从 CMSampleBuffer 播放音频

我在 iOS 中为群组创建了一个视频聊天应用程序。我一直在寻找一些方法来分别控制不同参与者的音频音量。我找到了使用静音和取消静音的方法isPlaybackEnabled in RemoteAudioTrack，但不控制音量。

我还想我们是否可以使用它AVAudioPlayer。我发现addSink。这是我尝试过的here https://stackoverflow.com/a/45055605/5567142:

class Audio: NSObject, AudioSink {
    var a = 1
    func renderSample(_ audioSample: CMSampleBuffer!) {
        print("audio found", a)
        a += 1

        var audioBufferList = AudioBufferList()
        var data = Data()
        var blockBuffer : CMBlockBuffer?

        CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(audioSample, bufferListSizeNeededOut: nil, bufferListOut: &audioBufferList, bufferListSize: MemoryLayout<AudioBufferList>.size, blockBufferAllocator: nil, blockBufferMemoryAllocator: nil, flags: 0, blockBufferOut: &blockBuffer)
        let buffers = UnsafeBufferPointer<AudioBuffer>(start: &audioBufferList.mBuffers, count: Int(audioBufferList.mNumberBuffers))

        for audioBuffer in buffers {
            let frame = audioBuffer.mData?.assumingMemoryBound(to: UInt8.self)
            data.append(frame!, count: Int(audioBuffer.mDataByteSize))
        }

        let player = try! AVAudioPlayer(data: data) //crash here
        player.play()
    }
}

但它崩溃了let player = try! AVAudioPlayer(data: data).

EDIT:
这是错误：Fatal error: 'try!' expression unexpectedly raised an error: Error Domain=NSOSStatusErrorDomain Code=-39 "(null)": file.

This is data所以我猜它没有转换：

▿ 0 bytes
  - count : 0
  ▿ pointer : 0x000000016d7ae160
    - pointerValue : 6131736928
  - bytes : 0 elements

这就是audioSample:

<CMAudioFormatDescription 0x2815a3de0 [0x1bb2ef830]> {
    mediaType:'soun' 
    mediaSubType:'lpcm' 
    mediaSpecific: {
        ASBD: {
            mSampleRate: 16000.000000 
            mFormatID: 'lpcm' 
            mFormatFlags: 0xc 
            mBytesPerPacket: 2 
            mFramesPerPacket: 1 
            mBytesPerFrame: 2 
            mChannelsPerFrame: 1 
            mBitsPerChannel: 16     } 
        cookie: {(null)} 
        ACL: {(null)}
        FormatList Array: {(null)} 
    } 
    extensions: {(null)}
}

您可以从以下位置获取完整的数据缓冲区CMS样例缓冲区并将其转换为Data:

let blockBuffer = CMSampleBufferGetDataBuffer(sampleBuffer)
let blockBufferDataLength = CMBlockBufferGetDataLength(blockBuffer!)
var blockBufferData  = [UInt8](repeating: 0, count: blockBufferDataLength)
let status = CMBlockBufferCopyDataBytes(blockBuffer!, atOffset: 0, dataLength: blockBufferDataLength, destination: &blockBufferData)
guard status == noErr else { return }
let data = Data(bytes: blockBufferData, count: blockBufferDataLength)

并且还可以参考AVA音频播放器 https://developer.apple.com/documentation/avfoundation/avaudioplayer#overview概述：

使用此类进行音频播放，除非您正在播放从网络流捕获的音频或需要非常低的 I/O 延迟。

所以我认为这对你不起作用。你应该更好地使用AVA音频引擎 https://developer.apple.com/documentation/avfoundation/avaudioengine or 音频队列服务 https://developer.apple.com/documentation/audiotoolbox/audio_queue_services.