我对 iOS8 中的新音频引擎有一个严重的问题。我有一个应用程序,它是用 AVAudioPlayer 构建的,我试图找出一种迁移到新架构的方法,但是我遇到了以下问题(我相信你会同意,这是一个严重而基本的障碍) :
我的头文件:
AVAudioEngine *engine;
AVAudioMixerNode *mainMixer;
AVAudioPlayerNode *player;
我的 m 文件(在 viewDidLoad 中):
engine = [[AVAudioEngine alloc] init];
player = [[AVAudioPlayerNode alloc] init];
[engine attachNode:player];
NSURL *fileUrl = [[NSURL alloc] initFileURLWithPath:[[NSBundle mainBundle] pathForResource:@"test" ofType:@"mp3"]];
AVAudioFile *file = [[AVAudioFile alloc] initForReading:fileUrl error:nil];
NSLog(@"duration: %.2f", file.length / file.fileFormat.sampleRate);
[player scheduleFile:file atTime:nil completionHandler:^{
AVAudioTime *nodeTime = player.lastRenderTime;
AVAudioTime *playerTime = [player playerTimeForNodeTime:nodeTime];
float secs = (float)playerTime.sampleTime / file.fileFormat.sampleRate;
NSLog(@"finished at: %.2f", secs);
}];
mainMixer = [engine mainMixerNode];
[engine connect:player to:mainMixer format:file.processingFormat];
[engine startAndReturnError:nil];
[player play];
上面的代码初始化了引擎和一个节点,然后开始播放我正在使用的任何文件。首先打印出音乐文件的时长,然后在播放结束后,在回调函数中打印播放器的当前时间。这两个应该是相同的,或者在最坏的情况下,彼此非常非常接近,但事实并非如此,这两个值之间的差异非常大,例如
duration: 148.51
finished at: 147.61
我做错了什么吗?这应该相当简单,我尝试过不同的文件格式、文件长度、数十个音乐文件,但差异总是在 1 秒左右或不到 1 秒。
最佳答案
更新:
从 iOS 11 开始,您可以指定 completionCallbackType: AVAudioPlayerNodeCompletionCallbackType
dataConsumed:
A completion handler indicating that the buffer or file data has been consumed by the player.dataRendered:
The buffer or file data that has been rendered by the player.dataPlayedBack:
A completion handler indicating that the buffer or file has finished playing.
更多信息:Documentation
原文:
根据 Apple 的 scheduleFile:atTime:completionHandler
文档:
It is possible for the completionHandler to be called before rendering begins or before the file is played completely.
关于ios8 - AVAudioEngine 不正确的时间管理和 AVAudioPlayerNode 的回调,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/29299017/