Buyer's Guide: Live Encoders
When it's got to be streamed live, you can't cut corners. Here's a list of questions to ask when selecting a live encoding solution.
This article appears in the February/March issue of Streaming Media magazine, the annual Streaming Media Industry Sourcebook. In these Buyer's Guide articles, we don't claim to cover every product or vendor in a particular category, but rather provide our readers with the information they need to make smart purchasing decisions, sometimes using specific vendors or products as exemplars of those features and services.
In the world of streaming video, the events we all talk about are those absolutely mammoth ones, often involving sports, that need to be delivered to television-sized audiences regardless of the form factor of the device and or bandwidth of the network the user chooses.
Those events get the most attention in the press, but before we delve into hardware-based video encoders for this Buyer's Guide, let's get a key fact out of the way: The vast majority of content on the web doesn't need to be streamed live. A recent study shows that 95% of all content consumption on the web is delivered as on-demand content, ranging from the Netflix and LoveFilms of the premium content world to the newest craze on YouTube. So when it comes time to buy an encoder, or encoding/production services, think for a moment whether you need live or can settle for on-demand delivery after the fact.
For those who need to push out live content, a wide range of options are available. Encoders come in all shapes and sizes, from the basic software packages that are available for free download-offered by the open-source community as well as major software server companies-to very high-end, powerful hardware encoders.
For hardware-based encoders, here are a few questions to consider.
1. Is free too expensive? The question of free encoders continues to rise to the top of the heap when it comes to encoder choice. Why would anyone pay extra money to use a live hardware encoder? We've seen free software encoders work, assuming the right hardware is in place to address the minimum specifications, but we've also worked on events that used free encoders-and crashed and burned due to the inconsistency of the experience. That's the bottom line: for important large events, a battle-tested hardware-based encoder is guaranteed to deliver consistently, day in and day out. The last thing needed in a major event is someone scrambling to Best Buy to pick up another consumer-grade computer on which to run free software.
2. Is adaptive live streaming a necessary part of your workflow? For those who plan to deliver live content to more than just a single format and bandwidth (e.g., a desktop computer) and whose viewers expect to be able to continue to watch the major event wherever they are, the ability to generate multiple bitrates and resolutions that can be served to several device types on varying network types (i.e., cellular, Wi-Fi, or fixed-line cable/DSL) then consider choosing a hardware encoder that will generate all the bitrates from a single encoder, rather than requiring multiple stand-alone encoders. In many ways, it is more cost effective-in terms of device management, overall cost, and power consumption-to use a live hardware encoder for multiple bitrates than to have multiple single-stream encoders.
3. Where does packaging occur? With the use of adaptive bitrate content, where every bitrate/resolution combination is divided (fragmented) at the same spot to allow for seamless switching between bitrates, many live hardware encoders perform the this segmentation within the hardware encoder itself.
At first glance, this seems the proper approach, but other hardware encoder companies have a different perspective, namely that the competition among the adaptive bitrate delivery solutions from Adobe, Apple, Microsoft, and the newer DASH standard is yet to be settled. For those events using multiple live hardware encoders, some hardware encoder manufacturers argue for the use of an external packaging device that can handle the segmenting-and, potentially other types of metadata insertion-more efficiently than the live hardware encoder can handle it. Encoders, they say, should be left to doing the heavy lifting of encoding, eking more streams out of a single box, rather than taking up 10 percent or more of the hardware encoder's processing time with segmentation and packaging.
Either approach has its benefits and drawbacks, but it's a key factor to consider if you're buying more than a handful of live hardware encoders.
4. Is bandwidth into the venue limited? If the event is held at a location that has constrained bandwidth, or the number of viewers will max out the hardware encoder's ability to serve out streams, consider purchasing a live hardware encoder that can interface seamlessly with a content delivery network (CDN) or a media server. A growing number of live hardware encoders have software shortcuts to popular CDNs, and a few even have painless integration into media servers (several of which can be found in the Buyers Guide on Page NN). This integration of downstream services has its origins in software transcoding systems that have automated the process of manipulating the video and audio content and then pushing it to the appropriate place to be served. The ease of use eliminates a number of frustrations during the critical pre-event set up time.
5. Can more than one input be transcoded in real time? Another area that sets live hardware encoders apart is the ability to handle several different inputs at the same time, often from different types of connections. Some live hardware encoders have multiple SDI / HD-SDI inputs, allowing different content (e.g., with or without graphic overlays) to be sent from master control to viewers on different services or device types. In addition, a number of live broadcast encoders also now allow IP ingestion, for live transcoding of packet-based content such as MPEG-2 Transport Streams, which we'll cover in a separate Buyer's Guide.
In conclusion, numerous reasons exist for using a live hardware encoder. Numerous choices also exist, with each positioned with an eye toward a particular type of workflow. Your workflow will largely determine the best type of live hardware encoder for the job, as will your need to scale from a handful to hundreds of live encoders.
What to look for when you need to transcode and transrate more than just one format
Streaming from the field offers enough challenges without having to worry about the transcoding. Here's what to look for in both hardware and software portable transcoding tools