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Re: [vox-tech] how to download a video file without an url
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Re: [vox-tech] how to download a video file without an url



On Sun, 8 Jun 2003, Peter Jay Salzman wrote:

> rtsp://a772.v08015.c801.g.vq.akamaistream.net/7/772/9135/0002/peta.download.akamai.com/9135/mym2002_med.mov
>
> but i don't recognize this kind of url.  could this be some kind of
> proxy?  i tried to download
> peta.download.akamai.com/9135/mym2002_med.mov but got a "forbidden"
> access error.

I got two answers...

The first part: As I recall, RTSP is a RealMedia protocol.  We used it
when I was involved with KDVS RealAudio streaming.  RealPlayer can handle
both RTSP and HTTP URI.  The difference is, with HTTP you can't jump
around the media stream, but RTSP lets you.  So with RTSP you can start
playing from 5 minutes into the media stream, but with HTTP you gotta wait
for the 5 minutes worth of file to download first before you can play the
5 minutes into the file.

It was my impression that you can only use RealMedia files with RTSP
protocol but apparently that's changed over the years (or I've just never
been aware of it.)  Whatever the case, it's using RTSP protocol so you can
jump around the media stream.  Also, the server is streaming media using
RTSP protocol which makes it harder to download the media file (it doesn't
use port 80, for one, and it communicates with the client for best
streaming technique.)

One more thing: If you reference RTSP to a server that doesn't have a
proper RTSP media streaming server, RealPlayer will fall back on HTTP.
So even if you see "rtsp://", it may still be HTTP (so you can still
download the file normally using wget or whatnot).  But if the RealPlayer
falls back to HTTP then you can't jump around the media stream anymore.

The second part: The streams are coming from one of the Akamai servers.
These servers are used to distribute server loads.  When you reference a
website, it'll bring up the website with links to Akamai servers that are
nearest to your location (or its best guess.)  Then you click on a link,
and you'll be connected to the Akamai servers nearest to your location.
You'll generally see only big media files on Akamai servers for several
reasons I won't get into since this e-mail is already too long.  Anyway,
the URI looks funky it was generated automatically by some Akamai program
(Akamai also has other customers, so the URI needs to be non-clashing with
other customers'.  Furthermore, it's gotta be fast so they may use some
URI referencing tricks to make the database access faster).  In short, the
whole thing is a URI, not just the latter half, and the URI looks funky
because it's automatically generated by some program.

-Mark


-- 
Mark K. Kim
http://www.cbreak.org/
PGP key available upon request.

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