Can DVI Carry Interlaced Video Modes?

Digital Visual Interface (DVI) has nuanced support for interlaced video modes like 1080i and 480i, depending entirely on whether the signal is transmitted via analog or digital pins. While the analog portion of the standard (DVI-A or DVI-I) natively handles interlaced video, the digital standard (DVI-D) does not officially support interlaced modes under the original DVI 1.0 specification. Consequently, while some hardware can transmit 1080i digitally through cross-compatibility with HDMI, formats like 480i generally fail over digital DVI connections due to fundamental clock-rate constraints.

The DVI Specification and Digital Video (DVI-D)

The official DVI 1.0 specification was designed primarily for PC monitors and strictly defines progressive scan modes (such as 480p, 720p, and 1080p). It explicitly omits native support for digital interlaced formats.

Because of this limitation, digital transmission behaves differently depending on the specific interlaced resolution:

• 480i over DVI-D: Digital 480i has a pixel clock of 13.5 MHz. The DVI 1.0 specification sets a hard minimum clock rate of 25.175 MHz for Transition-Minimized Differential Signaling (TMDS). HDMI overcomes this limit by utilizing "pixel repetition" to double the clock rate, but standard DVI lacks this mechanism. As a result, digital DVI cannot transmit standard 480i video.
• 1080i over DVI-D: A 1080i signal operates at a pixel clock of 74.25 MHz, which falls well within the valid DVI TMDS clock range (25.175 MHz to 165 MHz for single-link). Although not officially part of the DVI 1.0 specification, modern graphics cards and displays that share silicon with HDMI controllers often allow 1080i to pass through a DVI-D port. However, compatibility is not guaranteed across older or strictly compliant DVI-only PC monitors.

Analog Video (DVI-A and DVI-I)

The analog implementation of DVI is essentially an integrated VGA/RGB signal. Video standards that allow analog transmission, such as RGBHV or component video passed via DVI-I or DVI-A connectors, do not share the digital TMDS limitations:

• 480i and 1080i over Analog: Both modes are fully supported over the analog pins of DVI-I and DVI-A, provided both the source device and the receiving display support those specific analog timings. CRT monitors, broadcast monitors, and legacy projectors often utilize these pins to accept interlaced analog resolutions.

Practical Summary

If you are using a pure digital DVI connection (DVI-D), 480i is technically impossible without hardware-level scaling or deinterlacing to 480p, while 1080i may work informally due to HDMI-era backward compatibility. If you are using an analog DVI connection (DVI-A or the analog pins on DVI-I), both 480i and 1080i can be transmitted reliably to compatible displays.