Sync all skills and memories 2026-04-14 07:27

skills/creative/manim-video/references/rendering.md

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+# Rendering Reference
+
+## Prerequisites
+
+```bash
+manim --version       # Manim CE
+pdflatex --version    # LaTeX
+ffmpeg -version       # ffmpeg
+```
+
+## CLI Reference
+
+```bash
+manim -ql script.py Scene1 Scene2    # draft (480p 15fps)
+manim -qm script.py Scene1           # medium (720p 30fps)
+manim -qh script.py Scene1           # production (1080p 60fps)
+manim -ql --format=png -s script.py Scene1  # preview still (last frame)
+manim -ql --format=gif script.py Scene1     # GIF output
+```
+
+## Quality Presets
+
+| Flag | Resolution | FPS | Use case |
+|------|-----------|-----|----------|
+| `-ql` | 854x480 | 15 | Draft iteration (layout, timing) |
+| `-qm` | 1280x720 | 30 | Preview (use for text-heavy scenes) |
+| `-qh` | 1920x1080 | 60 | Production |
+
+**Text rendering quality:** `-ql` (480p15) produces noticeably poor text kerning and readability. For scenes with significant text, preview stills at `-qm` to catch issues invisible at 480p. Use `-ql` only for testing layout and animation timing.
+
+## Output Structure
+
+```
+media/videos/script/480p15/Scene1_Intro.mp4
+media/images/script/Scene1_Intro.png  (from -s flag)
+```
+
+## Stitching with ffmpeg
+
+```bash
+cat > concat.txt << 'EOF'
+file 'media/videos/script/480p15/Scene1_Intro.mp4'
+file 'media/videos/script/480p15/Scene2_Core.mp4'
+EOF
+ffmpeg -y -f concat -safe 0 -i concat.txt -c copy final.mp4
+```
+
+## Add Voiceover
+
+```bash
+# Mux narration
+ffmpeg -y -i final.mp4 -i narration.mp3 -c:v copy -c:a aac -b:a 192k -shortest final_narrated.mp4
+
+# Concat per-scene audio first
+cat > audio_concat.txt << 'EOF'
+file 'audio/scene1.mp3'
+file 'audio/scene2.mp3'
+EOF
+ffmpeg -y -f concat -safe 0 -i audio_concat.txt -c copy full_narration.mp3
+```
+
+## Add Background Music
+
+```bash
+ffmpeg -y -i final.mp4 -i music.mp3 \
+  -filter_complex "[1:a]volume=0.15[bg];[0:a][bg]amix=inputs=2:duration=shortest" \
+  -c:v copy final_with_music.mp4
+```
+
+## GIF Export
+
+```bash
+ffmpeg -y -i scene.mp4 \
+  -vf "fps=15,scale=640:-1:flags=lanczos,split[s0][s1];[s0]palettegen[p];[s1][p]paletteuse" \
+  output.gif
+```
+
+## Aspect Ratios
+
+```bash
+manim -ql --resolution 1080,1920 script.py Scene  # 9:16 vertical
+manim -ql --resolution 1080,1080 script.py Scene  # 1:1 square
+```
+
+## Render Workflow
+
+1. Draft render all scenes at `-ql`
+2. Preview stills at key moments (`-s`)
+3. Fix and re-render only broken scenes
+4. Stitch with ffmpeg
+5. Review stitched output
+6. Production render at `-qh`
+7. Re-stitch + add audio
+
+## manim.cfg — Project Configuration
+
+Create `manim.cfg` in the project directory for per-project defaults:
+
+```ini
+[CLI]
+quality = low_quality
+preview = True
+media_dir = ./media
+
+[renderer]
+background_color = #0D1117
+
+[tex]
+tex_template_file = custom_template.tex
+```
+
+This eliminates repetitive CLI flags and `self.camera.background_color` in every scene.
+
+## Sections — Chapter Markers
+
+Mark sections within a scene for organized output:
+
+```python
+class LongVideo(Scene):
+    def construct(self):
+        self.next_section("Introduction")
+        # ... intro content ...
+
+        self.next_section("Main Concept")
+        # ... main content ...
+
+        self.next_section("Conclusion")
+        # ... closing ...
+```
+
+Render individual sections: `manim --save_sections script.py LongVideo`
+This outputs separate video files per section — useful for long videos where you want to re-render only one part.
+
+## manim-voiceover Plugin (Recommended for Narrated Videos)
+
+The official `manim-voiceover` plugin integrates TTS directly into scene code, auto-syncing animation duration to voiceover length. This is significantly cleaner than the manual ffmpeg muxing approach above.
+
+### Installation
+
+```bash
+pip install "manim-voiceover[elevenlabs]"
+# Or for free/local TTS:
+pip install "manim-voiceover[gtts]"    # Google TTS (free, lower quality)
+pip install "manim-voiceover[azure]"   # Azure Cognitive Services
+```
+
+### Usage
+
+```python
+from manim import *
+from manim_voiceover import VoiceoverScene
+from manim_voiceover.services.elevenlabs import ElevenLabsService
+
+class NarratedScene(VoiceoverScene):
+    def construct(self):
+        self.set_speech_service(ElevenLabsService(
+            voice_name="Alice",
+            model_id="eleven_multilingual_v2"
+        ))
+
+        # Voiceover auto-controls scene duration
+        with self.voiceover(text="Here is a circle being drawn.") as tracker:
+            self.play(Create(Circle()), run_time=tracker.duration)
+
+        with self.voiceover(text="Now let's transform it into a square.") as tracker:
+            self.play(Transform(circle, Square()), run_time=tracker.duration)
+```
+
+### Key Features
+
+- `tracker.duration` — total voiceover duration in seconds
+- `tracker.time_until_bookmark("mark1")` — sync specific animations to specific words
+- Auto-generates subtitle `.srt` files
+- Caches audio locally — re-renders don't re-generate TTS
+- Works with: ElevenLabs, Azure, Google TTS, pyttsx3 (offline), and custom services
+
+### Bookmarks for Precise Sync
+
+```python
+with self.voiceover(text='This is a <bookmark mark="circle"/>circle.') as tracker:
+    self.wait_until_bookmark("circle")
+    self.play(Create(Circle()), run_time=tracker.time_until_bookmark("circle", limit=1))
+```
+
+This is the recommended approach for any video with narration. The manual ffmpeg muxing workflow above is still useful for adding background music or post-production audio mixing.