AT8xC51SND2C
Frame Information
The MP3 frame header contains information on the audio data contained in the frame.
These informations is made available in the MP3STA register for you information.
MPVER and MPFS1:0 bits allow decoding of the sampling frequency according to
Table 73. MPVER bit gives the MPEG version (2 or 1).
Table 73. MP3 Frame Frequency Sampling
MPVER
MPFS1
MPFS0
Fs (kHz)
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
22.05 (MPEG II)
24 (MPEG II)
16 (MPEG II)
Reserved
44.1 (MPEG I)
48 (MPEG I)
32 (MPEG I)
Reserved
Ancillary Data
MP3 frames also contain data bits called ancillary data. These data are made available
in the MP3ANC register for each frame. As shown in Figure 43, the ancillary data are
available by Bytes when MPANC flag in MP3STA register is set. MPANC flag is set
when the ancillary buffer is not empty (at least one ancillary data is available) and is
cleared only when there is no more ancillary data in the buffer. This flag can generate an
interrupt as explained in Section "Interrupt", page 66. When set, software must read all
Bytes to empty the ancillary buffer.
Figure 43. Ancillary Data Block Diagram
Ancillary
Data To C51
7-Byte
Ancillary Buffer
8
8
MP3ANC
MPANC
MP3STA.7
65
4341D–MP3–04/05
ATMEL [ ATMEL ]
