SAA2521GP Philips, SAA2521GP Datasheet - Page 17

• Manufacturer Part Number: SAA2521GP
• Description: Masking threshold processor for MPEG layer 1 audio compression applications
• Manufacturer: Philips

Philips Semiconductors
Status (LTCNT1(C) = logic 1, LTCNT0(C) = logic 1)
The SAA2520 and SAA2521 operation may be checked by
reading these bits. All, except the ready-to-receive bits,
are generated by the SAA2520.
The bit rate index indicates the bit rate of the sub-band
signal in units of 32 kbits/s. The SAA2521 is designed for
bit rates of 384, 256, 192 and 128 kbits/s only.
With EMPHASIS activated (S1 = T1 = 0 and S0 = T0 = 1)
only bit rates 384 and 256 kbits/s can be used.
A ready-to-receive S or E indicates whether or not the
SAA2521 can receive new settings or extended settings
respectively from the microcontroller and should be
checked prior to sending new information.
Table 10 Order of SAA2520 bits as they appear on the interface (see also Fig.14).
August 1993
T15
T11
T9
T8
T7
T5
T4
T3
T1
MSB
Masking threshold processor for MPEG
layer 1 audio compression applications
-
-
T14
T10
T6
T2
T0
BITS
T13
T12
LSB
bitrate index
sample frequency 44.1, 48 or 32 kHz indic.
ready-to-rec S
ready-to-rec E
MODE
SYNC
CLKOK
Tr0 - Tr1
EMPHASIS
17
The SAA2521 can only be used to encode stereo (mode
00) signals and 2-channel mono (mode 10) signals.
During the decoding mode this bit indicates if the operation
of the SAA2520 is in synchronization with the MPEG
coded signal. Should this not be the case the SAA2520
cannot perform the decoding.
CLKOK indicates whether or not the F
corresponds with the specified sample frequency.
EMPHASIS indication may be used to apply correct
de-emphasis. During the encoding 50 / 15 s mode the
SAA2521 will correct the calculated allocation if emphasis
is applied for a 44.1 kHz sampling frequency.
NAME
bitrate indication
1 - ready; 0 - not ready
1 - ready; 0 - not ready
sub-band signal mode ID
synchronization indic.
1 - OK; 0 - not OK
transparent bits
emphasis indication
FUNCTION
Preliminary specification
s
256 clock
SAA2521
enc/dec
enc/dec
enc/dec
enc/dec
enc/dec
dec
enc/dec
enc/dec
enc/dec
VALID IN