Using FFmpeg -lavfi to calculate the SSIM of each frame I would like to be able to take a single video, run it through ffmpeg, and have it spit out a log containing the SSIM of each frame with respect to the previous - that is, I want the SSIM scores comparing the previous frame to the current one. 

I am attempting to do so by running ffmpeg with the same video input twice, with the second input skipping ahead by one frame.

ffmpeg -i .\a.mp4 -i .\a.mp4 -filter_complex "[1:v]select=gte(n\,1)[f]" -map 0:v:0 -map "[f]" -lavfi ssim -f null -


When attempting to run this, I am given the error:

Cannot find a matching stream for unlabeled input pad 1 on filter Parsed_ssim_0


Is there a way I can correct this so that the second input skips one frame and both are run through -lavfi ssim?
You have to perform all filtering in a single filtergraph.

ffmpeg -i .\a.mp4 -i .\a.mp4 -filter_complex "[0:v]setpts=N/FR/TB[v0];[1:v]select=gte(n\,1),setpts=N/FR/TB[v1];[0v][1v]ssim=f=stats.log" -f null -