- ffmpeg writes JPEG XL with -update 1, so a % in a file name is never an
image-sequence pattern, and reads videos as file:<path>. The clear and a
startup sweep remove temp files that interrupted writes left behind.
- Convert outdated converts each group of same-stem files once, from the
first source in the R2 order. An old preview that is already gone counts
as removed, and each file's bytes count once. A current preview is only
kept if it decodes.
- An encoder that fails makes the write detect encoders again once. Another
encoder is used if one is found; with none, the file is written as WebP
and the availability Appearance shows is refreshed.
- Changing the thumbnail format, quality or size while Convert outdated runs
returns 409 busy. If the format still changes underneath, the job stops
without removing anything.
- Legacy preview spellings are matched case-insensitively, so X_thumb.JPG
counts as outdated.
- History's cover uses the same lookup as Images. It serves .jxl only when
Accept lists image/jxl, and otherwise the original or the placeholder.
- A video whose thumbnail the browser cannot show keeps its own element
(Images) or its label (Library).
POST /jobs/thumbnails {mode: "convert"} starts "Convert outdated
thumbnails" under the thumbnail job's kind, guarded admission, worker
threads and cancel at a file boundary. For each file whose preview is
in another format, it writes the new preview from the source (atomic,
verified; a video with no decodable frame fails instead of getting the
placeholder), then removes that file's old-format previews in its
thumbnails folder. A failure keeps the old preview; orphan previews
and links are never touched. The final line reports converted, failed
and bytes before and after. The plan counts it with mode=convert; the
legacy gallery stream refuses to attach to a running conversion.
Vito Sansevero