VS1011/VS1011e pdf datasheet (

VS1011e is a single-chip MPEG audio decoder.
The chip contains a high-performance, low-power
DSP processor core VS DSP4, working memory,
5 KiB instruction RAM and 0.5 KiB data RAM
for user applications, serial control and input data
interfaces, 4 general purpose I/O pins, as well as
a high-quality variable-sample-rate stereo DAC,
followed by an earphone amplifier and a common
buffer.
VS1011e receives its input bitstream through a serial
input bus, which it listens to as a system slave.
The input stream is decoded and passed through a
digital volume control to an 18-bit oversampling,
multi-bit, sigma-delta DAC. The decoding is controlled
via a serial control bus. In addition to basic
decoding, it is possible to add application specific
features, like DSP effects, to the user RAM memory.