Jerry and other AV folks:

I asked Dave Ackerman, our audio engineer, about the use of TCF for time
codes (since he was the one who originally asked for it), and he had a
couple of comments on this discussion.

First, he says that all of the listed SMPTE values are all fully described
by TCF, and with "sample accuracy", thus simplifying Jerry's list down to

BYTE - A byte offset into a content file
IDREF- An XML ID attribute value located within the content file
SMIL - a valid SMIL time value (e.g., 3.5s for 3.5  seconds)
MIDI - a MIDI time code; basically an extension of SMPTE
TIME - In essence, a SMPTE without a frame value, for those who don't want
to get into that level of precision.  It must follow the format of HH:MM:SS.
TCF  - pithy definition to be supplied

He also says that TCF is fully described in AES-31-3 available from AES
Standards (that's the international Audio Engineering Society). And he
still believes that we need it because it's the only timecode format that
can be equally applied to digital and analog sources that conveys sample
accurate timing. He says it also contains information important to
the video post community.

So there you have the rationale, and I'm sure he'd be happy to provide
more detail, maybe even a nice one-line definition of the TCF standard,
on request. Thanks,

MacKenzie Smith                                   [log in to unmask]
Digital Library Program Manager                   phone: (617)495-3724
Office for Information Systems                    fax:   (617)495-0491
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