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I've seen PNG as derivative of RIFF: in that it's a file comprised of atomic "chunks" (though PNG's chunks are much larger and not time-based), RIFF itself is b

I've seen PNG as derivative of RIFF: in that it's a file comprised of atomic "chunks" (though PNG's chunks are much larger and not time-based), RIFF itself is basically the same as EA's IFF format from 1985 - so it's not like good ideas like a well-reasoned file-format are a recent innovation. It does seem a bit weird to think that something as highly technical (and thus: subject to becoming stale quickly) as a multimedia file format has withstood the test of time so well - while "simpler" files like Office documents from 15 years ago are almost unreadable today.

TonyTrapp 5y ago
RIFF is not without issues either - all size fields are 32-bit, so handling RIFF files larger than 4GB is ambiguous, if not undefined. The header contains a size field that should indicate the total size of the RIFF container, and in theory this cannot exceed 4GB, just like each individual RIFF chunk cannot exceed 4GB. There are some specifications that try to solve this issue but they are not very widespread (e.g. RF64), and probably have their own issues as well.
GoblinSlayer 5y ago
Zip format is a sequence of chunks too: one file is one chunk marked by a signature, like png chunks, that's why files can be added to a zip archive relatively cheaply.
- klodolph 5y ago
  Sure, but with Zip, you can’t reliably figure out where the chunks start and stop. In PNG, you can easily enumerate the chunks and skip over any chunks your program does not parse.
unilynx 5y ago
It might be very problematic to read multimedia files from 15 years ago, weren't those the days of 'codec packs' and every downloaded movie seeming to require a different one ? But at least the multimedia files (and archive formats) were designed to be interchangeable between applications. '.DOC' word docs were basically a binary dump of its internal data structures - there was no intention of it being interchangeable with any other application, and it showed.

TonyTrapp 5y ago

RIFF is not without issues either - all size fields are 32-bit, so handling RIFF files larger than 4GB is ambiguous, if not undefined. The header contains a size field that should indicate the total size of the RIFF container, and in theory this cannot exceed 4GB, just like each individual RIFF chunk cannot exceed 4GB. There are some specifications that try to solve this issue but they are not very widespread (e.g. RF64), and probably have their own issues as well.

GoblinSlayer 5y ago

Zip format is a sequence of chunks too: one file is one chunk marked by a signature, like png chunks, that's why files can be added to a zip archive relatively cheaply.

klodolph 5y ago
Sure, but with Zip, you can’t reliably figure out where the chunks start and stop. In PNG, you can easily enumerate the chunks and skip over any chunks your program does not parse.

unilynx 5y ago

It might be very problematic to read multimedia files from 15 years ago, weren't those the days of 'codec packs' and every downloaded movie seeming to require a different one ? But at least the multimedia files (and archive formats) were designed to be interchangeable between applications. '.DOC' word docs were basically a binary dump of its internal data structures - there was no intention of it being interchangeable with any other application, and it showed.