On 08/21/2020 11:20 PM, Jim DeLaHunt wrote: -snip-
There is a great need for a glossary. It should be structured so that each term has an anchor, allowing references from anywhere in the documentation to the glossary. My nomination for entries: "fps", "GOP", "PTS", "time base".
-snip-
I have been working on a glossary for a very long time that includes all those and much more, and in which each and every element of a program stream has a clear, unambiguous structure definition sans implied relations (e.g. 'this' implies 'that') and sans vague references to metadata (e.g. a frame is a thing that metadata defines as a frame). I've worked my way deeply into the streams and am currently resolving macroblock internals [1]. The problem I'm encountering is that in order to create clear, unambiguous definitions, I have had to create names for differing things that currently have the same names that differ based on 'context' (which sucks), and that I suspect will raise much controversy. For example, the word "frame" is applied to a great number of things that are not frames -- I have created several unique 'sample-sets' that cover the variant frames, fields, and scans. For example, the word "picture" is applied to so-called 'progressive' sample-sets, to hard telecined, concurrent "field pictures" (which I call "half-pictures"), and even to successive fields (which I call "scans"). In my effort, I've tried very hard to not change too much of the current nomenclature.
[1] I've discovered that "interlace" applies not to lines on a display, but to samples within blocks within macroblocks. There are several interlace schemes and I'm defining each of them via easy to understand diagrams that simultaneously show how they are stored and traversed in-buffer versus where they wind up in slices on the display. While attempting to understand what ffmpeg developers mean when they refer to "interlace", I now appreciate that looking at top-level metadata in stream headers is futile -- they are not directly related. Without a "look" into how blocks and macroblocks are structured, one will never understand what ffmpeg developers say regarding "interlace".
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