HE-AAC (AAC+) v1, v2 Encoder and Decoder

High Efficiency AAC Profile (HE-AAC or aacPlus or Enhanced aacPlus) is a MPEG-4 standard for low bit rate coding . HE-AAC v1 profile uses Spectral Band Replication (SBR) for regeneration of high-frequency signal components to achieve coding gain of more than 30% compared to MPEG-4 AAC LC. Additionally, v2 profile uses PS (Parametric Stereo) to achieve further reduction in bitrate.

HE-AAC Decoder Technical Specification

• MPEG2 and MPEG4 AAC LC (Low complexity), SBR, PS
• Supports all sampling frequencies & bit rates for AAC only bit-streams
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• Channels: Mono/Stereo/Dual-Mono
• Performs Low Power SBR Decoding for stereo bit-stream and performs High Quality SBR Decoding for mono or PS bit-stream
• Robust against erroneous bit-streams
• Error concealment mechanism
• Tools Supported
• TNS (Temporal Noise Shaping)
• PNS (Perceptual Noise Shaping)
• Intensity Stereo & Mid/Side Stereo
• Bit-streams: ADIF, ADTS, GA Header
• Compliance: ISO/IEC 13818 - 4, 14496 - 4, 14496 - 3:2001/AMD1, 14496 - 4, 14496 - 3:2001/AMD2
• Performs Low Power SBR Decoding for stereo bit-stream and performs High Quality SBR Decoding for mono or PS bit-stream
• SBR Levels: Level 2 and 3
• For SBR bit-streams supports AAC sampling frequency upto 24/48 kHz (Level 2/3) and SBR sampling frequency upto 48 kHz
• SBR Signaling: Implicit, hierarchical explicit and backward compatible explicit
• Supports a simple C callable API with flexible memory allocation scheme
• Multi-channel, re-entrant software
• Optimized for low footprint and processing power

HE-AAC Encoder Technical Specification

• MPEG2 and MPEG4 AAC LC(Low complexity), SBR and PS
• Channels: Mono/Stereo/Dual-Mono
• Sample rates
• aacPlus encoding 32kHz - 48kHz
• Plain aac encoding 8kHz - 96kHz
• Bit-rates
• aacPlus encoding: stereo audio: 16 - 128kbps, mono audio: 8 - 64kbps
• Plain aac encoding: 8-160 kbps/channel
• Bit-stream formats: ADIF (Audio Data Interchange Format), ADTS (Audio Data Transport Stream)
• Tools: MS (Mid-side Stereo), TNS (Temporal Noise shaping), PNS(Perceptual Noise Substitution)
• Scratch memory management with reduced stack requirements
• Simple C callable API with flexible memory allocation scheme
• Multi-channel, re-entrant software
• Optimized for low footprint and processing power

Applications

• Streaming Media Servers
• Digital Media Players
• Mobile multimedia
• Digital Broadcasting

Platforms

• Currently supported on ARM (ARM9E™, ARM11™), TI DM320™, TI C64x™ (TMS320C64x™), TI C64+™/DaVinci™ (DM644x™)
• For other platforms contact mkt@ittiam.com