This release adds a number of quality improvements and some new
features; first, the quality of the variable bitrate (VBR) mode
has been greatly improved, especially for wideband. Also, some
improvements were made to the packetloss concealment code in order
to reduce artifacts caused by lost packets. There has been improvements
to the 2.15 kbps mode, which now sounds a bit better. The last
quality improvement is in the perceptual enhancement which is now
good enough to be enabled by default in speexdec (but not by default
in libspeex for now).
One of the new features in this release is a VAD (Voice Activity
Detection) mode that conserves bandwidth when there's no speech,
and even when VBR isn't enabled. VAD is coupled with DTX (Discontinuous
Transmission), a feature that can completely stop data transmission
when the noise is constant (in which case, comfort noise generation
is turned on). The last new feature in this release is an ABR
(Average Bitrate) option, which uses VBR with a quality that's
adjusted to meet a certain target (average) bitrate.
In 1.0beta3:
This is the third beta for Speex, implementing what should be the
last new features before 1.0. These new features are a new
"ultra-wideband" mode for encoding at 32kHz (up to 48kHz) and an
intensity stereo mode. Both of these are implemented to preserve
backward and forward compatibility with other releases. This means
that it is now possible to encode almost any wave file using Speex.
Most of the work left for 1.0 is now quality improvements regarding
VBR, perceptual enhancement and packet loss concealment.
In 1.0beta2:
This second beta release brings many, many optimizations to the
encoder and decoder. In some cases, the speedup is on the order of
50% to 100%. As part of the optimizations, some sections of Speex
have been written in assembly with SSE instructions which can be
enabled with the _USE_SSE flag when compiling with GCC. Finally,
the code has received a major cleanup.
The Speex project aims to build an open-source, patent-free voice
codec. Unlike other codecs like MP3 and Ogg Vorbis, Speex is
specially designed for compressing voice at low bitrates in the
8-32 kbps/channel range. Possible applications include Voice over
IP (VoIP), internet audio streaming, archiving of speech data (e.g.
voice mail), and audio books. In some sense, it is meant to be
complementary to the Ogg Vorbis codec.
