By Geoff Bennett
Director of Solutions and Technology
It is enlightening to consider how entertainment services have driven — and continue to drive — demand for higher data rates.
The first digital telephony service needed 56 or 64 kilobits per second (kb/s) of bandwidth, which is about the same data rate used by the earliest music streaming services. For comparison, let’s define that as a factor of 1.
A typical MP3 file is encoded at a 128 kb/s data rate, or a factor of 2. High-quality MP3 at 320 kb/s, is a factor of 5. So while the quantity of audio streaming and high-definition voice services might still drive growth in bandwidth demand, the quality won’t.
Advancements in video quality, by comparison, have really only just begun. Early internet video needed to be massively compressed to work with the dial-up services that were common at the time.
Standard-definition TV streaming at 480 pixels (480p) consumes 640 kb/s, or a factor of 10. But users soon began to demand better quality with high-definition television (HDTV), which requires 5 megabits per second (Mb/s), or a factor of 80. But this is only 720p, so there’s more to come.
Since the early days of the internet, the quality of the user experience for video has been limited by the speed of the network delivering it. In an apparent prediction of future broadband network requirements, the Federal Communications Commission (FCC) is suggesting that 25 Mb/s should be the national aspiration, which equates to a factor of 400. So does that data rate ensure that future services will deliver a high-quality user experience that won’t be limited by the network speed?
Actually no, because high-definition 1080p video with a high user experience compression rate, and at 60 frames per second (fps), blows through that national aspiration. A realistic benchmark would be that a “real” HD movie delivered by a local Blu-ray player at 1080p and low compression rates consumes up to 54 Mb/s – a factor of 800, and more than double the FCC aspiration. And this technology is already 10 years old!
We already know that 4K is the next major evolution in HDTV, and the early 4K services are doing what all these others have done in the past: using sophisticated compression algorithms at the expense of video quality. Some are talking about 30 Mb/s data rates for 4K streaming, for example, which at about factor 500 is still greater than the FCC’s aspiration.
These early 4K services are already being delivered by over-the-top (OTT) social media service providers like Vimeo and YouTube. These and other services allow ordinary people to become their own TV producers, creating everything from video snippets to tutorials and miniseries.
Last year YouTube launched a 360 -degree immersive panoramic video capability that works by taking a 4K video and “sharing it” across both eyes and 360 degrees of view using special encoding and a virtual reality (VR) headset. So it consumes about the same bandwidth as an equivalent 4K stream.
Yet again, we’re seeing the network limiting the quality of the user experience for these new applications. A recent study by Akamai found that only 21% of US homes have at least 15 Mb/s broadband data rates, which is the absolute minimum required for a heavily compressed 4K video stream. But at anything less than 25 Mb/s, the instant that anyone else in the house starts to use the internet, the videos will stutter without a lot of buffering.
For anyone who has seen demonstrations of even higher resolutions, such as 8K, you might have had the sense the image was so realistic, that there was a 3D feel to it, even though it’s a single image stream. These data rates required seem to grow and grow, so is there an upper limit? There clearly is for audio. Audience trials have shown that 320 kb/s MP3 is essentially indistinguishable from lossless audio (although many audiophiles will disagree with that finding). But vision is clearly (no pun intended) far more demanding.
What about the other senses: are they as demanding as vision? Haptic accessories are already available for gaming consoles that give the impression of bullet impacts or body blows. Other researchers are using puffs of air or scent capsules to enhance the VR experience. The problem with any haptic simulation, however, is that it requires physical mechanisms to stimulate our other senses.
A more obvious approach is to bypass those senses and simply send data directly to the brain. Our bodies might need to be kept in a deliberate paralysis state to prevent injury while our brains are fed the data needed to create a completely artificial reality. In that vision of future entertainment, we would be able to run, jump and even fly like Superman.
The days of the Star Trek holodeck may not be here yet, but from the visual perspective, at least we now know how to make it so – as long as the network itself can stop being the bottleneck!
• Nature Magazine: The Bandwidth Bottleneck That Is Throttling The Internet
• Infographic: The History of Opto-electronic Innovation
• Infinera Corporate Backgrounder: Redefining Optical Networking