协程导致统一崩溃

Question

我在脚本中添加了以下函数，它导致统一崩溃。

public void AddCurrentFrameToVideo()
{
    _addFrameFunctionHasBeenCalled = true;

    using (var encoder = new MediaEncoder(encodedFilePath, videoAttr, audioAttr))
    using (var audioBuffer = new NativeArray<float>(sampleFramesPerVideoFrame, Allocator.Temp))
    {

        IEnumerator SetFrame()
        {
            yield return new WaitForSeconds(0.3f);
            encoder.AddFrame(tex);
            encoder.AddSamples(audioBuffer);
            if (recordingButtonHasBeenPressed)
            {
                yield return StartCoroutine(SetFrame());
            }
            else
            {
                yield return null;
                yield break;
            }

        }

        IEnumerator mycoroutine;
        mycoroutine = SetFrame();

        if (recordingButtonHasBeenPressed)
        {
            StartCoroutine(mycoroutine);
        }
        else
        {
            StopCoroutine(mycoroutine);
        }

    }

}

我在 Update 函数的 if 语句中调用此函数。见：

void Update()
{
    _currentsframe = Time.frameCount;

    if (recordingButtonHasBeenPressed)
    {
        if (!videoBasicFileHasBeenCreated)
        {
            CreateVideoBasicFile();
        }

        if (!_addFrameFunctionHasBeenCalled)
        {
            AddCurrentFrameToVideo();
        }

    }

}

我还通过按钮OnClick() 在另一个脚本中控制了recordingButtonHasBeenPressed 变量。见：

public void RecordVideo_OnClick()
{
    if (videoIsRecording)
    {
        videoIsRecording = false;
        videoRecordButton.image.sprite = videoButtonIsNotRecordingSprite;

        _myRecorderSc.recordingButtonHasBeenPressed = false;
        _myRecorderSc.videoBasicFileHasBeenCreated = false;
    }
    else
    {
        videoRecordButton.image.sprite = videoButtonIsRecordingSprite;
        _myRecorderSc.recordingButtonHasBeenPressed = true;
        _myRecorderSc.videoBasicFileHasBeenCreated = false;
        videoIsRecording = true;
    }
}

我不知道为什么它会破坏统一性。我不认为这是一个无限循环。 我还测试了DO-While 循环而不是使用Croutine。见：

    using (var encoder = new MediaEncoder(encodedFilePath, videoAttr, audioAttr))
    using (var audioBuffer = new NativeArray<float>(sampleFramesPerVideoFrame, Allocator.Temp))
    {
        do
        {
                encoder.AddFrame(tex);
                encoder.AddSamples(audioBuffer);
        } while (recordingButtonHasBeenPressed);
    }

它也会导致统一崩溃。

我该怎么办？它有什么问题？

Answer 1

这个

    IEnumerator SetFrame()
    {
        yield return new WaitForSeconds(0.3f);
        encoder.AddFrame(tex);
        encoder.AddSamples(audioBuffer);
        if (recordingButtonHasBeenPressed)
        {
            yield return StartCoroutine(SetFrame());
        }
     }

是一个递归调用，您再次yield return 相同的例程（在内部yield returns 再次相同的例程等）所以它一直等到所有嵌套的子例程完成=> 所以在某些时候你会得到一个 StackOverflow！

---

这绝对是一个封闭的永无止境的while循环

using (var audioBuffer = new NativeArray<float>(sampleFramesPerVideoFrame, Allocator.Temp))
{
    do
    {
            encoder.AddFrame(tex);
            encoder.AddSamples(audioBuffer);
    } while (recordingButtonHasBeenPressed);
}

在循环内，recordingButtonHasBeenPressed 的值将永远被更改，Unity/您的应用会立即永远冻结！

---

你想要做的就是像这样的协程

IEnumerator SetFrame()
{
    // initially wait once
    yield return new WaitForSeconds(0.3f);

    // simply continue to execute the routine until the record shall be stopped
    while(recordingButtonHasBeenPressed)
    {
        encoder.AddFrame(tex);
        encoder.AddSamples(audioBuffer);

        // yield the next frames for 0.3 seconds before checking 
        // recordingButtonHasBeenPressed again
        yield return new WaitForSeconds(0.3f);
    }
}

你甚至不需要主动阻止它。您需要做的就是启动它，然后为了中断它只需将recordingButtonHasBeenPressed 设置为false。

---

事件驱动

现在一般来说，一旦在此处调用方法，您似乎会立即再次重置，而不是使用 Update 和多个控制器标志 bools 我宁愿让整个代码 事件驱动 并调用一次 在调用按钮时。这将防止并发例程意外运行，并使整个事情更好地阅读和维护。

我不知道你的完整代码，但它可能看起来像

public void RecordVideo_OnClick()
{
    // invert the toggle flag
    videoIsRecording = !videoIsRecording;

    // depending on the new flag value chose the sprite
    videoRecordButton.image.sprite = videoIsRecording ? videoButtonIsRecordingSprite : videoButtonIsNotRecordingSprite;

    if (!videoIsRecording)
    {
        _myRecorderSc.StopRecording();
    }
    else
    {
        _myRecorderSc.StartRecoring();
    }
}

然后在记录器脚本中你只需要

public void StartRecording()
{
    if(!recording)
    {
        StartCoroutine(RecorderRoutine);
    }
}

public void StopRecording()
{
    recording = false;
}

// flag to interrupt running record
private bool recording;

private IEnumerator RecorderRoutine()
{
    // Just in case prevent concurrent routines
    if(recording) yield break;
    recording = true;

    // initialize your file
    CreateVideoBasicFile();    

    // initially wait once
    yield return new WaitForSeconds(0.3f);

    using (var encoder = new MediaEncoder(encodedFilePath, videoAttr, audioAttr))
    using (var audioBuffer = new NativeArray<float>(sampleFramesPerVideoFrame, Allocator.Temp))
    {
        // simply continue to execute the routine until the record shall be stopped
        while(recording)
        {
            encoder.AddFrame(tex);
            encoder.AddSamples(audioBuffer);

            // yield the next frames for 0.3 seconds before checking 
            // recordingButtonHasBeenPressed again
            yield return new WaitForSeconds(0.3f);
        }
    }

    recording = false;
}