AVAudioPlayer.duration不等于AVURLAsset.duration

Question

我按AVAudioEngin录制音频文件，格式为：

@{ AVSampleRateKey:@(44100.0), AVNumberOfChannelsKey: @(1), AVFormatIDKey: @(kAudioFormatMPEG4AAC), }，

然后我用AVAudioPlayer，

播放它

self.player = [[AVAudioPlayer alloc] initWithData:[NSData dataWithContentsOfFile:self.outFilePath] error:nil];
NSTimeInterval duration = _player.duration; // 409.73357109834228

AVURLAsset*audioAsset = [AVURLAsset URLAssetWithURL:[NSURL fileURLWithPath:self.outFilePath] options:nil];
CMTime audioDuration = audioAsset.duration;
Float64 seconds = CMTimeGetSeconds(audioDuration); // 429.31374149659865

为什么duration不等于seconds？

我是否错过了为AVAudioPlayer设置的某些属性？

Answer 1

我在AVAsset.h中看到了一些关于持续时间属性的选项。如下： Indicates the duration of the asset. If @"providesPreciseDurationAndTiming" is NO, a best-available estimate of the duration is returned. The degree of precision preferred for timing-related properties can be set at initialization time for assets initialized with URLs. See AVURLAssetPreferPreciseDurationAndTimingKey for AVURLAsset below. 它告诉我，当提供PreiseDurationAndTiming 为NO时，持续时间不完全正确，你应该将 providePreciseDurationAndTiming 设置为YES，只需试一试。