Choose a passage with two clear boundaries
An A–B loop is useful for reviewing a short section of an authorized video, such as checking a subtitle line against dialogue or reviewing your own recorded presentation. It serves a different purpose from repeating an entire file or playlist. Choose a passage with a recognizable beginning and end before using a loop control.
Keep the source and playback speed fixed during the first test. If the source is a live or restricted-seeking stream, do not assume it supports the same repeat behavior as a local file. Establish ordinary seeking with the chosen input first and record any limitation rather than treating every loop problem as a keyboard issue.
Use the documented boundary control
Default l sets or clears A–B points. Read the visible feedback after each action. For an original review example, mark the first word of a sentence as the start and allow its final response to finish before choosing the end. The useful result is the same complete exchange repeating without an unrelated scene.
Let playback cross the intended end and observe whether it returns to the intended start. If the interval is wrong, clear the loop and set it again deliberately. Repeated presses without observing state can leave a boundary different from the one you intended. Keep one short interval as the reference until the behavior is clear.
Distinguish a passage loop from whole-file repeat
Default L concerns whole-file looping. Keep that scope separate from the short interval you are reviewing. If the result repeats a larger section than intended, preserve the current state and inspect which action was invoked. A note containing the two observed boundaries is more informative than simply reporting that repeat is broken.
For subtitle review, select the desired track before setting the loop. Compare the same spoken passage across repeats rather than changing the track and timing on every pass. A stable repeated interval gives useful evidence of a fixed offset or an incorrect subtitle edition. It does not repair a subtitle that belongs to another cut of the video.
Clear the temporary state and recheck normal playback
When the review is finished, use the documented clear action and confirm the player continues beyond the former end boundary. Check any whole-file repeat setting separately if it was changed during the test. This prevents a later viewer from mistaking an intentionally repeated passage for a playback fault.
Retain only the observations needed for the original task, such as the subtitle offset or the reviewed section. The expected outcome is a controlled review interval and a return to ordinary playback. It does not establish recording permission, create an edited export or modify the source media.
Questions answered
How do I know the marked interval is useful?
Let it repeat and verify that the complete passage of interest is included while unrelated material is excluded. Adjust one boundary at a time.
Why should I clear the loop when I finish?
The temporary interval can otherwise explain repeated playback at that point. Confirm the video continues beyond the previous boundary before ending the test.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.