I just attended the Watkins Glen opening day for the second year. It was, again, a blast.

I made some slight adjustments to my ffmpeg assembly procedure from last year.

Dashcam saves video in 5-minute chunks

Instead of creating .list files, I simply used a pipe as input:

for fo in AMBA091*; do echo file "$fo"; done \
    | ffmpeg -f concat -i - -c copy Front-Track1.mov

Front and Rear videos need to be combined

Much like last year, I made short samples to confirm if any offsets needed to be done. However, I decided to move the video to the bottom-right corner to cover the timestamps, since they were incorrect on some videos (well, correct. Just not for this time zone)

Math is basically the same as before for scaling, but instead of a left offset of 70, we want a right offset of 70, but using left-hand coords. Which works out to:

1920 - 480 - 70 = 1370

After the usual synchronization samples were made, it was time to perform the final assembly.

I used a slightly different file layout this time, keeping the front and rear videos separated. I used a loop to assemble them into a combined video:

$ time for FILE in Track{1,2,3}; do ffmpeg -i Front/DCIM/*${FILE}*mov -vf "movie=Rear/DCIM/Rear-${FILE}-cat.mov, scale=480:-1 [inner]; [in][inner] overlay=1370:740 [out]" -strict -2 ${FILE}.mov; done

You're going to want a good CPU. This is the execution time for just under 48 minutes of video on an Intel i5-2520M:

real    172m2.494s
user    619m51.494s
sys     1m37.383s

Final result

You can see the resulting videos on youtube: Part 1, Part 2, and Part 3. Part 3 has some bad sound. I'm not sure why.