Audio Algorithms by Adaptive Digital

MPEG-4 AAC-LD Encoder and Decoder

Advanced Audio Decoder C64x, C64x+

MPEG-4 Low Delay Advanced Audio Coding (AAC-LD)

Low Delay Advanced Audio Coding (AAC-LD) is the high-quality low-delay audio coding standard within MPEG-4. The MPEG-4 Low Delay Audio Coder is designed to combine the advantages of perceptual audio coding with the low delay necessary for two-way communication. It has achieved wide acceptance in high end video conference terminals and is used in professional broadcasting applications. The codec is closely derived from MPEG-4 Advanced Audio Coding (AAC-LC). It features an algorithmic delay of only 20 ms while offering good compression ratios and high sound quality audio quality for all kinds of audio signals including speech, music and atmospheric sounds. This way, AAC-LD bridges the gap between speech coding schemes and high quality audio coding schemes. Unlike common speech coders, the achieved coding quality scales up with bitrate, and transparent quality can be achieved.

AVAILABILITY

Currently supported on TI C64x™ (TMS320C64x™), TI C64x+™/DaVinci™ (DM644x™)

FEATURES

  1. Suitable for all kinds of audio signals including speech and music
  2. Audio quality better than ITU-T G.722/G.722.1-C, G.729.1 at the same bit rate
  3. Audio quality better than mp3 at the same bit rate
  4. Algorithmic delay of only 20 ms
  5. Delay of real-time DSP implementation down to 30 ms
  6. Multi-channel support
  7. Large range of bit rates possible
  8. Computational and storage complexity comparable to MPEG-4 AAC-LC
  9. 480 samples and 512 samples per frame supported
  10. Error resilient AAC-LD audio object type
  11. Decoding of mono and stereo streams supported
  12. eXpressDSP™ Digital Media compliant

SPECIFICATIONS

C64x

All Memory usage is given in units of byte.

Function
MIPS*
Program Memory
Data Memory
Per-Channel Data Memory
Encode
31
103 k
50 k
30 k
Decode
13
71 k
18 k
30 k

 

C64x +

All Memory usage is given in units of byte.

Function
MIPS*
Program Memory
Data Memory
Per-Channel Data Memory
Encode
29.5
98 k
50 k
30 k
Decode
12.4
67.5 k
18 k
30 k

 

APPLICATIONS

- MPEG-4 AAC-LD is the perfect choice for any high-quality low-delay communication application.

 

 

Adaptive Digital Technologies, Inc.
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