基准pc,捕获卡和软件混频器的高清捕获和流
确定系统产生和交付实时事件流所需的功能, we tested a range of computers (old and new), capture devices, and multiple live streaming software programs, streaming to one or more streaming services, recording archive/ISO files in various formats, and measuring CPU utilization. Read on for the results.
当你用自建的, computer-based system, 你的关注点会缩小到一个相关的问题上:系统是否足够强大,能够产生事件所需的流?
To help find out, we assembled a range of computers (old and new), obtained several capture devices, 下载了多个直播软件程序. Then we ran multiple tests, streaming to one or more streaming services, recording archive/ISO files in various formats, and measuring CPU utilization. On the Windows-based systems, 我们在Performance Manager中捕获结果,并对输出进行注释,以生成如图所示的图形 Figure 1. 在Mac上,我们只是在测试期间记录CPU利用率.
在讨论结果之前,让我们先谈谈测试过程. 首先,为了使结果正常化,我对所有测试使用了相同的高动作,高细节的AVCHD剪辑. Each time, I started the streaming and/or recording activity, triggered the recorded video, let it play through, and then stopped recording/streaming. Then I changed the configuration and started again. 为了增加一点复杂性,我在所有视频上都添加了一个徽标叠加.
我将详细介绍审查测试结果时使用的每个计算机系统和捕获设备. 对于混音软件,我使用了一个预发布版本的Telestream Wirecast 7.1. 我很高兴自己这么做了,因为CPU利用率比版本7明显下降了.0, which was way down from version 6.0. I tested vMix version 17.0.0.107 and version 0.15.4 of Open Broadcaster Software (OBS).
Let’s start with notebook testing.
Notebook Testing
我在HP ZBook Studio G3移动工作站上进行了第一次测试.8GHz至强四核(八核超线程技术[HTT]) E3-1505M CPU, 32GB RAM,运行Windows 10. 第一个捕获设备是基于USB 3的Epiphan AV.io 4K video grabber.
Figure 1 (below) 详细介绍使用Wirecast version 7运行测试的结果.尽管测试会随着软件混合器的功能而略有不同. I started with a 720p/2.25Mbps stream to Facebook Live, 然后添加了一个用x264编码的1080p/8Mbps存档, which boosted CPU utilization to more than 55%. By way of comparison, with Wirecast version 7.0.1, CPU utilization for x264 was more than 70%. 测试三是Facebook Live加上一个用更高效的英特尔快速同步视频编解码器编码的存档.
![](http://dzceab466r34n.cloudfront.net/Images/ArticleImages/InlineImages/108522-ozerbench1-ORG.png)
Figure 1. CPU utilization for Telestream Wirecast on a 2.8GHz HP ZBook with an Epiphan AV.io 4K video grabber
As a rule of thumb, once CPU utilization pushes past 70%, 您可能会在直播流或录制文件中开始掉帧. 虽然x264的质量略高于快速同步,但在8Mbps时,差异非常小. 如果您注意到CPU利用率一直超过60%左右, 考虑将存档版本切换到快速同步(如果可用).
请注意,我使用x264时,所有的直播流可用的Facebook和Ustream. 如果您发现系统上的CPU利用率高得令人不安, consider switching to Quick Sync (if available). 我使用了x264和非常快的预设,因为这是所有测试软件程序的默认设置. I ran some tests with the Medium preset, but this drove CPU utilization through the roof, and the quality difference was indiscernible.
Wirecast还提供了一个ISO存档,它生成一个基于MJPEG (Motion JPEG)的QuickTime文件. 而关于高效的cpu智慧的快速同步编解码器, 而动态JPEG文件是前者的11倍多(91.7Mbps(与8Mbps相比),这可能会给笔记本电脑的存储能力带来压力. As you’ll see later, I also found QuickTime MJPEG files slightly dingy, 所以我推荐使用MP4而不是MJPEG来提高质量和文件效率. 最后的测试包括向两个直播流媒体服务发送720p流媒体, Facebook and Ustream, 它需要和快速同步和ISO存档一样多的CPU.
What are the key takeaways? At 2.8GHz, an E3-1505M Xeon system, or a 2.8GHz i7 system, 应该有足够的功率来轻松处理720p输出流, 再加上x264或快速同步格式的存档版本. 相同cpu的较慢版本应该提供接近比例的性能, 虽然ZBook Studio提供的最慢的CPU是2.6GHz i7,其性能应该与测试型号相似. Changing the CPU completely, say to a dual-core i5 (four with HTT), changes the formula completely, and I briefly look at an i5-based system later.
Related Articles
本文解释了在选择捕获卡以将其合并到您的实时切换和流工作流程中时应该寻找哪些特性.