教程:使用罗兰VR-50HD多格式AV混音器进行现场切换制作

在Roland VR-50HD这样的系统上，你会注意到的第一件事是，它不仅仅是一个标准的视频切换器. It has an audio component on the left that takes up half the panel. There's a good reason for that: Audio is really important. On the right side of the panel, you'll find the video controls, as well as a multiview touchscreen video switcher (Figure 1, below).

Figure 1. The Roland VR-50HD. Click the image to see it at full size.

VR-50HD与传统视频切换器的另一个关键部分是它是一个流媒体设备. The USB output on the VR-50HD is a USB Class streaming appliance, and you can stream using just the USB to a connected computer, 这样你就不用使用中间的网络广播编码硬件了.

VR-50HD是真正的“一体化”混合器，正如罗兰对该产品的描述所暗示的那样. 你不需要有很多其他的设备来实现一个成功的实时切换生产和流. 例如，罗兰确实做了一个非常好的扫描转换器，VC1-SC (Figure 2, below). It has VGA, HDMI, and HD-SDI inputs, 它把这些信号转换成你需要的输出端. 但是这个视频切换器不需要扫描转换器，因为它有所有这些输入.

Figure 2. The Roland VC-1-SC Video Converter.

Roland VR-50HD Audio

你也不需要带你的音频混音板拍摄你做的VR-50HD, because it has a full audio mixer built-in. Let's take a closer look at it.

首先，在VR-50HD面板的左侧，有一个音频控制台(Figure 1). It's organized in terms of inputs. The controls for Inputs 1-4 correspond to the mic-level inputs, 哪些是XLR/TRS(尖端环套)组合输入，你看到在右边 Figure 3 (below). 您还可以组合RCA输入和尖端环套输入，它们是线电平-5/6, 7/8, 9/10, 11/12, shown just to the left of the mic-level inputs in Figure 3 (below).

Figure 3. Audio inputs on the VR-50HD. Click the image to see it at full size.

除了这些输入，您还可以接受来自HDMI或HD-SDI的音频输入. 这与视频方面的工作原理类似:你有很多不同的选择, and you can route those inputs where you want them to go. 有时我喜欢使用相机的音频——也许是为了环境目的——我可以使用HD-SDI或HDMI馈送将其输入VR-50HD. 其他时候，我与外部音频公司合作，我所需要的只是从他们的音板上输入一个声音. 其他时候，我使用麦克风，就像我在上面的视频教程中使用的那样——我戴着一个lavaliere和一个手持麦克风.

For this project, Input 1 is already set up, that's the lavaliere microphone I'm wearing in the tutorial video. Input 2 is the handheld mic. 设置麦克风时需要做的第一件事是调整增益. Leaving the slider at about parity, as shown in Figure 4 (below), I'll turn up the gain for that input, and the audio level will increase, 音频控制台右上方树上的灯将在适当的级别亮起. Finally, there's the main output, 如图4中音频控制台右下角所示的红色滑块. 这就是用VR-50HD设置麦克风输入的基本方法.

Figure 4. Adjusting gain for Input 2. Click the image to see it at full size.

现在我们已经探索了音频控制台上的滑块和附加控件, let's delve into the audio setup menu, shown in Figure 5 (below). 在设置菜单中，我们可以使用触摸屏来影响音频级别. We can adjust the overall audio and gain. We can also solo inputs. In audio testing, it's really important to have solo ability, so I hit the solo button, and can hear just one microphone with all the rest turned off. It's a great troubleshooting technique. 我还可以使用触摸屏左下角的按钮将输出静音. 

Figure 5. Adjusting audio in the audio setup menu.

Other controls include AUX Send button. 除了主线输出外，我们还有辅助音频输出. That's really convenient when you're doing two audio mixes. 你可以使用AUX发送按钮，当你发送一个混音档案录音或现场房子混音, and the other to the streaming output.

在菜单的更深处，你有很多不同的功能，比如延迟. Sometimes audio and video don't arrive at the same time, especially if they're going through different systems. The speed of light is a lot faster than the speed of sound. Sometimes you need to add in some delay for the audio.

在设置菜单中有一个3波段均衡器，所以你可以调整高，中，低. 菜单中真正提供很多附加价值的两个功能是闸门和压缩机. 有了门，你首先要建立一个噪音底限，低于这个底限的噪音就会被切断. It's great for eliminating air-conditioner hum, 还有其他你不想进入录音的房间噪音.

The compressor works at the other end of the audio spectrum. 它可以帮助那些原本会被剪辑的音频水平降低并压缩它们. 所以门和压缩机确实有助于扩展你的音频范围.

你会发现必不可少的第三个控制是USB音频控制, which is found at the top of the system (Figure 6, below). 这是旋钮，你可以转向调整USB音频水平独立于你的主人和你的AUX音频输出. You'd use this for your USB recording or your USB streaming. 

Figure 6. The USB audio output control.

重要的是要对所有不同的音频级别有单独的控制，因为在不同的时间, some of them might have different audio-level requirements.

Roland has a very strong legacy of audio equipment, 你可以看到一些他们添加到视频混音器中的不错的触摸. Another example is the headphone jack outputs. They've got both the mini for headphones, and the 1/4", 如果你有专业的标准或万一你有一个适配器.