MOS to SWF Converter
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Supports: MOS
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Need help?Convert MOS to SWF: Read This First
This route takes a Leaf medium-format raw capture and produces a Shockwave Flash movie holding that single developed frame. Before you spend time on settings, two facts decide whether it is worth doing at all.
Adobe stopped supporting Flash Player on 31 December 2020 and began blocking Flash content from running on 12 January 2021, and every mainstream browser removed the plugin in early 2021. A .swf produced today will not open in Chrome, Firefox, Edge or Safari, and there is no setting that re-enables it. And a .mos is a raw sensor capture from an Aptus or Aptus-II back — a many-megapixel still with full editing latitude, which this conversion develops, flattens to 8-bit, scales down to fit an encoder limit, and holds motionless in a video timeline.
There is one situation where that trade makes sense: a Flash-dependent toolchain you cannot replace — an older Adobe Animate or Flash Professional project, legacy courseware, or a kiosk or signage system that ingests .swf and nothing else. If that is not you, MOS to JPG gives you the picture and MOS to MP4 gives you a video that still plays.
How to Convert MOS to SWF
- Upload Your MOS File: Drag the
.mosonto the page or click "+ Add Files". Several frames can be queued; Merge strategy opens on Merge images, which joins them into one movie, and Video per image writes a separate.swffor each. - Set Image Duration: This is the control that decides the runtime, because a still has no length of its own. It opens at 5 seconds per frame and the list runs from a single frame (1/60s, 1/30s, 1/24s) up to 10 seconds.
- Leave Video Codec on FLV and Choose a Video resolution: Video Codec offers FLV — Sorenson Spark, what the page opens on — and MJPEG. Video resolution opens on Keep original; Fixed Resolutions gives explicit width-by-height pairs, and Preset Resolutions sets height with width following the source aspect.
- Convert and Download: Click Convert and save the
.swf. Files upload over an encrypted connection, are developed and encoded on our servers and are deleted automatically after a few hours — no sign-up, no watermark, never shared or made public.
Your 80-Megapixel Frame Will Not Arrive at 80 Megapixels
Before any encoding happens, the developed raw is normalised to a PNG and clamped so that neither side exceeds 4096 pixels. That is not negotiable and there is no control for it — it is a limit on what the encoder stage can reliably ingest, and it applies even when Video resolution is left on "Keep original".
For a Leaf back that is a very large reduction. Medium-format frames run to several thousand pixels on the long edge and the largest Aptus-II models pass ten thousand, so the clamp brings the frame down to 4096 across with height following the aspect ratio. Everything the back recorded beyond that is discarded before Flash ever sees it.
The practical consequence is that "Keep original" is a misleading name on this route, and you are better off deciding the frame size yourself. Pick a Fixed Resolution that matches the stage your Flash project actually uses — the list runs from 256 x 144 up to 8K, and something in the 800 x 600 to 1920 x 1080 range is what a real Flash timeline expects. Choosing explicitly also avoids the second surprise: where your frame's shape does not match the chosen stage, the leftover area is filled with Background Color, which opens on White rather than the black most video tools default to.
FLV and MJPEG Inside a SWF Are Not Interchangeable
| FLV — Sorenson Spark (opens here) | MJPEG | |
|---|---|---|
| How frames are stored | Predicted from their neighbours | Every frame a complete JPEG |
| Size on a five-second still | 58,337 bytes in our test encode | 204,687 bytes for the same frame and duration |
| Quality Preset | Renders | Renders |
| Constant Quality | Renders, on a 1-31 quantiser | Renders, on a 2-31 quantiser |
| Constraint Quality | Renders, with a Max bitrate field | Not offered — it disappears from the panel |
| Best for | Anything that behaves like ordinary video, which includes a held still | A tool that will pull individual JPEG frames back out |
Both numbers above come from encoding the same 1920 x 1080 still held for five seconds at one frame per second. The gap is larger on a still than it is on moving footage, and the reason is worth understanding: a held image is the ideal case for inter-frame prediction, because after the first keyframe every subsequent frame is a "nothing changed" delta costing almost nothing. MJPEG cannot exploit that — it writes a complete JPEG every second regardless.
The same effect makes duration nearly free on FLV. Doubling our test clip from five seconds to ten took it from 58,337 to 63,582 bytes: about 5 KB for five extra seconds. Set the duration your project needs and stop worrying about it; the levers that move the file are resolution first, quantiser second.
What Reaches the Encoder, and What Does Not
| Control on the page | What actually happens |
|---|---|
| Quality Preset | On a non-CRF codec the preset scales the source bitrate, and a still image has no bitrate to scale — so on both FLV and MJPEG it has nothing to work with here |
| Constant Quality | Reaches the encoder as a quantiser. The field is labelled CRF, but on both codecs lower is better on a 1-31 (FLV) or 2-31 (MJPEG) scale, which is the opposite direction the label implies |
| Constraint Quality | Available on FLV only, and the Max bitrate field is the most direct size control this page offers |
| Specific file size, Constant Bitrate, Variable Bitrate | Not offered on an image source — the modes are hidden rather than ignored |
| Audio Codec | Not offered. Image-to-video output has no audio stream at all, so the SWF container's usual MP3-only restriction never comes up |
| Trim | Not offered. There is no timeline to cut |
Frequently Asked Questions
The SWF will not open in my browser. Can that be fixed?
No, and it is not a fault in the file. Adobe ended Flash Player support on 31 December 2020 and started blocking Flash content on 12 January 2021; the browsers removed the plugin and there is no flag to bring it back. A valid .swf from this page still opens in the Ruffle emulator, in Adobe's standalone Flash Player Projector, or inside the Flash authoring tool you are targeting. What you cannot do is drag it into a browser tab.
Does the movie have sound?
No. Image-to-video output is silent — there is no audio stream in the file at all, not a silent one — and the Audio Codec control does not render on this page for that reason. That sidesteps a restriction people hit on SWF conversions from video sources, where the container accepts only MP3 and forces a 44,100 Hz sample rate. With no audio to write, none of that applies.
How long will the movie be, and how many frames does it contain?
Exactly the Image Duration you set, and one frame per second of it. A still has no motion, so the pipeline encodes at one frame per second and holds the picture — five seconds is five frames, ten seconds is ten. B-frames are disabled for the same reason: they are useless when every frame is identical and they push the stream's start time forward noticeably at one frame per second. Under Merge strategy, several .mos files at "Merge images" produce one movie whose length is the file count multiplied by the duration.
Will my raw look the way it does in Capture One?
No, and it is better to expect that up front. Our raw coder performs a neutral development — demosaic, the as-shot white balance the back recorded, a standard tone curve, then an 8-bit sRGB encode. There is no tone-mapping stage, so a frame exposed to protect a bright highlight may clip where your own recipe would have recovered it, and none of your profile or grade is applied. For colour-critical work, develop in Capture One, export a JPEG or TIFF, and convert that instead.
Why is the area around my picture white?
Because Background Color defaults to White on image sources, and your frame's aspect ratio does not match the stage you chose. A 4:3 medium-format frame inside a 16:9 Fixed Resolution leaves bars on both sides, and those bars take the background colour. Change it to Black — or to any of the other colours in the list — if white reads wrong against the rest of your Flash project. Picking a Fixed Resolution that matches your frame's shape removes the bars entirely.
Why is the CRF field not behaving like a CRF?
Because neither codec on this page uses CRF. That numeric input is shared with H.264-class encoders where the name is correct; Sorenson Spark and MJPEG both take a quantiser instead. The field is range-limited to each codec's real scale — 1 to 31 for FLV, 2 to 31 for MJPEG — and on both of them lower means better quality, which is the reverse of what the label suggests. The control works; only its name belongs to another codec family.
My Flash authoring tool rejected the file. What should I try?
Frame size first. Older Flash tools are particular about stage dimensions, and a 4096-pixel-wide movie is far outside what a Flash-era project expects. Set a modest Fixed Resolution — 640 x 480 or 800 x 600 — and re-convert before assuming the file itself is at fault. If it still refuses, try the other Video Codec: some tools that reject Sorenson Spark accept the MJPEG variant because it is just a run of JPEGs.
Should I convert the raw straight to SWF, or go through an image first?
Go through an image whenever you have the choice, because it gives you control over the part that matters most. Develop the .mos to MOS to JPG or MOS to PNG at the exact crop, exposure and pixel dimensions your project needs, then build the movie from that. Doing it in one step means accepting a neutral development at whatever size the 4096-pixel clamp lands on, which is rarely what a Flash stage wants.
What happens to my raw file after conversion?
It is uploaded over an encrypted connection, developed and encoded on our servers, and both the upload and the finished .swf are deleted automatically after a few hours. Nothing is shared or made public, there is no watermark and no account is required. Medium-format raws are large, so upload time is the part of the job you will actually wait on — the encode of a single held frame is quick.