objective-c - Mojave /macOS 10.14.0 : [AVPlayerItem duration] is always indefinite

Question

我正在尝试使用以下代码读取本地存储的音频文件的持续时间:

#import <Foundation/Foundation.h>
#import <CoreMedia/CoreMedia.h>
#import <AVFoundation/AVFoundation.h>

AVPlayer *player = [AVPlayer playerWithURL: urlForLocalAudioFile];
// busy wait - I know, not elegant, please ignore
int timeout = 0;
while (([player status] == AVPlayerStatusUnknown
        || [[player currentItem] status] == AVPlayerItemStatusUnknown)
        && timeout < 100) {
    [NSThread sleepForTimeInterval: 0.1];
    timeout++;
}
// make sure we have the right status
if ([[player currentItem] status] == AVPlayerItemStatusReadyToPlay) {
    CMTime cmTime = [[player currentItem] duration];
    if (CMTIME_IS_INDEFINITE(cmTime)) {
        NSLog(@"Duration is kCMTimeIndefinite");
    } else {
        NSLog(@"Time: %d", CMTimeGetSeconds(cmTime));
    }
} else {
    NSLog(@"Item not ready to play");
}

该代码不在主 AppKit 线程中执行，它曾经在 macOS 10.13.x 及更早版本下工作。现在 10.14.0 总是报告 "Duration is kCMTimeIndefinite" .即使在我开始播放文件之后。

有人可以请:

确认/否认这是 macOS 10.14.0 中的错误

建议解决方法

谢谢。

Answer 1

这是一个错误吗？
是的。见 rdar://45039043 .
解决方法
用

CMTime cmTime = [[[player currentItem] asset] duration];

代替

CMTime cmTime = [[player currentItem] duration];