Can I change glow values based on values in a CSV file?

[.Ava.]

Heya.

Am I able to modulate glow intensity based on values I have in a CSV file? I have a CSV file where I have the luminance value of each frame, and I want to be able to make the glow more intense when the frame is darker, and less intense when the frame is brighter.

I would like AE to somehow reference the CSV file and change the glow property based on the frame number and the luminance level in the CSV.

Is this possible?

Thanks.

[Dan Ebberts]

What does your CSV file look like?

[.Ava.]

There's many thousands of values, but here's a snippet:

Frame,Luminance,Cut
0,65.07,X
6,64.38,
12,63.55,
18,62.07,
24,61.25,
30,60.42,
36,61.15,
42,61.96,
48,62.44,X
54,62.94,
60,63.46,
66,64.56,
72,65.42,

And at the end of the CSV is:

Top 10 Brightest Frames
Rank,Frame,Luminance
1,4956,72.05
2,6354,71.95
3,4950,71.93
4,9096,71.92
5,4962,71.66
6,6384,71.65
7,9102,71.62
8,6390,71.61
9,18150,71.59
10,9126,71.45

Top 10 Darkest Frames
Rank,Frame,Luminance
1,36090,53.20
2,36096,54.48
3,29262,55.44
4,36102,55.53
5,48714,55.92
6,13722,56.10
7,51234,56.18
8,50940,56.25
9,45720,56.26
10,29256,56.2

The top 10 values are so I can go to the lightest and darkest frames to sample what the glow intensity looks like at it's most extreme values.

[.Ava.]

Oh, I should clarify, the "Cut" are the frames where a jump-cut occurs.

[Dan Ebberts]

This probably won't exactly fit your situation, but based on the info provided it should be helpful for you to try it. First, I think you'll need to truncate your CSV file so that it only has the first set of data (Frame, Luminance and Cut). Import that file into AE (I've assumed the file name is "Glow.csv"). Drag the file into your comp timeline, so the expression will able to retrieve the number of rows. Then apply this expression wherever you need to retrieve the current, interpolated luminance value:

numRows = thisComp.layer("glow.csv")("Data")("Number of Rows");
curFrameVal = timeToFrames(time);
prevFrameVal = nextFrameVal = 0;
for (i = 0; i < numRows; i++){
  prevFrameVal = nextFrameVal;
  nextFrameVal = footage("glow.csv").dataValue([0,i])
  if (curFrameVal <= nextFrameVal) break;
}
if (i >= numRows){
  footage("glow.csv").dataValue([1,numRows-1]);
}else{
  nextLumVal = footage("glow.csv").dataValue([1,i]);
  prevLumVal = i == 0 ? nextLumVal : footage("glow.csv").dataValue([1,i-1]);
  linear(curFrameVal,prevFrameVal,nextFrameVal,prevLumVal,nextLumVal);
}

[.Ava.]

Oh wow, so I can import CSV files into AE and even put them in the timeline? Do I need to put it in the timeline, or can it be from the project bin? Thanks so much.

[Dan Ebberts]

You can leave them in the project bin, but puting them in the timeline gives you access to the number of rows. Without that, you need to craft your expression so that it doesn't run off the end of the data and cause an error. That wouldn't be an issue if the last frame number is always beyond the end of your comp. Otherwise you might have to do a try/catch to catch the error locally (or use some capability I'm not aware of--which is certainly possible).