libavcodec wrapper for on-the-fly encoding of video from individual frames

I need to make a wrapper for libavcodec library for on-the-fly encoding of video from individual frames. There is a LabVIEW based system that generates image frame data at ~40fps. I'd like to be able to stream this data to a solution that till on-the fly add frames to libx264 encoded video. Currently I save frames as images and use following ffmpeg command: ffmpeg -y -report -f -image2 -framerate 40 -pattern_type sequence -i %[login to view URL] -vcodec -libx264 -crf 30 -preset fast -r 40 OutputDirectoryName/[login to view URL] I want to avoid such post processing, as well as necessity of saving individual frames as images). Therefore I need following api: start(filename, framerate) - initializes video codec and prepares system for adding images to video addFrame(*data) - add a frame to video "on the fly" as known structure of fixed resolution finish() - closes the file and cleans up I'd like to start encoding process, provide the process with frame data one by one (asynchronously), and finalize the encoding.