Ogg Vorbis

Why Change?

So you already have 2000 mp3 clips on your hard disk, a dedicated mp3

player, and an encoder for creating mp3 clips. Furthermore, you are

subscribed to one or more file sharing communities that enable you to

download and upload mp3 clips of almost anything that has ever been

recorded in that past 100 years. Why bother with a new format? After

all, isn't mp3 open?

No, it isn't. The MPEG consortium members claim that creating an mp3

encoder without using their patents is impossible. Worse yet, MPEG-4,

supposedly the next generation of Internet media streaming, is even

more tightly controlled.

In the past, we have seen outwardly open formats turning into closed,

proprietary standards whose owners charge royalties from their users.

If that doesn't sound troublesome enough, then collaboration between

the MPEG consortium and RIAA is becoming a tangible option.

The Alternative

Ogg Vorbis (http://www.xiph.org/ogg/index.html) is a fully open, non-

proprietary, patent-and-royalty-free, general purpose compressed audio

format for CD quality (44.1-48.0kHz sampling rate, 16+ bit resolution)

audio and music at fixed and variable bitrates ranging from 16 to 128

kbps per channel. In this regard, Vorbis is a viable competitor to

other audio encoding formats, including MPEG-1 audio layer 3, MPEG-4

audio, and PAC.

In terms of performance, Vorbis requires the same encoding and decoding

power as MP3. As the current Vorbis sources are still under development

and, therefore, unoptimized, Vorbis is likely to get faster in the

future. In terms of data compression rates, Vorbis is slightly better

than mp3.

Dispelling the Hype

Sadly, when it comes to open-source products, journalists often tend to

extol their miraculous qualities while omitting less pleasant aspect.

It's important to realize that Ogg Vorbis is still under development;

several important features including support for low bitrates, command

line interface, and real-time error correction haven't been implemented

yet. This will change in the coming weeks and months as the Vorbis

family of media streaming tools evolves and matures, yet DSP engineers

and CS students might frown when they discover that the Vorbis format

uses forward adaptive algorithms and MDCT, whereas wavelets (read more

on wavelets here:

http://www.amara.com/IEEEwave/IEEEwavelet.html#contents ) would

normally be the way to go.

A discussion about the technical differences is beyond the scope of

this article but suffice it to say that wavelets deal much better than

MDCT with fast audio transients, say percussion, drums, and sound

effects. Fortunately, since Vorbis is an open-source product, skilled

and open-minded developers can contribute and improve it. Stay tuned!

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