process_gopro_footage.bat

@ECHO OFF
echo You must download ffmpeg to use this batch file.
echo https://ffmpeg.zeranoe.com/builds/
echo .
echo A command prompt will pop up and churn for a while depending on the size
echo .
echo Add the list of files to concatenate to mylist.txt with "file " in front of the name. One per line.
echo Example:
echo file GOPR2307.MP4
echo file GP012307.MP4
echo file GP022307.MP4
echo .
echo This batch file will automatically concatenate, speed up the video 4x, and run extensive stabilization on the video.
echo .
echo Temporary files are in D:\tmp
pause

rem Get start time:
for /F "tokens=1-4 delims=:.," %%a in ("%time%") do (
   set /A "start=(((%%a*60)+1%%b %% 100)*60+1%%c %% 100)*100+1%%d %% 100"
)
echo Start time: %time%
ls %tmp%\*.mp4

echo #############################
echo ##### RUN CONCATENATION #####
echo #############################
mkdir D:\tmp
ffmpeg -f concat -safe 0 -i mylist.txt -c copy %tmp%\concatenated.mp4


echo #########################################################
echo ##### RUN STABILIZATION DETECTION (Create TRF file) #####
echo #########################################################
ffmpeg -i %tmp%\concatenated.mp4 -vf vidstabdetect=stepsize=6:shakiness=5:accuracy=15:result=concatenated.trf -f null -
echo ######################################
echo ##### RUN STABILIZATION ON VIDEO #####
echo ######################################
ffmpeg -i %tmp%\concatenated.mp4 -vf vidstabtransform=input=concatenated.trf:zoom=1:smoothing=30,unsharp=5:5:0.8:3:3:0.4 -vcodec libx264 -preset slow -tune film -crf 18 -acodec copy %tmp%\stabilized_1x_speed.mp4

echo ##########################
echo ##### RUN SPEEDUP 2X #####
echo ##########################
ffmpeg -i %tmp%\stabilized_1x_speed.mp4 -filter_complex "[0:v]setpts=0.5*PTS[v];[0:a]atempo=2.0[a]" -map "[v]" -map "[a]" %tmp%\concatenated_speedy_2x.mp4
echo ###########################################
echo ##### RUN SPEEDUP 2X (to be 4x speed) #####
echo ###########################################
ffmpeg -i %tmp%\concatenated_speedy_2x.mp4 -filter_complex "[0:v]setpts=0.5*PTS[v];[0:a]atempo=2.0[a]" -map "[v]" -map "[a]" %tmp%\concatenated_speedy_4x.mp4
echo ###########################################
echo ##### RUN SPEEDUP 2X (to be 6x speed) #####
echo ###########################################
ffmpeg -i %tmp%\concatenated_speedy_4x.mp4 -filter_complex "[0:v]setpts=0.5*PTS[v];[0:a]atempo=2.0[a]" -map "[v]" -map "[a]" concatenated_speedy_6x.mp4
echo ***** ALL DONE! *****

rem Get end time:
for /F "tokens=1-4 delims=:.," %%a in ("%time%") do (
   set /A "end=(((%%a*60)+1%%b %% 100)*60+1%%c %% 100)*100+1%%d %% 100"
)

rem Get elapsed time:
set /A elapsed=end-start

rem Show elapsed time:
set /A hh=elapsed/(60*60*100), rest=elapsed%%(60*60*100), mm=rest/(60*100), rest%%=60*100, ss=rest/100, cc=rest%%100
if %mm% lss 10 set mm=0%mm%
if %ss% lss 10 set ss=0%ss%
if %cc% lss 10 set cc=0%cc%
echo #############################################################################################
echo ##### Processing stabilization and outputting stabilized video took %hh%:%mm%:%ss%,%cc% #####
echo #############################################################################################

echo Press Ctrl+C or close this window to skip file cleanup.
echo If you press any other key, the temporary files will be deleted.
pause
del %tmp%\concatenated.mp4
del %tmp%\stabilized_1x_speed.mp4
del %tmp%\concatenated_speedy_2x.mp4
del %tmp%\concatenated_speedy_4x.mp4

Stabilizing before speeding up much helps it not generate erroneous stabilizations.

I found especially moving shadows would confuse the algorithm when sped up.