MOS to AVI Converter

How to Convert MOS to AVI Online

1. Upload Your MOS Files: Drag and drop or click "Add Files" to select Leaf/Mamiya MOS RAW images. Batch upload is supported, so you can drop an entire shoot at once.
2. Pick Merge Strategy: Choose "Merge images" to stitch every MOS into a single AVI, or "Video per image" to render one AVI per RAW. Merge is the right pick for slideshows and timelapses; per-image is the right pick when each capture needs its own deliverable.
3. Set Image Duration, Quality Preset, and Background Color (Optional): Image Duration ranges from 1/60s per frame (true 60fps timelapse) up to 10s per frame (review-style slideshow). Quality Preset goes from Lowest to Highest with "Very High" as the default. Background Color (default Black) fills any letterbox or pillarbox area when the MOS aspect ratio does not match your output Video resolution.
4. Convert and Download: Click Convert. Files process in your browser session — no sign-up, no watermark, no upload to a third party.

The default video codec is MPEG-4 with MP3 audio for broad AVI player compatibility. Under Advanced Options you can switch the Video codec to H.264, DivX, Xvid, or a number of legacy AVI codecs. Resolution can be Keep original, a Fixed Resolution (e.g. 1920x1080, 3840x2160), or a Preset Resolution (4320p down to 144p).

Why Convert MOS to AVI?

MOS is the proprietary RAW image format written by Leaf digital backs — Aptus, Aptus-II, and the early Credo line — used on medium-format bodies like the Mamiya 645AFD, Hasselblad V, and Contax 645AF. Aptus-II resolutions span 22 MP (5334x4008) to 80 MP on the Aptus-II 12, with single-file sizes from roughly 31 MB compressed up to 115 MB uncompressed depending on model. That is too much data and too proprietary an encoding to share casually, which is why a video container is often the practical deliverable.

• Client review reels — Producing a review AVI from a day's MOS captures lets a fashion or commercial client scrub through 50-200 frames in a media player without installing Capture One or Camera Raw.
• Studio-to-set playback — On set, a Windows Media Player-friendly AVI plays from any USB stick on any laptop. No codec packs, no Phase One license, no waiting on a tether.
• Timelapse from sequential captures — Aptus-II backs were commonly used for tabletop and architectural sequences. Converting a sorted MOS sequence at 1/24s or 1/30s per frame yields a true 24fps or 30fps timelapse without round-tripping through After Effects.
• Archive a finished selection as motion — When a still campaign is delivered, a low-bitrate AVI of the final selects becomes a lightweight reference for the marketing team, the agency, and the print buyer.
• Legacy editor ingest — Older NLEs and broadcast tools (Avid Media Composer through 2018, classic Premiere projects, VirtualDub) still consume DivX/Xvid AVI directly without re-wrapping.
• Hand off without RAW dependencies — A photographer's final delivery to a non-photo team avoids the question "what opens a .mos file" entirely.

MOS vs Common RAW and Video Targets

AVI Codec Quick Guide for MOS Slideshows

Frequently Asked Questions

What is a MOS file and which cameras produce it?

MOS is the RAW image format from Leaf digital backs, now owned by Phase One. It carries unprocessed sensor data from medium-format backs including the Aptus and Aptus-II series (22 MP through 80 MP) on bodies such as the Mamiya 645AFD, Hasselblad V, AFi/Hy6, and Contax 645AF. Each MOS file is a single still — converting to AVI turns one still or a sequence of stills into a video.

Why convert a still RAW format to a video container?

Three common reasons: (1) you have a sequence of MOS frames you want to play as a timelapse; (2) you want a portable review reel of an entire shoot a non-photographer can play without RAW software; (3) you want to embed the selects into a wider video edit and need a video-shaped asset. If you only need one MOS as a still, convert MOS to JPG or convert MOS to TIFF instead.

How long will each MOS image display in the AVI?

That is the Image Duration control. It ranges from 1/60s per frame (a true 60fps timelapse) through 1/30s, 1/24s, 1/10s, 1/2s, 1, 2, 3, 5, and 10 seconds per frame. For client reviews, 2-5 seconds per image is comfortable; for cinematic timelapse, pick 1/24s or 1/30s.

Can I merge multiple MOS files into one AVI video?

Yes. Set Merge strategy to "Merge images" and all uploaded MOS files are concatenated in upload order into a single AVI. To control the order, name files with a numeric prefix (0001_, 0002_) before uploading, or upload them one at a time in the order you want.

Which codec should I pick — MPEG-4, H.264, DivX, or Xvid?

MPEG-4 is the default and the safest choice for AVI compatibility on older Windows players and DVD-class hardware. H.264 produces noticeably smaller files at the same visual quality and is the right pick if your players are modern (VLC, MPC-HC, Windows 10/11 with HEVC/AVC extensions). DivX and Xvid are MPEG-4 ASP variants that mainly matter when targeting older hardware decoders.

Why is my output AVI so much larger than an MP4 would be?

Two reasons. First, AVI's container overhead is heavier than MP4's per-chunk. Second, AVI is most often paired with MPEG-4 ASP (DivX/Xvid) or MPEG-4, which compress less efficiently than H.264 or HEVC. If file size matters more than AVI compatibility, convert MOS to MP4 instead — the default H.264 in MP4 typically halves the file at matching quality.

Will the full medium-format resolution be preserved?

By default Video resolution is "Keep original," so a 5334x4008 Aptus-II 22 MOS becomes a 5334x4008 AVI frame. Most players handle this, but a 5K or 7K AVI is heavy and few NLEs accept it without proxying. For practical playback, pick a Preset Resolution (1080p or 2160p) under Video resolution. The Background Color fill kicks in here because medium-format aspect ratios (4:3 or close) do not match 16:9 output.

Do I need Phase One Capture One to use this converter?

No. xConvert decodes the MOS sensor data in your browser — you do not need Capture One, Leaf Capture, Lightroom, or Camera Raw installed. Note that any in-camera or sidecar adjustments you may have made in Capture One are not preserved; the conversion uses the unprocessed RAW data. If you need processed output that matches your Capture One look, export to TIFF from Capture One first, then convert that.

Can I add audio or a soundtrack to the AVI?

The converter writes a silent audio track (MP3) by default so the AVI plays cleanly in players that expect an audio stream. If you want a music bed, render the silent AVI here, then drop it into a video editor (Resolve, Premiere, Shotcut) and add the audio there. Alternatively, convert MOS to MOV or MP4 for formats that integrate more cleanly with modern editors.

What if I want a single PDF contact sheet instead of a video?

Use merge MOS to PDF — it lays the MOS frames out in a paginated PDF, which is usually a better format for static review than a video.