Why I built a native libmpv IPTV player for Windows — an HDR tone-mapping deep-dive

Up front, so there's no confusion: the app I'm describing (Nightmare TV) is a player only . You bring your own M3U / Xtream Codes playlist — it ships with no channels and no content. This post is about the playback engineering, not about where streams come from. Think "VLC for IPTV," not a content service. The problem that started it I watch a lot of live content on my PC — sports, mostly. And every IPTV player I tried on Windows fell into one of two buckets: An Android app running in an emulator. TiviMate and the good mobile players are Android-only, so on a desktop you end up in an emulator or a VM. Input lag, no real HDR path, fans spinning. A thin ExoPlayer / libVLC wrapper. These run natively, but most of them treat HDR as "pass the HDR10 metadata to the display and hope." On an SDR panel — or even a lot of HDR panels — bright skies in a football match blow out to a flat white blob, and 4K HEVC with a DTS track stutters because the decode path isn't doing what you think it is. I wanted the thing that didn't exist: a native Windows player with a reference-grade video path. So I built it on libmpv — the same playback core mpv uses — with a Flutter desktop shell on top for the UI. This post is the part I actually find interesting: the HDR tone-mapping pipeline. Why HDR "just passing through" isn't enough HDR10 content is mastered in the PQ (ST.2084) transfer function against a mastering display — often 1000 nits, sometimes 4000. Your screen is whatever it is: a 350-nit SDR laptop, a 600-nit "HDR400" monitor, an 800-nit OLED. If you map PQ straight to the panel, everything above the panel's peak just clips — all the highlight detail collapses to maximum white. Tone-mapping is the process of intelligently compressing the mastering range into the display range so you keep highlight detail instead of clipping it. The naive version (a fixed curve, or clipping) is what most wrapper players ship. The good version adapts to both the content and the display. The pipeline H