RealVideo and RealAudio codecs. However, FFmpeg's RMVB muxer accepts H.264 video and AAC audio streams, producing files with an .rmvb extension that modern FFmpeg-based players can decode. Legacy RealPlayer versions may not recognize H.264 inside RMVB, so if your target player is an old RealPlayer installation, compatibility is not guaranteed.
No. The 3G2 container can carry 3GPP2-specific metadata atoms such as recording device information, GPS tags, and creation timestamps. None of these are mapped into the RMVB container format during conversion, so that metadata is silently discarded. Standard A/V content — the video and audio streams themselves — is fully carried over.
The -crf flag controls video quality. CRF 23 is the default and a good all-around setting. Lower values like 18 or 10 produce higher quality at larger file sizes, while higher values like 28 or 35 produce smaller files with more visible compression artifacts. For source 3G2 files that were already heavily compressed on a mobile device, going below CRF 18 rarely yields a visible benefit. To change audio bitrate, replace -b:a 128k with a value like -b:a 96k or -b:a 192k.
The single-file command shown on this page can be adapted for batch processing in a shell loop. On Linux or macOS, use: for f in *.3g2; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "${f%.3g2}.rmvb"; done. On Windows Command Prompt, use: for %f in (*.3g2) do ffmpeg -i "%f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "%~nf.rmvb". This is especially useful for archiving a large folder of legacy mobile recordings.

Technical Notes

3G2 is structurally derived from the ISO Base Media File Format (MPEG-4 Part 12), sharing lineage with MP4 and MOV. Its video payload is typically H.264 (libx264) or MJPEG, and its audio is AAC or MP3. RMVB, while associated with RealNetworks' proprietary ecosystem, is handled by FFmpeg as a container that can accept H.264 and AAC streams — making this conversion straightforward at the codec level. The key quality lever is CRF: since both formats are lossy and 3G2 sources from CDMA handsets were often encoded at 128x96 or 176x144 resolution with very low bitrates, upscaling quality settings in the RMVB output will not recover detail that was never there. Neither format supports transparency, embedded subtitles, chapter markers, or multiple audio tracks, so the conversion is a clean stream-to-stream transcode with no feature regression. One practical note: the -movflags +faststart flag present in the 3G2 input profile is not used in the RMVB output command, as RMVB does not use the MP4-style moov atom structure that faststart optimizes. File size outcomes will vary significantly depending on the motion complexity of the original mobile footage.

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