How to Assemble a 4K Switching and Webcasting Solution for Less Than $5K

早在2016年11月，YouTube就在YouTube Live上增加了2160/60P的网络直播支持. Many modern professional video cameras support 4K internal recording and output, 所以现在是一个很好的时间来探索把一个完整的4K多摄像机视频切换和网络广播工作流程.

In this build, 我最初的目标是将尽可能多的功能打包到我的4K工作流程中，因为我可以在5美元内完成,000 budget. As it turns out, I was able to assemble a system with 2x 4K inputs for just under $4,200围绕一个一体化的视频计算机为基础的软件视频切换器和网络广播编码器. Because I had some leftover room in the budget, 我决定提供另一种选择，使用硬件视频切换器添加更多的4K输入，并构建一个功能稍弱的网络广播编码器.

这篇文章不仅会讨论我选择了什么和为什么，还会讨论我没有选择什么和为什么不选择. I have put a lot of thought into this workflow because I as I write this, I am actually purchasing these components and assembling this build. In keeping with our “4K for <$5K” goal, 在这个构建中，我要为自己设置的唯一规则是网络广播信号需要是本地2160P信号.

Video Capture Card

Any time I look at a workflow from start to finish, 我喜欢从确定我需要的所有组件以及工作流的哪一部分将限制我的选择开始. In this case, the most restricting component will be my video capture card, 唯一的原因是目前市场上只有少数视频采集卡支持4K采集.

I’ve written another new article that discusses how to select a video capture card, 因此，我将在这里开门见山，向您介绍我为这个版本考虑的两个选择:AJA Io 4K和Blackmagic Design DeckLink Mini Recorder 4K.

AJA解决方案售价1995美元，支持2160/60P，通过Thunderbolt 2连接电脑. 走这条路线将限制我在这个预算内使用单个捕获卡，并迫使我将其与启用Thunderbolt 2的计算机配对. MacBook Pro不在预算之内，而且不支持我计划使用的vMix软件, so I have to limit my computer options to a Windows system. Thunderbolt正通过支持Thunderbolt 3的USB-C接口进入许多Windows电脑. However, 将Io 4K连接到USB-C PC需要Thunderbolt 3 (USB-C)到Thunderbolt 2适配器和USB-C到USB-C电缆.

This approach could work for those who absolutely need a portable, laptop-based solution, but for this build, 相反，我要安装两台Blackmagic Design DeckLink迷你录音机4Ks (Figure 1, below) for $195 each. These capture cards cost 1/10 of the MSRP of the AJA solution, which leaves a lot of room in my budget for other equipment.

Figure 1. Capture card: Blackmagic Design DeckLink Mini Recorder 4K ($195 x 2)

The DeckLink Mini Recorder 4K supports both HDMI 2.0a and SDI 6G connections and is limited to 2160/30P inputs. 我不打算用这个构建最大化YouTube Live的2160/60P能力, but most of us don’t have video cameras that can output 2160/60P anyway, and 30P is plenty for an Ultra HD (UHD) webcast. 大多数4K采集卡都是PCIe卡，这意味着它们需要安装在计算机塔中. 这就排除了苹果的桌面产品，意味着我将构建一个Windows桌面系统.

Hardware Video Switcher Option

如果您需要大量的4K视频输入，那么您将需要一个硬件视频切换器. The Blackmagic ATEM Production Studio 4K (Figure 2, below)售价1695美元，支持8个总输入，分为4个HDMI和4个SDI输入. 2160P的最大帧率为30fps，与市场上大多数流行的4K UHD摄像机相匹配. 您需要注意的是，大多数UHD摄像机制造商通过HDMI输出UHD 4K, while Blackmagic’s own cameras output over 6G and 12G SDI. 这限制了你在没有4K格式转换器的情况下只能使用4台任何一种类型的摄像机. In this workflow, 您仍然需要将4K视频输出到带有网络广播捕获卡的计算机, 但如果你只有一个4K视频输入，你的电脑需求会比我要做的要低.

Figure 2. Hardware switcher (optional): Blackmagic ATEM Production Studio 4K ($1,695)

If you decide to build the same system that I am going to detail below, you will need to make a few changes to stay within the $5,000 budget, such as purchasing only one media drive, and selecting the previous generation or lower line of motherboard, CPU, and graphics card. I have outlined the part list for the ATEM build here.