2013年3月26日
By 1月时特约编辑
专题文章

Review: Teradek VidiU, a 第一个 Look at the Compact H.264编码器

的 Teradek VidiU ($699) is an affordable, service-provider agnostic on-camera H.264 encoder that produced very good video quality at all tested data rates. VidiU is also well-featured, with comprehensive preview and control provided via a free iOS app. 的 only thing stopping me from giving it an unabashed buy rating was a slight audio artifact that became evident when we listened to the live streams.

VidiU硬件

VidiU的尺寸为3 × 4 × 1英寸, just slightly larger in all dimension than a deck of cards, and comes with a cold-shoe mount so you can sit it atop your camcorder. Powered by an internal rechargeable lithium-ion battery that's rated for 90 minutes of operation, 该设备包括一个以太网端口, 双频MIMO 802.11 a/b/g/n Wi-Fi, and a USB port for a 3G/4G modem.

的 unit accepts HDMI input with an optional line for mic audio input, and there's a headphone output for monitoring. 您可以发送高达1080p的视频, and the unit can encode at that resolution, though the maximum resolution for the two platforms that I tested, liveststream和Ustream, 是720便士. You can drive the unit directly via a four line OLED display with joystick and navigation buttons in front, but most users will prefer using the free iOS application for configuring the unit.

VidiU软件

Whether you operate the unit via the joystick/OLED display or the iOS application, 基本的菜单结构是相同的, with major categories for broadcast settings, 音频和视频配置, 网络设置, 和系统设置(在左侧的图1). 的 broadcast settings are where you choose your service provider (new Livestream, Ustream, 或通用RTMP服务器), 输入您的证书, and choose your quality settings (on the right in 图1).

Video is where you choose your video inputs, though auto-sensing worked fine for me. Audio is where you choose the input (HDMI or Mic/Line), Network is for connectivity settings and System is for updates and resets.

图1. 的 basic configuration options on the left; quality settings on the right.

的 unit offers six quality levels as shown in 表1. Note that the full HD option isn't shown in 图1 because it's not available for Livestream or Ustream, 我测试的两项服务.

VidiU表

表1. Quality settings and their configurations.

的 quality settings screen has several noteworthy features. 首先是建议的质量函数, which runs a quick bandwidth test on the VidiU unit and reports back a suggested setting. 二是自适应比特率函数, which will automatically throttle down the outbound signal to match the available bandwidth. For example, I tested the unit in my office using the HD setting, which consumes 2.4mbps的带宽. Since the outbound bandwidth in my office is a paltry 850 kbps, the outbound video should have quickly swamped the connection. 而不是, the VidiU simply throttled down the connection to a lower quality level and the video kept smoothly streaming through.

Also noteworthy is that the device encodes two streams during operation, the first is transmitted to the streaming service provider, the second is sent via Wi-Fi to your iOS device to use for confidence monitoring, 定位, 诸如此类. 这是实时流, not transmitted through the live streaming service provider, and I found it helpful when controlling the box during my test encodes.

图2. 的 iPhone app features a real time stream from the VidiU for confidence monitoring

视频入门

VidiU ships with a barebones getting started guide. 如果你运行过Teradek的其他产品, you'll catch on fast; if you're a novice, 可能需要几分钟. 这里有一些入门技巧.

第一个, it's easier to operate the unit via the iPhone app than the OLED display and joystick, though you have to get VidiU connected to the internet via controls on the VidiU before you can switch over to your iOS device. If you're running the VidiU and the iOS device on the same LAN, they'll see each other automatically after a few moments. 当你运行iOS设备应用时, the first thing it does is check for the VidiU, so you'll know right away if they connect.

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