Media diagnostics · Primary-source explanation; examples are illustrative. Instructions are based on publisher guidance; a UK IPTV account was not tested on this platform.
Name the event being timed
MDN defines responseEnd around receipt of the last resource byte or transport connection closure, whichever comes first. It is a request timing property, not a first video frame event. A small downloaded segment can finish while the player is still waiting for other required data or local processing. A performance dashboard should not relabel the end of one request as successful picture presentation without observing that later stage.
Keep an illustrative timeline readable
Suppose a permitted sample request begins at 100 milliseconds and its response ends at 400 milliseconds, while the first visible frame is observed at 550 milliseconds on a compatible observation clock. The request interval is 300 milliseconds and the additional observed interval is 150 milliseconds. These invented numbers demonstrate separate stages, not benchmark results. They do not establish that all of the second interval was decoder work; other application activity may be involved.
Compare the same resource and scope
Record which request is being measured, especially when a player uses manifests, initialisation data and many media segments. The documentation distinguishes timing a final fetch from including redirects, so keep the selected formula explicit. A completed homepage or artwork request does not establish completed media delivery. This article improves diagnostic labelling and reports no measured startup latency, network speed or rendering performance for the website or an account.