Render the ice as long videos and play them as wallpapers

render_wallpaper.py drives headless Firefox frame by frame (four at a time,
resuming where it stopped), then ffmpeg. Thirty seconds at 30 fps is exactly
one plasma cycle, so frame 900 meets frame 0 and the loop has no seam.

plasma-plugin/dev.emil.video is a minimal Plasma 6 video wallpaper: one file
per screen, filling the screen, looping. H.264 is encoded Baseline because
Qt here decodes through openh264, which rejects High profile and leaves a
frozen frame; a new source also has to be played explicitly.

The #shot hash learned info=0 to hide the on-screen hint for renders.

README.md

@@ -54,6 +54,40 @@ python3 build_plasma.py 10_ice_fish.frag    11_ice_over_fish.frag ice_fish.html
 `build_plasma.py` вставляет оба шейдера в шаблон страницы. После правки шейдеров страницу
 надо пересобрать — HTML сам по себе не обновляется.
 
+## Обои
+
+Готовые рендеры с рыбами — по файлу на монитор (в репозиторий не входят, они тяжёлые):
+
+| файл | экран | размер |
+| --- | --- | --- |
+| `~/Videos/wallpapers/ice_fish_2560x1080.mp4` | DP-2, ультравайд | 110 МБ |
+| `~/Videos/wallpapers/ice_fish_2560x1440.mp4` | HDMI-A-1 | 112 МБ |
+
+30 секунд, 30 fps, петля бесшовная: кадр 900 совпадает с кадром 0, потому что цикл
+плазмы ровно 30 с. Профиль H.264 — **Baseline**: Qt на Fedora декодирует через openh264,
+который отвергает High profile и молча оставляет замерший кадр.
+
+Пересобрать:
+
+```sh
+python3 render_wallpaper.py ice_fish.html ~/Videos/wallpapers/ice_fish_2560x1440.mp4 2560 1440 30 30
+```
+
+Скрипт гонит кадры в headless Firefox по четыре за раз, кладёт их в `*.frames/`
+(можно удалить) и кодирует через `h264_nvenc`. Повторный запуск продолжает с места
+обрыва.
+
+Обоями видео ставит плагин `dev.emil.video` (исходники — `plasma-plugin/dev.emil.video/`,
+установленная копия — `~/.local/share/plasma/wallpapers/dev.emil.video/`). Он проигрывает
+файл из своего конфига, заполняя экран, и зацикливает его:
+
+```sh
+kpackagetool6 --type Wallpaper -i plasma-plugin/dev.emil.video
+```
+
+Дальше — правый клик по рабочему столу → «Настроить рабочий стол…» → тип обоев
+Video Wallpaper → путь к файлу. Настройки у каждого экрана свои.
+
 ## Проверка
 
 ```sh
@@ -73,5 +107,7 @@ python3 -m unittest test_ice
   и преломления льда надо переносить во все три файла.
 - `debug_fish.frag` + `debug_fish.html` — плоский рендер силуэтов рыб для отладки формы.
 - `renders/*.jpg` — картинки для этого README, к сборке отношения не имеют.
+- `render_wallpaper.py` — кадры + ffmpeg, длинное видео для обоев.
+- `plasma-plugin/dev.emil.video` — минимальный видео-обои плагин для Plasma 6.
 - `build.py` собирает `playground.html` со всеми `.frag` подряд, `render.py`/`shot.py` —
   старые вспомогательные скрипты.

build_plasma.py

@@ -79,6 +79,7 @@ const shot = location.hash.startsWith('#shot');
 const shotParams = new URLSearchParams(location.hash.slice(1));
 let mouseX = Number(shotParams.get('mx') ?? 0.5), mouseY = Number(shotParams.get('my') ?? 0.5);
 let speed = 1, time = Number(shotParams.get('t') ?? 0), previous;
+if (shotParams.get('info') === '0') document.getElementById('info').style.display = 'none';
 addEventListener('pointermove', e => { mouseX = e.clientX / innerWidth; mouseY = 1 - e.clientY / innerHeight; });
 addEventListener('keydown', e => {
   if (e.key === '-' || e.key === '_') speed = Math.max(0.125, speed / 2);

ice_fish.html

@@ -65,6 +65,7 @@ const shot = location.hash.startsWith('#shot');
 const shotParams = new URLSearchParams(location.hash.slice(1));
 let mouseX = Number(shotParams.get('mx') ?? 0.5), mouseY = Number(shotParams.get('my') ?? 0.5);
 let speed = 1, time = Number(shotParams.get('t') ?? 0), previous;
+if (shotParams.get('info') === '0') document.getElementById('info').style.display = 'none';
 addEventListener('pointermove', e => { mouseX = e.clientX / innerWidth; mouseY = 1 - e.clientY / innerHeight; });
 addEventListener('keydown', e => {
   if (e.key === '-' || e.key === '_') speed = Math.max(0.125, speed / 2);

plasma-plugin/dev.emil.video/contents/config/main.xml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<kcfg>
+    <group name="General">
+        <entry name="videoPath" type="String">
+            <default></default>
+        </entry>
+        <entry name="playbackRate" type="Double">
+            <default>1.0</default>
+        </entry>
+    </group>
+</kcfg>

plasma-plugin/dev.emil.video/contents/ui/main.qml

@@ -0,0 +1,58 @@
+import QtQuick
+import QtMultimedia
+import org.kde.plasma.plasmoid
+
+// Plays one video file, filling the screen and looping for ever. Plasma keeps a
+// separate configuration per screen, so every monitor gets its own video.
+WallpaperItem {
+    id: root
+
+    readonly property var activeConfiguration: {
+        if (typeof wallpaper !== "undefined" && wallpaper && wallpaper.configuration)
+            return wallpaper.configuration
+        return typeof configuration !== "undefined" ? configuration : null
+    }
+
+    function option(name, fallback) {
+        if (!activeConfiguration)
+            return fallback
+        const value = activeConfiguration[name]
+        return value === undefined ? fallback : value
+    }
+
+    readonly property string videoPath: String(option("videoPath", ""))
+    // shortcut: keeps decoding behind fullscreen windows too, add window tracking
+    // (as the shader wallpaper plugin does) if the cost ever shows up in a game
+    readonly property bool shouldPlay: videoPath.length > 0 && root.visible
+
+    Rectangle {
+        anchors.fill: parent
+        color: "#03111d"
+    }
+
+    VideoOutput {
+        id: output
+        anchors.fill: parent
+        fillMode: VideoOutput.PreserveAspectCrop
+    }
+
+    MediaPlayer {
+        id: player
+        videoOutput: output
+        source: root.videoPath.length > 0 ? "file://" + root.videoPath : ""
+        loops: MediaPlayer.Infinite
+        playbackRate: Number(root.option("playbackRate", 1.0))
+
+        // Some containers do not restart on their own when they run out of frames.
+        onMediaStatusChanged: {
+            if (mediaStatus === MediaPlayer.EndOfMedia) {
+                position = 0
+                play()
+            }
+        }
+
+        onErrorOccurred: console.warn("video wallpaper:", error, errorString)
+    }
+
+    Component.onCompleted: player.play()
+}

plasma-plugin/dev.emil.video/metadata.json

@@ -0,0 +1,17 @@
+{
+    "KPackageStructure": "Plasma/Wallpaper",
+    "KPlugin": {
+        "Authors": [
+            {
+                "Name": "Emil"
+            }
+        ],
+        "Id": "dev.emil.video",
+        "License": "GPL-3.0-or-later",
+        "Name": "Video Wallpaper",
+        "Version": "0.1.0",
+        "Description": "Plays a video file as the wallpaper, scaled to fill the screen"
+    },
+    "X-KDE-ParentApp": "org.kde.plasmashell",
+    "X-Plasma-API-Minimum-Version": "6.0"
+}

render_wallpaper.py

@@ -0,0 +1,69 @@
+#!/usr/bin/env python3
+"""Render a seamless video of one of the pages: frames first, then ffmpeg.
+
+    render_wallpaper.py <page.html> <out.mp4> <width> <height> [seconds] [fps]
+
+Frames land in <out.mp4>.frames/ as PNG and are kept so a re-run resumes.
+The page's loop is exactly 30 s, so keep the duration a multiple of that to
+make the video loop without a seam."""
+import os
+import subprocess
+import sys
+import time
+from concurrent.futures import ThreadPoolExecutor
+from pathlib import Path
+
+page, out = Path(sys.argv[1]).resolve(), Path(sys.argv[2]).resolve()
+width, height = int(sys.argv[3]), int(sys.argv[4])
+seconds = float(sys.argv[5]) if len(sys.argv) > 5 else 30.0
+fps = int(sys.argv[6]) if len(sys.argv) > 6 else 30
+workers = min(4, os.cpu_count() or 2)  # 8 headless Firefox at once segfaults the GPU driver
+
+frames = out.with_suffix('.frames')
+frames.mkdir(parents=True, exist_ok=True)
+profiles = [Path(f'/tmp/ff_wall_{i}') for i in range(workers)]
+for profile in profiles:
+    profile.mkdir(exist_ok=True)
+
+total = int(round(seconds * fps))
+
+
+def render(index):
+    target = frames / f'{index:04d}.png'
+    if target.exists() and target.stat().st_size > 20000:
+        return 0.0
+    url = f'{page.as_uri()}#shot&t={index / fps:.6f}&info=0'
+    profile = profiles[index % workers]
+    for attempt in range(4):
+        started = time.time()
+        result = subprocess.run(['firefox', '--headless', '--new-instance',
+                                 '--profile', str(profile),
+                                 f'--window-size={width},{height}',
+                                 f'--screenshot={target}', url],
+                                timeout=300,
+                                stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
+        if result.returncode == 0 and target.exists() and target.stat().st_size > 20000:
+            return time.time() - started
+        target.unlink(missing_ok=True)
+        time.sleep(1 + attempt)
+    raise RuntimeError(f'frame {index} failed')
+
+
+began = time.time()
+with ThreadPoolExecutor(workers) as pool:
+    for done, _ in enumerate(pool.map(render, range(total)), 1):
+        if done % 30 == 0 or done == total:
+            elapsed = time.time() - began
+            print(f'{done}/{total} frames, {elapsed:.0f}s elapsed, '
+                  f'~{elapsed / done * (total - done):.0f}s left', flush=True)
+
+out.parent.mkdir(parents=True, exist_ok=True)
+subprocess.run(['ffmpeg', '-y', '-hide_banner', '-loglevel', 'warning',
+                '-framerate', str(fps), '-i', str(frames / '%04d.png'),
+                # Baseline on purpose: Fedora's Qt Multimedia decodes H.264 through
+                # openh264, which rejects High profile ("DecodeFrame failed" in the
+                # journal) and then Plasma shows a frozen frame.
+                '-c:v', 'h264_nvenc', '-profile:v', 'baseline', '-preset', 'p7',
+                '-rc', 'constqp', '-qp', '18', '-pix_fmt', 'yuv420p',
+                '-movflags', '+faststart', str(out)], check=True)
+print(f'{out} written ({out.stat().st_size / 1e6:.1f} MB)')