HEVC, VP9, AV1, and VVC: Presenting a Codec Update in 11 Charts
One major concern I had with AV1 in my First Looks review was playback CPU requirements. For the most part, these were allayed. Figure 7 shows CPU requirements playing back 1080p video on the same notebook I used for the review (HP ZBook notebook powered by a 2.8 GHz Intel Xeon E3-1505M v5 CPU with an NVIDIA Quadro M1000M graphics chipset along with the HD Graphics 530 GPU embedded in the CPU). At 20 percent, c’mon in, the water’s fine.
Figure 7. AV1 playback overhead was minimal on my HP ZBook (whew!).
On most of the videos I played, I had no issues. On two, however—the Halo Trailer and Hello Sexy Pants (it’s research, people!)—I had severe issues, including slow downs and stoppages. These didn’t appear to be related to either CPU or network issues, so I’m not sure what was going on.
You see the frames dropped in Halo in Figure 8; this screen grab is from the ZBook, but I got the same results on my 40-core Z840 workstation, seemingly indicating that it’s not a CPU issue.
Figure 8. I had severe issues with the Halo trailer.
Figure 9 shows the frame drops in Hello Sexy Pants. Note that playback on all other videos that I tried was problem free, which left me scratching my head.
Figure 9. And the Hello Sexy Pants music video.
The major point is, however, that AV1 will likely play on a whole lot more machines than I originally thought, which is a good thing. Kudos to the AV1 and Chrome teams for making this happen. That said, without major reductions in encoding time that appear to be coming soon, AV1 is still only appropriate for publishers who routinely get seven figure views for their videos. I look forward to testing with Firefox in the near future.
AV1 Encoding Speed Increase is Coming
At press time, we saw a tweet from Bitmovin CIO and co-founder Christian Timmerer, who was attending the 2018 IEEE International Conference on Image Processing running October 7 to 10, 2018 in Athens, Greece. One presentation discussed performance enhancements with the AV1 codec, and Timmerer posted the slide shown in Figure 10.
You can read as well as I that the improvements appear substantial. We’ll verify them when they make their way into FFmpeg. For the record, in our AV1 First Look, we encoded with cpu-used=0, and AV1 encoding time was about 1,000 times longer than VP9. Dropping that to 40x would dramatically change the breakeven point for AV1 encoding and make the codec useful to a much broader group of producers.
Figure 10. Performance enhancements for AV1 encode and decode.
Versatile Video Coding is Coming (and So Are the AV1 Quality Challenges)
At IBC, AOMedia member BBC discussed a paper showing that AV1 had only a 2 to 7 percent quality advantage over HEVC (HM in Figure 9) and that the upcoming Versatile Video Coding technology (JEM in the figure) averaged about 25 percent savings over AV1 and 31.5 percent over HEVC. As a broadcaster and AOMedia member, BBC obviously has lots of credibility and these results are disappointing for AV1 and impressive for VVC. You can read more about BBC’s tests. Harmonic and Ateme also released papers with less than favorable results for AV1. Of course, absent a major shift in royalty policy, VVC may find itself hobbled by the same uncertainty that stunted HEVC’s growth, and VVC deployments are years away.
Figure 11. VVC (JEM) is coming, and BBC says it’s looking good.
As the commercial antithesis of the hugely unpopular HEVC codec, AV1 has enjoyed breathless approval from much of the technology press, and as evidenced by the Bitmovin survey, by many in the user community as well. At some point, however, the codec has to prove itself both within and beyond its founding members. It’s still early days, and AOM has made some impressive performance gains, but we look forward to observing the bitrates used by actual deployments at scale to identify the real world benefits that the codec delivers.
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