MAS 35x9F
DATA SHEET
2.9. MPEG Synchronization Output
The signal at pin SYNC is set to ‘1’ after the internal
decoding for the MPEG header has been finished for
one frame. The rising edge of this signal can be used
as an interrupt input for the controller that triggers the
read out of the control information and ancillary data.
As soon as the MAS 35x9F has received the SYNC
reset command (see Section 4.6.2.6. on page 77), the
SYNC signal is cleared. If the controller does not issue
a reset command, the SYNC signal returns to ‘0’ as
soon as the decoding of the next MPEG frame is
started. MPEG status and ancillary data become
invalid until the frame is completely decoded and the
signal at pin SYNC rises again. The controller must
have finished reading all MPEG information before it
becomes invalid. The MPEG Layer 2/3 frame lengths
are given in Table 2–2. AAC has no fixed frame length.
t
= 24...72 ms
frame
Vh
Vl
t
read
Fig. 2–12: Schematic timing of the signal at pin SYNC.
The signal is cleared at t when the controller has
read
issued a Clear SYNC Signal command (see
Section 4.6.2.6. on page 77). If no command is
issued, the signal returns to ‘0’ just before the
decoding of the next MPEG frame.
Table 2–2: Frame length in MPEG Layer 2/3
f /kHz
Frame Length
Layer 2
Frame Length
Layer 3
s
48
24 ms
24 ms
44.1
32
26.12 ms
36 ms
26.12 ms
36 ms
24
24 ms
24 ms
22.05
16
26.12 ms
36 ms
26.12 ms
36 ms
12
not available
not available
not available
48 ms
11.025
8
52.24 ms
72 ms
16
June 30, 2004; 6251-505-1DS
Micronas
MICRONAS [ MICRONAS ]
