[advocacy] Proposed Open Source Speech Codec

[Beni Cherniavksy]

On 2001-10-31, Bacchus Thirteen wrote:

> --- Kristoff Bonne <kristoff.bonne at skypro.be> wrote:
>
> > AFAIK, ogg is a codec made for music; and 'low
> > bitrate' is one of the
> > features that seams to be 'in the pipeline'; but can
> > you just apply the
> > ogg codec to low-speed "voice"?
> > I guess the needs for a 'voice' codec (especially
> > when used in a
> > almost 'real time' applications like VoIP) are very
> > different then one for
> > 'music'.
>
> Yes, there used to be discussions in the users' list.
> Ogg is not designed for voice coding.  However, I am
> not a programmer and I thought that 'low bitarte'
> could be applied to voice coding as well.  Simply, I
> did not know that they were technically so
> incompatible.  O.K.  You can laugh at my ingnorance on
> technological issues.
>
The voice (of a solo person) is much more limited than arbitrary sound.
Thus the space of possible voice waveforms can be encoded into less bits
at the same quality (or with higher quality at the same bitrate).  On the
other hand, even two voices at the same time can't be represented well by
voice codecs.  The encoder can only encode it into a bitstream that when
decoded means a more or less a single voice (which obviously is far from
the original).

> > Or, is there a need for a completely new codec?
> > Is this what David Rowe proposed? A new non-patented
> > codec; that would be
> > added to the vorbis 'group', but completely
> > different from ogg.
>
Just a little note: the group is named Ogg and Vorbis is the specific
music compression codec we all now use.  Ogg is a framing format
(responsible for stream multiplexing, error checking, seeking marks and
packet boundary marking).  Vorbis is a way to encode audio data into
packets.  It can also be used with other framing formats for example RTP
provides facilities overlapping with Ogg so raw vorbis packets without Ogg
framing will be fed to RTP).  The whole project (of creating free codecs
to solve the multimedia needs of the internet) is also called the Ogg
Project.


--
Beni Cherniavsky <cben at tx.technion.ac.il>
(also scben at t2 in Technion)

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