Scalable Speech Coding for IP Networks: Beyond iLBC IEEE：2013 WU,DONG-HAN

Outline Introduction Method Experimental Results Conclusions

iLBC MULTI-RATE iLBC

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

iLBC、G.729A、G.723.1 封包遺失品質關係圖

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

Block diagram of iLBC encoder

Block diagram of DCT-based start state encoder.

Block diagram of scalable multi-rate iLBC encoder

Block diagram of scalable multi-rate iLBC decoder

Experimental Results Objective Evaluation Subjective Evaluation

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

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

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

comparison of the original iLBC and G.718.

11.95 kbps USING 20 ms MODE 14.7 kbps USING 20 ms MODE

A-B comparison test results for the proposed codec using 20 ms frame at 11.95 kbps vs G.718 at 12 kbps.

A-B comparison test results for the proposed codec using 20 ms frame at 11.95 kbps vs the original iLBC at 15.2 kbps.

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.

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