Convert video file to TIFF with ffmpeg.dll or avcodec.dll? Is "on-the-fly" possible?

Question

I want to create a program, which gets a video-file from Qt, converts that video file to TIFF-files and sends them to an algorithm which handles these TIFF-Files.
My questions:

• is it possible with ffmpeg or avcodec not to convert a video-file to TIFF-files first on harddrive and send them to the algorithm after that, but to convert frame for frame and send it to the algorithm right away?
• The more important question: Is it possible to do that not with an external process with ffmpeg.exe, but with ffmpeg.dll? Or is it only possible with avcodec.dll? (It doesn't have to be "on-the-fly" like at my point above) How can I create a ffmpeg.dll with header and lib?

Answer 1

Surely, it is possible to decode video file using avcodec library and encode each frame to TIFF format. Here and here you could find tutorial on how to decode video.