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Audio Coding Video Tutorials and Python Notebooks

Prof. Dr. -Ing. Gerald Schuller
Jupyter Notebooks and Videos: Renato Profeta

Applied Media Systems Group
Technische Universität Ilmenau

Content

01 Basics of Multirate Signal Processing:
NBViewerBinderGoogle ColabYoutube

  • Sampling
    • Sampling a Discrete Time Signal
    • Downsampling
    • Upsampling
    • Real-Time Python Example: Sampling
  • Effects in the z-Domain
  • Modulation
    • Real-Time Python Example: Modulating a Speech Signal
  • Mid-rise and Mid-tread quantization
    • Real-Time Python Example: Quantization

02 Filter Banks I :
NBViewerBinderGoogle ColabYoutube

  • Filter Banks
  • Downsampling
  • Upsampling
  • Filter Bank Structure
  • Perfect Reconstruction
  • Analysis Filter Bank
  • Synthesis Filter Bank
  • Polyphase
  • Transforms as Filter Banks
  • Real-Time Python Examples

03 Filter Banks II :
NBViewerBinderGoogle ColabYoutube

  • Modulated Filter Banks - Extending the DCT
  • Modulated Filter Banks
    • Frequency Shifts
    • The Window Function
  • Fast Implementation: Analysis Polyphase Matrix
  • The MDCT Filter Bank
  • Graphical Interpretation of Analysis Matrix 𝐹𝑎
  • MDCT, Perfect Reconstruction
  • MDCT Filter Banks, Sine Window
    • Sine-Window Frequency Response
  • MDCT, Advantages
  • MDCT Filter Banks, Impulse Responses
  • MDCT Filter Banks, Frequency Responses
  • MDCT: Python Examples
    • MDCT Fast Implementation
  • Extending the Length of the MDCT
    • Zero-Delay Matrix
    • Maximum-Delay Matrix
    • Design Method
    • Real-Time Example

03b Filter Banks III :
NBViewerBinderGoogle ColabYoutube

  • Block Switching
  • Wavelets, QMF (Quadradutre Mirror Filter) Filter Banks
    • QMF (Quadrature Mirror Filter)
  • CQMF: Conjugate QMF
  • Pseudo-QMF (PQMF)
    • PQMF used in MPEG4

04 Psychoacoustics :
NBViewerBinderGoogle ColabYoutube

  • Block Diagram of a Perceptual Audio Encoder
  • Structure of the Human Ear
    • Cochlea
    • Organ of Corti
  • Preprocessing of Sound in the Peripheral System
  • Information Processing in the Auditory System
  • Sound Perception
    • Frequency and Level Range of Human Hearing
    • Threshold in Quiet or the Absolute Threshold
    • Hearing Threshold and Age
    • Loudness
    • Critical Bands
      • Frequency Grouping in Human Hearing
      • Excursus - Critical Bands and Loudness
    • Bark Scale
    • Masking
      • Masking of Pure Tones by Noise -Broad-Band Noise
      • Masking of Pure Tones by Noise -Narrow-Band Noise
      • Masking of Pure Tones by Low-Pass or High-Pass Noise
      • Masking of Pure Tones by Pure Tone
      • Masking of Pure Tone by Complex Tones
      • Tonality
      • Masking - Spreading Function
      • Calculating the Masking Threshold
      • In-Band Making
      • Masking Neighboring Bands
      • Temporal Masking Effects

05 Psychoacoustics Models :
NBViewerBinderGoogle ColabYoutube

  • Spreading Function: Python Example
  • Masking Neighboring Bands Non-Linear Superposition
  • Bark Scale Approximations:
    • Zwicker&Terhard
    • Traunmueller
    • Schröder
  • Bark Scale Approximations: Comparisons
  • Bark Scale Mapping
  • Mapping from Bark scale back to Linear
  • Hearing Threshold in Quiet
  • The Complete Psycho-Acoustic Model
  • Physical Models of Hearing

06 PQMF Filter Bank, MPEG-1 / MPEG-2 BC Audio :
NBViewerBinderGoogle ColabYoutube

  • The Basic Paradigm of T/F Domain Audio Coding
  • MPEG Audio Standardization Philosophy
  • MPEG 1/2
    • MPEG-1 Audio
      • The main building blocks
      • MPEG Audio - Short Description of the Layers
      • Block Diagram MPEG-1 Layer 1
      • Block diagram Layer-3
  • Example for the Time/Frequency Resolution for the 2-Stage Layer III Coder
  • MPEG - Layer-1, -2 and -3 Compression: Header
  • The Pseudo-Quadrature-Mirror Filter Bank (PQMF)
    • PQMF Definition
    • PQMF Reformulation
    • PQMF Design
  • Python Example Optimization
  • PQMF Optimization
    • Optimization Function
    • Python Example
    • Unity Condition
  • PQMF Polyphase Implementation
  • Hybrid Filter Bank & Aliasing
    • Problem of Aliasing in a Cascaded Filter Bank
    • Aliasing Reduction Structure (MP3)
  • MPEG Audio - Layer-3: Bitstream
  • MPEG-1 Audio Decoder
    • MPEG Audio – General Decoder Structure
    • MPEG - Audio Decoder Process (1) Layer-3 Decoder flow chart
    • MPEG - Audio Decoder Process Layer-3 Decoder Diagramm
  • Annex: Abbreviations and Companies

YouTube Playlist

Youtube

Requirements

Please check the following files at the 'binder' folder:

  • environment.yml
  • postBuild

Note

Examples requiring a microphone will not work on remote environments such as Binder and Google Colab.

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