Solutions Abound for High-Volume Live Video Cloud Transcoding

Live transcoding is the ideal operation to perform in the cloud since it reduces outbound 带宽需求 and CapEx. 随着分辨率的提高和编解码器变得越来越复杂, 然而, it becomes harder to encode your complete encoding ladder in a single cloud instance, and splitting the task between two or more machines adds cost and complexity. 幸运的是, there are multiple solutions for efficient high-volume cloud transcoding, including several showcased at 流媒体 West in November 2018.

让我们从底部开始, 从效率的角度来看, which is software-only encoding to x264 or x265 via FFmpeg installed in a cloud instance. 只要你能产生一个四到六阶的H.264 encoding ladder, you should be able to encode on a single machine.

Next up are software-only encoders that are simply more efficient than FFmpeg. 在他的流媒体西部演讲中， IDT’s Lowell Winger explained how the company’s software- and hardware-accelerated codecs deploy multiple techniques to deliver up to 40% more throughput than FFmpeg for H.264 encoding, which translates to significant savings over a plain-Jane FFmpeg solution.

当然, 超越仅软件的x264和x265编解码器, FFmpeg offers several hardware-accelerated codecs for more efficient encoding. 例如，根据您的CPU, FFmpeg支持H.264, H.265, VP9编码和解码通过英特尔快速同步, 哪些应该在大多数云实例上可用. 您还可以访问nvidia加速的H.264和HEVC通过实例与NVIDIA gpu. 您还可以利用第三方, gpu加速编码，如IDT的HEVC编码器, which can transcode 4Kp60 10-bit HDR HEVC on a consumer off-the-shelf server platform.

The next level of performance is provided by field-programmable gate arrays (FPGA), which are general-purpose hardware devices that can be programmed to deliver close to the performance of application-specific chipsets. Cloud services like AWS are now deploying FPGA-based instances where they can be accessed by different software developers to provide a diverse array of functions. 在他的演讲中，在Twitch TV上使用VP9进行直播，抽搐的 Tarek Amara described how the service was deploying live VP9 encoding using Xilinx FPGAs driven by software from NGCodec, VP9的巨大技术支持, FPGAs, 和NGCodec. Note that you can directly provision FPGA-driven HEVC and VP9 encoding from NGCodec in the AWS Marketplace.

当然, the most efficient transcoding will always be performed by application-specific encoding hardware. 在流媒体 West， NETINT技术” Ray Adensamer described how his company’s System on Chip (SOC) encoder, 在高密度T400中, 能启用80x 1080p 30h吗.265 sessions in a single 1RU server with 10 T400s installed. Rather than selling the T400 as a standalone encoding appliance, 然而, NETINT designed the module for installation in NVM表达-based storage servers. (简要, NVM表达, 或NVMe, is an interface specification for connecting SSD-based storage to servers via the PCI Express bus. NVMe is used in cloud facilities and increasingly in the enterprise. 大概, leveraging NVMe will simplify on-prem deployment for large-scale encoding shops and perhaps even convince a cloud service to install an application-specific device within a standards-based platform.)

很明显, 需要GPU的编码平台, FPGA, 而基于nvme的解决方案每小时的成本更高, though it should be relatively simple to compute a per-stream cost to compare to software-only encoding. 质量分析就没那么简单了. The rap against Intel and NVIDIA-based encoding has traditionally been quality, 虽然我读到质量差距正在缩小, 我还没有通过测试确认. I have tested enough encoders to know that if you run your own tests, you shouldn’t simply compare the high-level peak signal-to-noise ratio (PSNR), 视频多方法评估融合, or SSIMPLUS scores; also examine your test files for transient quality issues. 例如, though faster x264 presets like Ultrafast and Veryfast deliver close to the same average PSNR/VMAF scores as Medium, they often contain multiple five- to 10-frame regions of really awful quality that would seriously degrade QoE.

如果所有这些关于供应的讨论听起来过于复杂, 你可以雇人帮你做. 在这方面, there were multiple providers at 流媒体 West with live transcoding capabilities, 包括Bitmovin, Brightcove, 电影《百家乐软件app最新版下载》英文名, 和Wowza.

[This article appears in the January/February 2019 issue of 流媒体杂志 作为“实时转码选项”."]

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实时视频流的大规模编码

Many of today's live video encoding solutions require extensive compute resources, limiting the ability of live streaming business models to economically scale. This article will introduce a new real-time video encoding solution, 结合片上系统(SoC)编码的性能, 基于nvme的云基础设施的创新, which together provides an economical and high quality solution to deliver encoding at scale for live video streaming.

11月29日2018