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Comparing:
VGA, DVI, HDMI, DP
-- Tarek ELDEEB
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What are the basic video signals?
● It all started with the analog TV
1. Line marker (Horizontal sync)
2. Frame marker (Vertical Sync)
3. Color Data for each line
● Going Digital needs an extra CLK
○ Either SRC+Display agree on a frequency (set)
○ Send the CLK from SRC → Display
● What about the audio?
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VGA
● Introduced in 1987: Basic Video, no audio
● Initially supporting up to 640×480
○ Now 1080p60 and above
● Analog color data (0 → 5v), no clear/sharp images
● Not hot-pluggable
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DVI
● Introduced 1999, DDWG
● Digital and/or Analog Links
○ Analog is backward compatible with VGA
○ Digital has 3 differential (TDMS) + 1 Clk
■ Clock is allowed to vary 25 → 165 MHz
● Maximum data rate (including 8b/10b overhead) is 4.95 Gbit/s @ 165 MHz
● UXGA (1600 × 1200) @ 60 Hz
● I2C for EDID block:
○ The display's identification
○ color characteristics (such as gamma value),
○ and table of supported video modes (resolutions)
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HDMI
● Introduced in 2004, proprietary, actively maintained
● Backward compatible with DVI (digital)
● Audio + Data streams are interleaved with Video
● HDMI 1.4 added HEC: Back audio + Ethernet
● Maximum data rate of 42 Gbps
● HDMI 2.1 supports 8K@120Hz
>> More features: 3D, Content Protection, CEC, .. etc
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DisplayPort
● Introduced on 2008 by VESA (open standard)
● Uses 1-4 LVDS channels + 1 data
○ No clock: Trained using a predefined set
○ Data streams are packetized (future proof)
● Backward compatible with HDMI, but lacks CEC
● DP v2.0 supports maximum data rate of 80 Gbps
● Supports 16K display @ 60Hz and 30 bpp HDR
● Supports compression and multiple devices
● Has many variants: mini, micro, embedded, wireless, USB-C !
Lane-0
Lane-1
Lane-2
Lane-3
AUX
3v3 Pwr
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Comparison
Audio Digital EDID Data
Cable
Length
Max Resolution License
VGA
45m
1920×1080
@60Hz
DVI ✓
(TDMS)
✓ 4.5m
1600×1200
@60Hz
HDMI
✓ ✓
(TDMS)
✓ ✓
(HEC,CEC)
15m
7680×4320
@120Hz
❌
DP
✓
✓
(LVDS,
packets)
✓ ✓
(AUX)
1.8m
15360x8460
@60Hz +HDR
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Other Display Technologies
● Mobile Industry Processor Interface (MIPI): DSI & CSI
○ 1-4 LVDS Channels (like DP) + 1 CLK Channel (like HDMI)
○ Commonly known as Flat Panel Display: FPD-Link
○ DSI/CSI-2 released in 2021 supporting Automotive Lidars/Camera
■ IEEE 2977-2021: A-PHY
● Thunderbolt (from Apple/Intel):
○ Similar to the MiniDP but with 8 LVDS Lanes
○ Supports PCIe, Newer versions use the USB-C connector
● USB-C Alt-Mode (10Gbps + 100W power)
○ Non-USB data, DisplayPort 1.3 support