Windows 10竟会损坏用户文件？教你解决这个Bug

如果你是一名音乐发烧友，那么应该知道Flac这种常见的无损音乐格式。Flac音乐文件支持metadata，用户可以编辑metadata，让音乐文件带有艺术家、所属专辑、音轨等等信息。通常来说，metadata和音频数据并不相关，修改metadata并不会影响音频本身。但是，近日微软官方公布了Win10中存在一个Bug，在Win10中用资源管理器修改Flac文件的metadata，竟会导致音频的损坏!

根据Windows Latest的报道，微软最新发布的一份支持文件披露，如果在Win10的2004或者更高版本中，使用文件资源管理器修改Flac音乐文件的metadata，就会损耗Flac音频文件。这个Bug在Win10专业版、家庭版、企业版、工作站版乃至其他版本的Win10中均有出现。

根据微软本月早些时候发布的支持文件，Win10的文件资源管理器导致了这个错误，它破坏了Flac文件头包含的ID3框架也就是metadata，而这个ID3框架负责存储音频的注释，例如音乐标题、艺术家、专辑、曲目编号等。在Win10上，Flac的处理程序忽视了ID3框架，该程序认为Flac文件在使用4字节的文件头，当Flac文件被Win10编辑的时候，ID3框架被覆盖了，导致没有了开始代码，导致了音乐播放器无法识别被修改后的文件。

因此，在Win10中，如果你直接用文件资源管理器修改Flac音乐文件的标题、艺术家等metadata，会导致该文件无法播放。

幸运的是，微软已经确定了Bug的根本原因，用户可以通过Windows Update升级KB5003214补丁进行修复。

在KB5003214补丁中，微软确认了上文提到的错误已经被修复，修改了Flac的标题、艺术家等metadata后，Flac不会再变得无法播放。而对于已经损坏了的Flac文件，微软则发布了一个PowerShell脚本来进行修复，运行该脚本后Flac文件即可重新播放，不过已经从ID3框架中丢失了的metadata信息并不能恢复。

下面是利用PowerShell脚本修复Flac文件的具体方法。

1、开启记事本;

2、复制以下字符，粘贴到记事本中：

# Copyright 2021 Microsoft
　# This script will repair a FLAC file that has been corrupted by Media Foundation in reference to KB5003430.
　# Refer to KB5003430 for further information
　param(
　[parameter(Mandatory=$true,
　HelpMessage="The path to the FLAC file that has been corrupted by Media Foundation",
　ValueFromRemainingArguments=$true)]
　[ValidateScript({ -not [String]::IsNullOrEmpty($_) -and (Test-Path $_) })]
　[String]$File
　)
　# We need to back up the current file incase we have any errors
　$FileDirectory = Split-Path -Resolve $File
　$Filename = Split-Path -Leaf -Resolve $File
　$FullPath = Join-Path -Resolve $FileDirectory $Filename
　$Filename = [String]::Format("Backup_{0:yyyyMMdd_hhmmss}_{1}", [DateTime]::Now, $Filename)
　$BackupLocation = Join-Path $FileDirectory $Filename
　Write-Output "Microsoft FLAC Repair Tool. This tool will repair a FLAC audio file that was corrupted when editing its details."
　Write-Output "Affected File: $FullPath"
　Write-Output "A backup of the file will be made: $BackupLocation"
　Write-Output "Do you wish to continue?"
　$choice=$host.ui.PromptForChoice("Fixing FLAC Script", "Do you wish to continue", ('&Yes', '&No'), 1)
　function ParseStreamInfoMetadataBlock([System.IO.FileStream]$stream)
　{
　$blockType = $stream.ReadByte()
　$lastBlock = ($blockType -shr 7) -ne 0
　$blockType = $blockType -band 0x7F
　if ($blockType -ne 0)
　{
　return $false
　}
　$blockSize = (($stream.ReadByte() -shl 16) -bor ($stream.ReadByte() -shl 8) -bor $stream.ReadByte())
　if ($blockSize -lt 34)
　{
　return $false
　}
　$minAudioBlockSize = ($stream.ReadByte() -shl 8) -bor $stream.ReadByte()
　$maxAudioBlockSize = ($stream.ReadByte() -shl 8) -bor $stream.ReadByte()
　if ($minAudioBlockSize -lt 16 -or $maxAudioBlockSize -lt 16)
　{
　return $false
　}
　$minFrameSize = (($stream.ReadByte() -shl 16) -bor ($stream.ReadByte() -shl 8) -bor $stream.ReadByte())
　$maxFrameSize = (($stream.ReadByte() -shl 16) -bor ($stream.ReadByte() -shl 8) -bor $stream.ReadByte())
　$sampleInfo = (($stream.ReadByte() -shl 24) -bor ($stream.ReadByte() -shl 16) -bor ($stream.ReadByte() -shl 8) -bor $stream.ReadByte())
　$sampleRate = $sampleInfo -shr 12
　$channelCount = (($sampleInfo -shr 9) -band 0x7) + 1
　$bitsPerSample = (($sampleInfo -shr 4) -band 0x1F) + 1
　[UInt64]$sampleCount = (($stream.ReadByte() -shl 24) -bor ($stream.ReadByte() -shl 16) -bor ($stream.ReadByte() -shl 8) -bor $stream.ReadByte())
　$sampleCount = (([UInt64]$sampleInfo -band 0xF) -shl 32) -bor $sampleCount
　$MD5HashBytes = New-Object byte[] 16
　$stream.Read($MD5HashBytes, 0, $MD5HashBytes.Length)
　$MD5Hash = [Guid]($MD5HashBytes)
　if ($sampleRate -eq 0)
　{
　return $false
　}
　# Passing these checks means that we likely have a stream info header and can rebuild the file
　Write-Output "File Stream Information"
　Write-Output "Sample Rate: $sampleRate"
　Write-Output "Audio Channels: $channelCount"
　Write-Output "Sample Depth: $bitsPerSample"
　Write-Output "MD5 Audio Sample Hash: $MD5Hash"
　return $true
　}
　if ($choice -eq 0)
　{
　Copy-Item $FullPath -Destination $BackupLocation -Force
　$stream = [System.IO.File]::Open($FullPath, [System.IO.FileMode]::Open)
　$stream.Seek(4, [System.IO.SeekOrigin]::Begin)
　while ($stream.ReadByte() -eq 0) {}
　# We now need to figure out where a valid FLAC metadata frame begins
　# We are likely pointing to the last byte of the size member so we'll seek back 4 bytes and retry
　$flacDataStartPosition = $stream.Position - 4
　$stream.Seek($flacDataStartPosition, [System.IO.SeekOrigin]::Begin)
　while (-not(ParseStreamInfoMetadataBlock($stream)))
　{
　$flacDataStartPosition = $flacDataStartPosition + 1
　$stream.Seek($flacDataStartPosition, [System.IO.SeekOrigin]::Begin)
　}
　# Insert the start code
　$stream.Seek($flacDataStartPosition, [System.IO.SeekOrigin]::Begin)
　if (Test-Path "$FullPath.tmp")
　{
　Remove-Item "$FullPath.tmp"
　}
　$fixedStream = [System.IO.File]::Open("$FullPath.tmp", [System.IO.FileMode]::CreateNew)
　[byte[]]$startCode = [char[]]('f', 'L', 'a', 'C');
　$fixedStream.Write($startCode, 0, $startCode.Length)
　$stream.CopyTo($fixedStream)
　$stream.Close()
　$fixedStream.Close()
　Move-Item -Force "$FullPath.tmp" $FullPath
　}