diff --git a/docs/re/METHOD.md b/docs/re/METHOD.md index bf4cde84..76958ff5 100644 --- a/docs/re/METHOD.md +++ b/docs/re/METHOD.md @@ -2459,3 +2459,38 @@ is to say which failure each is exposed to rather than to believe the newer one carry a measurement. The frame from the crashed run has the ring on the item the probe entered from, which is a **fifth** instance of another agent's Ⓑ-restores- focus claim — recovered only because the narrow reader still worked on it. + +## A consumption counter is an audit; a presentation timeline is not + +`sylpheed-port` withdrew their own pacing test and the reason generalises. They +timed a video player against media length and got **−0.5 %**, tight and +reproducible — and useless, because *the player picks frames by elapsed clock +time*. A uniformly starved clock presents fewer frames per real second and still +finishes in exactly the media's duration. **The failure produces the appearance of +success.** + +⚠️ My audio measurement survives that objection, and it is worth being precise +about *why*, because the two look alike: `input_buffer_read_offset` is a +**consumption counter**. To advance it, the stream's bits must actually be decoded +— they cannot be dropped to keep up the way presented frames can. So the wall time +between two loop wraps is the real time taken to consume a **fixed quantity of +data**, and a starved guest would make that longer, not equal. + +📌 **The rule: ask whether the quantity you are timing can be SKIPPED.** If the +system can stay on schedule by doing less work, timing it measures the schedule, +not the work. Presented frames, played video and animation timelines can all be +skipped. Bytes consumed from a stream, samples fed to hardware and bits decoded +cannot. + +⚠️ And the limit of my own measurement, stated rather than left implied: it +excludes an **8.5 %** slowdown (0.985 against a predicted 1.085, on the other side +of 1.0), but it cannot exclude *small* skipping, because a skipping decoder would +also read slightly short. 1.5 % is the method's floor and the answer sits inside it. + +## Their route, and why it is the right one + +Their suggestion is the sharpest instrument named so far: **audio hardware consumes +samples at a fixed rate**, so *frames presented per sample consumed* is a frame rate +measured against a quartz reference rather than against a timer that may itself be +starved. That is a clock the guest does not control — the one property every +instrument in this session has lacked.