1. Scalable Speech Coding for IP Networks: Beyond iLBC
IEEE： WU,DONG-HAN

2. Outline
Introduction
Method
Experimental Results
Conclusions

3. iLBC
MULTI-RATE iLBC

4. Introduction a.What is iLBC? iLBC -internet Low Bitrate Codec
higher robustness to packet loss then G.729A,
13.3kbit/s 30ms 、15.2kbit/s 20ms
Royalty Free Codec

5. iLBC、G.729A、G 封包遺失品質關係圖

6. Method SCALABLE MULTI-RATE iLBC Framework of Multi-Rate Operation
Performance Enhancement Schemes
Complexity
Packet Loss Concealment

7. Block diagram of iLBC encoder

8. Block diagram of DCT-based start state encoder.

9. Block diagram of scalable multi-rate iLBC encoder

10. Block diagram of scalable multi-rate iLBC decoder

11. Experimental Results
Objective Evaluation
Subjective Evaluation

12. Using the different number of adaptive codebook refinement stages when only the core layer is used

13. Effect of using the different frame length when only the core layer is used

14. Effect of using the enhancement
Effect of using the enhancement layer and coding only low-frequency MDCT coefficients in enhancement layer.

15. comparison of the original iLBC and G.718.

16. 11.95 kbps USING 20 ms MODE 14.7 kbps USING 20 ms MODE

17. A-B comparison test results for the proposed codec using 20 ms frame
at kbps vs G.718 at 12 kbps.

18. A-B comparison test results for the proposed codec using 20 ms frame at kbps vs the original iLBC at 15.2 kbps.

19. Conclusions
we presented a scalable speech codec for IP networks based on a combination of multi-rate iLBC and improved scalable structure.
Furthermore, the improvement of packet-loss robustness may be possible.

20. THANKS!
Any questions?