In article ,
Ron Garret wrote:

In article ,
"Peter Duniho" wrote:

"Ron Garret" wrote in message
...
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

There is no such thing as an "mpeg" format; without a version number, the
phrase "mpeg" by itself does not describe a video compression format. Your
demo simply illustrates that there are two different "Content-Type" tags.

No, it illustrates that there are two different file formats that go
along with those two different content-type tags.

Here's the definitive scoop.

There is such a thing as "an mpeg format." It is not a video
compression format, it is a file format. It is described he

http://www.graphcomp.com/info/specs/ms/editmpeg.htm

Files of this format typically have an extension of .mpg or .mpeg, and
can usually be identified by the sequence header code 000001B3 at the
beginning of the file. (I say usually because a file starting with this
sequence may or may not be a .mpeg file, but a .mpeg file will always
start with 000001B3.)

The 747 extreme landing video file is in this format.

There is a distinct MPEG-4 file format (which is related to but not the
the same thing as the MPEG-4 video compression format) described he

http://www.chiariglione.org/mpeg/sta...peg-4.htm#10.9

Files in this format normally have an extension of .mp4. They do NOT
start with the .mpg sequence header code. In fact, as far as I can tell
there is no way to definitively identify a .mp4 file from its data, but
typically a .mp4 file will contain MPEG-4 encoded video which can be
identified by the header 'moov' (in ascii).

The Alexis Inn site is serving a file in the first format with a
content-type header for the second format. This is definitively a
server-side bug (notwithstanding that some clients are able to recover
from this).

rg