ios - Swift 3 中的 AVAudioRecorder : Get Byte stream instead of saving to file

Question

我是 iOS 编程的新手，我想使用 Swift 3 将 Android 应用程序移植到 iOS。该应用程序的核心功能是从麦克风读取字节流并实时处理该流。因此，将音频流存储到文件并在录制停止后对其进行处理是不够的。

我已经找到了可用的 AVAudioRecorder 类，但我不知道如何实时处理数据流(过滤、将其发送到服务器等)。 AVAudioRecorder 的初始化函数如下所示:

AVAudioRecorder(url: filename, settings: settings)

我需要的是一个类，我可以在其中注册一个事件处理程序或类似的东西，每次读取 x 个字节时都会调用它，以便我可以处理它。

AVAudioRecorder 可以吗？如果没有，Swift 库中是否有另一个类允许我实时处理音频流？在 Android 中，我使用 android.media.AudioRecord，所以如果 Swift 中有一个等效的类，那就太好了。

问候

Answer 1

在核心音频框架中使用音频队列服务。 https://developer.apple.com/library/content/documentation/MusicAudio/Conceptual/AudioQueueProgrammingGuide/AQRecord/RecordingAudio.html#//apple_ref/doc/uid/TP40005343-CH4-SW1

static const int kNumberBuffers = 3;                            // 1
struct AQRecorderState {
    AudioStreamBasicDescription  mDataFormat;                   // 2
    AudioQueueRef                mQueue;                        // 3
    AudioQueueBufferRef          mBuffers[kNumberBuffers];      // 4
    AudioFileID                  mAudioFile;                    // 5
    UInt32                       bufferByteSize;                // 6
    SInt64                       mCurrentPacket;                // 7
    bool                         mIsRunning;                    // 8
};

Here’s a description of the fields in this structure:

1 Sets the number of audio queue buffers to use. 2 An AudioStreamBasicDescription structure (from CoreAudioTypes.h) representing the audio data format to write to disk. This format gets used by the audio queue specified in the mQueue field. The mDataFormat field gets filled initially by code in your program, as described in Set Up an Audio Format for Recording. It is good practice to then update the value of this field by querying the audio queue's kAudioQueueProperty_StreamDescription property, as described in Getting the Full Audio Format from an Audio Queue. On Mac OS X v10.5, use the kAudioConverterCurrentInputStreamDescription property instead.

For details on the AudioStreamBasicDescription structure, see Core Audio Data Types Reference.

3 The recording audio queue created by your application.

4 An array holding pointers to the audio queue buffers managed by the audio queue.

5 An audio file object representing the file into which your program records audio data.

6 The size, in bytes, for each audio queue buffer. This value is calculated in these examples in the DeriveBufferSize function, after the audio queue is created and before it is started. See Write a Function to Derive Recording Audio Queue Buffer Size.

7 The packet index for the first packet to be written from the current audio queue buffer.

8 A Boolean value indicating whether or not the audio queue is running.