30fps Gif to 20fps apng

這應該是最重要的目標

透過ffmpeg砍fps
ffmpeg -i input.gif -r 20 -vframes 20 frame_%d.png
APNG Assembler
apngasm output.png frame*.png -l4

bat

@echo off
setlocal enabledelayedexpansion

rem Check if files were dragged onto the script
if "%~1"=="" (
    echo Please drag and drop GIF files onto this script.
    pause
    exit /b 1
)

rem Loop through all dragged files
:process_files
if "%~1"=="" goto end_process

rem Get the full path of the dragged file
set "gif_path=%~1"

rem Extract file name and directory
set "file_name=%~n1"
set "gif_folder=%~dp1"

rem Change to the GIF folder
cd /d "%gif_folder%"

rem Step 1: Convert GIF to PNG frames with 20fps
ffmpeg -i "%gif_path%" -r 20 -vframes 20 "%file_name%_frame_%%d.png"

rem Step 2: Assemble PNG frames into APNG
apngasm "%file_name%.apng" "%file_name%_frame_*.png" -l4

rem Clean up PNG frames
del "%file_name%_frame_*.png"

shift
goto process_files

:end_process
echo Conversion complete!
pause

Update Line 貼圖只吃 300x270 其中一邊限定270

-filter_complex

padding
- "[0:v] pad=w=300:h=270:x=(ow-iw)/2:y=(oh-ih)/2:color=#00000000, split [a][b]; [a] palettegen=max_colors=32 [p]; [b][p] paletteuse"
scale
- "[0:v] scale=-1:270, split [a][b]; [a] palettegen=max_colors=32 [p]; [b][p] paletteuse"

palettegen=max_colors=32 (色彩深度? 反正就是顏色幾種用越多越大 )

REF
https://superuser.com/questions/1049606/reduce-generated-gif-size-using-ffmpeg https://stackoverflow.com/questions/35603464/transparency-is-gone-while-resizing-scaling-gif-using-ffmpeg

這我沒試過都是GPT寫的

PS1

param (
    [string[]]$gif_paths
)

if (-not $gif_paths) {
    Write-Output "Please drag and drop GIF files onto this script."
    pause
    exit
}

foreach ($gif_path in $gif_paths) {
    # Extract file name without extension and directory
    $file_name = [System.IO.Path]::GetFileNameWithoutExtension($gif_path)
    $gif_folder = [System.IO.Path]::GetDirectoryName($gif_path)

    # Change to the GIF folder
    Set-Location $gif_folder

    # Step 1: Convert GIF to PNG frames with 20fps
    $frame_pattern = "$file_name`_frame_`%d.png"
    Start-Process ffmpeg -ArgumentList "-i", $gif_path, "-r", "20", $frame_pattern -NoNewWindow -Wait

    # Step 2: Assemble PNG frames into APNG
    $output_apng = "$file_name.apng"
    Start-Process apngasm -ArgumentList $output_apng, "$file_name`_frame_*.png", "-l4" -NoNewWindow -Wait

    # Clean up PNG frames
    Remove-Item "$file_name`_frame_*.png"
}

Write-Output "Conversion complete!"
pause

以後可能用的到 https://www.npmjs.com/package/sharp-apng#encoderoptions

Line Animation Sticker

30fps Gif to 20fps apng

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