@Stefano-Guandalini Blu-ray or DVD disc? You could try in Media Properties, General tab ticking "Reduce Interlace Flicker".

What should I do?

Not to use options of a former century anymore?

 

@j-v Stefano may have reasons for wishing to burn a disc. He came here for help not your sarcastic comments. By the way I still burn discs, in addition to putting videos on thumbdrives.

When showing (or burning) a perfectly flawless MP4 video created in Vegas Pro 19, in several places DVD Architect (build 84) creates an annoying flickering lasting a few seconds

Is there any similarity in the video at the points where the flickering occurs (e.g. source media, slow-motion, FX, etc)?

Does the render from Vegas Pro 19 match the project preferences that you are using in DVD Architect? For example, being in PAL-land I use 25 fps - but DVDA only has interlaced as a project property for 25 fps projects so I need to make the Vegas Pro render upper interlaced rather than progressive. Also, for HD I use an .avc render for use in DVDA.

Just to check, isn't DVD Architect build 84 in fact DVD Architect Studio that originally came with Sony Movie Studio? If indeed it is DVD Architect Pro it is likely to be version 5.0 which was released before the improved - from memory - version 5.2 and then version 6.0.

I've recently used an HD .avc render (mostly 4K original media) from Vegas Pro 19 and it rendered without a problem using DVDA Pro 6.0.

Thank you Dexcon and EricLZN (I will not expand on the comment by J-V although I am tempted...). To try to address some of the meaningful comments: 1)this was a DVD. I will try the suggestion; 2) no, there are no similarities between the segments involved; 3) yes, the render matched the project that was at 25fps, being taken from an old PAL video at 4:3; 4) I think the DVDA is 7.0 but cannot tell since it only says "build 84". Finally: out of frustration i went ahead and bought Cyberlink Power2go ($39) and burned a perfectly working DVD. But I still prefer the Vegas/Magix/Sony and will remain loyal to it :)

The last version of DVDA 7 is Build 100 https://www.vegascreativesoftware.info/us/forum/vegas-dvd-architect-update-3-build-100--115059/ I haven't checked the download link but anyway @Stefano-Guandalini it should be available from your Magix account. Like Build 84 the "About" screen only shows the build number not the version.

@Dexcon The Studio version was dropped a few years ago and the "Pro" version was provided with VMS. That's how I have DVDA 7.