I. INTRODUCTION
II. GENERAL CONCEPTS OF AV BIOMETRIC VERIFICATION SYSTEM
A. BIOMETRIC SYSTEM COMPONENTS
B. PRESENTATION ATTACK DETECTION (PAD)
C. PERFORMANCE METRICS
III. AV BASED FEATURE EXTRACTION
A. AUDIO FEATURES
B. VISUAL FEATURES
IV. AV BASED FUSION AND CLASSIFICATION
A. PRE-MAPPING OR EARLY FUSION
B. MIDST-MAPPING OR INTERMEDIATE FUSION
C. POST-MAPPING OR LATE FUSION
V. AUDIO-VISUAL BIOMETRIC DATABASES
VI. PRESENTATION ATTACK DETECTION (PAD) ALGORITHMS
A. AUDIO-VISUAL FEATURES USED FOR LIVENESS DETECTION
C. FORGERY ATTACKS IN AV BIOMETRICS
VII. CHALLENGES AND OPEN QUESTIONS
A. DATABASES AND EVALUATION
B. AV BIOMETRICS IN SMART DEVICES
C. PRIVACY PRESERVING TECHNIQUES IN AV BIOMETRICS
E. PERFORMANCE EVALUATION FOR AV BIOMETRICS
VIII. CONCLUSION AND FUTURE WORKS
A. FUTURE WORKS