Allowable sampling rates are 8, 16 and 32 kHz corresponding to narrowband, wideband and ultrawideband coding.
The achievable bitrates are somewhat between 2.2 kBit/sec and 48.9 kbit/sec. More technical details on the implementation will be available soon, outlining the WAVEFORMATEX header, as well as the payload structure and alignment.
The codec has a configuration dialog box that allows setting the encoder complexity (1-10). Level 1 encodes about 5 times faster than level 10, but achieves less quality. The bitrate is not dependent on this setting. Also you can disable and enable the decoder's perceptual enhancement filter here.
The control panel can be accessed for example through the Sound and Audio Devices Properties Control Panel. Follow these steps: (Open the control panel via Settings menu. Select the Hardware Tab; Select Audio Codecs; Click the Properties Button; Select the Properties Tab; Select Speex Voice Audio CODEC ; Click the Properties Button; Click the Settings Button.)
Currently only CBR (constant bitrate) modes are available. The codec has been optimized for optimal bit packing efficiency by minimizing padding loss between frames. That means the WAVE files will be somewhat shorter than those in the default Ogg container format.
This release comes with speexdec_wav. This is a command line decoder for both Ogg Speex and WAVE Speex files. It is identical to speexdec, except for the added support for the WAVE container.
The codec has so far been tested with Windows Sound Recorder (sndrec32.exe), GoldWave, Real One Player, Windows Media Player 6.4 and 9.
- Speex 1.0.5 (which contains the ACM Codec - speexw.acm)
seems to be incompatible with Speex Voice ACM Codec 22.214.171.124
. Install only one of them.
The ACM codec supports 11 quality modes, corresponding to Speex quality settings 0-10. Mono and Stereo modes are supported.