Convert RMVB to 3GPP — Free Online Tool
Convert RMVB files to 3GPP format optimized for mobile playback, re-encoding RealMedia's variable bitrate video into H.264 with a low 64k AAC audio bitrate suited for 3G-era devices and mobile streaming. This tool runs entirely in your browser — no upload required.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your RMVB file here
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Free — no uploads, no signups. Your files never leave your browser.
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
RMVB uses RealNetworks' proprietary RealVideo codec, which is not natively supported by the 3GPP container. This means the video must be fully re-encoded — not simply remuxed — from RealVideo into H.264 (libx264) using a CRF of 23, which targets a visually balanced quality-to-filesize ratio. The audio, likely encoded as RealAudio in the source RMVB, is also re-encoded into AAC at 64k, a bitrate specifically appropriate for 3GPP's mobile-first, bandwidth-constrained design. The `-movflags +faststart` flag reorganizes the MP4-family metadata to the front of the file, enabling progressive playback on mobile browsers and media players before the full file is downloaded.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool. In this browser-based tool, FFmpeg runs as a WebAssembly binary (FFmpeg.wasm) entirely within your browser — no file data leaves your device. |
-i input.rmvb
|
Specifies the input RMVB file. FFmpeg will detect the RealMedia container and identify the RealVideo and RealAudio streams inside it for decoding. |
-c:v libx264
|
Re-encodes the video stream using the libx264 encoder, producing H.264 video compatible with the 3GPP container. This is required because RealVideo, the codec used in RMVB, is not supported by 3GPP. |
-c:a aac
|
Re-encodes the audio stream to AAC, replacing the RealAudio codec from the RMVB source. AAC is the standard audio codec for 3GPP and is widely supported on mobile devices. |
-crf 23
|
Sets the Constant Rate Factor for H.264 encoding to 23, which is the default balance between visual quality and file size. For 3GPP's mobile target audience, this produces acceptable quality without inflating the file beyond what mobile networks can comfortably handle. |
-b:a 64k
|
Sets the AAC audio bitrate to 64 kilobits per second, which is the default for 3GPP output in this tool. This low bitrate is intentional — 3GPP was designed for 3G mobile delivery, and 64k AAC is sufficient for voice and general audio on device speakers. |
-movflags +faststart
|
Moves the MP4/3GPP metadata (the moov atom) to the beginning of the output file, enabling progressive playback on mobile devices and browsers. Without this flag, the entire file must be downloaded before playback can begin. |
output.3gp
|
Specifies the output filename with the .3gp extension, which signals FFmpeg to write the converted streams into a 3GPP container — the mobile-standard format designed for 3G-era devices and streaming. |
Common Use Cases
- Playing classic RMVB video content downloaded in the early 2000s on a modern Android or iOS device that no longer ships with a RealPlayer-compatible codec
- Preparing video files for upload to 3G-compatible mobile platforms or legacy content management systems that require 3GPP format
- Archiving or sharing old RMVB drama and anime episodes in a mobile-friendly format without requiring specialized media players
- Embedding video into apps or web pages targeting low-bandwidth mobile connections in regions where 3GPP remains a standard delivery format
- Reducing file size for RMVB content that needs to be transferred to feature phones or older smartphones with limited storage and codec support
- Extracting and converting RMVB lecture recordings into a 3GPP format for offline mobile viewing in low-connectivity educational environments
Frequently Asked Questions
Unlike formats that share a common codec (such as MKV to MP4 with H.264 video, which can often be remuxed instantly), RMVB uses RealNetworks' proprietary RealVideo codec, which must be fully decoded and re-encoded frame by frame into H.264. This is computationally intensive, especially in the browser via WebAssembly. Longer videos or those with high original bitrates will take proportionally more time.
Yes. The 3GPP (.3gp) format using H.264 video and AAC audio is broadly supported on Android and iOS devices. The `-movflags +faststart` flag also ensures the file is structured for streaming, meaning it can begin playback before fully loading. However, very old 3GP-only feature phones may have stricter resolution or bitrate caps that could require additional constraints like `-vf scale=176:144`.
RMVB files are already heavily compressed using variable bitrate encoding, so the file size change depends on the original RMVB bitrate versus what CRF 23 produces for H.264. In many cases the output 3GPP file will be similar in size or slightly smaller, especially with the 64k audio bitrate — down from the typical 128k+ found in RMVB files. If the source RMVB had a very high quality setting, you may see a reduction in file size with some perceptible quality loss.
No. The 3GPP format does not support subtitle tracks or chapter markers, and this conversion does not attempt to extract them. Additionally, RMVB files sometimes contain RealText or RealPix subtitle streams that FFmpeg cannot reliably extract. If you need subtitles, you would need to burn them into the video using a `-vf subtitles=` filter before converting, which is a separate workflow.
To change video quality, modify the `-crf` value: lower numbers like 18 produce higher quality and larger files, while higher numbers like 28 reduce quality and file size. The range supported by this tool's 3GPP output is CRF 18–28. To change audio bitrate, replace `64k` in `-b:a 64k` with values like `96k` or `128k`. Keep in mind that 3GPP is designed for low-bandwidth mobile use, so very high audio bitrates are often unnecessary and increase file size without meaningful benefit on the target devices.
Yes. On a desktop with FFmpeg installed, you can adapt the command into a shell loop. On Linux or macOS: `for f in *.rmvb; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 64k -movflags +faststart "${f%.rmvb}.3gp"; done`. On Windows Command Prompt, use a `for` loop with `%f`. The browser-based tool processes one file at a time, so batch processing is best handled locally for large collections.
Technical Notes
RMVB (RealMedia Variable Bitrate) uses RealVideo 8, 9, or 10 as its video codec and RealAudio as its audio codec — neither of which is natively supported in the 3GPP container. This makes a full transcode mandatory: there is no remux path. The output H.264 stream is encoded by libx264 at CRF 23, which is a widely accepted default producing good visual quality for the output file size. The 3GPP container is structurally similar to MP4 (both are based on the ISO Base Media File Format), so the `-movflags +faststart` flag, which moves the `moov` atom to the beginning of the file, is meaningful and enables mobile streaming. Audio is re-encoded to AAC at 64k — this is intentionally conservative for 3GPP's mobile-first use case, where bandwidth and device speaker quality often make higher bitrates imperceptible. Note that RMVB files sometimes use aspect ratios and frame rates uncommon in mobile video (e.g., non-standard DAR or 15fps), which may result in playback quirks on some 3GPP players. Metadata from the original RMVB (title, author, copyright fields) is not reliably transferred, as RealMedia uses a proprietary metadata structure that FFmpeg does not map to 3GPP atoms.