SPR Vocoders 1000 bps
Classic | Robust
SPR Classic ™ 1000 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 1000 bps vocoder provides high speech quality. very near to quality of 1200 bps vocoders.
Moreover, all other characteristics of the SPR 1000 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 1000 bps vocoder shows good robustness, conceding to SPR Robust 1000 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 1000 provides 60 ms delay only. It is superior value for such low bit rate.
Frame size is 40 ms (320 speech samples).
SPR 1000 is very effective vocoder and requires very little of the computing resources.
Only 16 MIPS for TI's C55xx.
SPR 1000 bps needs uniquely little memory, providing high rate of the quality/cost.
SPR Classic 1000 bps vocoder is available right now as:
- Object Code for TI's C55xx DSP,
- DLL (Win32) for PC
Also it is available for any other DSP, RISC or general-purpose platform during two-three months.
- SPEECH QUALITY
- ALGORITHMIC DELAY
- COMPUTING COMPLEXITY
- MEMORY USAGE