NVIDIA RTX and the future of game streaming: 5 Mbps is enough for 4K at 60p thanks to AV1

Game streaming (or game broadcasting) is now a cultural phenomenon. It’s a form of live television that was born around the need to broadcast gaming sessions and expanded to include other content that wasn’t necessarily playful. Just as TV quality has grown over the years, perhaps more so abroad than in Italy, streaming game sessions has grown as well. Requires more attention than ever to detail, resolution and frame rate.

Today, fiber optic connections make it relatively easy to transmit high-quality content, but users who want to transmit at high frame rates and high resolutions will find that content is virtually impossible to appreciate in game graphics. We take it for granted that we have flawless rendering. You always have to compromise or push your transmission bitrate to excessive levels, which you can’t always manage.

Everything changed with the arrival of AV1. Just over 5 Mbps is enough to send a match in his 4K at 60p, less than half the speed needed for a stream of comparable quality in H264. Not only that, but considering the quality, even with the same bandwidth: AV1 performs much better in terms of visual perception.

Recently, the release candidate for version 29.1 of OBS Studio, Open Broadcaster Software, the most used software by streamers, was released. This release brings something new to everyone who owns his NVIDIA RTX card with NVENC hardware encoder. AV1 hardware encoding support with GPU section. So I decided to take MSI’s Katana 15, which had already been used for DLSS 3.0 testing, and turn it into a small AV1 broadcast studio.

Katana 15 B12V, a small workstation with a gaming look

The notebook used for testing was a Katana 15 B12V, the same MSI notebook that was already used for the DLSS 3.0 tests. It’s a very interesting product in terms of value for money and design, and falls within the gaming laptop canon without being overly flashy. It’s perfectly capable of being used as a workstation for content creators (which many gamers and streamers do), but only a 4-zone RGB keyboard betrays its playful origins.

It has a 15.6 inch screen and weighs just over 2 kg. Part of that weight is due to the large heatpipes that combine the Intel Core i7-12650H processor and his NVIDIA RTX4060 GPU into a single large active heat dissipation system. Cooler Booster 5 (that’s the name MSI gave to its heat dissipation system) moves heat from the two processors to the peripheral area, keeping the keyboard area cool.

The Katana 15 B12V offers many interesting ideas for those who don’t just want to play, but want to build experiences around their games. There are three traditional USB ports suitable for connecting headsets, webcams and USB mics, but Type C mics like the excellent Sennheiser profile can also take advantage of this connection, with a port on the right side.

The keyboard is very comfortable. Despite the lack of fingertip dimples and less key travel, the feedback is very good, and there’s also a practical numeric keypad on the side. This isn’t always apparent on the 15.6-inch product, but the diagonal. The small webcam mounted on the top frame of the Full HD screen is clearly not suitable for streaming, but the built-in microphone and his two speakers perform better than your average notebook.

In any case, using an external device for input and output is practically mandatory for anyone wanting to send. Even if the integrated Wi-Fi module is very good in terms of bandwidth and reception, a wired connection is a must, and in fact there is a classic network socket on the side. If you want to update the network module, unscrew the bottom screw, ask your helper for permission, and replace the small module. Instead, if the SSD or RAM is replaced or upgraded, no approval is required and the warranty will not be voided. Everything is socketed and nothing is soldered.

AV1 compression on GeForce RTX 4xxx

NVIDIA’s Ampere architecture introduced hardware-accelerated AV1 decoding for the first time last year. Ada Lovelace loads and takes it all home. Not only is she the first to add her AV1 encoder with hardware her acceleration in addition to the existing encoders, It is also possible to have multiple hardware encoders on the same GPU.. This means that encoding software using the new Video Codec SDK 12.0 can compress video clips over 4K (e.g. 8K) with AV1 or HEVC by sending parts of the frames to another encoder. It’s called Split Frame Encoding, and only the RTX 4090 for laptops has double encoders, and the RTX 4060 we own has a single encoder, so we couldn’t try it on a laptop. bottom.

FFMpeg was the first to integrate support for AV1 hardware encoding, and later some of the software that relies on the well-known open source encoder inherited FFMpeg. These include some of the most well-known software for anyone streaming videos and games, such as the latest releases of his Discord and his OSB for that matter. Software used for testing.

What should you expect? When describing NVENC AV1 performance, NVIDIA used two of the best-known criteria for evaluating compressed video streams: PSNR and VMAF scores.

The first shows the ratio between the signal level of the compressed video samples and the noise introduced by the compression. The second is a metric used to assess signal quality from a visual perspective rather than from an instrument perspective. opinion.

In both cases, the 1080p 60 fps stream at 4 Mbps performed significantly better than the H.264 stream, with the difference clearly decreasing as the compression decreased.

The Katana 15 B12V has a full HD monitor and we compared it at 1080p 60.

Cyberpunk with DLSS 3.0 and path tracing was chosen for two reasons. The first is the impact games have on the GPU, and the second is the existence of benchmarks that can be submitted in both AV1 and H.264. Since it’s the exact same clip, you can capture a few frames to compare quality.

Also, thanks to the benchmark, you can evaluate how many frames you lose when compressing with AV1 during playback.

Let’s start with a benchmark without active streaming sessions. Average FPS with path tracing, DLSS 3.0, RTX4060 is 63, min 27 fps, max 80 fps.

When I configure OBS for a live stream of 1080p H.264 with P6 quality level (hence excellent quality) and start a streaming session, the average FPS drops to 57.

With the AV1 encoder, the same quality profile, and always set to stream at a fixed 5 Mbps, the average is still 57 frames, so we can say: The GPU impact of AV1 compression compared to h.264 is virtually zero.

no streaming	With h.264 streaming	With AV1 streaming
63fps	57fps	57fps

Something is obviously lost when you stream or record while gaming. Average fps drops slightly, but really negligible. AV1 is heavy, but RTX handles it just like H.264.

But if you look at some frames recorded while streaming, you can see dramatically higher levels in the AV1 stream at the same bitrate. Not only does the occasional macroblock disappear completely, as can happen, the resolution itself is also lost. Image is excellent. Below are some comparison screenshots with the same bitrate, same sequence, same starting quality but different codecs.

open original

open original

Here’s another series of captures from Death Stranding, always captured at 1080p and 4 Mbps data rate, where you can appreciate the difference in detail.

open original

open original

open original

In the 2 Mbps video clip below, you can see the difference between AV1 and older codecs like H.264, which are still most popular for game streaming. The difference is stark.

AV1 is a must-have step for anyone looking for streaming quality. NVIDIA RTX is a turnkey solution

As we’ve already seen last time, the Ada Lovelace architecture did a particularly good job with a very high performance/power ratio, especially in the laptop version. Thanks to DLSS 3.0, not only can you play games with ray tracing on your notebook at very good frame rates, However, given the number of games supported, this is actually normal.

Added another element to this: game streaming. The RTX 4060 we tested manages on a notebook thanks to an integrated AV1 encoder running in hardware. Transmit your game session with ray tracing at a much higher quality compared to traditional h.264 streaming.. It’s no small achievement. With AV1, you get the same visual perception boost as going from 720p to 1080p. It has no negative impact on end users. When game or event broadcasters submit their streams to Google, Discord, or Twitch servers, the servers convert the streams according to the compatibility of different clients. Sending in AV1 doesn’t mean that only people with computers with AV1 decoders can enjoy the stream. This means providing the server with a much higher quality source stream than usual. I streamed some Fortnite games to YouTube. The maximum AV1 quality was switched from OBS, and his VP9 converted stream from YouTube retained its original quality, albeit with minor differences.

AV1 is a true revolution and future in the world of video. A future where game streamers are already giving users a taste.