Is there a high quality, energy-efficient solution for speech encoding and decoding in voice recording applications?
Speex, an open source and free audio codec, provides a high level of compression while maintaining sound quality for speech encoding and decoding. It is based on Code-Excited Linear Prediction (CELP) and can compress voice at bitrates ranging from 2 to 44 kbps.
Features that make Speex ideal for the aforementioned requirements include intensity stereo encoding, packet loss concealment, variable bitrate operation (VBR), voice activity detection (VAD), and noise suppression, among others.
The Speex encoder consists of an audio input interface and speech encoding module as demonstrated by this image:
Fig: Hardware flow of Speex encoder
The Speex decoder is made up of an audio output interface and speech decoding module as shown in the following figure:
Fig: Hardware flow of Speex decoder
Together with an EFM32 Giant Gecko board, Speex can be the energy-efficient solution for speech applications requiring audio compression.
Read the complete application note here for more details and software examples on how to run the Speex encoder and decoder with the EFM32GG-DK3750.