[vlc-devel] Smooth Streaming manifest, track IDs

Frederic YHUEL fyhuel at viotech.net
Wed Feb 15 21:38:16 CET 2012

Hello Martin, ringo, all,

I've asked myself this question for a long time, about Smooth Streaming:

Why does the (client) manifest *not* contain the track IDs?

I guess that what Microsoft had in mind, when they wrote the specs, is
that the client can associate an arbitrary ID to each track. Since the
client does know from which track belongs each chunk, all should go

But the way VLC is done makes things tricky. Retrieving the "real"
track IDs is compulsory, if we use avformat demux, and is very helpful
otherwise (I'm working on VLC's MP4 demux).

Do you think my guess is correct? Or maybe there is a simple way to
retrieve the track IDs after all? The only way I have in mind, is to
pre-fetch the first (lowest quality) chunk of each track, and to parse
the tfhd atom to finally get the track ID.

I would appreciate any help or thoughts you can provide about this. In
the worst case, I will opt for the "prefetch solution", this is not
that a big deal, but well... MS could have make my life easier ;-)

Best Regards,


More information about the vlc-devel mailing list