HDMI to SDI with MD-HX and MD-LX: format, scaling and output routing

The MD-HX format is correct, but the output is not using the scaler

The MD-HX 1.5 manual, printed pp. 3–5 / PDF pp. 4–6, separates SDI OUT SOURCE from DUC Source and Scaling > Output Format. The 2.0 manual, printed pp. 5–8 / PDF pp. 6–9, retains that separation, using DUC/TPG Source and Scaling/TPG. Selecting Output Format configures the scaler; you still need to confirm that the output in use takes its signal from Scaler.

Off-air, first record Input Status and the settings in the table. To convert an HDMI input to SDI, check that HDMI IN is the scaler source and Scaler is selected for SDI OUT SOURCE. Choose an Output Format the receiver supports and verify the received signal there. HDMI OUT SOURCE is a separate setting: a correct HDMI picture does not verify the SDI output.

Both manuals also document Output 1 is loop: 1.5, printed p. 4 / PDF p. 5, and 2.0, printed p. 7 / PDF p. 8. If output pair 1 copies the SDI input, that connector does not verify the scaler format. Identify the BNC in use and check the destination after changing the setting.

Identify the MD-HX serial prefix and firmware before following a setup procedure

The Decimator product page cited here directs serial prefixes CLA, CLB and CLC to manual 1.5, and CLD, CLE and CLF to 2.0. The 2.0 heading also specifies CLD/E/F. Read the label and record the installed firmware; the serial prefix identifies the relevant documentation but does not establish that the unit already has newer features.

Use the control names shown on that unit. For example, DUC Source and DUC/TPG Source belong to different layouts. Version 2.0 also includes a test-pattern generator and overlays. If you test with an internal pattern, confirm afterward that the actual source is restored and those test aids are removed from program.

The 2.0 manual, printed p. 3 / PDF p. 4, documents VESA formats on the HDMI input. Its Output Format list, printed p. 8 / PDF p. 9, lists scaler outputs separately. Support for a computer input does not make every PC resolution available as an SDI output. Check both lists before planning a 16:10 presentation.

Scaler source, format and reference serve different purposes

DUC REF in manual 1.5, printed p. 4 / PDF p. 5, and DUC/TPG REF in 2.0, printed p. 6 / PDF p. 7, offer SOURCE, FREE-RUN, SDI IN and HDMI IN. FREE-RUN is described as operation without a reference; 2.0 clarifies that it allows the scaler output to continue without an input present. That state does not verify that the speaker's content is arriving.

For the test, record which reference the system requires and whether the selected signal is present. Check this separately from the picture source. If you test FREE-RUN to compare a path, check received format, content, motion and synchronization; do not make it a default setting for every switcher.

Before using an external reference, check the receiver's requirements and configuration. FREE-RUN does not establish genlock synchronization with an AV-HS410.

Two MD-LX units and a 16:10 projector: compare signal and framing

If direct HDMI fills the picture but the MD-LX chain makes it smaller, compare the received format and framing on both paths.

The MD-LX Brochure V1.0, ©2017–2023, page 1, lists direct HDMI/SDI routes and their supported formats. It does not document a scaling or frame-rate conversion block like the MD-HX. To change format, choose equipment that documents that function; for the MD-LX, check that both source and destination support the signal being carried. A 16:10 projector alone does not establish a native 1920×1200 output.

Prepare a test pattern with a visible border and a circle. Record the signal detected at the projector and compare direct HDMI with the full chain using the same content. Note picture width, bars, cropping and circle distortion. If the received signals differ, work backward to locate the format change; if they match, check that input's settings in the exact projector manual.

If a direct connection produces a picture but the converter path fails, compare formats and settings at each stage. Identify the projector and save its configuration before considering an aspect-ratio menu or reset.

Identify every output and test sample

In the blank converter and scaler worksheet, record the source, scaler, reference, output and connector in use. Save a sample before and after each change, along with the settings needed to restore the starting point.

For a talk or conference, check fine text and edges; for a multicamera production or concert, add motion and audio. The MD-HX manuals state that changes affect the signal as you scroll through parameters, so compare settings off-air. At the end, check that the receiver is getting the actual source.

The camera HDMI guide distinguishes the recorded file from the live output. For screen size and room content, see event video and screens. The video processing plan needs to include the format required by each destination and where each conversion will happen.

Switching laptops while maintaining the capture format: an MD-HX test

Identify the serial prefix and firmware as described above. In 1.5, PDF pp. 4–6 / printed pp. 3–5, use DUC Source and Scaling > Output Format; in 2.0, PDF pp. 6–9 / printed pp. 5–8, use DUC/TPG Source and Scaling/TPG > Output Format. For an HDMI source, verify HDMI IN as the scaler input, the format agreed for the capture device, and Scaler on the output in use. Check Output 1 is loop if the cable uses that SDI output pair.

The 2.0 manual, PDF p. 7 / printed p. 6, explains that FREE-RUN allows the scaler output to continue without an input. The 1.5 manual, PDF p. 5 / printed p. 4, defines it as operation without a reference. Signal continuity does not promise replacement content, switching without black frames or synchronization with another system. First confirm the reference required by the setup.

Off-air, record H and D in Input Status and the format received by the capture device with each laptop, during disconnection and when the next laptop connects. If D maintains the selected format but capture is lost, save the receiver state to investigate that part of the path. If the physical output changes format, check output source and loop-through; D alone does not verify what leaves the BNC.

Complete the source-change worksheet and the capture and format-change diagnosis (Spanish guide). In the video processing plan, mark the conversion point and each destination. Check actual picture, motion, framing and audio when content returns; the manuals state that parameter changes affect the output as you scroll through them.

HDMI return without program audio: check the MD-HX audio pairs

Manuals 1.5, printed p. 7 / PDF p. 8 and 2.0, printed p. 11 / PDF p. 12 document Audio > HDMI Out Pair 1–4 and SDI Out Pair 1–8. Each selector takes a source pair or Off. To prepare HDMI without audio, record all four HDMI Out Pair settings and test Off on each, preserving the SDI Out Pair settings. Do not consider the path muted just because the first pair is Off.

Before comparing, identify the video route and physical connector. The Flow Chart in 2.0, printed p. 4 / PDF p. 5, shows an SDI loop-through path from the input; check that connector separately. Processed-pair selections do not verify what an active loop carries or replace a measurement at the receiver.

Check the HDMI return first, then SDI program: use the same source with identified picture and audio, before and after the change. Verify that the mix-minus (n-1) interface still delivers the agreed content and that the remote voice does not return over HDMI. Muting that branch does not configure the interface mix or establish that no other return path exists.

The hybrid panel guide helps prepare the mixes. Record each output in the blank MD-HX audio worksheet. Identify the serial prefix, firmware and receiver before testing; save the initial selections so you can restore them.

Remapping a pair and swapping its two channels are different tasks

Identify the exact converter and firmware. MD-HX scaling functions do not apply to every HDMI/SDI converter.

In MD-HX 1.5 Audio and 2.0, selection is by pair. For example, HDMI Out Pair 1 can take Group 1 Pair 2. That selects a different pair; those menus do not document reversing the two channels within it. If Center/LFE are swapped within a pair, do not present pair remapping as a confirmed fix.

Prepare a channel-identification signal and record what each destination receives. Compare the captured file and live monitoring as separate results. If the order changes, locate the affected segment using input and output records before correcting the file. A post-production correction does not verify the return heard during the event.

Desktop Video options depend on the model and version; they are not shared by every DeckLink, Intensity or UltraStudio. This section's diagnosis is limited to the MD-HX pair selectors.

HDMI OUT TYPE, two or eight channels, and restoring actual content

HDMI OUT TYPE appears in 1.5, printed p. 4 / PDF p. 5 and 2.0, printed p. 6 / PDF p. 7. It separates DVI RGB444 from HDMI RGB444, YCbCr444 or YCbCr422 modes with 2C or 8C. Record the mode compatible with the receiver and the HDMI Out Pair selections in use. Selecting a two-channel mode is not documented there as a downmix of a 5.1 mix.

For units covered by manual 2.0, Scaling/TPG, printed pp. 8–9 / PDF pp. 9–10 documents SDI Out Test Aud(io) and HDMI Out Test Au(dio), with Off and test tones. If used, return them to Off before checking actual content. Audio Meters, printed p. 12 / PDF p. 13, allows overlays by group; record where they are applied and remove them when finished.

A received tone verifies that test path; the event source, its channels and the final destination still need checking. After switching laptops, verify a known voice or track, channel identification, picture and continuity at every output. Save the result and the restored settings, including test aids.

The manuals warn that changes affect the signal as you scroll through parameters. Make these comparisons off-air. To prepare video processing and distribution, add the audio map to the signal diagram and the source-change worksheet above.