Technology - Audio-Visual Coding 2 - MPEG 2 AAC and Video

Synopsis

We discuss Advanced Audio Coding and how it improves on MP3. We explain enhancements to both AAC including Spectral Band Replication, Parametric Stereo and Scalable Lossless Coding. We discuss HILN parametric audio coding and voice compression algorithms including CELP. We also explain the process of MPEG-2 video compression, which is the basis of almost all digital television systems.

Table of Contents

• 1. Synopsis
  
• 2. Introduction
  
• 3. MPEG-2 Transport Stream
  
• 4. MPEG-2 audio compression
  
  • 4.1 5.1 channels
    
• 5. MPEG-2/4 Advanced Audio Coding (AAC)
  
  • 5.1 MDCT block lengths
    
  • 5.2 Temporal Noise Shaping (TNS)
    
  • 5.3 Frequency domain prediction
    
  • 5.4 Perceptual Noise Substitution (PNS)
    
  • 5.5 Long Term Prediction (LTP)
    
  • 5.6 Low Complexity (AAC-LC)
    
  • 5.7 Scalable Sample Rate (AAC-SSR)
    
  • 5.8 Bit-Sliced Arithmetic Coding (AAC-BSAC)
    
  • 5.9 AAC advantages over MP3
    
  • 5.10 Low Delay AAC
    
  • 5.11 Error Resilient AAC
    
  • 5.12 HE-AAC – aacPlus
    
  • 5.13 Spectral Band Replication (SBR)
    
  • 5.14 Parametric Stereo
    
  • 5.15 Scalable Lossless Coding (SLS)
    
• 6. MPEG-4 Parametric Audio Coding – HILN
  
  • 6.1 Speech compression
    
    • 6.1.1 Code-Excited Linear Predictive (CELP)
      
    • 6.1.2 Harmonic Vector Excitation Coding (HVXC)
      
• 7. MPEG-2 video compression
  
  • 7.1 Chroma sub-sampling
    
  • 7.2 Motion compensation
    
  • 7.3 Discrete Cosine Transform (DCT)
    
  • 7.4 Variable bit rate
    
  • 7.5 Encoder – decoder compatibility
    
  • 7.6 Profiles and levels
    
    • 7.6.1 MainProfile@MainLevel (MP@ML)
      
    • 7.6.2 MainProfile@HighLevel (MP@HL)
      
    • 7.6.3 SNR Profile – Scalable for Hierarchical Broadcasting
      
    • 7.6.4 SpatialProfile@High-1440Level
      
• 8. Related reports