downsample png sequence to match mpeg artefacts

[Marc Nibor]

believe it or not. this crappy mpeg is everything that’s available. period! ; ) i made every effort to get my hands on the original source. it doesn’t exist anymore.
so the matchmove had to be done from the crap version too. it was handtracked frame by frame, because no tracker could pick up the features. it even was a double track – moving camera plus moving object.
and the 3D portion of the project was also quite a hassle, cause ontop of of all the other problems there was some really weird lens distortion that had to be matched.

well, i know it’s insane… but on the other hand it’s mighty satisfying to succeed in the end cause everyone else turned this thing down because they said it’s impossible.

anyhow… the only major thing that is left for now is the downsampling part.

i know that somehow i will solve this problem too, but i thought i’d save myself a couple hours of trying and ask this question here first.

any ideas ? : )

mdm

[Brendan Coots]

Here’s few different things you can try:

1. Scale the entire PNG 3d sequence down to like 50% of its original size and render it out to a jpg sequence set to something like 70% quality. Then pull it back in to AE and scale back up to its original size. This should introduce some blocky artifacts. You will need to experiment with the different values above to get proper results.

2. Effect>Stylize>Mosaic in limited doses will complement the above technique to give you more blocky artifacting

3. Use the Match Grain feature (Effects>Grain>Match Grain) on your 3d sequence to match the grain of the source footage. This really works better for matching actual grain, but in this case it might help you match in the 3d plate.

[Roland R. kahlenberg]

I would render out a short segment of the 3D stuff with varying compression settings for MPEG-2 output. One of these should be close enough to what you’re trying to match. I would start at 5Mbits and work downwards to 1.5Mbits.

HTH
Roland Kahlenberg

https://www.broadcastGEMs.com – AE Project Files
https://www.myspace.com/rorkrgbspace

[Marc Nibor]

thanks alot for both suggestions,

beenyweenies: the mosaic effect does an excellent job after some tweaking! it seems like this is a great solution in this case! : )

beenyweenies and RoRK: there is one part in both of your suggestions about the downsampling which i don’t really understand.
if i downsample the footage to either jpg or MPEG2 format then my transparency from the png sequence is gone, right? or am i missing something?

here once again what i have: there is a lowquality mpeg footage as base. “ontop” of that are the 3Drendered parts (the png sequence) which will be attached to the roof of the vehicle which can be seen in the mpeg. the png sequence is of course transparent so that i see only the rendered parts which should create the illusion of something that is attached ontop of the vehicle in the final movie.

the whole problem was to downsample the png sequence so that at some point the artefacts show up. the fileformat for this doesn’t really matter. i just don,t know how to do that and keep the transparency.

if there is a missunderstanding or i am just not getting your point then please let me know.

as i said, the mosaic will probably be good enough for now, but i am very curious how the other solution would work.

thanks alot

mdm