Convert 3GP to RMVB — Free Online Tool
Convert 3GP mobile video files to RMVB format using H.264 video and AAC audio encoding, all processed locally in your browser via FFmpeg.wasm. This tool is particularly useful for repurposing low-bandwidth 3G-era mobile clips into the variable-bitrate RMVB container historically favored for compressed video distribution.
to
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
3GP files typically carry H.264 or MPEG-4 video with AAC or AMR audio, optimized for the constrained bandwidth and storage of 3G mobile networks. During conversion to RMVB, the video stream is re-encoded using libx264 with a CRF of 23, which means the encoder targets consistent visual quality rather than a fixed bitrate — appropriate since RMVB's defining characteristic is variable bitrate encoding. The audio is transcoded from the 3GP source (often at a low bitrate like 64k due to mobile constraints) to AAC at 128k, effectively doubling the audio fidelity. Notably, the special scale filter used for 3GP input (ensuring even pixel dimensions required by H.264) is not needed on the RMVB output side, simplifying the pipeline. The result is a larger, higher-quality file suited for desktop playback or archiving.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg binary, the open-source multimedia processing engine that handles all decoding, encoding, and container remuxing in this conversion. In the browser, this runs as FFmpeg.wasm compiled to WebAssembly. |
-i input.3gp
|
Specifies the input file in 3GP format — the mobile-optimized multimedia container. FFmpeg will demux the 3GP container to extract the raw video and audio streams for re-encoding. |
-c:v libx264
|
Encodes the output video stream using the libx264 H.264 encoder. Since RMVB does not support native RealVideo encoding in FFmpeg, libx264 is the only viable video codec for this output, and it produces well-compressed, widely playable H.264 video inside the RMVB container. |
-c:a aac
|
Encodes the output audio stream as AAC, transcoding from whatever audio codec the 3GP source used (often low-bitrate AAC or AMR). AAC is chosen over libmp3lame here as it offers better quality at the same bitrate, which is beneficial given the constrained audio often found in 3GP source files. |
-crf 23
|
Sets the Constant Rate Factor to 23 for the libx264 video encode. This instructs the encoder to target consistent perceptual quality across the entire clip rather than a fixed bitrate — aligning with RMVB's variable-bitrate philosophy. A CRF of 23 is the libx264 default and represents a good balance between quality and file size for typical 3GP source material. |
-b:a 128k
|
Sets the audio output bitrate to 128 kilobits per second for the AAC stream. This is double the 3GP default audio quality of 64k, meaning the RMVB output will have noticeably cleaner and fuller audio than the original mobile-recorded file. |
output.rmvb
|
Specifies the output filename and signals FFmpeg to write the result into an RMVB container. FFmpeg determines the container format from the .rmvb file extension, wrapping the libx264 video and AAC audio streams into the RealMedia Variable Bitrate container structure. |
Common Use Cases
- Archiving old 3GP clips recorded on early Nokia or Sony Ericsson phones into RMVB, a format that was widely used for storing compressed video libraries on desktop PCs in the 2000s and 2010s.
- Preparing mobile-recorded footage for distribution on platforms or communities that historically shared video content exclusively in RMVB format.
- Improving the audio quality of a 3GP recording — which may have been encoded at as low as 32k AAC — by repackaging it with 128k AAC audio in an RMVB container.
- Converting 3GP video content for playback in legacy media players like RealPlayer that were built around the RealMedia ecosystem and handle RMVB natively.
- Re-encoding compressed 3GP footage at a specific CRF quality level for variable-bitrate RMVB output, allowing action-heavy scenes to use more bits while static scenes stay small.
- Standardizing a batch of heterogeneous 3GP clips from different mobile devices into a single consistent RMVB format for a legacy video archive or collection.
Frequently Asked Questions
Not inherently — 3GP files are captured or compressed for mobile use, so any quality limitations baked into the source video (low resolution, heavy compression artifacts) are permanent and cannot be recovered during conversion. What this conversion does do is re-encode the video at CRF 23 using libx264, which is a high-quality setting that avoids introducing additional degradation. The audio quality will likely improve noticeably, since 3GP files often cap audio at 64k AAC while the RMVB output defaults to 128k AAC.
3GP was specifically designed to minimize file size for 3G network transmission, so the source file is often aggressively compressed at low bitrates. The RMVB output re-encodes video at CRF 23 (a quality-first setting) and audio at 128k, both of which prioritize fidelity over size. Since the source was likely encoded at much lower bitrates to fit mobile constraints, the RMVB output will almost always be larger even though both formats are lossy.
The RMVB container format was designed for RealNetworks' own variable-bitrate RealVideo codec. However, since native RealVideo encoding is not supported in FFmpeg, this conversion uses libx264 inside the RMVB container — which still benefits from H.264's own rate control mechanisms via CRF. The file will not use RealVideo but will retain the RMVB container structure, which may be required for compatibility with certain legacy players or archiving conventions.
No. Neither 3GP nor RMVB (as handled by this tool) support subtitles or chapter metadata, so there is nothing to preserve on either side of this conversion. If your 3GP file contained any embedded text tracks, they will be dropped during conversion. This is a known limitation of both container formats in this pipeline.
Adjust the -crf value in the command. CRF controls quality inversely — lower values mean higher quality and larger files, while higher values mean more compression and smaller files. For this conversion, the range spans from 0 (lossless-equivalent) to 51 (very heavy compression). A CRF of 18 is often considered visually near-lossless for H.264, while values above 28 will introduce visible blocking, especially on the already-compressed 3GP source material. For example: ffmpeg -i input.3gp -c:v libx264 -c:a aac -crf 18 -b:a 128k output.rmvb
Yes. On Linux or macOS you can loop over all 3GP files in a directory with: for f in *.3gp; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "${f%.3gp}.rmvb"; 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 "%~nf.rmvb". This is especially useful for large batches or files over 1GB, which exceed the browser tool's limit.
Technical Notes
3GP imposes strict constraints inherited from the 3GPP standard: video must have even pixel dimensions (enforced by the scale=trunc(iw/2)*2:trunc(ih/2)*2 filter in 3GP workflows), audio tracks are typically single-channel or stereo at very low bitrates, and the container does not support multiple audio tracks, subtitles, or chapters. RMVB, originally a RealNetworks format, is handled by FFmpeg as a container that accepts libx264 video and AAC or MP3 audio despite its RealVideo heritage — native RealVideo (rv40) encoding is not available in FFmpeg. This means the resulting RMVB file will not be bit-for-bit compatible with files produced by RealProducer, but it will play in most modern players that support RMVB. The CRF-based encoding means output file size will vary depending on the motion complexity of the source clip — a 3GP clip with lots of motion will produce a larger RMVB file than a static talking-head clip at the same CRF setting. AMR audio, which is sometimes found in 3GP files recorded on older phones, will be automatically decoded and re-encoded to AAC 128k during this conversion, which is a significant quality improvement for voice recordings.