I have created my own software to generate SWF files from images. So I run my program, and it generates an SWF file. The problem is when I load the resulting SWF file into Flash Player the image doesn't appear (though it does correctly scale the size of the flash player window based on the SWF header FrameSize field). I believe I have all required tags in my SWF file to accomplish what is needed. I have already read through the SWF file specification version 19 (the latest version). But my SWF file isn't working in Flash Player.
Is there any kind of debugger or "file specification validator" I can use, that will analyze my SWF file, and tell me where the file is broken?
We don't provide any validation tools for determining whether or not a SWF is well-formed (except for Flash Player itself).
You might try some of the third-party SWF decompilers, like SWFWire Inspector or SWF Investigator to see if you can figure out how that SWF is actually getting interpreted.
You might also think about creating a comparable SWF with Animate CC as a baseline for comparison.
I'm curious about the motivation for doing this. It's super interesting, but it seems like a convoluted way to load an image.
I just remembered something. There's a debugger version of Flash Player on the downloads page for Flash Player (the extra downloads page, that also includes older versions of Flash Player). Might that be what I need? What does this debugger version do exactly?
It provides debugging capabilities (breakpoints, etc.) for debugging content in Adobe Animate. It still assumes well-formed content.
I don't think you're going to get much help on this from Adobe. We just don't have tools to make this easy.
There are a number of open-source projects that already generate SWF files. I think you're going to be better off looking at one of the more mature projects or asking for expertise from someone that has written a SWF compiler in one of those communities.
Also, make sure you are aware of the announced end of Flash Player in 2020, with some browsers probably sooner.