MP3 Audio Decoder

This section describes Intel IPP functions for assembling audio decoders compliant with the layer III portions of the ISO/IEC 11172-3 MPEG-1 and ISO/IEC ISO/IEC 13818 MPEG-2 audio specifications (see these specifications and provides a reference guide to the Intel IPP MP3 Application Programming Interface (API). As shown in Figure  below, the MP3 API consists of seven functions, two data structures, and several pre-defined constants and macros.

• UnpackFrameHeader MP3
  Unpacks audio frame header.
• UnpackSideInfo _MP3
  Unpacks side information from input bitstream for use during decoding of associated frame.
• UnpackScaleFactors_MP3
  Unpacks scalefactors.
• HuffmanDecode_MP3, HuffmanDecodeSfb_MP3, HuffmanDecodeSfbMbp_MP3
  Decodes Huffman data.
• ReQuantize_MP3, ReQuantizeSfb_MP3
  Requantizes the decoded Huffman symbols.
• MDCTInv_MP3
  Performs the first stage of hybrid synthesis filter bank.
• MDCTInvWindow_MP3
  Performs 36 or 18 points IMDCT and windowing depending on block type.
• SynthPQMF_MP3
  Performs the second stage of hybrid synthesis filter bank.
• SynthesisFilterInit_PQMF_MP3
  Initializes PQMF MP3 synthesis specification structure.
• SynthesisFilterInitAlloc_PQMF_MP3
  Allocates memory and initialized the PQMF MP3 synthesis specification structure.
• SynthesisFilterGetSize_PQMF_MP3
  Returns size of PQMF MP3 synthesis specification structure.
• SynthesisFilterFree_PQMF_MP3
  Frees memory allocated for PQMF MP3 synthesis specification structure.
• SynthesisFilter_PQMF_MP3
  Transforms PQMF MP3-processed subband signals into time domain samples.

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