Why I built Remux Doctor
Physical media is having a moment, and owning your films in full quality is worth it. Making sense of the files shouldn’t take a dozen command-line tools and a forum thread, so I built a fast, native Mac app for it.
I buy films on disc again. A lot of people do. After a decade of streaming being the obvious answer, physical media is having a real resurgence, and once you’ve seen a good 4K Blu-ray on a decent screen it’s easy to see why.
Streaming is convenient, not the best version
A 4K stream typically runs somewhere around 15 to 25 megabits a second. A UHD Blu-ray can go up to around 100 or more. That gap shows up exactly where you’d expect: dark scenes, film grain, fast motion, smoke and rain, which are the moments that make a film look like a film. Audio is the same story. Streaming Atmos is a lossy, compressed track; the disc usually carries the lossless one.
And streaming is borrowed. Films leave services with little warning, versions get swapped, and what you can watch depends on which subscriptions you’re paying for this month. I wanted the films I care about to be mine, in the best fidelity they were released in, on my own drives, playable whenever I like.
Then you try to make sense of the files
Ripping your own discs to remuxes, a lossless copy of the film in a single file, is the natural next step. And then it gets complicated very quickly.
Is this file Dolby Vision profile 7 or 8? Does its enhancement layer actually carry picture detail, or is it minimal? What’s CM v4.0 and do I want it? Why does this audio track say TrueHD and that one say E-AC-3? Why are the subtitles pictures?
The tools to answer these questions exist, and they’re excellent: MediaInfo, MKVToolNix, FFmpeg, dovi_tool. But they’re separate programs, mostly command-line, each with its own vocabulary. The knowledge of how to combine them lives in long forum threads and scripts people pass around, half of which are out of date. Doing it for one film is a project. Doing it for a whole library is a weekend you won’t get back, and one wrong step can quietly throw away part of a file you can’t easily replace.
What I wanted instead
I wanted one app, on my Mac, that would:
- Tell me what’s in a file in plain English. Not a wall of codes, but something like “Dolby Vision profile 7 with a minimal enhancement layer, HDR10 base, TrueHD Atmos, picture subtitles.” With the raw details one click away for when I want them.
- Check files against what I want. I decide what my files should look like, and the app shows me which ones match and which don’t, across the whole library at once.
- Fix the differences without re-encoding. The whole point of a remux is that the picture is untouched. Any fix that re-encodes the video defeats the purpose. Lossless fixes are also fast, because the video is copied rather than rebuilt.
- Be careful. Write new files, check them before keeping them, and never touch an original unless I ask.
- Feel like a Mac app. Native, quick, drag and drop, notifications when it’s done. Not a web UI or a wrapper around a terminal.
I couldn’t find that, so I built it.
What Remux Doctor does
Remux Doctor reads MKV, MP4, M4V, MOV, TS and M2TS files and explains each one in words: Dolby Vision profile and enhancement layer, HDR format, audio and Atmos, subtitle formats. You choose a target, such as MKV or MP4, which Dolby Vision profiles you allow, which audio codecs, and text or picture subtitles, and every file is checked against it. Watched folders pick up new files as they arrive.
When something doesn’t match, it can fix it without re-encoding the picture: convert Dolby Vision profile 7 to 8.1, remove CM v4.0 metadata, add a Dolby Digital Plus track made from your lossless audio, turn picture subtitles into text, or remux between MKV and MP4. Profile 7 files are sampled first so you know whether the enhancement layer is minimal or full, and full layers are always left for you to decide on.
Everything happens on your Mac. Nothing about your files is uploaded, and the app makes no network connections of its own beyond the App Store for the purchase.
One thing it deliberately doesn’t do is tell you what will play on your TV. Every setup is different, and I’d rather the app state facts about your files and your own target than make promises about hardware.
Where it’s at
Remux Doctor is coming soon for Macs with Apple silicon running macOS 15 or later. Examining and checking files will be free, and so will fixing your first three files, so you can see a real result on your own setup first. A single one-time purchase, with Family Sharing, unlocks the rest. No subscription, because the whole point is owning things.