audacity音轨加伴奏

Switching tracks suddenly in your audio/video projects can be really jarring for the audience. Crossfades can help make natural-sounding transitions between audio tracks, and you can really take advantage of them if you know a little about how sound works.

在音频/视频项目中突然切换曲目可能会给观众造成很大的困扰。 交叉淡入淡出可以帮助在音轨之间进行自然听起来的过渡，如果您对声音的工作原理有所了解，则可以真正利用它们。

什么是交叉淡入淡出？ (What is a Crossfade?)

Odds are you know what a fade is, though maybe not by name. When an audio track starts with silence and the volume rises up out of nowhere, that’s called a “fade-in.” When a track slowly lowers its volume until it’s nothing but silence, it’s called a “fade-out.” How “sharp” a fade is directly involves how much volume is lost or gained over what period of time. Sharper fades happen quickly while duller or steadier fades take a long time. This is what a fade-out looks like visually:

奇怪的是，您知道什么是淡入淡出，尽管也许不是名字。 当音轨以静默开始并且音量突然升高时，这称为“淡入”。 当轨道缓慢降低音量直到无声无息时，就称为“淡出”。 衰减的“锐度”程度直接涉及在什么时间段内丢失或获得多少音量。 较清晰的渐变会很快发生，而较暗或较稳定的渐变则需要较长时间。 这是淡入视觉效果：

A fade-in looks similar.

淡入外观类似。

A crossfade is essentially doing both simultaneously to two separate tracks. The first track slowly fades out and the second fades in, but instead of there being silence in between, it happens concurrently. It usually sounds like you opened the door to another room with different music, then went through it and closed the door behind you.

交叉淡入淡出实际上是同时对两个单独的音轨进行。 第一首曲目逐渐淡出，第二首曲目逐渐淡入，但它之间并没有发生沉默，而是同时发生。 听起来通常是您打开了另一间带有不同音乐的房间的门，然后穿过它又关上了身后的门。

为什么有用？ (Why is it Useful?)

Many songs use fading techniques to great effect when starting or ending, or at particular parts in the song. The same goes for video; it’s useful to be able to fade in to a crowd’s cheer, or fade out of an original audio source in favor of narration of some kind. Crossfading is valuable because it allows these changes to happen quickly without being jarring, without introducing silence, and while sounding smooth and more natural. DJs often use this technique while matching beats of two different songs to produce a continuum of sound, while editors often use crossfades (as well as fade-ins and fade-outs) to make the introductions of different sound components sound less “sudden” and more natural.

许多歌曲在开始或结束时或在歌曲的特定部分使用衰落技术效果非常好。 视频也是如此； 能够淡入人群的欢呼声或淡出原始音频源以支持某种叙事是很有用的。 交叉淡入淡出很有价值，因为它可以使这些更改Swift发生而不会造成震颤，不引入静音，同时听起来更平滑自然。 DJ经常使用此技术，同时匹配两首不同歌曲的节拍以产生连续的声音，而编辑人员经常使用交叉淡入淡出(以及淡入和淡出)，以使不同声音成分的引入听起来不那么“突然”，更自然。

You can group crossfades into three vague categories, and each sounds very different from the others.

您可以将淡入淡出分为三个模糊的类别，每种听起来与其他声音非常不同。

Mid: Each track is linearly faded. You can download a short sample track here: mid crossfade. Visually, it looks like this:

中：每条音轨线性衰减。 您可以在此处下载简短的示例音轨： mid crossfade 。 在视觉上，它看起来像这样：

You can see that the volume increase/decrease looks steady. Depending on the volume of the original tracks, this sounds more or less even.

您可以看到音量增加/减少看起来很稳定。 根据原始音轨的音量，这听起来或多或少均匀。

High: The faded-out track starts fading slowly, then picks up speed as time goes on. The faded-in track, on the other hand, picks up volume fairly quickly and that increase of volume slows down over a period of time. You can download a short sample track here: high crossfade. Visually, it looks like this:

高：逐渐消失的音轨开始逐渐淡入，然后随着时间的流逝加快速度。 另一方面，渐弱的音轨会很快拾起音量，而音量的增加会在一段时间内变慢。 您可以在此处下载简短的示例音轨：高淡入淡出。 在视觉上，它看起来像这样：

The volume changes look like bulges here, with the effect that the both tracks have a high volume through the duration of the fade, and there is still some abruptness to it.

此处的音量变化看起来像是凸起，结果是两条轨道在淡入淡出的过程中都具有很高的音量，并且仍然有些突兀。

Low: The faded-out track drops its volume pretty quickly and the speed of this drop slows down over a period of time. The fade-in track starts gaining volume slowly but it picks up speed as time goes on. You can download a short sample track here: low crossfade. Visually, it looks like this:

低：淡入淡出的音轨会很快降低其音量，并且在一段时间内该速度会变慢。 淡入音轨开始逐渐增加音量，但随着时间的流逝它加快了速度。 您可以在此处下载简短的示例音轨： low crossfade 。 在视觉上，它看起来像这样：

The changes here look like concave cuts. For the duration of the fade, both tracks have a reduced volume until the original track is almost completely gone. The effect feels almost like a lull (but lacking complete silence) and the volume then builds up quickly again after, almost like a swoop.

这里的变化看起来像凹切。 在淡入期间，两个音轨的音量都会减小，直到原始音轨几乎完全消失为止。 效果感觉几乎像是平静(但缺乏完全的静音)，然后音量又Swift增大，几乎像扑扑一样。

When the two tracks crossover, their volume builds. For mid-level crossfades, at halfway through the transition the volume of each track is half. Low-level crossfades are below half volume halfway through the transition, and high-level crossfades are above half-volume halfway through the transition.

当两条轨道交叉时，它们的音量就会增加。 对于中级交叉淡入淡出，在过渡的一半，每个音轨的音量为一半。 在过渡的中途，低级别的交叉淡化低于一半的音量，而在过渡的中途，高级的交叉淡化高于一半的音量。

交叉淡入淡出中的声音差异 (Sound Differences in Crossfades)

Sound is measured in Bels, or more commonly, as fraction of that unit: decibels. Human hearing is very sensitive to acute changes in sound. Just like how we can hear very low frequencies (like 20 Hz) and very high frequencies (like 20,000 Hz), we can hear very soft sound and very loud sounds. In fact, our ears have a sensitivity from 1 to 130 decibels, which is to say that the loudest sound you can hear is roughly 10 trillion times loader than the softest sound you can hear! As such, what appears to be a “linear” change in volume is actually logarithmic. In crossfades, if you want to mess with the rate of change of volume, you need to more aggressively change it. It helps to see things visually.

声音以贝尔为单位，或更常见的是，以该单位的分数为单位：分贝。 人类的听力对声音的剧烈变化非常敏感。 就像我们可以听到非常低的频率(例如20 Hz)和非常高的频率(例如20,000 Hz)一样，我们可以听到非常柔和的声音和非常响亮的声音。 实际上，我们的耳朵的灵敏度在1到130分贝之间，也就是说，您听到的最大声音大约是加载器的10万亿倍，比您听到的最柔和的声音大！ 这样，看似体积的“线性”变化实际上是对数的。 在交叉淡入淡出中，如果您想弄乱音量的变化率，则需要更积极地进行更改。 视觉上看东西很有帮助。

大胆的线性交叉渐变 (Linear Crossfades in Audacity)

In Audacity, it’s easy to add linear crossfades. Align the two tracks you want to crossfade in the timeline, either by editing or by using the time shift tool. When you’re lined up, select a portion of the track you want to fade out. Go to Effect > Cross Fade Out.

在Audacity中，添加线性交叉渐变很容易。 通过编辑或使用时移工具，在时间轴上对齐要淡入淡出的两条轨道。 排队后，选择要淡出的部分曲目。 转到效果>交叉淡出。

Then, in the next track, select the portion you want to fade in. Go to Effect > Cross Fade In.

然后，在下一首曲目中，选择要淡入的部分。转到“效果”>“交叉淡入”。

You can delete the rest of the first track if you’re done with it. Be careful with the track that you’re fading in, though, as deleting it will move it back to the beginning. You can either use the time shift tool to bring it back to where it needs to be, or better yet, just convert the first part of the track to silence.

完成后，您可以删除第一首曲目的其余部分。 不过，请谨慎对待您正在逐渐消失的音轨，因为删除它会将其移回到开头。 您可以使用时移工具将其恢复到需要的位置，或者更好的方法是将轨道的第一部分转换为静音。

淡入淡出高或低 (Crossfading High or Low)

Making high or low crossfades isn’t automated in Audacity. One way to easily do it requires the use of the Envelope Tool.

在Audacity中无法自动制作高或低交叉淡入淡出。 一种轻松做到这一点的方法需要使用信封工具。

The Envelope Tool will allow you to change the volume of any track without actually changing the amplitude. As the actual sound wave isn’t changed, the source file will remain untouched. You can add multiple points to further shape the necessary change. After selecting this tool, click on your track, and drag to change the level of volume.

包络工具将允许您更改任何轨道的音量，而无需实际更改振幅。 由于实际的声波没有改变，因此源文件将保持不变。 您可以添加多个点以进一步塑造必​​要的更改。 选择此工具后，单击您的曲目，然后拖动以更改音量。

Each click will add a new handle in the form of a white dot that you can move. Just manually shape the curve to about what we described above. Of course, your track may have different needs. If your track’s volume itself changes, then you can compensate or ignore it. As always, do what sounds right.

每次单击都会以白点的形式添加一个新的手柄，您可以移动它。 只需手动将曲线调整为我们上面描述的形状即可。 当然，您的足迹可能有不同的需求。 如果轨道的音量本身发生变化，则可以对其进行补偿或忽略。 与往常一样，做听起来正确的事情。

Crossfading has a variety of uses for both audio and video editing. Depending on what type of crossfade you do, you’ll be able to achieve a variety of effects for different purposes. Now that you know how crossfades work, you can choose which one works best in your projects. After all, it’s all about choice isn’t it?

淡入淡出在音频和视频编辑中有多种用途。 根据您进行淡入淡出的类型，您将能够实现不同目的的各种效果。 现在您知道交叉渐变的工作原理，您可以选择哪种项目最适合您的项目。 毕竟，一切都是关于选择的，不是吗？

Note: The music used in the sample tracks is by Talvin Singh; “Traveller” and “Butterfly” from the album OK

注意：示例音轨中使用的音乐是Talvin Singh创作的； 专辑中的“旅行者”和“蝴蝶”

Other articles in the Audio Editing series:

音频编辑系列中的其他文章：

• The How-To Geek Guide to Audio Editing: the Basics

  音频编辑入门指南：基础知识

• The How-To Geek Guide to Audio Editing: Basic Noise Removal

  音频编辑入门指南：基本噪声消除

• How To Add MP3 Support to Audacity

  如何将MP3支持添加到Audacity

• The How-To Geek Guide to Audio Editing: Cutting, Trimming & Arranging

  音频编辑入门指南：剪切，修剪和排列

翻译自: https://www.howtogeek.com/57252/how-to-use-crossfade-in-audacity-for-seamless-transitions-between-audio-tracks/

audacity音轨加伴奏