SPR Vocoders 800 bps
Classic | Robust
SPR Classic ™ 800 bps vocoder is based on Sinusoidal Pulsed Representation (SPR) model, where excitation signal includes mixture of pitch-harmonics, noisy and aperiodic impulses.
It allows to synthesize correctly any speech sounds, including mixed voiced+unvoiced and complex transients.
Additionally, choice of optimal quantization schemes and high algorithmic optimization provided superior characteristics of this vocoder in comparison with others for the same bit rate
We used ITU-T P.50 multilanguage speech base and ITU-T P.862 utility to estimate speech quality.
SPR 800 bps vocoder provides high speech quality, very near to quality of the SPR Classic 1000 bps vocoders.
Moreover, all other characteristics of the SPR 800 vocoder excel considerably appropriate characteristics of the well-known vocoders.
We passed encoded bit streams through AWGN channel simulator with various SNR and estimated quality of decoded speech.
SPR Classic 800 bps vocoder shows good robustness, conceding to SPR Robust 800 bps vocoder only.
Time delay is very important characteristic of communication system. Algorithmic delay of vocoder does play determinative role in total delay. Well known, the delay more than 100 ms is not acceptable for normal conversation.
SPR 800 provides 100 ms delay. It is better, than MELPe 600 (110 ms).
Frame size is 80 ms (640 speech samples).
SPR 800 is very effective vocoder and requires very little of the computing resources.
Only 14 MIPS for TI's C55xx.
SPR 800 bps needs uniquely little memory, providing high rate of the quality/cost.
SPR 800 bps is available right now for TI's C55xx DSP and for PC (Win32) platforms and also is available for any other DSP, RISC or general-purpose platform during two-three months.
- SPEECH QUALITY
- ALGORITHMIC DELAY
- COMPUTING COMPLEXITY
- MEMORY USAGE