Does that mean that a QuickTime movie is a standards-compliant MPEG-4 file
if it uses only codecs from the MPEG-4 standard?
Necessary but not sufficient; there are other changes.
If yes, then is it an
invalid MPEG-4 file if it uses other media codecs such as GIF or Sorenson?
Yes, it is invalid.
What about if the movie has refs to other files (the Alias Manager is
probably not in the MPEG-4 spec)
URL data references are used in MPEG-4 aqnd are valid in QuickTime.
or has a compressed header (is zlib in the
MPEG-4 spec?)?
No compressed headers in MPEG-4.
Vice versa, is an MPEG-4 media file automatically a QuickTime movie, or are
there additions (it says "based on") that aren't supported by QuickTime?
Yes, additions and some minor changes.
Does an MPEG-4 file need to be hinted to be streamed or does DSS include
real-time packetizers for the MPEG-4 data formats?
DSS requires hinting. Other servers might not.
And now for the big question:
Where are the affordable MPEG-4 content creation tools?
Coming, I think. Lots of companies working on them (see the ISMA
membership for some of the possible culprits).
--
David Singer
Apple Computer/QuickTime
