convert pixiv ugoira to webp

pixiv_to_webp.ps1

param (
    [Parameter(Mandatory = $true)]
    [string]$PixivZipPath
)

# 检查 ffmpeg 是否可用
function Check-FFmpeg {
    $ffmpegPath = Get-Command ffmpeg -ErrorAction SilentlyContinue
    if (-not $ffmpegPath) {
        Write-Error "ffmpeg is not installed or not in PATH."
        exit 1
    }
}

# 生成独立的临时目录用于解压缩
function Create-TempFolder {
    $baseTempPath = [System.IO.Path]::GetTempPath()  # 跨平台的临时路径
    $tempFolder = [System.IO.Path]::Combine($baseTempPath, [System.Guid]::NewGuid().ToString())
    New-Item -ItemType Directory -Path $tempFolder | Out-Null
    return $tempFolder
}

# 解压缩Pixiv动图文件
function Unzip-File($zipFilePath, $destinationFolder) {
    Add-Type -AssemblyName System.IO.Compression.FileSystem
    [System.IO.Compression.ZipFile]::ExtractToDirectory($zipFilePath, $destinationFolder)
}

# 解析Pixiv文件名获取帧间隔时间
function Get-FrameInterval {
    param (
        [string]$filename
    )
    if ($filename -match '@(\d+)ms') {
        return [int]$matches[1]
    } else {
        Write-Error "Cannot find frame interval in filename: $filename. Assuming 100ms as default."
        return 100
    }
}

# 将解压出来的图片转成webp动图
function Convert-ToWebp {
    param (
        [string]$inputFolder,
        [string]$outputWebpPath,
        [int]$frameInterval
    )
    
    # 获取所有 JPG 和 PNG 图片
    $imageFiles = Get-ChildItem -Path $inputFolder | Where-Object { $_.Extension -in '.jpg', '.png' } | Sort-Object Name

    if ($imageFiles.Count -eq 0) {
        Write-Error "No image files found in $inputFolder"
        exit 1
    }

    # 输出调试信息，查看文件名
    Write-Host "Found images:"
    foreach ($file in $imageFiles) {
        Write-Host $file.Name
    }

    # 计算帧率
    $frameRate = [math]::Round(1000 / $frameInterval, 2)
    Write-Host "Using framerate: $frameRate"

    # 使用 FFmpeg 合成 WebP 动图
    $ffmpegArgs = @(
        "-y",
        "-framerate", $frameRate,
        "-i", "$inputFolder/%06d.jpg",
        "-c:v", "libwebp",
        "-lossless", "0"         # 启用有损压缩
        "-qscale", "75"          # 设置质量 (0-100, 越高越好, 通常 75-95 是不错的范围)
        "-preset", "text"        # 预设 (default, photo, drawing, icon, text)
        "-method", "6"           # 编码方法 (0-6, 越高压缩越慢，质量可能更好, 4 或 6 通常较好)
        "-pix_fmt", "yuva420p",  # 使用 YUV 格式
        "-loop", "0",
        $outputWebpPath
    )

    Write-Host "Running ffmpeg with arguments: $($ffmpegArgs -join ' ')"

    # 执行 ffmpeg 命令
    try {
        $result = & ffmpeg @ffmpegArgs
        Write-Host "FFmpeg result: $result"
    } catch {
        Write-Error "FFmpeg command failed with error: $_"
    }
}

# 主程序
Check-FFmpeg

# 获取文件名用于解析帧间隔
$baseName = [System.IO.Path]::GetFileNameWithoutExtension($PixivZipPath)
$frameInterval = Get-FrameInterval -filename $baseName

# 创建临时文件夹
$tempFolder = Create-TempFolder

try {
    # 解压缩Pixiv Zip文件
    Unzip-File -zipFilePath $PixivZipPath -destinationFolder $tempFolder

    # 输出路径，设置为当前目录
    $outputWebpPath = [System.IO.Path]::ChangeExtension([System.IO.Path]::GetFileName($PixivZipPath), '.webp')
    $outputWebpPath = Join-Path -Path (Get-Location) -ChildPath $outputWebpPath

    # 转换为 WebP
    Convert-ToWebp -inputFolder $tempFolder -outputWebpPath $outputWebpPath -frameInterval $frameInterval

    Write-Host "WebP animation has been created at: $outputWebpPath"
}
finally {
    # 删除临时文件夹
    Remove-Item -Recurse -Force $tempFolder
}