>received: by carmenta.se id fB68E3826667; Thu, 6 Dec 2001 09:14:03 +0100 (MET)
Are there any docs, papers or list dwellers that can answer the following
(maybe very dumb but nevertheless interesting) questions:
"The MP4 file format ... design is based on the QuickTime. format from Apple
Computer Inc"
(from http://mpeg.telecomitalialab.com/standards/mpeg-4/mpeg-4.htm)
Does that mean that a QuickTime movie is a standards-compliant MPEG-4 file
if it uses only codecs from the MPEG-4 standard? If yes, then is it an
invalid MPEG-4 file if it uses other media codecs such as GIF or Sorenson?
What about if the movie has refs to other files (the Alias Manager is
probably not in the MPEG-4 spec) or has a compressed header (is zlib in the
MPEG-4 spec?)?
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?
Envivio's streaming MPEG-4 server is based on DSS, but their client (Real/QT
plugin) does not route its data through QuickTime's RTP/reassembler - they
use their own homerolled UDP connections (and a local file can't be exported
since they seem to do drawing directly in DirectDraw and not by
decompressing frames for QT to render).
Based on the license for DSS, one could assume that the MPEG-4 streaming
capabilities in DSS 4 comes partly from Envivio's work (or the other way
around if Apple supplied Envivio with a prerelease DSS before it became
publically available).
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?
And now for the big question:
Where are the affordable MPEG-4 content creation tools?
Per Bergland
Carmenta AB - www.carmenta.se
