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当声音在 OpenAL 中播放完毕时收到通知

发布于 2024-07-25 22:34:18 字数 110 浏览 2 评论 0原文

我在 iPhone 上使用 OpenAL 同时播放多个音频样本。

当单个样本播放完毕时，我可以让 OpenAL 通知我吗？

我想避免对样本长度进行硬编码并设置计时器。

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剩一世无双 2024-08-01 22:34:18

我在 OpenAL 中的回调方面运气不佳。在我的状态机中，我只需轮询源并延迟转换直到完成。


    - (BOOL)playing {
        ALint sourceState;
        alGetSourcei(sourceID, AL_SOURCE_STATE, &sourceState);
        return sourceState == AL_PLAYING;
    }

// ... //

    case QSTATE_DYING:
        if (![audioSource playing])
            [self transitionTo:QSTATE_DEAD];

如果这不是您所需要的，那么最好的选择可能是计时器。您不需要对任何值进行硬编码。您可以在填充缓冲区时确定播放时间。

对问题“为什么”的一些深入了解可能会提供一些额外的选择。

I didn't have much luck with callbacks in OpenAL. In my state machines, I simply poll the source and delay the transition until it's done.


    - (BOOL)playing {
        ALint sourceState;
        alGetSourcei(sourceID, AL_SOURCE_STATE, &sourceState);
        return sourceState == AL_PLAYING;
    }

// ... //

    case QSTATE_DYING:
        if (![audioSource playing])
            [self transitionTo:QSTATE_DEAD];

If this isn't what you need, then you're best bet is probably a timer. You shouldn't need to hardcode any values. You can determine the playback time when you're populating your buffers.

A bit of insight into the "why" of the question might offer some additional choices.

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诗笺 2024-08-01 22:34:18

如果您将 OpenAL 源抽象为一个类，我想您可以在启动声音时简单地调用 performSelector:afterDelay: ：（

- (void) play
{
    [delegate performSelector:@selector(soundHasFinishedPlaying)
        afterDelay:self.length];
    …
}

如果您同时手动停止声音，则可以取消回调，请参阅 NSObject 类参考。）或者您可以轮询 AL_SOURCE_STATE：

- (void) checkStatus
{
    ALint state;
    alGetSourcei(source, AL_SOURCE_STATE, &state);
    if (state == AL_PLAYING)
        return;
    [timer invalidate];
    [delegate soundHasFinishedPlaying];
}

我不知道如何让 OpenAL 给您回电。您到底想要回调做什么？有些事情不需要回调就能更好地解决。

If you have the OpenAL source abstracted into a class, I guess you can simply call performSelector:afterDelay: when you start the sound:

- (void) play
{
    [delegate performSelector:@selector(soundHasFinishedPlaying)
        afterDelay:self.length];
    …
}

(If you stop the sound manually in the meantime, the callback can be cancelled, see the NSObject Class Reference.) Or you can poll the AL_SOURCE_STATE:

- (void) checkStatus
{
    ALint state;
    alGetSourcei(source, AL_SOURCE_STATE, &state);
    if (state == AL_PLAYING)
        return;
    [timer invalidate];
    [delegate soundHasFinishedPlaying];
}

I don’t know how to have OpenAL call you back. What exactly do you want the callback for? Some things can be solved better without a callback.

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