Netflix Rolling Out AV1 Content to TVs and More
AV1-encoded content is now being made available on TVs, including some 8K TVs from major brands. It is now also supported on the PS4 Pro game console and some Amazon Fire TV devices. The AV1 codec was developed by the Alliance of Open Media (AOMedia), of which Netflix is a member. One of the key benefits of AV1 is the lower bit rates needed for the same quality compared to HEVC or AVC, and the smaller file sizes.
The newly supported devices must meet Netflix’s specifications for the decoder in order to receive the AV1 streams. Those specifications have not yet been made public, but we will publish them when we can. If the device does not meet the required specs, an HEVC or AVC encoded stream will be sent.
According to a report in the Verge, the following devices are now newly certified.
- Select Samsung 2020 UHD Smart TVs
- Select Samsung 2020 UHD QLED Smart TVs
- Select Samsung 2020 8K QLED Smart TVs
- Samsung The Frame 2020 Smart TVs
- Samsung The Serif 2020 Smart TVs
- Samsung The Terrace 2020 Smart TVs
- Any TV connected to a PS4 Pro streaming with the Netflix app
- Select Amazon Fire TV devices with Fire OS 7 and above
- Select Android TV devices with Android OS 10 and above
Unfortunately, only SDR AV1 content will be available at launch with HDR encoding still to come. Also a bit odd is that the PS4 Pro and not the PS5 are on the initial launch list. It seems logical to assume PS5 and Xbox5 devices are on Netflix’s to-do list.
YouTube has offered AV-1 encoded 8K content for TVs since May 2020 while Netflix has offered AV1-encoded content for some Android mobile phones since February 2020.
The Netflix blog said, “We always encode at the highest available source resolution and frame rate.” Content from Netflix will include 4K and high frame rate titles, but so far, no 8K/HDR content.
Netflix pioneered a concept called per-title encoding. They encode the content many times at different resolutions and bit rates to find the optimum resolution-bitrate solutions for the instantaneous bandwidth available to the end-user.
With AV1, they have added dynamic optimization as well. “With dynamic optimization, we allocate more bits to more complex shots to meet Netflix’s high bar of visual quality, while encoding simple shots at the same high quality but with much fewer bits,” said the company blog.
The key to the roll-out of AV1 is the availability of decoders. The Android mobile phone launch was facilitated by the use of the software-based decoder dav1d. This is an open-source decoder built by the VideoLAN, VLC, and FFmpeg communities and sponsored by AOMedia.
A software-based decoding solution using libaom reference software can also run on the Xbox One game consoles. Still, even with GPU acceleration, the platform can only decode content up to 2K resolution at 30 fps.
Software decoding is not a good enough for higher resolution content like 8K. Here, hardware decoders are needed. SoC companies have responded with solutions like the MediaTek S900 8KTV SoC chipset capable of hardware-based AV1 decoding up to 8K resolution.
At CES 2021, Samsung announced that their TVs would support AV1 decoding up to 8K with HDR10+ support. As noted earlier, no HDR capability is yet supported in Netflix’s AV1 encoded offerings.
Netflix did not detail what content is now encoded in AV1 for TV streaming but did say they will start with their most popular titles. But in tests on thousands of pieces of content prior to launch, Netflix says they confirmed that AV1 encoded content had higher VMAF scores or improved visual quality for the same bitrate compared to the previous encodes. “Some streams have a peak bitrate close to the upper limit allowed by the spec”, said the blog, which probably refers to AV1 level 5.0 (30 Mb/s bitrate for Main) or level 5.1 (40 Mb/s bitrate for Main).
They also said, “The improvement is particularly significant among sessions that experience serious network congestion and the lowest visual quality. For these sessions, AV1 streaming improves quality by up to 10 VMAF without impacting the rebuffer rate. On some TVs, noticeable drops in quality fell by as much as 38%.”
More background on AV1 can be found on this web page.
