4K camera chains now appear in more mid-tier venues, yet many production switchers and distribution amplifiers still expect 1080i59.94. The Decimator MD-HX remains a common choice for format and frame-rate conversion because of its compact 1RU footprint and low per-unit cost, often under $1,200. Integrators therefore encounter its scaling behavior more often when mapping 3840×2160 59.94p sources into legacy 1080i infrastructures.
The MD-HX uses a single-pass polyphase scaler followed by a field-combiner for interlaced output. When the input is 4K59.94 progressive, the scaler first reduces horizontal and vertical resolution by a factor of two, then applies temporal filtering to create the 59.94 fields. Installers report visible ringing along high-contrast edges and moiré on fine detail such as fabric patterns or LED wall pixels. These artifacts become most noticeable after the signal passes through additional distribution stages or compression encoders that amplify the ringing.
Real-world economics push teams to retain the MD-HX rather than replace it outright. Swapping to a higher-end cross-converter with dedicated de-interlace hardware can add $3,000–$4,000 per channel plus rack space and power. In a 12-input house-of-worship install, that difference quickly exceeds the original equipment budget, so technicians instead insert inexpensive noise-reduction or sharpening stages downstream to mask the worst effects.
Workflow Adjustments Observed in Current Projects
Technicians now pre-scale critical 4K sources to 1080p59.94 in the camera menu or at an upstream 12G-SDI router before the MD-HX ever sees the signal. This reduces the scaling ratio and eliminates most moiré, though it sacrifices one generation of resolution. Some crews also lock the MD-HX output to 1080p instead of 1080i when the downstream switcher accepts progressive input, trading broadcast compatibility for cleaner imagery. Cable length and clock jitter have been shown to worsen the artifacts, so recent jobs specify 6 Gbps-rated coax or fiber extenders even for runs under 30 m.
Forward planning now includes budgeting for at least one higher-performance converter per venue or moving selected signal paths to SMPTE 2110 over managed networks. Either approach reduces reliance on the MD-HX for primary downconversion while preserving it for monitoring and backup duties where the artifacts remain acceptable.
Testing with standard test patterns such as the BBC QE-1 and ChromaDuMonde reveals that the MD-HX introduces approximately 1.5 dB of overshoot on vertical transitions when operating at the 2:1 reduction ratio required for 4K-to-1080 conversion. This overshoot manifests as a faint halo that becomes objectionable once the signal encounters the mild compression typical of NDI or SRT contribution links. Field engineers have begun carrying portable 12G-SDI analyzers to quantify edge energy before finalizing rack layouts.
Another emerging tactic involves feeding the MD-HX with 1080p59.94 derived from a camera’s 4K sensor but cropped and scaled internally, thereby shifting the burden of resolution management away from the Decimator’s single scaler stage. Early adopters note that this approach also improves lip-sync margins because the camera’s internal processing already accounts for the added delay. In venues where multiple MD-HX units share a common reference, locking all units to the same genlock source further reduces temporal misalignment between fields, although it does not eliminate the spatial ringing.
Manufacturers of competing converters have responded by highlighting multi-pass scaling engines and adaptive diagonal filters in their product literature, positioning these features as direct remedies to the MD-HX limitations. While the price gap remains significant, the performance delta is now quantifiable on side-by-side monitors, prompting some rental houses to retire older MD-HX inventory in favor of units that handle 4K-native downconversion more gracefully. Over the next two years, the continued proliferation of 4K sources will likely accelerate this replacement cycle even in budget-conscious segments of the market.
