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– Based on Speex open-source standard version 1.2.rc1.
– Fixed-point ANSI C implementation.
– Re-entrant implementation.
– C-callable APIs.
– Operates on/Generates 20ms frame size/duration.
– Operates on/Generates speech signals sampled at 16KHz or 8 KHz.
– Supports bit-rates 2.15, 3.95, 5.95, 8, 11, 15, 18.2, and 24.6 kbps in narrow band (8 KHz) mode.
– Supports bit-rates 3.95, 5.75, 7.75, 9.8, 12.8, 16.8, 20.6, 23.8, 27.8, 34.2, and 42.2 kbps in wide band (16 KHz) mode.
– Supports configuring the complexity level at init-time.
– Supports configuring the quality or bit-rate at init-time.
– Optional support for xDM APIs.
– Optional library provided ogg container format.
– Supports integrated Packet Loss Concealment (PLC) algorithm.
– Tested for bit-exactness with standard as well as a large database of non-standard test vectors.
– Module is fully interruptible.
– ARM implementation tested for any illegal memory access.
– Tested for compliance with register preservation requirements.
– Tested for Input buffer corruption.
– Tested for I/O buffer alignment requirements.
– Tested for multi-instance implementation.
– Tested for 100% code coverage.
– Range validation for all the API parameters.
– Tested with scratch contamination at frame boundaries.
– Tested for packet loss conditions with 5% loss to 25% loss.
– ARM implementation validated on OMAP3530 (Cortex-A8) and DM6446/DM6467 (ARM926EJ-S) platforms.
Speex was developed as an open source standard in the year 2003. The codec operates on each 20 ms frame of 16-bit PCM speech signals sampled at 8 KHz, 16 KHz, or 32 KHz and generates a compressed bit-stream having bit-rates in the range of 2.15 kbps to 42.2 kbps respectively. Speex is based on Code Excited Linear Prediction (CELP) algorithm. The encoder provides an option of selecting the bit-rate using the quality index (varying from 0 – 10) and the degree of codebook search using the complexity index (varying from 0 - 10). The recommended complexity index is between 2 and 4. The decoder supports packet loss concealment and provides an option to generate either narrow band (8 KHz) or wide-band (16 KHz) speech output. Speex is designed for packet networks and voice over IP (VoIP) applications.
Development work may be ongoing. For the most current information on the performance specifications and availability of the implementation on various DSPs, please send your enquiry to email@example.com. CouthIT reserves the right to make changes to the specifications or availability.