How To Stream Sim Racing

Sim racing never works without tinkering. That holds true for general settings, car setups and, of course, mods. Streaming sim racing is another element to add to the list, and it might seem very complicated, especially if you are just starting out.

Since we have learned a lot about this topic via our own streams, we want to share our knowledge with you. What is an easy to implement way to stream Simracing? And how to do it in the most effective, resource-friendly and comfortable way with good quality? What about using a dual PC setup WITHOUT the need of buying an Audio Mixer? In our guide, you will also learn a few things that will make a good addition to your rig, even without streaming.

Streaming And Racing On The Same PC​

For many years, I streamed from the same PC that was connected to my rig, running the games and the streaming software at the same time. It is also the easiest way to share your sim racing successes and failures with the world. All you need next to your rig is a microphone, a stable internet connection and streaming software like OBS or Streamlabs, as these are considered the gold standard for the average user. This is where you set up your gameplay scene for your viewers to see:

• Game or window capture of the sim you are racing
• Audio output
• Microphone input
• Camera source, if you’d like to be visible in your stream

By default, these sources will use the standard device used for their respective purposes pre-selected as a source, but be sure to double check, especially if you are using a webcam. Otherwise, your audio capture might happen via the built-in microphone of the cam and not sound as good as it would via your microphone. A common mistake, also in work-related video calls.

Aspect Ratio​

Once these are added, fitting your game capture into the preview frame (usually called canvas) is your next step. Note that the output resolution, the resolution for the livestream, may differ from the base resolution of the canvas and will be scaled down from 1440p to 1080p. Most devices and platforms use a 16:9 resolution, so this is the aspect ratio you should be streaming in as well.

Twitch, for example, does not yet allow different formats. Do not worry if you are running an ultrawide or triple screen setup, though: You can move around the game capture as you see fit. If you are a 21:9 or 32:9 user, you sometimes cannot prevent HUD elements from being cut off. Assetto Corsa Competizione with its border option or iRacing with Alt + K UI toggle will allow you to adjust the HUD placement if you want everything you see to be visible to your audience.

Audio​

Next, it is time to set up your audio levels properly. To do this, first adjust the game volume to a comfortable level using the Windows volume mixer. Then go to the streaming software’s mixer and check the output. I usually run a replay in the cockpit view to make sure my microphone output level matches the game audio. You should always do a test recording before you go live to make sure everything sounds good and is level.

Video Encoder​

Finally, onto two of the more technical settings. One is that of the encoder. Mostly, it will come down to whether you want software or hardware encoding, meaning this is done either via your CPU or GPU.

The most common choices for hardware encoders are Nvidia NVENC and AMD AMF. And these are also the options that make sense in most cases and are preferable to the software encoder, both in terms of quality and distribution of system resources, as we tend to be CPU bottlenecked in Simracing. If you want to deepen your knowledge about this, Nvidia has a detailed, very readable blog on their website.

Bitrate​

The other setting to take care of is your stream’s bitrate, which translates to image quality for those who are watching your stream. If you plan on streaming on Twitch, this is an easy setting – the maximum bitrate the platform supports is 6 Mbps. So, your internet connection should have a stable upload of at least 8 Mbps with a little overhead, otherwise you will have to lower the quality a bit.

If you are not sure how good your upload is, you can simply type in speed test on Google and see what works for you. YouTube, on the other hand, can handle much higher bitrates.

If you are streaming directly via the PC you are also racing on, this requires a bit of trial and error to determine the bitrate you can run without it impacting your in-game performance too much. An RTX 4080, 4090 or RX 7900 XT will have a much easier time encoding your stream and running your sim in high detail on a single screen compared to an older or less powerful GPU.

For sim racing or racing games in general, however, we are always aiming for high FPS numbers, at least 60, preferably 90, but in the best case up to 165 or even 240 if the monitor’s refresh rate can keep up. This and the correlation to the observed input latency is a science which we might shed some light on in the future, if you would like.

In the end, this fight for FPS led me to feel more and more that the performance impact of streaming was noticeably bothering me when I switched to triples and that driving was simply a touch worse than without streaming. And that brings us to the dual PC setup.

Streaming With A Dual PC Setup​

Here is a sketch of my current setup, which I am very happy with. It is kept as simple as possible and can be implemented with minimal components. We will get into the details in a moment.

The important thing is that you always have the option to hear your teammates or guests in Discord and on stream. The Streaming PC does not have to have a high-end GPU either. In my case, it is just my old “main PC” on which I now work, edit and play other games. Something much simpler with a graphics card under €300 is also sufficient, because the PC does nothing but simply encode the stream.

How To Capture The Signal​

In my setup, the additional challenge is that my PCs are a few feet apart. But let us start with the heart of the matter – getting your video signal from the rig PC to the streaming PC. I am still using an Elgato HD60S+ for this purpose, but with the X-series, improved options are availavle. Originally, I wanted to use a built-in Elgato 4k Pro, but there is one thing to be aware of.

The MSI MPG B550 GAMING PLUS motherboard in my streaming PC has a lane limitation. This means that the open PCIe slot number 3 only works if you do not have an M.2 SSD in it. So be sure to check your motherboard’s manual to see if this applies to your hardware. In my case, however, the external cards work without restrictions and have no disadvantages, especially when we are talking about 1080p60 streams.

In your Windows display settings, you now want to mirror the main screen of your rig PC to the capture card. For triples, this would be the center screen. You should also make sure that your graphics card has the appropriate connectors. My triples are connected via three display ports, as the one free HDMI port on your GPU is needed for the capture card.

If you have a quad screen setup like I do, or a dashboard that runs via HDMI and you do not want to give up that fourth, or in this case fifth, screen, there is a way to connect it via the HDMI port of your motherboard as a fifth screen. But I will not go into that now, otherwise, this guide might run on way too long.

Capturing The Audio Signal​

Now that we have the video signal from the capture card, we want to transfer the engine sounds and audio from our rig PC to the software on the streaming PC. The capture card, in this case the HD60 S+, has its own audio output on your rig PC, which must be active.

However, this would mean that the output for your headphones is no longer audible. And this is where we need to use a little trick. We need software that can combine multiple outputs on the PC into one active output. As part of the Game Capture HD tool, which is now listed as legacy software, Elgato has just such software, namely Elgato Sound Capture. We need this on both PCs for my setup to work. You can still download it from their website – look for ‘Legacy Products’ in the blue ‘Select your product’ drop-down menu.

In Sound Capture on the rig PC, go to Advanced and activate the sources of your headphones and the HD60 S+. Before streaming, make sure the Sound Capture application is running and used as your default playback and communication device in Windows. In my example, the microphone and camera are connected directly to the Streaming PC. Of course, you may have friends in Discord with whom you want to communicate and who you also want to be audible to the audience. This is where a 3.5mm AUX cable comes into play. In my case, it is 5 meters long, and I also use a ground loop isolator to minimize interference.

This goes into the line-out of your streaming PC, into the ground loop isolator, which then goes into the line-in of the rig PC. There, in “More Sound Settings” under “Recording” under “Listen”, you set this line-in source to be played back via your default playback device. If everything is set up correctly, you will now hear the desktop audio of your streaming PC on your rig PC, including Discord and, if you are using it, the alerts of your streaming software.

Do not forget to activate and mix the desktop audio of your streaming PC in the streaming program. In this case, my headphones are connected to the front audio output to check the test recordings, since our line out at the back is occupied by the AUX cable. This is also why we need Elgato Sound Capture on the streaming PC. Again, two outputs need to be active, as shown in the sketch.

I also experimented with an alternative where both Discord and the microphone run directly on the rig PC. This requires another AUX cable combination that transmits the microphone input to the streaming PC in the same way that we transmit the desktop audio to the rig PC.

This method has the advantage that everything can be set up directly on the PC, but the microphone quality in the stream was a bit worse and had more noise. So, I prefer to use a longer USB cable instead of the additional AUX.

NDI Tools As An Alternative​

You now have a solid setup. Before I move on to some more helpful gadgets that will make your life easier, I’d like to briefly mention another option that I tried first. This is streaming through NDI tools. In a nutshell, you can send video and audio from one PC to another over your network and feed it into the streaming software using plugins. @Rene / GRunner has been using this option for a long time, but it did not work well for me. The reliability, latency, and generally poorer bit rate and quality made me quickly switch to the capture card option.

Helpful Gadgets: Stream Decks​

I also cannot imagine my rig without two Elgato Stream Decks. One is connected to the streaming PC and allows me to control the scenes and audio sources in Streamlabs even though it is located in another room. The second is a Stream Deck+ on the rig PC which I use for macros to quickly launch additional software.

For example, ACC needs the SWRE tool every time I start the sim on triples, I also use Real Head Motion, and I can launch the home page of the competition platform of my choice with a simple button press. There is also an extensive free iRacing plugin that allows you to assign many functions to the Stream Deck if you run out of buttons on the wheel.

The rotary knobs on the Stream Deck+ also provide convenient volume control, so you do not have to go to the Windows volume mixer if you want to turn up the engine noise or hear the Discord better. For transparency’s sake, we need to mention that Elgato provided us with Stream Decks and other devices that help us do our job, be it lights, prompters, capture cards, or face cams. Their well-rounded portfolio makes life easier for creative people with accessible products.

The final tip I can give you is to pay attention to the specifications of the cables and only buy high-quality ones. Especially in my case with the longer cables, they should be of a high standard, particularly for the capture card using USB 3.0 and the HDMI cable. Make sure you use the appropriate connector, as the USB 3 ones are usually highlighted in blue, or it explicitly says USB 3.0 or 3.1 on them.

Of course, there are still a few details we have not gone over in this guide, especially regarding camera and microphone settings, as everyone uses something different.

If you have any questions or tips on how to tweak things, please let us know in the comments. We hope our guide helps you to get started on your own sim racing streaming adventure!