Convert HEVC to RMVB — Free Online Tool
Convert HEVC/H.265 video files to RMVB format by transcoding from the highly efficient x265 codec to H.264 (libx264) wrapped in RealMedia's variable bitrate container. This is useful when you need to play H.265 content on legacy media players or devices that support RMVB but lack HEVC decoding capability.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your HEVC 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
Because HEVC and RMVB use entirely different video codecs — x265 versus libx264 — this conversion requires a full video transcode, not a simple remux. Every frame of the H.265 stream must be decoded and then re-encoded as H.264 using libx264 at CRF 23, which represents a moderate quality setting. If the source HEVC file contains audio, it will also be transcoded to AAC at 128k bitrate, since RMVB as implemented here carries AAC or MP3 audio rather than passthrough from arbitrary input codecs. The RMVB container itself is a variable bitrate variant of RealMedia, meaning the output bitrate will fluctuate based on scene complexity rather than being locked to a fixed rate. One important implication of this double-encode is that some generation loss is inevitable: the source was already compressed with x265, and re-compressing with x264 at CRF 23 will introduce additional quantization artifacts, particularly in high-detail or fast-motion scenes. File sizes will generally increase relative to the HEVC source, because H.264 is less compression-efficient than H.265 at equivalent perceptual quality.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg program, which is running here as a WebAssembly build (FFmpeg.wasm) entirely inside your browser — no data is sent to any server. |
-i input.hevc
|
Specifies the input file, which is your HEVC/H.265 source. FFmpeg will demux the raw H.265 bitstream and decode it frame by frame in preparation for re-encoding as H.264. |
-c:v libx264
|
Selects libx264 as the video encoder for the output RMVB file, replacing the source's H.265 codec. This is necessary because RMVB players universally support H.264 but rarely support HEVC decoding. |
-c:a aac
|
Encodes the audio stream as AAC (Advanced Audio Coding), which is the default and most compatible audio codec for this RMVB output. Any audio format in the source HEVC file — AC-3, DTS, Opus, etc. — will be transcoded to AAC. |
-crf 23
|
Sets the Constant Rate Factor for libx264 to 23, which is the x264 default and represents a good balance between file size and visual quality. Lower values (e.g., 18) yield higher quality larger files; higher values (e.g., 28) compress more aggressively. |
-b:a 128k
|
Sets the AAC audio bitrate to 128 kilobits per second, which is sufficient for stereo dialogue and music in most RMVB content. Raise this to 192k or 256k if the source has high-quality surround audio being downmixed to stereo. |
output.rmvb
|
Defines the output filename with the .rmvb extension, which signals FFmpeg to use the RealMedia muxer and package the H.264 video and AAC audio into the variable bitrate RealMedia container. |
Common Use Cases
- Playing H.265 video on older Android-based media players or set-top boxes that have built-in RMVB support but no HEVC hardware decoder
- Sharing video with users in regions where RMVB remains a common distribution format for downloaded movies and TV shows, particularly on legacy Chinese media software like RealPlayer or PPS
- Downgrading a 4K or HDR HEVC master to an H.264-based RMVB file for compatibility with older Blu-ray players or network-attached storage media servers that index RMVB but not HEVC
- Converting an HEVC-encoded recording from a modern drone or action camera into RMVB so it can be opened in older video editing software that predates H.265 support
- Preparing video content for distribution on platforms or file-sharing communities where RMVB is the expected or required container format for SD and HD content
- Testing how an H.265 source degrades through a generation-loss transcode to H.264 for quality-assurance or archival research purposes
Frequently Asked Questions
Yes, some quality loss is unavoidable. Your HEVC source is already a compressed file encoded with x265, and this tool re-encodes it with libx264 at CRF 23, introducing a second round of lossy compression. H.264 at CRF 23 is a reasonable quality setting, but it is less efficient than H.265, so fine detail and gradients may show slightly more blockiness or banding in the output. For most standard-definition or 1080p content the difference is subtle, but on high-detail 4K HEVC sources the loss is more perceptible.
HEVC (H.265) achieves roughly 40–50% better compression than H.264 at equivalent visual quality, so when you decode an x265 stream and re-encode it as x264, you need a higher bitrate to preserve a similar level of detail. At CRF 23 in x264, the output bitrate will typically be substantially higher than the original x265 stream was, resulting in a larger file. If you want to keep file sizes smaller, you can raise the CRF value (e.g., to 28 or higher) in the FFmpeg command at the cost of some additional quality reduction.
RMVB via libx264 does not carry HDR metadata in any meaningful way. If your HEVC source contains HDR10 or Dolby Vision color information, that metadata will be stripped during the transcode and the output will be tone-mapped to SDR by the decoder. The RMVB container technically allows high resolutions, but very few RMVB-capable players are designed for 4K playback, so the format is generally impractical for 4K HDR content even if the encode completes successfully.
No. RMVB as configured here supports only a single video stream and a single audio track, and carries no subtitle or chapter data. If your source HEVC file has multiple audio tracks, only the first will be transcoded to AAC; the rest are discarded. Any embedded subtitle streams or chapter markers will be lost entirely in the output RMVB file.
To adjust video quality, change the -crf value: lower numbers (e.g., 18) produce higher quality at a larger file size, while higher numbers (e.g., 28–35) reduce file size with more compression. To change audio bitrate, replace 128k in -b:a 128k with a value like 192k or 256k for better audio fidelity, or 96k to save space. For example: ffmpeg -i input.hevc -c:v libx264 -c:a aac -crf 18 -b:a 192k output.rmvb
Yes. On Linux or macOS you can loop over files with: for f in *.hevc; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "${f%.hevc}.rmvb"; done. On Windows Command Prompt, use: for %f in (*.hevc) do ffmpeg -i "%f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "%~nf.rmvb". This is especially practical for large batches or files over 1GB that exceed the browser tool's limit.
Technical Notes
This conversion involves two codec boundaries: the video goes from HEVC (libx265) to H.264 (libx264), and the audio is transcoded to AAC regardless of its original format. The RMVB container is a legacy format from RealNetworks and has not been actively developed in many years; its specification does not formally define H.264 as a supported codec, but in practice most RMVB-capable players that include an H.264 decoder will play files produced this way. Native RealVideo codecs (RV40, etc.) are not used here because libavcodec's RealVideo encoders are not part of standard FFmpeg builds. The -x265-params log-level=error flag present on the input side is irrelevant to RMVB output but suppresses verbose x265 logging during any intermediate decode step. One known limitation is that the RMVB container does not support B-frame reference structures beyond what H.264 baseline/main profiles allow; if you encounter playback issues on strict RMVB players, adding -profile:v main to the command can improve compatibility. Because RMVB is a variable bitrate format, the output file's bitrate envelope will fluctuate with scene complexity, which is actually advantageous for preserving quality in action sequences without inflating file size in static scenes.