Media diagnostics · Primary-source explanation; examples are illustrative. Instructions are based on publisher guidance; a UK IPTV account was not tested on this platform.
Separate playback composition from export
The Media3 media item guide describes setting custom start and end positions for clipping a source, internally wrapping it in a clipping media source. That is a player configuration. It does not claim to create a newly encoded standalone file on disk. An application which offers play this section should not report export complete merely because it successfully constructed that media item.
Follow a short source example
For an original conceptual exercise, a permitted two minute local clip is configured to play a section beginning at 30 seconds and ending at 45 seconds. The desired viewing segment is fifteen seconds, but the original file is still a separate asset. Verify the chosen playback range and then inspect storage independently if the application also promises an export. Do not delete the original on the assumption that the player has saved the selected part elsewhere.
Account for the starting decode work
The documentation notes that a start which is not on a keyframe can require decoding and discarding earlier material before presentation, introducing startup delay. That is a different observation from the player intentionally displaying unwanted earlier content. Keep the requested boundary and observed first presentation in the report. This article explains a playback versus export distinction and does not promise frame exact editing, a tested processing time or permission to trim and distribute a protected programme.