如何淡出 NSSound 对象

发布于 2024-07-09 02:03:51 字数 550 浏览 6 评论 0原文

我写了一个便宜的& 我在 Mac 上安装了欢快的音板，然后我用 NSSound 播放各种声音，如下所示：

-(void)play:(NSSound *)soundEffect:(BOOL)stopIfPlaying {
    BOOL wasPlaying = FALSE;

    if([nowPlaying isPlaying])  {
        [nowPlaying stop];
        wasPlaying = TRUE;
    }   

    if(soundEffect != nowPlaying)
    {
        [soundEffect play];
        nowPlaying = soundEffect;
    } else if(soundEffect == nowPlaying && ![nowPlaying isPlaying] && !wasPlaying) {
        [nowPlaying play];
    }
}

我希望它在几秒钟左右的时间内淡出，而不是让它停止播放。

原文

I've written a cheap & cheerful sound board in for my Mac, and I play the various sounds with NSSound like this:

-(void)play:(NSSound *)soundEffect:(BOOL)stopIfPlaying {
    BOOL wasPlaying = FALSE;

    if([nowPlaying isPlaying])  {
        [nowPlaying stop];
        wasPlaying = TRUE;
    }   

    if(soundEffect != nowPlaying)
    {
        [soundEffect play];
        nowPlaying = soundEffect;
    } else if(soundEffect == nowPlaying && ![nowPlaying isPlaying] && !wasPlaying) {
        [nowPlaying play];
    }
}

Rather than just stop it dead, I'd like it to fade out over a couple of seconds or so.

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千仐 2024-07-16 02:03:51

我会使用 NSTimer 来避免阻塞主线程。

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狼性发作 2024-07-16 02:03:51

这是该方法的最终版本：

-(void)play:(NSSound *)soundEffect:(BOOL)stopIfPlaying {
    BOOL wasPlaying = FALSE;

    if([nowPlaying isPlaying])  {
        struct timespec ts;
        ts.tv_sec = 0;
        ts.tv_nsec = 25000000;

        // If the sound effect is the same, fade it out.
        if(soundEffect == nowPlaying)
        {
            for(int i = 1; i < 30; ++i)
            {
                [nowPlaying setVolume: (1.0 / i )];
                nanosleep(&ts, &ts);
            }           
        }

        [nowPlaying stop];
        [nowPlaying setVolume:1];
        wasPlaying = TRUE;
    }   

    if(soundEffect != nowPlaying)
    {
        [soundEffect play];
        nowPlaying = soundEffect;
    } else if(soundEffect == nowPlaying && ![nowPlaying isPlaying] && !wasPlaying) {
        [nowPlaying play];
    }
}

因此，只有当我传入相同的声音（即单击相同的按钮）时，它才会淡出，而且，我选择了 nanosleep 而不是睡眠，因为它的粒度为 1 秒。

我花了一段时间试图弄清楚为什么我的 200 毫秒延迟似乎没有任何效果，但 200 纳秒实际上并没有那么长，是吗:-)

This is the final version of the method:

-(void)play:(NSSound *)soundEffect:(BOOL)stopIfPlaying {
    BOOL wasPlaying = FALSE;

    if([nowPlaying isPlaying])  {
        struct timespec ts;
        ts.tv_sec = 0;
        ts.tv_nsec = 25000000;

        // If the sound effect is the same, fade it out.
        if(soundEffect == nowPlaying)
        {
            for(int i = 1; i < 30; ++i)
            {
                [nowPlaying setVolume: (1.0 / i )];
                nanosleep(&ts, &ts);
            }           
        }

        [nowPlaying stop];
        [nowPlaying setVolume:1];
        wasPlaying = TRUE;
    }   

    if(soundEffect != nowPlaying)
    {
        [soundEffect play];
        nowPlaying = soundEffect;
    } else if(soundEffect == nowPlaying && ![nowPlaying isPlaying] && !wasPlaying) {
        [nowPlaying play];
    }
}

So it only fades out if I pass the same sound in (ie, click the same button), also, I went for nanosleep rather than sleep, as that on has a granularity of 1 second.

I struggled for a while trying to work out why my 200 millisecond delay didn't seem to have any effect, but then 200 NANOseconds isn't really that long is it :-)

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第几種人 2024-07-16 02:03:51

也许是这样的？您可能想要更线性的下降，但基本思想是创建一个循环并休眠一段时间直到下一次更新。

if([nowPlaying isPlaying])  {
    for(int i = 1; i < 100; ++i)
    {
        [nowPlaying setVolume: (1.0 / i)];
        Sleep(20);
    }
    [nowPlaying stop];
    wasPlaying = TRUE;
}

Something like this perhaps? You probably want a more linear dropoff, but the basic idea is make a loop and sleep the period of time till the next update.

if([nowPlaying isPlaying])  {
    for(int i = 1; i < 100; ++i)
    {
        [nowPlaying setVolume: (1.0 / i)];
        Sleep(20);
    }
    [nowPlaying stop];
    wasPlaying = TRUE;
}

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