NAB '19: Netflix and Intel Release SVT-AV1 Codec as Open Source
This morning at NAB, Intel and Netflix together announced the SVT-AV1 codec which is capable of real-time 4K/60p 10-bit encoding when running on Intel Xeon Scalable processors and Intel Xeon D processors. To our knowledge, this is the first software-only AV1 implementation capable of real-time encoding and it represents an order of magnitude acceleration of AV1 encoding. The companies released SVT-AV1, or Scalable Video Technology for AV1, into the open source community for immediate availability.
The slide above provides much of what we know about the new codec. On the right, we see that the codec is targeting half the bitrate of x264 for the same quality. On the bottom, we see that the codec has 12 encoding modes. On the left is Mode 0 for VOD which delivers the highest quality and slowest encoding speed. On the right is Mode 12 which delivers real-time CPU-only 4Kp60/10-bit encoding.
What we don’t know is which mode delivers the 50% data rate drop compared to H.264 and how encoding times vary between the modes. Hopefully, we’ll be able to get answers to these questions at NAB.
By way of background, Scalable Video Technology is “a software-based video coding technology that allows encoders to achieve, on Intel Xeon Scalable processors, the best possible tradeoffs between performance, latency, and visual quality.” It’s a codec-agnostic technology that can be used with different codecs like H.264, HEVC, and AV1, and different codec implementations (like x265 compared to the Main Concept HEVC encoder).
As with many open-source projects, Intel has been slowly releasing versions of SVT-AV1. On April 6, 2019, a tester at Phoronix output 1080p video at 81.38 fps using SVT-AV1, along with 365 fps with SVT-HEVC, and 404 fps for SVT-VP9, all much faster than the stock codecs available in FFmpeg. It’s a great endorsement for SVT-related performance but doesn’t address the quality side. An Intel White paper entitled Scalable Video Technology for the Visual Cloud discusses quality, but primarily for HEVC, which performed well. Still, the stigma of CPU/GPU accelerated encoding has always been lower quality, and it will be interesting to see how SVT-AV1 output quality compares to FFmpeg.
Even if SVT-AV1 drops the cost of AV1 encoding to more affordable levels, it’s unclear how quickly that will spur AV1 usage beyond the early adopters currently working with AV1, most of which are in the Alliance for Open Media. Phones and other devices with hardware-based AV1 decode aren’t scheduled to appear for another 12 months or so. Still, assuming the quality is there, which Netflix’s presence would seem to ensure, SVT-AV1 should dramatically reduce the cost of AV1 encoding, removing perhaps the most significant obstacle to AV1 deployment.
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