Re: can multi-content-type in a message?

lilley (
Tue, 22 Aug 1995 12:17:27 +0100 (BST)

Robert Wang said:

> I want to program a cgi to transfer a piece of audio together with a text/html
> back to the browser. The audio can be a explanation to the file or even a some
> music. I need it because the file is in English and the audio explanation is
> in Chinese, and the audio should be immediately played without a user to click.
> So, can I transfer different types of contents in a single message? From the
> http draft I can see no hint whether it is possible or impossible.

This topic has come up before, and the consensus seems to be that the
spec lets you do it (multipart Internet Media types), and creative use
of Internet Media types lets you use an external synchronising "viewer"
on a suitable multipart message, but that existing browsers do not
support it.

On Fri, 3 Dec 93 12:46:45 PST Vinay Kumar (vinay@eit.COM)[1] said:

Yes, XMosaic itself cannot handle sync. multimedia. However, the
way i am handling synchronized multimedia is by spawning off my
external viewer, a MIME Multiplayer. It creates synch. MIME
multipart+parallel messages that can be stuck in the Web. Using
XMosaic's ".mailcap", one can spawn off this external viewer from
XMosaic to play MIME multimedia messages. As of now, i can handle
Synchronized Graphics, Audio and PointerMotion Gestures (no video

So, this works provided the multiple parts are all suited to being handled
by external viewers.

On Sun, 05 Dec 93 16:36:32 +0100 Axel Belinfante
([2] said:

In addition to the above use of MIME multipart messages, it would be
nice to be able to return a html document together with audio or
video, it would eg be nice for my 'esperanto demo', as it would
allow me to combine:

(click on an object, see its name, _and_ hear its pronounciation).

I suppose that one could return a MIME message that contains both
html and audio, but if it is handled to metamail, where does the
html show up? A quick hack could be to write a 'html-viewer' script
that talks to Mosaic via the 'external control' feature (very nice,
btw!). Is there a similar way to do this with the other browsers?

As Axel notes, the problem is when one of the multiple parts is HTML,
which you probably want the browser to display. There is no single user
interface to get different browsers to display a particular file. Mosaic
has had two different ways, Netscape has a different way, and so on.

On Wed, 08 Dec 1993 13:42:32 +0100[3] said:

Perhaps what we really need is URLs that point to a group of files
which should be fetched and presented simultaneously (a "compound
node" in the terminology of the Dexter hypertext reference model).
I don't know enough about HTTP, but possibly a variant of
Content-type: multipart could be used here?

I have suggested before (but cannot now find the reference, so I will
say it again) that one of the multiple parts should be some sort of
synchronisation data, to allow more subtle orchestrations than "start
everything together, then stop".

For example, with a synchronised audio/basic, video/x-fli and text/html
if the user pauses the video should the audio pause or continue? If the
user rewinds to an earlier part of the video, should the audio continue
(for example, as with background mood music) or rewind to the equivalent
point (as with a speech commentary). Should the scroll bar or equivalent
device on the HTML viewer also be sensitive to such movements? (for
example, with audio and video of a play, the actors lines and stage
directions being marked up in HTML).

What happens if the displaying platform cannot play the video part
quickly enough - should it drop frames to keeop in sync, slow down the
other components, or what?

Possibly the ISO work on PREMO[4], amongst other things, could provide
clues here.

[1] <URL:>
[2] <URL:>
[3] <URL:>
[4] <URL:>

Chris Lilley, Technical Author
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