Show pageOld revisionsBacklinksFold/unfold allBack to top This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong. ====== Video Control ====== ===== Projectors ===== ==== Terminology ==== * **Definition**: Total number of pixels in an image (e.g. 1920×1080, 3840×2160). Often incorrectly referred to as "resolution" in English. * **Resolution**: Pixel density per unit (e.g. DPI – dots per inch). ==== Key Specifications ==== * **Contrast Ratio**: Ratio between brightest and darkest output (e.g. 2000:1, 4000:1). Higher values improve perceived image depth. * **Brightness**: Measured in lumens. * ~1500 lumens: suitable for dark environments (home cinema) * >3000 lumens: recommended for environments with ambient light * **Definition (Format)**: * FHD (1920×1080) minimum standard * Higher than source → no benefit * Lower than source → visible quality loss * **Noise Level**: Measured in dBA. * Typical acceptable range: 25–28 dBA * Manufacturer values may be optimistic * **Throw Ratio**: * Formula: **Throw Ratio = Distance / Image Width** * Example: ratio 1.5 → 1m width at 1.5m distance * Defines projection size range depending on placement ==== Image Processing Options ==== * **Overscan**: Crops image edges and scales slightly beyond source resolution ---- ===== NDI ===== * **NDI Monitor**: * Provides preview (low-resolution proxy) * Not suitable for full-quality signal transmission ---- ===== Software ===== * LPMT (Linux Projection Mapping Tool) * Millumin * Resolume Arena * MadMapper * QLab * Modulo Kinetic / Modulo Player * mplayer (video playback) ---- ===== FFmpeg ===== === Re-encode into Apple ProRes === <code bash> ffmpeg -i input.mp4 -vcodec prores -acodec copy output.mov </code> === Rotate Video === <code bash> ffmpeg -i input-video.mp4 -vf "transpose=1" output-video.mp4 </code> * 0 → 90° CCW + flip * 1 → 90° CW * 2 → 90° CCW * 3 → 90° CW + flip === Control Quality (CRF) === * CRF range: 0 (lossless) → 51 (worst) * Typical values: 15–20 === Trim Video === To create a 1min clip starting 1min into the video: <code bash> ffmpeg -i input-video.mp4 -c:v libx264 -crf 15 -c:a aac -ss=60 -t=60 output-video.mp4 </code> === ffmpeg commands === <code bash> $ffmpeg -codecs D..... = Decoding supported .E.... = Encoding supported ..V... = Video codec ..A... = Audio codec ..S... = Subtitle codec ...I.. = Intra frame-only codec ....L. = Lossy compression .....S = Lossless compression $ffmpeg -encoders V..... = Video A..... = Audio S..... = Subtitle .F.... = Frame-level multithreading ..S... = Slice-level multithreading ...X.. = Codec is experimental ....B. = Supports draw_horiz_band .....D = Supports direct rendering method 1 $ffmpeg -h encoder=libx264 //list all options on encoder </code> ---- ===== Signal Formats & Bitrates ===== {{regie:video_formats_bitrates.png?500}} ---- ===== Color Pipeline (Bit Depth, Color Space, Gamma) ===== ==== Bit Depth ==== * Defines **precision of color values** * 8-bit → 256 levels per channel * 10-bit → 1024 levels per channel * Benefits of 10-bit: * Smoother gradients * Reduced banding * Better fades (especially on LED displays) * Important: * Bit depth does **not** define color range * It improves **how smoothly colors transition** ---- ==== Color Spaces ==== * **Rec.709** * Standard HD color space * Used in most video and LED workflows * Predictable and widely supported * **Rec.2020** * Wider color gamut (UHD / HDR) * Enables more saturated colors * Requires full pipeline support (rare in real-time systems) * Key distinction: * Color space = **range of colors available** * Bit depth = **precision within that range** ---- ==== Gamma / Transfer Function ==== * Defines how brightness is encoded * Common values: * **Gamma 2.4** → video standard (recommended baseline) * **Gamma 2.2 / sRGB** → desktop environments * **PQ / HLG** → HDR workflows * In real-time playback systems: * Gamma is often assumed, not explicitly managed ---- ==== Practical Notes (Real-Time & LED Workflows) ==== * Most pipelines are effectively **Rec.709-based** * Color management is usually **not enforced** * Wide gamut (Rec.2020) only useful if: * Playback engine supports it * Signal chain preserves it * Display can reproduce it * Otherwise: * Colors may be clipped or altered ---- ==== Validation (10-bit Workflow) ==== * Use a **10-bit grayscale gradient test pattern** * Interpretation: * Smooth gradient → full pipeline is 10-bit * Banding → limitation exists in: * media encoding * GPU output * signal chain (HDMI/SDI) * processor * display ---- ==== Notes ==== * **sRGB**: * Close to Rec.709 but not identical * Not relevant in video signal pipelines * **HDR (Rec.2020 + PQ/HLG)**: * Requires full end-to-end support * Not guaranteed in real-time playback systems ---- regie/regie_video.txt Last modified: 2026/04/14 23:53by mh