Pixel Repetition - Analog Devices ADV7850 Hardware Manual

formats. In this case, the VIC should be manually set to 0.
vfe_fmt_vid[5:0], Addr B8 (Main), Address 0x3E[7:2] (Read Only)
This readback indicates the VIC detected by the video front end.
vfe_aux_vid[2:0], Addr B8 (Main), Address 0x3F[7:5] (Read Only)
This readback indicates the video input formats that are not inside the 861B table.
Function
vfe_aux_vid[2:0]
000 
001
010
011
100
101
110
111
asp_ratio, Addr B8 (Main), Address 0x17[1]
This control is used to set the aspect ratio of the input video.
Function
asp_ratio
0 
1
vfe_prog_mode[1:0], Addr B8 (Main), Address 0x3F[4:3] (Read Only)
This readback indicates the progressive mode information about 240p and 288p.
Function
vfe_prog_mode[1:0]
01
10
11

Pixel Repetition

13.11.3
Pixel repetition is used in HDMI to increase the amount of blanking period available to send packets or to increase the pixel clock to meet
the minimum TMDS clock rate of 25 MHz. The ADV7850 offers three choices for the user to implement pixel repetition in the Tx core.
These choices or modes are described below and can be set via pr_mode[1:0].
Automatic mode:
In automatic mode, the ADV7850 uses the audio sampling rate and the detected VIC information as parameters to decide if pixel
repetition is needed to obtain sufficient blanking periods to send the audio. For an I2S input stream, the sampling rate is always set by the
user via i2s_sf[3:0]. If the pixel repetition factor is adjusted to meet bandwidth requirements, the detected input VIC may be different
from the VIC sent to the downstream sink. The VIC of the actual video sent across the HDMI link to the downstream sink, and which is
included in the AVI InfoFrame, can be read from vid_to_rx[5:0].
Manual mode:
In manual pixel repetition mode, the VIC sent in the AVI InfoFrame needs to be set. The factor between the pixel clock input to the Tx
core and the output TMDS clock frequency must be programmed in ext_pll_pr[1:0]. The pixel repetition value sent to the HDMI sink
Rev. A May 2012
Description
Set by vfe_fmt_vid
240p not active
576i not active
288p not active
480i active
240p active
576i active
288p active
Description
4:3
16:9
Description
262 lines (240p),312 lines (288p)
263 lines(240p),313 lines (288p)
undefined(240p),314lines (288p)
357
ADV7850