alc268 Realtek Semiconductor Corporation, alc268 Datasheet - Page 22

• Manufacturer Part Number: alc268
• Description: 2+2 Channel High Definition Audio Codec
• Manufacturer: Realtek Semiconductor Corporation

7.2. Frame Composition
7.2.1.
An outbound frame is composed of one 32-Bit command stream and multiple data streams. There are one
or multiple sample blocks in a data stream. Only one sample block exists in a stream if the HDA
controller delivers a 48kHz rate of samples to the codec. Multiple sample blocks in a stream means the
sample rate is a multiple of 48kHz. This means there should be 2 blocks in the same stream to carry
96kHz samples (Figure 8).
For outbound frames, the stream tag is not in SDO, but in the SYNC signal. A new data stream is started
at the end of the stream tag. The stream tag includes a 4-Bit preamble and 4-Bit stream ID (Figure 9).
To keep the cadence of converters bound to the same stream, samples for these converters must be placed
in the same block.
2+2 Channel High Definition Audio Codec
SYNC
Previous Frame
SDO
Frame SYNC
Sample 1
Block 1
Outbound Frame – Single SDO
Command Stream
Sample Block(s)
msb
A 48kHz Frame is composed of Command stream and multiple Data streams
Sample 2
Block 2
SYNC
BCLK
...
SDO
lsb
Figure 9.
..
..
.
.
msb first in a sample
Previous Stream
Stream 'A' Data
Figure 8.
Stream 'A' Tag
(Here 'A' = 5)
One or multiple blocks in a stream
Sample Z
Preamble Stream=10
Block Y
SDO Stream Tag is Indicated in SYNC
(4-Bit)
7 6 5 4
Stream Tag
msb
1
For 48kHz rate, only Block1 is included
For 96kHz rate, Block1 includes (N)
includes (N+1)
SDO Outbound Frame
3
Z channels of PCM Sample
(4-Bit)
0
2
lsb
1 0
1
14
0
Data of Stream 10
th
time of samples
Stream 'X' Tag
(Here 'X' = 6)
Stream 'X' Data
Null Field
Track ID: JATR-1076-21
th
time of samples, Block2
0s
ALC268 Series
Padded at the
end of Frame
Next Frame
Datasheet
Rev. 1.3