name: Install FFmpeg (Windows)
description: >-
  Download a pinned FFmpeg GPL build for Windows from BtbN/FFmpeg-Builds and put
  ffmpeg.exe / ffprobe.exe on PATH. We bypass `choco install ffmpeg` because
  the Chocolatey community feed regularly returns 503 / 504 / NuGet resolver
  errors with no retry, which makes it unsuitable as a CI dependency. From the
  consumer's perspective this is equivalent — `where ffmpeg` (the PR #336
  validation) and `findFFmpeg()` both pass.

inputs:
  release-url:
    description: >-
      URL of a BtbN/FFmpeg-Builds zip to install. Pinned to a specific
      autobuild tag so a new upstream nightly can't silently change encoder
      behavior under us. The asset filename embeds the git hash, so both
      the tag and the filename must be bumped together when upgrading.
    required: false
    default: https://github.com/BtbN/FFmpeg-Builds/releases/download/autobuild-2026-04-30-13-44/ffmpeg-N-124278-gcc3ca17127-win64-gpl.zip
  max-attempts:
    description: Max download attempts before failing.
    required: false
    default: "8"

runs:
  using: composite
  steps:
    - name: Install FFmpeg from BtbN/FFmpeg-Builds
      shell: pwsh
      run: |
        $ErrorActionPreference = 'Stop'

        $url = '${{ inputs.release-url }}'
        $maxAttempts = [int]'${{ inputs.max-attempts }}'

        $zip = Join-Path $env:RUNNER_TEMP 'ffmpeg.zip'
        $dir = Join-Path $env:RUNNER_TEMP 'ffmpeg'
        New-Item -ItemType Directory -Force -Path $dir | Out-Null

        for ($attempt = 1; $attempt -le $maxAttempts; $attempt++) {
          Write-Host "--- Downloading ffmpeg from BtbN/FFmpeg-Builds (attempt $attempt/$maxAttempts) ---"
          try {
            Invoke-WebRequest -Uri $url -OutFile $zip -UseBasicParsing
            break
          } catch {
            Write-Warning "Download failed: $($_.Exception.Message)"
            if ($attempt -eq $maxAttempts) { throw }
            Start-Sleep -Seconds (30 * $attempt)
          }
        }

        Write-Host "--- Extracting ffmpeg ---"
        Expand-Archive -Path $zip -DestinationPath $dir -Force

        $bin = Get-ChildItem -Path $dir -Recurse -Filter 'ffmpeg.exe' | Select-Object -First 1
        if (-not $bin) { throw "ffmpeg.exe not found after extracting $url" }

        Add-Content -Path $env:GITHUB_PATH -Value $bin.Directory.FullName

        Write-Host "--- ffmpeg sanity check ---"
        & $bin.FullName -version | Select-Object -First 1