Contents 1 RealAudio 8 Fixed-Point Decoder 2 Key Features 3 Technical Specifications 3.1 Average CPU Usage 3.2 Memory Usage 4 Frequently Asked Questions 4.1 Where is the code in CVS? 4.2 Where does the build system put the code in my local source tree? 4.3 How does the build system decide whether to build the fixed-point or floating-point RealAudio 8 decoder? 4.4 Is there an optimized fixed-point version of the RealAudio 8 encoder too?

RealAudio 8 Fixed-Point Decoder

RealAudio 8 is an efficient, high-quality audio codec for low- to mid-bitrates (8 - 96 kbps). Both floating-point and fixed-point decoder implementations are available. The fixed-point decoder is optimized especially for ARM processors but can run on any 32-bit fixed-point processor which can perform a long multiply operation (two 32-bit inputs generating a 64-bit result).

---

Key Features

• Pure 32-bit fixed-point implementation
• High-quality C reference code for porting to new platforms
• Optimized for ARM processors
• Fully reentrant and statically linkable
• Optional C++ API for compatibility with Helix clients
• Designed for high performance and low power consumption in handheld and mobile devices

---

Technical Specifications

Average CPU Usage

Sample Rate	Channels	Bit Rate	Processor Model (1)							On-Device Tests (2)
			ARM7TDMI	ARM720T	ARM9TDMI-REV2	ARM920T	ARM9E	StrongARM1	XScale	StrongARM 1110
11025 Hz	mono	11 Kbps	3 MHz	4 MHz	2 MHz	3 MHz	2 MHz	2 MHz	2 MHz	3 MHz
22050 Hz	mono	20 Kbps	6 MHz	7 MHz	5 MHz	6 MHz	5 MHz	5 MHz	5 MHz	7 MHz
44100 Hz	mono	32 Kbps	11 MHz	13 MHz	9 MHz	10 MHz	8 MHz	8 MHz	9 MHz	11 MHz
44100 Hz	stereo (dual)	96 Kbps	22 MHz	26 MHz	18 MHz	21 MHz	16 MHz	16 MHz	17 MHz	25 MHz
44100 Hz	stereo (joint)	96 Kbps	21 MHz	25 MHz	17 MHz	19 MHz	15 MHz	15 MHz	16 MHz	21 MHz

(1) Tested with ARMulator, simulated zero-wait-state memory
(2) Tested on iPaq 3650, 206 Mhz, PPC 3.0

Memory Usage

• ROM = 28481 Bytes (const globals)
• RAM = 20328 Bytes (heap)
  • Total Data Memory = 48809 Bytes
• Code Size = 10000 Bytes (approximately - depends on compiler)

---

Frequently Asked Questions

Where is the code in CVS?

• See the Helix RealAudio decoder project page: http://rarvcode-audio.helixcommunity.org

Where does the build system put the code in my local source tree?

• datatype-restricted/rm/audio/codec/ra8lbr/fixpt/decoder

How does the build system decide whether to build the fixed-point or floating-point RealAudio 8 decoder?

• If HELIX_CONFIG_FIXEDPOINT is defined in your profile, it will build the fixed-point decoder. Otherwise it will build the floating-point version.

Is there an optimized fixed-point version of the RealAudio 8 encoder too?

• Yes! Both fixed-point and floating-point implementations of the encoder are available. See the RealAudio 8 Fixed-Point Encoder Overview.

---