AVAudioPlayer.duration not equal AVURLAsset.duration

Question

I record a audio file by AVAudioEngin, with out-format:

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

Then I playback it with AVAudioPlayer ,

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

why duration is not equal to seconds?

Did i missed some properties to set for AVAudioPlayer?

Answer 1

i see some options at AVAsset.h, about the duration property. as below: 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. it tells that when the providesPreciseDurationAndTiming is NO, the duration is not exactly correct, you should set providesPreciseDurationAndTiming to YES, just have a try.