51 What other topics do I have to keep in mind? Tell me about the complexity of Layer-3. (MPEG Audio Layer-3 Applications)
Description
This article is from the MPEG FAQ, by Frank Gadegast phade@cs.tu-berlin.de with numerous contributions by others.
51 What other topics do I have to keep in mind? Tell me about the complexity of Layer-3. (MPEG Audio Layer-3 Applications)
O.K. First, we have to separate between decoder and encoder, as the
workload is distributed asymmetrically between them, i.e. the encoder
needs much more computation power than the decoder.
For a stereo Layer-3-decoder, you may either use a DSP (e.g. one
DSP56002 from Motorola) or an "ASIC", like the masc-programmed DSP
chip MAS 3503 C from Intermetall, ITT. Some rough requirements are:
computation power around 12 MIPs
Data ROM 2.5 Kwords
Data RAM 4.5 Kwords
Programm ROM 2 to 4 Kwords
word length at least 20 bit
Intermetall (ITT) estimated an overhead of around 30 % chip area for
adding the necessary Layer-3 modules to a Layer-2-decoder. So you need
not worry too much about decoder complexity.
For a stereo Layer-3-encoder achieving reference quality, our current real-
time implementations use two DSP32C (AT&T) and one DSP56002. With
the advent of the 21060 (Analog Devices), even a single-chip stereo
encoder comes into view.
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