AAC Decoder
Introduction
AAC stands for Advanced Audio Coding, a part of MPEG4 (ISO/IEC 14496-3) and MPEG2 (ISO/IEC 13818-3) standards published by ISO/IEC. AAC supports sampling frequency from 8 to 96 khz and bitrates up to 576 kbps.
AAC decoding process consists of the following steps:
  • The bit-stream is parsed, huffman decoded and dequantised to get transform domain samples
  • The samples are converted to time domain using Inverse Modified Discrete Cosine Transform (IMDCT)
Salient Features
  • MPEG4 AAC-LC (Low Complexity )
  • MPEG4 AAC-SSR (Scalable Sample Rate)
  • Supports stereo and multichannel up to 7.1 channels
  • Fully compliant with ISO/IEC 14496-3
  • Sampling rates: 8 to 96 khz
  • Bit rates: Supports all the bit rate as per ISO/IEC 14496-3
  • Little endian
Benefits
  • Low Mhz
  • Supports raw, adts and adif file formats
  • Built in error handling to take care of corrupted bit-streams. Tested for various types of corrupted bit-streams
  • Re-sync support for fast forward/rewind (with ADTS header)
  • Multi instance and re-entrant implementation
  • Simple API interface
  • Ported and tested on hardware platform with linux OS
Applications
  • Portable audio players
  • Streaming
  • Mobile phones
  • Gaming consoles
  • Broadcast audio
Platform
  • ARM
    • ARM9, ARM11, Cortex A8
  • MIPS
    • MIPS 74kf
    • Base core, DSP and FPU version available
  • TI
    • TMS320C67x, TMS320C66x

Case studies

Developing an Asynchronous Sample Rate Converter

Designing an Asynchronous Sample Rate converter that offers high THD and low ripple across a range of frequencies is no mean achievement. We not only designed the ASRC but implemented it with low MHz on a fixed point processor.

Video codecs on a multi-core highly-parallel custom core

We worked with SiliconHive (now part of Intel) to develop High Definition video codecs that are designed to run optimally on a multi-core environment. Our contribution also included efficient coding for a VLIW core and algorithmic innovations to address memory bandwidth constraints.

Showcase

Android Auto projection on Telechip TCC8930 running WinCE 7.0
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RACE Media & Connectivity IVI suite
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