ios - 是什么可以防止用MTAudioProcessingTap调用进程回调？

Question

我已经准备了AVPlayer和AVAssetExportSession，它们都使用相同的MTAudioProcessingTap，但我都无法调用process回调。我很乐意提供一些帮助，以帮助您识别为什么不调用回调函数而却调用其他回调函数的原因。

我只是试图用轻拍来处理音频，以便按比例增加音量以增加音量。我能够添加包括audioMix的audioTapProcessor，但在运行应用程序时，它仅调用init和finalize回调。

缺少什么阻止了process回调的运行？

    var callbacks = MTAudioProcessingTapCallbacks(
        version: kMTAudioProcessingTapCallbacksVersion_0,
        clientInfo: UnsafeMutableRawPointer(Unmanaged<AnyObject>.passUnretained(self as AnyObject).toOpaque()),
        init: tapInit,
        finalize: tapFinalize,
        prepare: tapPrepare,
        unprepare: tapUnprepare,
        process: tapProcess)

    var tap: Unmanaged<MTAudioProcessingTap>?
    let status = MTAudioProcessingTapCreate(kCFAllocatorDefault, &callbacks, kMTAudioProcessingTapCreationFlag_PostEffects, &tap)
    if status != noErr {
        debugPrint("Failed to create audio processing tap.")
        throw BoosterExporterError.failure
    }

我已经在GitHub上发布了完整项目的代码。链接在下面。

https://github.com/brennanMKE/Boosted/blob/master/BoosterKit/BoosterPlayer.swift#L153

Answer 1

您需要找出音频trackID并将其设置为AVMutableAudioMixInputParameters才能使其正常工作。

AVMutableAudioMixInputParameters *audioMixInputParameters = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:self.audioAssetTrack];

请参阅此处的苹果示例
https://developer.apple.com/library/content/samplecode/AudioTapProcessor/Listings/AudioTapProcessor_MYAudioTapProcessor_m.html#//apple_ref/doc/uid/DTS40012324-AudioTapProcessor_MYAudioTapProcessor_m-DontLinkElementID_6