Netflix Discusses VP9-Related Development Efforts
This is an interesting time in the codec world, an inflection point where the power of an expensive standard is being challenged by a free, open source codec. And that open source codec will soon be supplanted by another free codec from an alliance of high-tech royalty with dominating positions in the codec, content, mobile, OTT, and CPU/GPU/SOC camps.
The expensive standard is HEVC (H.265), for which known annual royalties could exceed $60 million, with many IP owners not yet part of a pool.
The free codec is Google's VP9, which, as of April 2015, had already streamed over 25 billion hours of YouTube content. While VP9 originally seemed destined for the same obscurity suffered by its older sibling, VP8, recent support from bigwigs like Netflix, JW Player, Brightcove, Telestream, and Amazon show an upturn in overall market acceptance and deployment.
The alliance-based codec is AV1, the first codec created by the Alliance for Open Media, with a scheduled ship date of Q1 2017. The Alliance is promising an improvement of 50 percent over VP9 and HEVC with “reasonable increases” in encoding and playback complexity. Since AV1 is largely built on Google’s VP10, which was pretty far along before the alliance formed, there’s a good chance that AV1 could ship on time and on target.
The Alliance’s membership assures that AV1 will enjoy prompt deployment once available. Members Google, Microsoft, and Mozilla ensure fast integration into Chrome, Edge, and Firefox, while members Amazon, Google, and Netflix should start distributing AV1-encoded content soon after playback is widely available. Members AMD, ARM, Intel, and NVIDIA should offer support in their CPUs, GPUs, SoCs, and other hardware components, which Google and Microsoft should rapidly deploy on their mobile platforms, and Amazon and Google quickly integrate in their OTT devices.
The outcome won’t be binary. HEVC will dominate traditional broadcast markets, at least in the short term, while VP9 and AV1 will win the browser wars. But the broadcast market largely exists to feed living room TVs, which are now smarter and increasingly less connected to traditional broadcast channels. In April 2015, Netflix’s Reed Hastings proclaimed, “Linear TV has been on an amazing 50-year run. Internet TV is starting to grow. Clearly over the next 20 years internet TV is going to replace linear TV.” You can’t call Hastings neutral on this issue, but you also can’t find many people who disagree with him.
What happens to broadcast standards when the broadcast model wanes, and the streaming that used to be the tail of the distribution ecosystem becomes the dog? We’re about to find out.
To find out, we spoke with David Ronca, Netflix’s director of encoding technologies, who describes Netflix’s efforts with VP9. Netflix is a charter member of the Alliance and VP9 is the technological precursor to AV1. Netflix’s experience is a good reality check as to where VP9 stands from a performance, usability, and deployability perspective.
Streaming Media: When did you start using VP9?
Ronca: Our VP9 effort is currently in development. We are not yet streaming VP9.
Streaming Media: Why did you start looking at VP9?
Ronca: At the low end, VP9 provides efficiency advantages over AVC for VP9-capable mobile devices. At the high-end (4K, 10-bit) VP9 offers an alternative to HEVC.
Streaming Media: How are you packaging VP9?
Ronca: We are using fragmented 14496-12 streams that follow the draft VP9 MPEG specification written by Kilroy Hughes and David Ronca.
Streaming Media: Any issues with DRM?
Ronca: For fragmented MP4, Common Encryption (ISO 23001-7) works well.
Streaming Media: Where are you distributing VP9-encoded files? Assume compatible browsers, what about Android or compatible OTT?
Ronca: The primary VP9 targets will be mobile/cellular and 4K.
Streaming Media: What’s the data rate savings compared to H.264 and HEVC?
Ronca: We are hesitant to make broad statements with respect to codec efficiency without providing the supporting data. That said, we are seeing very good results with VP9 vs. x264.Our current data suggests that VP9 is less efficient than HEVC, but still very good. We are currently conducting codec comparisons, and will publish our results around the end of summer.
Streaming Media: How does encoding time compare to H.264 and HEVC?
Ronca: VP9 is considerably slower than x264. However, we use a highly parallelized encoding model, and we run most encodes on idle web servers which provides nearly free compute time, so we do not consider the encoder speed a problem. That said, we believe that the current libvpx VP9 encoder would benefit from some optimizations. [Editor’s note: libvpx is the encoder executable supplied by Google.]
Streaming Media: What encoding technique are you using? For example, JW Player will be using capped CRF, and obviously single and two-pass CBR and VBR are available.
Ronca: We are exploring all of the opportunities that libvpx provides and have not yet settled on a recipe.
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