Merge pull request opencv#11733 from alalek:opencv_ffmpeg_download_ps1

.gitattributes

@@ -81,6 +81,8 @@ org.eclipse.jdt.core.prefs -text whitespace=cr-at-eol merge=union
 *.cmd       text eol=crlf
 *.cmd.tmpl  text eol=crlf
 *.dsp       text eol=crlf -whitespace
+*.ps1       text eol=crlf
+*.ps1.in    text eol=crlf
 *.sln       text eol=crlf -whitespace
 *.vcproj    text eol=crlf -whitespace merge=union
 *.vcxproj   text eol=crlf -whitespace merge=union

3rdparty/ffmpeg/ffmpeg-download.ps1.in

@@ -0,0 +1,63 @@
+$url = "https://raw.githubusercontent.com/opencv/opencv_3rdparty/@FFMPEG_BINARIES_COMMIT@/ffmpeg/opencv_ffmpeg_64.dll"
+$expected_md5 = "@FFMPEG_FILE_HASH_BIN64@"
+$output = "$PSScriptRoot\@OPENCV_BIN_INSTALL_PATH@\opencv_ffmpeg@OPENCV_DLLVERSION@_64.dll"
+
+Write-Output ("=" * 120)
+try {
+    Get-content -Path "$PSScriptRoot\etc\licenses\ffmpeg-readme.txt" -ErrorAction 'Stop'
+} catch {
+    Write-Output "Refer to OpenCV FFmpeg wrapper readme notes about library usage / licensing details."
+}
+Write-Output ("=" * 120)
+Write-Output ""
+
+if(![System.IO.File]::Exists($output)) {
+    try {
+        Write-Output ("Downloading: " + $output)
+        Import-Module BitsTransfer
+        $start_time = Get-Date
+        Start-BitsTransfer -Source $url -Destination $output -ErrorAction 'Stop'
+        Write-Output "Downloaded in $((Get-Date).Subtract($start_time).Seconds) seconds"
+    } catch {
+        $_ # Dump error
+        try {
+            Write-Output ("Downloading (second attempt): " + $output)
+            $start_time = Get-Date
+            Invoke-WebRequest -Uri $url -OutFile $output
+            Write-Output "Downloaded in $((Get-Date).Subtract($start_time).Seconds) seconds"
+        } catch {
+            Write-Output ("Can't download file: " + $output)
+            Write-Output ("URL: " + $url)
+            Write-Output "You need to download this file manually. Stop"
+            Pause
+            Exit
+        }
+    }
+} else {
+    Write-Output ("File exists: " + $output)
+    Write-Output ("Downloading is skipped. Remove this file and re-run this script to force downloading.")
+}
+
+if(![System.IO.File]::Exists($output)) {
+    Write-Output ("Destination file not found: " + $output)
+    Write-Output "Stop"
+    Pause
+    Exit
+}
+
+try {
+    $hash = Get-FileHash $output -Algorithm MD5 -ErrorAction 'Stop'
+
+    if($hash.Hash -eq $expected_md5) {
+        Write-Output "MD5 check passed"
+    } else {
+        Write-Output ("MD5     : " + $hash.Hash.toLower())
+        Write-Output ("Expected: " + $expected_md5)
+        Write-Output "MD5 hash mismatch"
+    }
+} catch {
+    $_ # Dump error
+    Write-Output "Can't check MD5 hash (requires PowerShell 4+)"
+}
+Pause
+Write-Output "Exit"

3rdparty/ffmpeg/ffmpeg.cmake

@@ -35,3 +35,8 @@ function(download_win_ffmpeg script_var)
     set(${script_var} "${FFMPEG_DOWNLOAD_DIR}/ffmpeg_version.cmake" PARENT_SCOPE)
   endif()
 endfunction()
+
+if(OPENCV_INSTALL_FFMPEG_DOWNLOAD_SCRIPT)
+  configure_file("${CMAKE_CURRENT_LIST_DIR}/ffmpeg-download.ps1.in" "${CMAKE_BINARY_DIR}/win-install/ffmpeg-download.ps1" @ONLY)
+  install(FILES "${CMAKE_BINARY_DIR}/win-install/ffmpeg-download.ps1" DESTINATION "." COMPONENT libs)
+endif()