AAC Reference Software

Building

MPEG-4 Audio Reference Software

• Latest Public Release http://standards.iso.org/ittf/PubliclyAvailableStandards/c050470__ISO_IEC_14496-5_2001_Amd_20_2009_Reference_Software.zip

Dependencies

• AFsp: ftp://ftp.tnt.uni-hannover.de/pub/audio/AFsp/AFsp-v8r2.tar.gz
• Systems: http://standards.iso.org/ittf/PubliclyAvailableStandards/c045527_ISO_IEC_14496-5_2001_Amd_12_2007_Reference_Software.zip

The systems software appears to have at least one bug that makes it difficult to use it to mux various AAC formats to mp4. [1] A newer version is available at request from the MP4 Registration Authority (Apple)

Build Process

• The software is not 64-bit safe. On a 64-bit system "-m32" should be added to CFLAGS and LDFLAGS.
• Build AFsp and libisomediafile
• Set up environment variables in the make-all script
• Select "kits" to build, the important kits for AAC/HE-AAC decoding are:
  • mp4mcDec - reference decoder and file format converter
  • conf_ssnrcd - Segmental SNR and cepstral distortion tool
  • conf_pns - PNS conformance tool
  • conf_sbr - SBR conformance tool
• Create a set of NOSBRKITS like LPSBRKITS set and give them the parameters SBR=0 PARAMETRICSTEREO=0. Include mp4mcDec in this set. This can be used to decode AAC files without SBR to test the core decoder of on an HE-AAC file.

Usage

Run any tool with no arguments to see usage information.

mp4mcDec

mp4audec_mc [options] aacfile pcmfile

useful options:

-3 create 24-bit output files

-D<string> print out various bits of diagnostic info

Debug options:

v verbose
V show all tools used
N show frame numbers
h show header info
c debug channel coupling
f debug scalefactors
i debug intensity stereo
m debug mid/side stereo
p debug prediction
P debug PNS and pulse data
q debug quantization
r debug prediction resets
s debug sfb (scale factor band) information
R debug DRC (dynamic range control)
T debug TNS
w debug window sequences
x show DSE and FIL elements
X show DSE contents

3GPP Reference implementation

• HE-AAC Reference implementation http://www.3gpp.org/ftp/Specs/html-info/26410.htm