Buyer's Guide: Hardware and Cloud Transcoding
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.
You've just finished a successful live two-hour encoding session, streaming a conference keynote speaker out to a good-sized audience. The conference chairman approaches you, saying that the keynote speaker has agreed to allow conference organizers to make the keynote speech available on-demand to conference attendees for the next two weeks.
The chairman requests the keynote be made available on-demand for "a number of platforms, like the iPhone and Macs and Windows and maybe an Android version", adding "it shouldn't be too difficult to do, so please have it ready to go tomorrow morning so we can announce it" before hurrying off to a meet-and-greet with a group of journalists.
While a software-based file transcoder won't cut it for the short timeframe, a hardware-based transcoder might just be the ticket-or perhaps an on-line encoding solution-as both have the potential to generate dozens of variations in screen size, resolution, bandwidth and aspect ratio from a single file, all in close to real time.
Hardware Transcoding
Here are a few key things to look for in a hardware-based file transcoder.
1. Do you have the tools on hand? In some instances, the live encoding solution you just used for the event may also have the ability to do file-based transcoding. While the units can't do both simultaneously (live encoding and file-based transcoding) there's a distinct possibility you may already have the necessary tools.
2. What formats and codecs will a hardware-based transcoder support? Even if your live encoder doubles as a file-based transcoding solution, the number of formats or codecs may be limited by the encoder. For instance, an H.264 encoder may not support WebM file-based transcoding, since WebM isn't integral to the primary use of the H.264 encoder.
3. How many profiles can be supported by the hardware-based encoder? This is a bit of a black art, since all file-based hardware transcoder companies will tell you they can transcode files in faster than real time. This is true for long-form content and also true if only a single or handful of profiles is being simultaneously encoded, but the true answer for the number of profiles is "it depends" on the type of content and the profiles chosen. A robust hardware-based transcoding system will cross-check the profiles to determine redundancies which the transcoding system can leverage decoding or segmentation or other forms of packaging (watermarking, media analytics, etc).
4. How much power do you need to do this? Sometimes a software solution is sufficient, especially in non-time-sensitive scenarios, and the time-versus-money balance is always a major decision point. A software-based solutions is dependent on the hardware used for transcoding, but one of the benefits of a hardware-based transcoding appliance is the thought that's gone in to leveraging all the hardware to maximum advantage.
A software solution, for instance, may use either general purpose (CPU) or graphics processing (GPU) chips, while a hardware solution might force the audio transcoding on to the CPU while optimizing throughput on the GPU. In addition, a number of hardware-based solutions now rely on ASICs, DSPs and FPGAs to fully optimize code for specialized silicon, often generating 50 percent or higher processing throughput over general-purpose solutions. In addition, if adaptive bitrate segmentation is also needed, many hardware-based transcoders will perform that function on a general purpose chipset while leaving the specialized chips to do the heavy lifting.
Many hardware-based transcoding boxes will come with a "rule of thumb" for a variety of resolutions (eg, a certain number of SD, 720p or 1080p outputs can be simultaneously performed.
5. What platforms will you deliver to? We mentioned WebM above to bring up another decision point about hardware-based transcoders. Many hardware-based solutions will support a number of legacy codecs and formats, but will be slower to implement new codecs and formats. The process normally involves reaching critical mass in terms of end users who are able to view content in a particular format, on a particular platform, and then confirming that both the codec and the platform (eg, a web browser) have stabilized before committing into silicon a recent codec that's yet been standardized.
Cloud Transcoding
Here are a few things to look for in a cloud-based transcoding solution.
1. Does the online transcoding solution support the codecs and formats that you plan to use? Many online solutions support a limited number of codecs and formats; adaptive bitrate may or may not be supported and newer codec support may also vary between online offerings.
2. How quickly do you need the final output? The cloud-based nature of online transcoding should make even insane deadlines possible with long-form content, but the transcoding is only one-third of the equation. The first part is the uploading of content, which can be at the mercy of a variety of external factors especially on consumer-grade shared internet connectivity such as cable. The third part of the equation is the length of time it takes to move content from the online transcoding solution to a content delivery network (CDN) or other server location. Uploading will always be an issue, but the movement of transcoded content to a CDN can be automated-or even eliminated if the CDN offers online transcoding.
3. How does the company charge? Some online transcoding companies charge by the megabyte, others charge by the minute of transcoding content. Bulk discounts are available, both in the form of a multi-month commitment and for content for which multiple versions will be created.
4. Do you trust the cloud or do you want to have in-house control? One consistent uncertainty that I've heard expressed over the last two years is the question of whether an online transcoding solution can deliver within a set timeframe. In a way, this is more a subjective measure, questioning where a particular transcoding job ranks in the queue of other clients' jobs or exhibiting a lack of market education on the part of online transcoding solutions, but it remains a critical issue for the time being.
5. Does the company allow for free test encodes? To address question 4, companies are now offering free test encodes, allowing potential customers to kick the tires on the number of formats, codecs and profiles, as well as gaining a sense of the speed at which a file can be upload, transcoded and then moved to its proper delivery location.
The two checklists presented here cover just a small number of the options and tips you should consider when choosing between an in-house, hardware-based transcoding appliance or an online transcoding service. On Page nn, you'll read more about software-based transcoding tools.