Speech coding techniques
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This document discusses speech coding techniques. It introduces speech processing which includes compression, manipulation, storage, transfer and reconstruction of speech. It explains that speech coding is needed for applications like mobile communication, voice over internet protocol, satellite broadcasting and PSTN networks. The document outlines various attributes of speech coders like low bit-rate, high speech quality and low computational complexity. It also describes different types of speech coders like waveform coders, source coders, time domain coders and frequency domain coders. Objective and subjective measures for evaluating performance of speech coders are discussed.
Speech coding techniques
- 1. Speech Coding Techniques BY: Kailash Karki 152040006 KL University Andhra Pradesh,India Kailash202012@gmail.com
- 2. Introduction Speech processing includes: o Compression o Manipulation o Storage o Transfer o Output(Reconstruction) Can be considered as a special case of digital signal processing.
- 3. Why speech coding is needed?
- 5. Attributes of Speech Coders • Low bit-rate • High speech quality • Channel errors • Low memory requirements • Less computational complexity • Low coding delay
- 6. Hierarchy of Speech Coders Speech Coders Waveform Coders Source Coders Time Domain LPC VOCODERSFrequency Domain NonDifferential Differential Delta ADPCM SBC ATCPCM
- 7. Performance Evaluation of Speech Coders • Objective Measures • Subjective Measures Quality Scale Score Listening Effort Scale Excellent 5 No effort required Good 4 No appreciable effort required Fair 3 Moderate effort required Poor 2 Considerable effort required Bad 1 No meaning understood with reasonable effort
- 8. Performance of Coders Coder MOS 64 kbps PCM 4.3 14.4 kbps QCELP13 4.2 32 kbps ADPCM 4.1 8 kbps ITU-CELP 3.9 8 kbps CELP 3.7 13 kbps GSM Codec 3.54 9.6 kbps QCELP 3.45 4.8 kbps CELP 3.0 2.4 kbps LPC 2.5
- 9. Applications: • Mobile Communication • Voice over internet protocol • Satellite broadcasting • PSTN Network etc.