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But here's a mystery:
但这里有个小谜团:
When you press pause on the VCR, the screen doesn't go blank.
当你按下录像机的暂停键,屏幕并不是一片空白。
Instead, you get a frozen image.
相反,你看到的是停止的画面。
Remember,you need a changing magnetic signal to create even a still video image.
记住,你需要改变的磁信号创建静止的视频画面。
If the video tape isn't moving, where is this changing signal coming from?
如果录像带没有向前播放,这个改变的信号来自哪里?
We're used to VCRs doing this, but it's actually kind of strange.
我们习惯了录像机这样的工作方式,但实际上有点奇怪。
It would be like pressing pause on a cassette deck and having the sound remain in your speakers,Pavarotti holding his high C until you press play again.
这就像在录音机上按下暂停,声音仍然在你的扬声器中,帕瓦罗蒂的高音C会等你再按播放才开始。
VCRs do this trick by moving both the tape, AND the playback heads, which spin rapidly past the tape as it moves through the machine.
录像机的这个小秘密是通过带子向前播放及整个机器中滑过带子的放音磁头实现的。
Pausing a video tape does indeed stop the tape, but it doesn't stop the spinning playback heads.
暂停确实使带子停止,但没有停止放音磁头。
These continue to swipe past the stationary tape, detecting enough of a magnetic signal for one still frame of video.
放音磁头继续通过静止的带子,因此侦测到的足够磁信号就产生了静止的视频画面。
Modern, hi-fi VCRs automatically mute the sound when they are paused, so you don't get a sustained audio sound as well!
现代高保真录像机会在暂停的时候自动将声音静音,这样就不会听到持续的声音!
