Free Trial

Safari Books Online is a digital library providing on-demand subscription access to thousands of learning resources.

  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint
Share this Page URL
Help

Chapter 9: Audio Coding > 9.7 MPEG-4 Audio Coding

9.7 MPEG-4 Audio Coding

The MPEG-4 audio coding standard consists of a family of audio and speech coding methods for different bit rates and a variety of multimedia applications [Bos02, Her02]. Besides a higher coding efficiency, new functionalities such as scalability, object-oriented representation of signals and interactive synthesis of signals at the decoder are integrated. The MPEG-4 coding standard is based on the following speech and audio coders.

  • Speech coders
    • CELP: Code Excitated Linear Prediction (bit rate 4–24 kbit/s).
    • HVXC: Harmonic Vector Excitation Coding (bit rate 1.4–4 kbit/s).
  • Audio coders
    • Parametric audio: representation of a signal as a sum of sinsoids, harmonic components, and residual components (bit rate 4–16 kbit/s).
    • Structured audio: synthetic signal generation at decoder (extension of the MIDI standard1) (200 bit–4 kbit/s).
    • Generalized audio: extension of MPEG-2 AAC with additional methods in the time-frequency domain. The basic structure is depicted in Fig. 9.19 (bit rate 6–64 kbit/s).

  

You are currently reading a PREVIEW of this book.

                                                                                                                    

Get instant access to over $1 million worth of books and videos.

  

Start a Free 10-Day Trial


  
  • Safari Books Online
  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint