vid2gif.bat

@ECHO off
REM since GIFs can only use 256 colors, ffmpeg analyzes the image to determine the best 256 colors to use
REM an output palette image is created in memory and passed to a separate ffmpeg process during conversion
REM see http://blog.pkh.me/p/21-high-quality-gif-with-ffmpeg.html

REM check if ffmpeg is present, download from zeranoe if not.
SET ffmpeg="%~dp0\ffmpeg-4.0-win64-static\bin\ffmpeg.exe"
SET zip_file="%appdata%\ffmpeg.zip"
If NOT EXIST %ffmpeg% (
    ECHO.
    ECHO ffmpeg cannot be found, downloading...
    ECHO.
    powershell -Command "(New-Object Net.WebClient).DownloadFile('http://ffmpeg.zeranoe.com/builds/win64/static/ffmpeg-4.0-win64-static.zip', '%zip_file%')"
    powershell -Command "Add-Type -AssemblyName System.IO.Compression.FileSystem;[System.IO.Compression.ZipFile]::ExtractToDirectory('%zip_file%', './')"
    del %zip_file%
)

REM need to set this so variables can be set inside if statement
Setlocal EnableDelayedExpansion

REM default values
SET start=0
SET end=9999
REM set to 1 to prompt for start/end time of video.. by default, converts entire file
IF 1 == 1 (
    SET /p start="Enter start time in seconds s.S (default is start of video)"
    SET /p end="Enter end time in seconds s.S (default is end of video)"
)

SET filters="fps=20,scale=iw:-1:flags=lanczos"
!ffmpeg! -y -ss !start! -to !end! -i %1 -vf !filters!,palettegen -f image2pipe -vcodec png - | ^
!ffmpeg! -y -ss !start! -to !end! -i %1 -i - -filter_complex "!filters! [x]; [x][1:v] paletteuse" "%~dpn1.gif"
PAUSE