The ffmpeg TOC file does not need to contain the list of files.

Here is how to test this for TIFF files:

1) render using options: ffmpeg / tif

2) for ease of use, put the files in /tmp/test/test%5d.tif   (so create /tmp/test directory first)

3) do the render and you will see that test%5d.tiff will contain ONLY:

 IMAGE2
# Frame rate: 29.970030
# Width: 352
# Height: 240

and all of the test00###.tiff files exist in the /tmp/test directory

4) now just add a video track and drag the test%5d.tiff from the Media folder of the Resources window and it works correctly

    or later just load /tmp/test%5d.tiff and it works.

Now for the interesting part, yesterday and this morning DPX was working on my builds and AppImages from October, November, and December UNTIL I switch to using TIFF instead of DPX.  Now DPX no longer works so there is something going on and I have not figured it out yet.

  Also, yesterday, I tried it on Arch dated 10/30/2020 and DPX did not work (have to check to see if TIFF does).  The correct contents of the dpx file is:

IMAGE2
# Frame rate: 29.970030
# Width: 352
# Height: 240

with NO listing of each individual dpx files needed. 

I tried to do a dpx render; it came with all the images and a TOC file
that doesn't have the links to the images. Then I created a second TOC
file using imagelist.sh. A TOC came up with the links to the dpx
images. This doesn't work when imported into CinGG; it's obvious
because imagelist.sh uses only jpeg images and not dpx.
So I took the first TOC and pasted in the links from the second TOC.
This TOC+ works in CinGG and Natron; it doesn't work in Kdenlive and
OpenShot (but I don't know if these programs support DPX).