程序等待使用者的是什么？请详述你发现的。
What is the binary waiting from the user? Please detail how you found it.
在传输之后，接下来的两个函数可以导致程序等待，直到传输完成为止。
After the transfer, the next two functions cause the program to wait until the transfer is completed.
我们必须做的第一件事情是保证应用程序等待，知道下一帧准备好。
The first thing we have to do is to ensure that the application waits until the next frame is ready.
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