From 49b3604848e492a875d6db13f757f8384928f7a5 Mon Sep 17 00:00:00 2001 From: Nick Porcino Date: Thu, 16 Nov 2023 09:21:44 -0800 Subject: [PATCH 1/3] add rendering notes --- docs/tutorials/otio-timeline-structure.md | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/docs/tutorials/otio-timeline-structure.md b/docs/tutorials/otio-timeline-structure.md index 966b235bb7..d113bdfae1 100644 --- a/docs/tutorials/otio-timeline-structure.md +++ b/docs/tutorials/otio-timeline-structure.md @@ -5,6 +5,26 @@ clips, gaps, and transitions. This document is meant to clarify how these objects nest within each other, and how they work together to represent an audio/video timeline. +## Rendering + +Rendering of the image tracks in a timeline is done in painter order. The layers +in a stack are iterated from the bottom (the first entry in the stack) towards +the top (the final entry in the stack). Images in a stack overlay lower images +with no blending. + +Within a track, clips may overlap via a transition. In that case, the +contribution of track is the linear blend of the elements joined by the +transition. + +If there are effects on a clip, OpenTimelineIO does not say anything about the +impact of the effect and deviation from the base behavior is application +specific. + +Rendering of the audio tracks is additive. It is strongly advised, but not +required, that the summed audio is summed as floating point, and that it is +processed through a compression filter in order to prevent clipping and +distortion. + ## Simple Cut List Let’s start with a simple cut list of a few clips. This is stored as a From bfb3878e306a7c707ca8b3d093a73fca3e6c5b1d Mon Sep 17 00:00:00 2001 From: Nick Porcino Date: Thu, 7 Dec 2023 15:36:17 -0800 Subject: [PATCH 2/3] Update docs/tutorials/otio-timeline-structure.md Signed-off-by: Nick Porcino --- docs/tutorials/otio-timeline-structure.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/docs/tutorials/otio-timeline-structure.md b/docs/tutorials/otio-timeline-structure.md index d113bdfae1..ea7ca24efa 100644 --- a/docs/tutorials/otio-timeline-structure.md +++ b/docs/tutorials/otio-timeline-structure.md @@ -10,7 +10,7 @@ audio/video timeline. Rendering of the image tracks in a timeline is done in painter order. The layers in a stack are iterated from the bottom (the first entry in the stack) towards the top (the final entry in the stack). Images in a stack overlay lower images -with no blending. +using an alpha composite operation respecting any alpha in the source materials. Within a track, clips may overlap via a transition. In that case, the contribution of track is the linear blend of the elements joined by the From 86b007426212addadb8d31ebbe1d4743decbbed2 Mon Sep 17 00:00:00 2001 From: Nick Porcino Date: Thu, 7 Dec 2023 23:34:22 -0800 Subject: [PATCH 3/3] Update docs/tutorials/otio-timeline-structure.md Signed-off-by: Nick Porcino --- docs/tutorials/otio-timeline-structure.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/docs/tutorials/otio-timeline-structure.md b/docs/tutorials/otio-timeline-structure.md index ea7ca24efa..341a02e462 100644 --- a/docs/tutorials/otio-timeline-structure.md +++ b/docs/tutorials/otio-timeline-structure.md @@ -11,7 +11,7 @@ Rendering of the image tracks in a timeline is done in painter order. The layers in a stack are iterated from the bottom (the first entry in the stack) towards the top (the final entry in the stack). Images in a stack overlay lower images using an alpha composite operation respecting any alpha in the source materials. - +All compositing is assumed to occur over a background of zero values in color components, and 100% values for alpha components. Within a track, clips may overlap via a transition. In that case, the contribution of track is the linear blend of the elements joined by the transition.