iOS和解码内存缓冲区中的MP3 / AAC数据 [英] iOS and decoding MP3/AAC data from memory buffer

问题描述

请原谅我，我在iOS上非常新 - 并且通常以这种规模进行编程。

Forgive me, I very new at iOS - and programming at this scale in general.

我一直在挖掘iOS文档，我知道有一些功能像ExtAudiofile ...用于解码MP3 / AAC文件，但有没有可以在已经在内存中的Mp3 / aac数据上运行？

I have been digging through iOS documentation, I know there are some functions like ExtAudiofile... for decoding MP3/AAC files, but are there any that will operate on Mp3/aac data that's already in memory?

我可能需要提取来自另一个文件的媒体数据（逐字节; iOS确实允许吗？），所以我不能只给它一个URL。

I will probably have to extract the media data (byte by byte; iOS does allow that right?) from inside another file, so I can't just give it the URL.

编辑：mp3数据将采用非标准文件格式，Apple提供的功能应该无法读取它们。我听说iOS有一个可以在一个音频流上运行的硬件解码器，如果有多个流，操作系统将回退到软件解码。

the mp3 data will be in a non-standard file format, Apple provided function should not be able to read them. I heard iOS has a hardware decoder that works on one audio stream and the OS will fallback to software decoding if there are multiple streams.

我宁愿使用Apple提供的功能，然后将MP3解码器集成到应用程序中。

I would rather use what Apple provides then integrate a MP3 decoder into the app.

推荐答案

您可以使用ExtAudioFileRead读取内存中的文件，但必须使用AudioFileOpenWithCallbacks。我不是我的工作电脑，所以我不能给你确切的代码，但这是一般的过程：

You can use ExtAudioFileRead to read a file that is in memory, but you have to use AudioFileOpenWithCallbacks. I'm not by my work computer so I can't give you exact code, but here's the general process:

• 使用fopen / fread将给定文件读入内存缓冲区数组。使用简单的C数组而不是NSArray或NSData - 您需要速度，并且需要它与下一步兼容。


• 为read / get size创建一些基本的C函数回调。


• 将AudioFileOpenWithCallbacks与您编写的回调一起打开
  内存中的音频文件。


• 使用ExtAudioFileWrapAudioFileID开始解码文件记忆。
  这取代了ExtAudioFileOpenURL。

• Use fopen/fread to read the given file into a memory buffer array. Use a simple C array and not an NSArray or NSData - you need speed and you need for it to be compatible with the next step.
• Create some basic C function callbacks for read / get size.
• Use AudioFileOpenWithCallbacks with the callbacks you wrote to open the audio file in memory.
• Use ExtAudioFileWrapAudioFileID to start decoding the file in memory. This is in replacement of ExtAudioFileOpenURL.

如果你是Google + AudioFileOpenWithCallbacks + ExtAudioFileWrapAudioFileID，你会发现有些人有已经完成了这个并发布了他们的代码。

If you Google +AudioFileOpenWithCallbacks +ExtAudioFileWrapAudioFileID, you'll find that some folks have already done this and published their code.

我不确定你的非标准mp3数据是什么意思，所以你应该尝试使用另一个应用来播放该文件看它是否兼容。

I'm not sure what you mean by non-standard mp3 data, so you should try to play the file using another app to see if it will be compatible.

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