Decimator Design's MD-HX has sat in thousands of integrator racks for years because it handles 12G-SDI to HDMI cross-conversion at a price point that fits most fixed-install budgets. Yet reports from recent sports-arena and corporate-event projects show consistent scaling problems when the unit downsamples 4K59.94 progressive to 1080i59.94 interlaced. The artifacts appear as horizontal twitter on fine detail and occasional field-order reversal that scopes confirm as incorrect 3:2 cadence insertion.
Market pressure drives the issue. Many venues still run 1080i59.94 switchers and recorders bought before 4K camera fleets became standard. Rather than rip out the entire signal chain, crews drop an MD-HX in the path between a 4K PTZ or server output and the house router. The converter's internal Lanczos-style scaler, tuned more for progressive-to-progressive work, does not apply proper vertical low-pass filtering before the interlace step. Resulting moiré on LED walls and on-camera talent clothing forces last-minute talent repositioning or source cropping.
Install economics shift quickly once artifacts surface. A typical two-day arena integration now includes four to six hours of extra bench time with a waveform monitor and a consumer 1080i display to verify every MD-HX channel. At prevailing labor rates that adds roughly $1,800 per rack. Some crews carry spare AJA FS-HDR or Blackmagic Teranex units as hot-swaps, but those raise both capex and power-draw calculations in already crowded equipment rooms.
Workarounds Observed in Current Projects
Technicians have settled on a short list of practical steps. First, lock the MD-HX to its "fast" scaling preset and force output to 1080p59.94, then let a downstream frame-store or router perform the final interlace. This removes the MD-HX's own interlace engine but adds one frame of latency that must be budgeted into IMAG timing. Second, feed the converter a pre-scaled 1080p59.94 signal from the 4K source whenever possible, bypassing the 4K-to-HD step entirely. Third, when 12G fiber runs are already in place, insert a simple distribution amplifier with built-in downconversion before the MD-HX so the unit only handles HDMI or SDI format translation, not resolution change.
These adjustments change cable counts and connector access points. Integrators now spec larger wall boxes and deeper racks to accommodate the added DA or second converter. They also document exact firmware versions, because Decimator's 2.4.3 release altered vertical filter coefficients and reduced but did not eliminate the twitter on certain test patterns.
Looking ahead, the continued rollout of 1080p-native production switchers and the slow retirement of interlaced infrastructure should shrink the number of times an MD-HX must perform this particular conversion. Until then, field teams treat the unit as a format translator rather than a resolution engine on any job that mixes 4K acquisition with legacy 1080i distribution.
Field tests at two NFL stadiums last month quantified the twitter as a 12–18 dB rise in energy above 400 cph when 4K graphics plates hit the MD-HX. Operators also logged repeated A/B frame-order flips on animated lower-thirds, forcing editors to add post-fix de-interlace passes that erase the converter’s supposed cost advantage. Rental houses have begun tagging MD-HX units “1080p only” and routing any interlaced requirement to AJA or Teranex frames to protect their reputation.
Decimator support has acknowledged the pattern but states the MD-HX scaler was tuned for progressive workflows; a firmware branch addressing vertical filtering is promised for Q3 yet carries no published beta date. In the interim, several large integrators have standardized on a two-box cascade—first a low-cost 4K-to-1080p60 downconverter with proper low-pass filtering, followed by the MD-HX solely for format translation—accepting the added rack space and one-frame latency in exchange for artifact-free 1080i deliverables.
Looking further ahead, the gradual replacement of 1080i infrastructure with 1080p and 2160p-native routers will reduce exposure, yet the installed base of legacy switchers ensures the issue will linger through at least the 2026 season. Until then, careful signal-chain mapping and selective use of the MD-HX remain the only reliable safeguards.
