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Packet loss concealment using audio morphing Presentation Transcript
1. Packet loss concealment using audio morphing
2. Motivation In packet data networks, excess traffic leads to delays or loss in delivery of information. In voice communication, long delays are intolerable and network delay budgets have strong influence on the design of packet voice systems. To increase the tolerance of packet voice systems to lost packets some techniques have been developed. These techniques do not use the a posteriori information of the next packet that indicates and detects the lost of one or several frames. However those techniques are not adapted for long lost periods (>15ms) because of the non long-term stationnarity of speech signal.
This a posteriori information is generally available because of the playout buffer management and real time network protocol.
The technique proposed uses the knowledge of the frame received after the last lost one, the models of the last received frames, and a model interpolation to synthesized the missing signal.
3. Outline
Introduction
Morphing audio principle
Voiced / Unvoiced strategy
Modelisation and Interpolation
Blocks concatenation and smoothing
Some results of concealed signal
Comparisons and performances
Configuration
Results
Conclusion
4. Morphing audio principle
Context of lost :
Voiced/Unvoiced strategy
5. Morphing audio principle
Modelisation and Interpolation:
6. Morphing audio principle
7. Morphing audio principle
8. Morphing audio principle
Some results of concealed signal
9. Comparisons and performances Ten subjects were participating to an informal test: they were asked to listen to coded speech signals that have been corrected by different concealment techniques
10. Comparisons and performances
11. Comparisons and performances
Results for G.723.1 codec
12. Conclusion
Proposed technique improves the quality of the frame correction for strong lost rate (5 % and 10 %);
Morphing audio adds latency (Frame B is required), but is acceptable for application of VoIP;
Another modelisation are possible and voiced condition can be controlled to improve restitution quality
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