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Old November 5th 05, 07:17 AM
Ron Garret
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Default Boeing 747 & 777 autoland in crosswind certification video - impressive!

In article ,
"Peter Duniho" wrote:

"Ron Garret" wrote in message
...
[...]
As you can see, the file extension says it's an mpeg (which it is), but
the content-type header says it's an mp4. So any browser that believes
the content-type header will try to play it as an mp4 and barf. (This
explains why it works when you download it first, because then the
information from the content-type header is lost and the (correct) file
extension is used instead.)


I'm not sure I completely get your point here. "mp4" is short for "MPEG4",
which is an MPEG format (the one that the current Quicktime and Windows
Media Video are both based on), just as the file extension suggests. It's
not actually a Quicktime format file (in spite of the close relation to
Quicktime), and so I don't see how it's relevant to the question of people
having problems with Quicktime movies.

Your statement that "the file extension says it's an mpeg (which it is)"
isn't inconsistent with the "Content-Type:" field.

"MPEG" by itself isn't a format, it's a standards group. The MPEG formats
all have version numbers, and the most common MPEG format found for online
videos is MPEG4 (MPEG1 is out of favor, MPEG2 is the format used for DVDs
and requires non-free decoders to play, and MPEG3 doesn't really exist in
the wild as far as I know).

I can see how, if someone has their Quicktime plug-in configured to attempt
to play those "video/mp4" files, that might cause problems (if the Quicktime
player doesn't handle them correctly...my computer is configured to use
Windows Media Player for those files, and it works fine). But that's still
an issue with the client configuration, not the server.


I'm not an expert on codecs, but I've set up a little demo to show that
there is an mpeg format that is distinct from the mp4 format (and that
the video in question is an mpeg file and NOT an mp4 file):

http://www.flownet.com/ron/video.html

There are two little movies there, one in mpeg format (the 747 landing
video in question) and one in mp4 format. There are two links to each
file. One serves the file with the correct content-type header, and the
other serves up the same file with the incorrect header. If you are on
a Mac you will see that both files work fine with the correct header,
and both break when the header is incorrect.

QED.

rg