测试Vitec MGW Ace和MGW D265的HEVC编码/解码

当我第一次看到原型机时 Vitec 媒体网关(MGW)王牌2015年2月, I was struck by two facts: The HEVC-based unit wasn’t much bigger than the H.264-based real-time encoders that Vitec had shown me before—making it ideal for field use—and the Ace had all the markings of a product that could be useful in the burgeoning 4K video market.

我只说对了一半. MGW Ace确实是现场使用的理想选择, but its primary focus is in the sub-4K mid- and low-bitrate range in which its primary target customers—military, 安全, 而监控用户通常会操作.

现在MGW Ace已经上市近6个月了, after launching at the National Association of Broadcasters (NAB) show in early April 2015, 流媒体 同意对航运单位进行审查. It was in the running for several awards at the IBC show in Amsterdam at time of our review, 是在维泰克的展位上做的吗. 还有编码器, 我们还看了一个新的, 配套产品:基于硬件的MGW D265解码器. 正如其命名约定所暗示的那样，它是一个基于硬件的H.265解码器, which allows content acquired in HEVC to be played back without requiring a robust computer to decode the H.265的内容.

This review, for those of you following the licensing issues surrounding H.265/HEVC, is set against a backdrop of uncertainty for widespread HEVC adoption. 话虽如此, the MGW Ace and D265 form an end-to-end HEVC hardware encode/decode solution, which means that users of this closed system can choose to bypass both the licensing and higher computational requirements of a software-based H.265年解码.

除了, Ace-D265组合提供了一些独特的功能, 如紫溪集成中的D265, 这有助于解决网络间歇性问题. 我们的评论将简要介绍这些端到端特性.

MGW王牌, 虽然, 不仅限于交付给D265, a key factor for those considering using the Ace with a traditional media server. So we will also touch on interoperability of the Ace with software-based decoders.

幕后故事

MGW Ace是关于实时交付的. 因此，这种基于fpga的编码解决方案提供了H.265的4:2:0或4:2:2分辨率高达1080p.

伊莱加滕, Vitec的产品管理副总裁, answered a few of the questions we had about the exclusion of 4K 决议s, 以及4:2:0和4:2:2压缩的选项,.

“我们开发了一种具有两种模式的编解码器，”Garten说. “Each is optimized to a different use case group: one for high-rate broadcast content and another for ISR-specific imagery with very low rates.”

加藤注意到情报, 监测, and reconnaissance (ISR) communities don’t really have a way to consume 4K content in the field, especially since many of the real-time streams generated need to go to field operatives watching content on mobile phones or other small form-factor devices.

Garten added that the ISR community often has to deal with low-bandwidth requirements that aren’t necessarily an issue for broadcast content acquisition. The result was a single HEVC codec inside the Ace that branches to two modes, 取决于用例, “each of which behaves differently and uses different HEVC tools to offer the best processing approach for each vertical.

“我们只有一组参数, 一个非常广泛的问题,加藤说。, noting that the parameters are based on how the user configures the output settings (bitrate, 帧率, 决议, 元数据等.).

”也, 基于我们使用算法检测到的内容,他说, “we calibrate many other codec settings internally to produce the best compresses video. The main point is that we decided that encoding military footage requires a different approach than encoding general content and broadcast footage, and have developed specific handling for each use case so that the visual experience in each vertical will be perfect.”

单输入，双输出

MGW Ace的输入接口包括复合接口和SDI接口, 包括3G的单bnc连接器, HD / SD-SDI输入. 此外，Ace还包括HDMI v1.3 and DVI-I inputs, with the former capable of carrying at least two channels of embedded audio.

在视频信号方面, Ace超越1080p60，提供高达1080p @85Hz, 这意味着高动作获取是可能的. It also supports a gamut of raster sizes below 1920x1080, bottoming out at 720x480.

Audio inputs include embedded audio on both the HDMI and SDI connectors, as well as a multipin connector that allows balanced and unbalanced analog audio.

除了, 考虑到它在ISR和军事环境中的应用, Ace提供元数据处理, 符合北约对KLV和STANAG元数据的要求.

Besides the single-input option—and accompanying metadata—the Ace has the proverbial ace up its sleeve when it comes to handling legacy H.264台设备. 在承认需要提供H.264编码，Ace有第二个H.264编码芯片. 这意味着Ace可以同时流到H.264软件解码器以及基于硬件的H.可能用于代理流的264解码器.

The Ace contains several additional ports, some of which are not yet active as of this writing. The company says they will be activated via firmware updates at a later date.

这些端口包括第二个千兆以太网端口. 虽然我们没有任何可靠的细节, 因为端口尚未激活, it would seem logical the second Gigabit Ethernet port would allow H.265和H.264 to be streamed on two discrete IP addresses or to replicate a single H.264或HEVC流到双网络额外的冗余.

“We support both transport streams and elementary streams,” says Garten. “But we currently offer only one stream at a time, so no support for two concurrent input streams.”

除了, two BNC connectors used for output—SDI out and DVB/ASI out—are dormant until the firmware update. Our opinion is that Vitec should cover these ports until such a time as they are active, as potential buyers may design a system using these Ethernet and BNC ports, 结果发现端口当前处于非活动状态.

当地的记录

Ace有两个前面板插槽用于本地录制内容. 第一种是标准的USB 2.0 connector, to which a USB flash drive or external hard drive can be attached. 第二个是受保护的SD卡插槽. 一旦两个螺丝和小面板被拆除, 可以插入SD卡并重新连接面板. By using a removable faceplate, the Ace protects the SD card from exterior elements,

接收流

When it comes to hardware decoding, the MGW D265 is more than just an H.265 / HEVC译码器. The D265 has hardware decoding for both MPEG-2 Transport Streams (M2TS) as well as H.264 IP流.

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