使用ExtAudioFileWrite在文件末尾写入

Question

我试图打开一个文件并使用ExtAudioFileWrite将数据追加到它。现在，创建/初始写入（创建时）/转换工作很好，但不幸的是，我似乎无法打开文件以供后来写入。只有一个函数似乎打开文件：ExAudioFileOpenURL，但仅用于阅读。那么，如果我无法打开文件进行写入，我该如何在文件末尾编写代码？

Answer 1

我可能是错的，或不完全理解你的问题。但是，一旦使用ExtAudioFileWrite开始写入文件，您可以通过再次调用ExtAudioFileWrite来继续写入文件。我要冒险进入没有编译器的编码，希望你会得到的想法

例子：

....variables declaration and your logic..... 

//1.Create File to write output 
ExtAudioFileRef outputFile; 

//+++++++ LOOP to append as many files as you want +++++++// 

//2.Create file reference to files you want to merge 
ExtAudioFileRef audioFileObject = 0; 

//3.open the first file 
ExtAudioFileOpenURL (firstFileURL, &audioFileObject); 

//4.get file properties 
AudioStreamBasicDescription AudioFileFormat = 0; 
UInt64 numberOfPacketsToReadInCurrentFile = 0; 
ExtAudioFileGetProperty(audioFileObject, 
         kExtAudioFileProperty_FileLengthFrames, 
         sizeof(numberOfPacketsToReadInCurrentFile), 
         &numberOfPacketsToReadInCurrentFile 
         ); 

ExtAudioFileGetProperty(audioFileObject, 
         kExtAudioFileProperty_FileDataFormat, 
         sizeof(AudioFileFormat), 
         &AudioFileFormat 
         ); 
//5.Set destination ASBD 
ExtAudioFileSetProperty(audioFileObject, 
         kExtAudioFileProperty_ClientDataFormat, 
         sizeof (importFormat), 
         &importFormat 
         ); 

//6.Set/Create/Allocate Some Buffers 
//use AudioFileFormat to setup your buffers accordingly 

AudioBufferList theBufferList = 0 // bufferList setup (I dont remember that) 

//7.Read the file into the buffer 
ExtAudioFileRead(audioFileObject,&numberOfPacketsToReadInCurrentFile,theBufferList); 

//8.Write the buffer to a File  
ExtAudioFileWrite(outputFile, numberOfPacketsToReadInCurrentFile, theBufferList); 
free(theBufferList); 

//if you want to append more files go to point 2 with the next file URL 

//+++++++CLOSE LOOP+++++++++// 

//once you are done.. just dispose the file and clean up everything left 
ExtAudioFileDispose(outputFile); 

这将无法编译，我猜。但希望能帮助你明白这个想法。