[vorbis] need speech and music in one

[gtgbr at gmx.net]

f u wrote:
> If vorbis will go that low, fine.  I was under the
> impression from a faq I skimmed some time back that
> the quality setting did not range so low.

Yahwell, the FAQ is a bit outdated ... :) It might still contain that
Vorbis isn't tuned for anything but 44.1kHz, but this is not true any
more since the 1.0 release. (I haven't verified my assumption.)

> If speex is superior for the voice range, and I did
> produce the cd with music tracks as .ogg and the
> speech tracks in speex format, would a common decoder
> read and playback both?

Unfortunately not - Speex is an entirely different Codec wrapped in Ogg.
A compliant Vorbis decoder that doesn't know how to play Speex will
simply skip/not play any Speex parts in the respective .ogg file.

> Here, I would be looking to the future, where playback
> would be by a hardware player with a dedicated decoder
> not a computer which could have decoders for dozens of
> different audio formats.

Realistically, Vorbis support might happen eventually in hardware, but
Speex? At least not in common portable players. Since Speex is a low
bitrate voice Codec, its main strength is VoIP and anything remotely
related to this. I really doubt we'll ever see it in consumer hardware
like today's MP3 players. I mean, who of the people that buy those
devices actually want to listen to hours and hours of speech? I guess
music is a bit more attractive there ...

> Or is there a plan to incorporate the speex codec into
> vorbis to optimize the voice band?  If it is unlikely
> that speex will be supported for portable cd players,
> then I suppose the compromise would be to use .ogg
> only - but it would seem that the speex format would
> allow many more hours of speech to be stored on a cd.

I can't really comment on that ... but squeezing Speex into the Vorbis
specs somehow, so that even a Vorbis 1.0rc2 decoder can play it... Mh,
doesn't sound likely :)

Note that Ogg is a framework, i.e. a container format - it's a format
where the raw output of Codec bitstreams get packetized, CRCed, etc. If
a player understands Ogg, it also has to understand the contented of the
.ogg, for example Vorbis, Speex, Theora or FLAC, or any combination of
these and future Codecs.

As soon as music comes to play, Vorbis is the way to go. Speex *will
never* properly encode music (at all?) as good as Vorbis, even at
not-that-low bitrates. If it's only about voice at low bitrates, go
Speex.

<p>Moritz
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