Application Programs and Systems - Heterogeneous Multicore Processor Technologies for Embedded Systems - page 178

Table 6.1 Speci fi cations for evaluated chip
Process technology 90-nm 8-layer CMOS

Supply voltage 1.0 V (internal), 1.8 V/3.3 V (I/O)

Operating frequency 600 MHz for CPU, 300 MHz for FE-GA/bus

Performance 19.2 GOPS (FE-GA maximum)

Local memories 128 KB + 8 KB/1 CPU, 40 KB/1 FE-GA

On-chip shared memory 128 KB

a b

Start

Huffman
coding 4%

Bitstream
generation 8%

Frame read

Filter bank

M/S stereo

Filter bank
& M/S stereo
57%

Quantization
32%

Quantization

Huffman coding

Stream generation

For CPU
For FE-GA

Processing flow Profiling results on CPU

Fig. 6.3 Processing fl ow and pro fi ling result of AAC encoder

Table 6.2 Conditions for AAC encoding

Pro fi le AAC encoder LC (low complexity)

Bit rate 128 kbps

Input data 16 bits, 44.1 KHz, PCM-formatted

Music-1 (192 s), Music-2 (87.9 s)

Memory allocation Input: PCM

Output: AAC streams placed on off-chip
shared memory

6.1.2 Processing Flow of AAC Encoding

The encoding process for the AAC consists of the use of a filter bank and mid-side
(M/S) stereo, quantization, Huffman coding, and bit-stream generation. The process
is performed frame by frame, which is a unit of sampled points in input pulse-code
modulation (PCM) data. Figure 6.3 outlines the process flow and profiling results
for the AAC encoding. The profiling results in (b) indicate that the filter bank, M/S
stereo, and quantization account for 89% of the total encoding time. Table 6.2 lists
the specifications of the encoder used for the evaluation.