[Live-devel] Requesting Book recommendations
finlayson at live.com
Thu Feb 12 09:17:03 PST 2004
>Would anyone care to recommend a book that can give me
>a good overview of the current state of streaming?
I suggest also asking this on some other, more general 'streaming' mailing
list - e.g., "advanced at lists.infotoday.com" (although you tend to find a
lot of Microsoft-brainwashed people on that mailing list).
>I keep thinking that its going to converge on some standard (I once
>thought that would be MPEG4) but that doesn't seem to be the
Well, note the distinction between *protocols* and *codecs*. (MPEG-4 is a
As far as protocols are concerned, there's no doubt: RTP is the
winner. Witness the recent explosion in VOIP (voice over IP) - which uses
RTP - plus the fact that RealNetworks is migrating from their own
proprietary protocol to RTP, plus, of course, that Apple has used RTP in
QuickTime for years (including in their new "iChat" video streaming stuff).
Codecs, however, are a different story. Codecs continue to evolve
(improve), so we're unlikely to find one single standard video codec and
one single standard audio codec anytime soon. But here's what I'm seeing
For video: For high bitrates, MPEG-2 is not likely to go away anytime soon,
as there's a *lot* of legacy MPEG-2 content (and hardware) out there -
e.g., DVDs and cable/satellite TV. At lower bitrates, H.263 is still
seeing lots of use (e.g., in videoconferencing, including Apple's new
"iChat"). At lower bitrates still, MPEG-4 is getting used more and more,
although it has been stymied so far by interoperability problems (different
companies' implementations of MPEG-4 video don't always work
together). Lately, I've been seeing more and more interest in H.264 video
(aka. MPEG-4 AVC, aka. MPEG-4 part 10), which has even better compression
than regular MPEG-4. (BTW, H.264 will get supported in the LIVE.COM code
when someone wants it.)
For audio: MP3 (MPEG-1 or 2, layer III) is, of course, the standard
'legacy' audio codec, although it still tends to be streamed over TCP
(e.g., HTTP) far more than over RTP. AAC (MPEG-4 audio) is getting lots of
momentum these days, thanks in part to Apple's use of it in "iTunes". For
low-bitrate audio, there's lots of interest these days in "aacPlus" (aka.
AAC-SBR) - a backwards-compatible variant of AAC audio that produces
amazing audio quality, even at very low bitrates. (FYI, this is the codec
that's used by XM satellite radio.) IMHO, a 32 kbps aacPlus stream sounds
as good as a 128 kbps MP3 stream, and even an 8 kbps aacPlus stream sounds
pretty good. FYI, LIVE.COM now supports "aacPlus" encoding and decoding
(in a licensed, closed-source implementation).
Of course, all of this is ignoring Microsoft, which is going to continue to
try to use its monopoly position to try to get their "Windows Media" codecs
and protocols adopted as the 'de facto' standard whereever possible.
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