如果路径太长，mciSendString将无法播放音频文件 [英] mciSendString won't play an audio file if path is too long

问题描述

当文件的路径+文件名非常长时，我注意到了

When the path+filename of a file is really long, I've noticed that

PlaySound(fName.c_str(), NULL, SND_ASYNC);

有效，但无效

mciSendString((L"open \"" + fName + L"\" type waveaudio alias sample").c_str(), NULL, 0, NULL);
mciSendString(L"play sample", NULL, 0, NULL);

命令失败的示例:

打开"C:\ qisdjqldlkjsqdjqdqjslkdjqlksjlkdjqsldjlqjsdjqdksq \ dajdjqjdlqjdlkjazejoizajoijoifjoifjoifjdsfjsfszjfoijdsjfoijdsoifoidsjfojdsofjdsoijfoisjfoijdsjpjjjjjjjjjjjjjjjjjjdjjjjjjjjjjjjjjjjjjwjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjwjjjjjjjjjwjjjjjjjjjwjjjjjjjjwjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjj音符."

open "C:\qisdjqldlkjsqdjqdqjslkdjqlksjlkdjqsldjlqjsdjqdksq\dajdjqjdlqjdlkjazejoizajoijoifjoifjdsfjsfszjfoijdsjfoijdsoifoidsjfojdsofjdsoijfoisjfoijoisdjfosjfqsd\Windows Critical Stop.wav" type waveaudio alias sample

但是:

• 我真的需要mciSendString而不是PlaySound()，因为PlaySound()不会播放某些文件(48 khz音频文件，有时是24位文件等)

• I really need mciSendString instead of PlaySound(), because PlaySound() doesn't play certain files (48 khz audio files, sometimes 24-bit files, etc.)

我需要能够播放路径很长的音频文件，因为我的应用程序的最终用户可能会有这样的文件

I need to be able to play audio files with potentially long paths because the end user of my app might have such files

如何使mciSendString接受长文件名?

注意:

• 我也尝试使用最大路径名+文件名长度为127(127:有效，128+:无效)

  The max path+filename length is 127 (127: working, 128+: not working)

  如果真的无法使 mci * 函数使用大于127个字符的文件名，我可以使用winapi(没有外部库)?( PlaySound 不是一个选项，因为它不能真正适用于所有wav文件，例如48 khz:无效等).

  If really it's impossible to make mci* functions work with longer-than-127-char filenames, what could I use instead, just with winapi (without external libraries)? (PlaySound is not an option because doesn't work realiably with all the wav files, such as 48 khz: non-working, etc.)

  推荐答案

  127的极限看起来很奇怪.我没有在MSDN上找到任何有关此的信息.

  The 127 limit looks strange. I didn't find any information on MSDN about it.

  1. 还有另一种可打开的语法:您可以尝试的一个选项是将工作目录更改为文件目录，然后限制仅适用于文件名.-> SetCurrentDiectory

     An option You could try is to change the working directory to the directory of the file, then the limit only applies to filename. -> SetCurrentDiectory

     要缩短文件名，可以使用Winapi函数

     To shorten the filename a Winapi function can be used GetShortPathName
     But:

     SMB 3.0不支持连续共享的短名称可用性功能.

     SMB 3.0 does not support short names on shares with continuous availability capability.

     弹性文件系统(ReFS)不支持短名称.如果你打电话磁盘上没有任何短名称的路径上的GetShortPathName，调用将成功，但是将返回长名称路径.NTFS卷也可以实现这种结果，因为没有确保给定的长名称存在短名称.

     Resilient File System (ReFS) doesn't support short names. If you call GetShortPathName on a path that doesn't have any short names on-disk, the call will succeed, but will return the long-name path instead. This outcome is also possible with NTFS volumes because there's no guarantee that a short name will exist for a given long name.

  基于MSDN的示例:

  #include <string>
  #include <Windows.h>
  
  template<typename StringType>
  std::pair<bool, StringType> shortPathName( const StringType& longPathName )
  {
      // First obtain the size needed by passing NULL and 0.
      long length = GetShortPathName( longPathName.c_str(), NULL, 0 );
      if (length == 0) return std::make_pair( false, StringType() );
  
      // Dynamically allocate the correct size 
      // (terminating null char was included in length)
      StringType  shortName( length, ' ' );
  
      // Now simply call again using same long path.
      length = GetShortPathName( longPathName.c_str(), &shortName[ 0 ], length );
      if (length == 0) return std::make_pair( false, StringType() );
  
      return std::make_pair(true, shortName);
  }
  
  
  #include <locale>
  #include <codecvt>
  
  #include <iostream>
  std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>> converter;
  
  //std::string narrow = converter.to_bytes( wide_utf16_source_string );
  //std::wstring wide = converter.from_bytes( narrow_utf8_source_string );
  
  int main( int argc, char** argv )
  {
      std::wstring myPath = converter.from_bytes( argv[0] );
  
      auto result = shortPathName( myPath );
      if (result.first)
          std::wcout << result.second ;
  
  
      return 0;
  }
  

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