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Published byDwight Wade Modified over 9 years ago
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Brian White CS529 SPEAK WITH FORWARD ERROR CORRECTION: IMPLEMENTATION AND EVALUATION
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Perceptual Evaluation of Speech Technology (ITU-T P.862) Standard methodology for analysis of voice quality “Full Reference” Test – original vs. degrade Produces a mean opinion score (MOS) Temporal alignment Sample by sample comparison ITU provides a reference implementation PESQ: WHAT IS IT?
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WHAT DOES PESQ DETECT?
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Media Specific Forward Error Correction Include fully redundant data in next packet Sequence Number Primary Audio Secondary Audio SPEAK FEC IMPLEMENTATION A[N]A[N+1]N+1A[N-1]A[N]N
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Handling packet loss (packet N) SPEAK FEC IMPLEMENTATION A[N]A[N+1]N+1A[N-1]A[N]NA[N-2]A[N-1]N-1 A[N-1]A[N]A[N+1]
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Subjective evaluation with 5 test subjects 22 seconds audio played through a Speak application channel. With and Without FEC Various error rates (0%,5%,7%,10%,12%,15%) The audio of each session was recorded and run through PESQ 3 Questions on quality Overall quality Impression vs. landline Impression vs. cellphone EVALUATION
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SO HOW WELL DOES FEC PERFORM?
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COMPARISON TO LANDLINE PHONE
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PESQ EVALUATION
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FEC is valuable for networks that expect moderate loss To fully work, an adaptive buffering scheme should be adopted Work with speech detection Future work to evaluate FEC implementation in a two-way conversation test. Expand on informal evaluation of PESQ as a testing methodology. Are there cases were PESQ diverges from subjective results? CONCLUSION
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