RMVB to SWF Converter

RMVB to SWF: Moving Between Two Dead Formats

This conversion carries video out of RealNetworks' RealMedia Variable Bitrate container and into Adobe's Shockwave Flash movie format. Both ends are obsolete, and it is worth saying that plainly before you spend time on settings.

RMVB dates from 2003 and was the standard way Asian film and drama releases circulated for years; no browser has ever decoded RealVideo, and most current editors have dropped RealMedia support. SWF is Flash: Adobe stopped supporting Flash Player on 31 December 2020 and began blocking Flash content from running on 12 January 2021, and every major browser removed the plugin in early 2021. A .swf produced today will not open in Chrome, Firefox, Edge or Safari.

There is exactly one situation where SWF is the right answer: a Flash-dependent toolchain you cannot replace — an older Adobe Animate or Flash Professional timeline, legacy courseware, kiosk or signage software that ingests .swf and nothing else. If that is not you, stop here and use RMVB to MP4.

How to Convert RMVB to SWF

1. Upload Your RMVB File: Drag the .rmvb onto the page or click "Add Files" to browse. Several files can be queued and they all run with the same settings.
2. Choose a Video Codec: Video Codec offers two entries — FLV, which is Sorenson Spark and is what the page opens on, and MJPEG. The choice changes both the file size and which compression modes remain available, as set out below. Audio Codec has a single entry, MP3, because the SWF muxer accepts nothing else.
3. Set File Compression, Video resolution and Trim (Optional): On FLV, File Compression opens on Quality Preset at Very High (Recommended) with Specific file size, Constant Bitrate, Variable Bitrate, Constant Quality and Constraint Quality alongside. Video resolution opens on Keep original. Trim offers Unchanged or a Time Range with a Start time and Duration in seconds or as HH:MM:SS.sss.
4. Convert and Download: Click Convert and save the .swf. Files are uploaded over an encrypted connection, re-encoded on our servers, and deleted automatically after a few hours — no sign-up, no watermark.

Walk-through: The Two Codecs Are Not Interchangeable

Picking between FLV and MJPEG is the biggest decision on this page, and it does more than swap an encoder.

FLV (Sorenson Spark) is the codec Flash video was built on. It uses motion prediction, so only the differences between frames are stored, and it keeps the full rate-control surface: Quality Preset, Specific file size, Constant Bitrate, Variable Bitrate, Constant Quality and Constraint Quality all render and all do something. This is the default and it is the right choice for anything that resembles ordinary video.

MJPEG stores every frame as a complete, independent JPEG. Nothing is predicted from the neighbouring frames, which has two consequences. First, the files are dramatically bigger — encoding the same short clip both ways at comparable settings produced an MJPEG movie a little over twice the size of the Spark one. Second, the control surface shrinks: with MJPEG selected, the bitrate modes and Specific file size disappear, leaving Quality Preset and Constant Quality only, and Constant Quality's numeric field runs on a 2-to-31 quantiser scale where lower is better. Choose MJPEG only when the tool you are feeding specifically wants motion-JPEG frames — for instance because it will pull individual frames back out.

One thing neither codec changes: the audio is resampled to 44,100 Hz whether you want it or not. The SWF container accepts only three sample rates — 44,100, 22,050 and 11,025 Hz — and anything else makes the muxer refuse the job outright. Rather than let that happen, the conversion pins the rate at 44,100 Hz server-side, and there is no control for it on the page. If your RMVB carried a 22,050 Hz RealAudio track, it is being upsampled; that adds no quality but it does add bytes.

FLV and MJPEG Inside a SWF, Compared

RMVB and SWF at a Glance

Common Errors and How to Fix Them

• "The SWF will not open in my browser." Expected, and not fixable. Flash is blocked everywhere. Open it in the Ruffle emulator, in a standalone Flash Player Projector, or inside the Flash-based application you are targeting.
• "The file is enormous." You are probably on MJPEG. Switch Video Codec back to FLV, which predicts between frames instead of storing each one whole.
• "My audio sounds no better than before, but the file grew." The sample rate was pinned to 44,100 Hz to satisfy the container. A low-rate source track gets upsampled, which costs bytes without adding information. Nothing on the page changes this.
• "The picture is soft." This is a lossy-to-lossy re-encode, and RMVB was designed for very small files in the first place. Raising the preset stops the second encode adding damage but cannot recover what RealVideo discarded.
• "There is no audio at all." Some RMVB files use RealAudio variants the decoder cannot handle, or carry no audio stream. Check the source in VLC first; if it is silent there, it is silent here too.
• "My import tool rejects the SWF." Older Flash authoring tools are picky about frame size and frame rate. Set an explicit modest frame with Width x Height — 640 x 480 or smaller — before assuming the file itself is at fault.

When This Doesn't Work

If the destination has already dropped Flash — a browser, a modern video editor, a web embed, anything made in the last several years — no RMVB-to-SWF conversion helps, because nothing will play the result. Convert to a living format instead: RMVB to MP4 for a file that plays essentially everywhere, or RMVB to FLV if the tool wants Flash Video specifically but not the SWF movie wrapper. And if you have inherited a .swf and need its content in a usable form, go the other direction with SWF to MP4. Reserve this page for the narrow case where a still-Flash-dependent pipeline genuinely demands SWF input.

Frequently Asked Questions

Why won't my converted SWF play in Chrome or Firefox?

Because browsers no longer run Flash at all. Adobe ended Flash Player support on 31 December 2020 and began blocking Flash content on 12 January 2021, and Chrome and Firefox both removed the plugin in early 2021 — there is no setting to re-enable it. A valid .swf from this page still opens in the Ruffle emulator, in the standalone Adobe Flash Player Projector, or in the legacy Flash authoring tool you are targeting. It will never open in a normal browser tab again.

Why is MP3 the only audio codec I can pick?

Because the SWF muxer supports MP3 audio and nothing else — that is a container limitation, not a policy choice, so the dropdown offers one entry rather than letting you build a file that fails to mux. The related restriction is on sample rate: SWF accepts only 44,100, 22,050 and 11,025 Hz, and the conversion pins the output at 44,100 Hz because anything outside that set makes the muxer abort with "swf does not support that sample rate".

Should I pick FLV or MJPEG for the video?

FLV unless you have a specific reason not to. Sorenson Spark predicts frames from their neighbours, which is what keeps a video file a sensible size, and it keeps every compression mode available. MJPEG stores each frame as a full JPEG, so the file grows sharply — a bit over double on a like-for-like encode of the same short clip — and the bitrate modes and Specific file size vanish from the panel, leaving only Quality Preset and a 2-to-31 quantiser. MJPEG earns its place only when the consuming tool wants independent frames.

Why is the Constant Quality field labelled CRF when it is not a CRF?

Because that numeric control is shared with H.264-class codecs, where CRF is the correct name. Neither Sorenson Spark nor MJPEG uses CRF — both take a quantiser, 1 to 31 for Spark and 2 to 31 for MJPEG, and on both scales lower is better, which is the opposite direction from the CRF scale the label implies. The control does work; it is just wearing another codec family's name. If you are not deliberately setting a quantiser, leave File Compression on Quality Preset.

Will the SWF keep the RMVB's subtitles?

No. RMVB releases that carry subtitles usually do so as a separate .srt or .ass file alongside the video rather than inside the container, and where subtitles are embedded, the SWF format has no subtitle track to put them in. Nothing on this page burns subtitles into the picture either. If the subtitles matter, keep the sidecar file and pair it with an MP4 in a player that loads external subtitles.

Can I convert only one scene instead of the whole file?

Yes. Switch Trim from Unchanged to Time Range and set a Start time and a Duration, in seconds or as HH:MM:SS.sss. That is also the sane way to work with RMVB sources, which are often full-length films or episodes — a Flash timeline rarely wants ninety minutes of video, and trimming first means you are not waiting on a full re-encode to find out whether your settings were right.

Does converting to SWF improve anything about the video?

Nothing. Both formats are lossy, so this is a second generation of compression on a source that was already compressed hard — RMVB's entire purpose was fitting long content into small files. The picture can only stay the same or get slightly worse. The only thing the conversion buys is a container that a Flash-era tool will accept, which is why it is worth doing only when a specific tool demands it.

Is there any way to view the SWF to check the result?

Yes, outside a browser. Ruffle is an actively maintained open-source Flash Player emulator that runs .swf files as a desktop application, and Adobe's standalone Flash Player Projector still exists and still opens .swf files on the desktop. The Flash authoring tool you are targeting will also open the file. What you cannot do is drag it into a browser tab and expect anything to happen.

What happens to my files after the conversion?

Your .rmvb is uploaded over an encrypted connection, decoded and re-encoded on our servers, and both the upload and the resulting .swf are deleted automatically after a few hours. Files are never shared or made public, and there is no sign-up, no watermark and no account required.