Altera DisplayPort MegaCore Function - Manual (Page 57)

Figure 5-9: Typical Secondary Stream Packet
0
0
0
HB2
0
0
0
HB3
0
0
0
HB1
0
0
0
DB15
DB10
DB9
DB8
DB7
DB14
DB13
DB12
DB11
DB6
DB5
DB4
DB3
DB2
DB1
HB0 DB0
DB31
DB26
DB25
DB24
DB23
DB30
DB29
DB28
DB27
DB22
DB21
DB20
DB19
DB18
DB17
DB16
Data[127:0]
End of Packet
Start of Packet
Valid
Audio Interface
The audio interfaces are downstream from the secondary stream decoder. They extract and decode the
audio infoframe packets, audio timestamp packets, and audio sample data.
The audio timestamp packet payload contains M and N values, which the sink uses to recover the source’s
audio sample clock. The
rxN_audio
port uses the values to generate the
rxN_audio_valid
signal
according to sample audio data. Data is clocked out using the
rx_ss_clk
signal. The
rx_ss_clk
signal
comes from the rx parallel clock from the RX transceiver. This clock runs at link data rate/20 for dual
symbol mode and link data rate/40 for quad symbol mode.
The sink generates the
rxN_audio_valid
signal using the M and N values, and asserts it at the current
audio sample clock rate. The
rxN_audio_mute
signal indicates whether audio data is present on the
DisplayPort interface.
UG-01131
2015.05.04
Audio Interface 5-21
DisplayPort Sink Altera Corporation
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