The final 47 oversized files held no big art and no big lyrics - just
empty reserved space, up to 478 KB of padding against 39 bytes of
frames, all in the DJ Sets tree. The player pages through padding like
anything else. A tag past 200 KB total is rewritten regardless of what
fills it; the save already zeroes padding.
The 49 files the art pass left behind were fat with USLT, not APIC -
the worst held the complete text of Angela's Ashes (1.5 MB of Frank
McCourt) in an Eels track, some tagger malfunction. AVPlayer pages
through the whole tag before the first audio frame regardless of what
fills it, so absurd lyrics cost the same silence as absurd art. No
song has 50 KB of lyrics; anything past it is junk and is removed.
Redundant with the v2 frames, 128 bytes of legacy, and the thing whose
sync update tripped the audio guard. Applies to files being rewritten;
files already slimmed before this keep their synced v1.
mutagen updates an existing v1 tag on save - it normalised the genre
byte 0xFF to 0x0F on Shamrocks and Shenanigans and the guard refused a
whole album of good rewrites over one metadata byte. The v1 block is
metadata, not audio; the guard now hashes strictly the frames between
the v2 tag and any trailing TAG block.
A tagger that writes a non-standard size field puts the header claim and
the real tag end in different places. mutagen preserves audio from where
it parsed the tag to end; the guard hashed from where the header claimed,
and refused good rewrites across a whole album. Both hashes now use the
same authority. Failed files stay untouched and a re-run picks them up.
iOS AVPlayer reads a streamed file head in ~32 KB range requests and cannot
reach audio until it is past the ID3 tag - a 955 KB embedded JPEG cost ~30
sequential round trips, a two-second silence Android never feels. 28% of the
library (20,487 files, 1,488 albums) carries art that size.
Keeps an embedded front cover (other users of these files see it) but at
600px/JPEG stepped to fit 80 KB, ~3 chunks. Audio region is hashed before
and after; any mismatch keeps the original. Rescues art to cover.jpg first
when the folder has none.
pastilhas