AVAudioPlayer currentTime 问题 [英] AVAudioPlayer currentTime issue

问题描述

我正在尝试使用带有滑块的 AVAudioPlayer 来寻找轨道(并不复杂).

I'm trying to use the AVAudioPlayer with a slider in order to seek into a track (nothing complicated).

但我有一个奇怪的行为......对于 currentTime 的某些值(在 0 和 trackDuration 之间)，播放器停止播放曲目，并进入 audioPlayerDidFinishPlaying:successfully:成功到NO.它没有进入 audioPlayerDecodeErrorDidOccur:error:

But I have a weird behavior... for some value of currentTime (between 0 and trackDuration), the player stop playing the track, and goes into audioPlayerDidFinishPlaying:successfully: with successfully to NO. And it did not go into audioPlayerDecodeErrorDidOccur:error:

就好像它无法读取我给它的时间.

It's like it can't read the time I'm giving to it.

例如曲目的时长为:295.784424 秒我将 currentTime 设置为 55.0s(即:54.963878 或 54.963900 或 54.987755 等......当打印为 %f 时).当 currentTime 为 54.987755 时，崩溃"总是发生......我真的不明白为什么......

For exemple the duration of the track is: 295.784424 seconds I set the currentTime to 55.0s (ie: 54.963878 or 54.963900 or 54.987755, etc... when printed as %f). The "crashes" always happen when the currentTime is 54.987755... and I really don't understand why...

所以如果你有任何想法...^^

So if you have any idea... ^^

推荐答案

我也很难通过 'AVAudioPlayer setCurrentTime:` 使音频跳过正常工作

I also struggled to get audio skipping working properly with 'AVAudioPlayer setCurrentTime:`

经过大量实验，我发现了一个可以在模拟器和设备上可靠运行的序列:(在 OS3.1+ 上测试)

After alot of experimentation i've found a sequence that works reliably on the simulator and the device: (tested on OS3.1+)

// Skips to an audio position (in seconds) of the current file on the [AVAudioPlayer* audioPlayer] class instance
// This works correctly for a playing and paused audioPlayer
//
- (void) skipToSeconds:(float)position
{
    @synchronized(self) 
    {
        // Negative values skip to start of file
        if ( position<0.0f )
            position = 0.0f;

        // Rounds down to remove sub-second precision
        position = (int)position;

        // Prevent skipping past end of file
        if ( position>=(int)audioPlayer.duration )
        {
            NSLog( @"Audio: IGNORING skip to <%.02f> (past EOF) of <%.02f> seconds", position, audioPlayer.duration );
            return;
        }

        // See if playback is active prior to skipping
        BOOL skipWhilePlaying = audioPlayer.playing;

        // Perform skip
        NSLog( @"Audio: skip to <%.02f> of <%.02f> seconds", position, audioPlayer.duration );

        // NOTE: This stop,set,prepare,(play) sequence produces reliable results on the simulator and device.
        [audioPlayer stop];
        [audioPlayer setCurrentTime:position];
        [audioPlayer prepareToPlay];

        // Resume playback if it was active prior to skipping
        if ( skipWhilePlaying )
            [audioPlayer play];
    }
}  

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