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Broadcasting with Two Computers

Last Updated: Nov 03, 2016 12:26PM PDT

Broadcasting with Two Computers

This article discusses two-computer streaming setups, why you might want one, and one possible way to set it up. 

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When it comes to streaming with two computers, there are many ways to do it, but the walkthrough below will focus on using a capture card and two PCs.

Jump to: 
Hardware and Software Requirements
Step by Step Guide
Final Tips

Why do I need two computers to stream?
The short answer is, you don't. Streaming can quickly and easily be set up with one computer, and it will cost you less money to stream with one computer. 99% of all broadcasters will be perfectly fine streaming on one computer, and many of the top broadcasters on Twitch are able to stream with just one computer.

However, many broadcasters will find that they get a lot of "input lag" when playing video games. If your computer is not powerful enough, your game may lag, and it will affect your performance. For some games, such as Hearthstone, this does not make a difference. Even though streaming is tough on your computer, it will not matter for this kind of turn-based game. For other games that are more resource intensive and are played in real-time, it can be difficult to play if you're getting less than optimal performance from your computer.

What is the problem that needs to be addressed?
Some games are very CPU-intensive and require a strong computer to run. These games are tough on your processor, especially if you are running the game on the highest settings. To make matters worse, streaming is an extremely CPU-intensive process. Combine these two together, and it is trouble. If, on top of that, you open a browser to read chat, another program to play music, and a third program to keep track of donations, you might find that your game lags more than you would like.

The solution? Use two computers to split up the workload. One computer (called the "Gaming PC") will run the game and handle most of your applications, while a second computer (called the "Streaming PC") will handle the streaming. This isn't the most cost-effective setup, but if you have the money to spare and want to reduce the workload on your gaming PC, this is the best option for you. Other alternatives to a two-computer setup would include continuing to use your one-computer setup, upgrading your existing hardware, overclocking, reducing your game settings, or closing your background programs.

If you are able to stream with one computer and it works for you, that is awesome. However, if you are looking to stream with two computers, this article will walk you through the process and help you get a basic setup going.

How does a 2 PC setup work?
The main problem is getting the video and audio from one computer to the other. There are many ways that you can do it, but using a capture card is one of the easiest ways to make that happen. Plus, once everything is arranged the way that you like, you will only have to make a few clicks each time that you are ready to stream.

The gaming PC will run the game, while the streaming PC runs the streaming software (Xsplit, OBS, etc.). You can continue to use your gaming PC for all of the functions that you currently have it for: gaming, listening to music, talking with your friends using VoIP, etc. The streaming PC handles all of the streaming stuff so that you do not have to worry about it, and if you do it right, you will not even notice that you are streaming because all of the streaming programs will be on a separate computer. You can also use this kind of setup to stream console games, and if you go that route, the console would act as the gaming PC. The following diagram in MS Paint to give you an idea of what the setup would look like: 

Hardware/Software Requirements
  • Two monitors
  • Two computers (preferably very strong ones)
  • A compatible capture card or portable capture card
  • An HDMI cable
  • A microphone
  • Headphones
  • Audio Repeater (Free Software)
  • A webcam (optional)
What this setup might look like:

Gaming Computer:
  • GPU: GeForce GTX 770
  • CPU: Intel i7-3930K @ 4.3GHz
  • RAM: 8 GB DDR3-2133 RAM
  • Microphone: Blue Snowball

Streaming Computer:
  • GPU: GeForce GTX 580
  • CPU: Intel i7-4790K @ 4.0 GHz
  • RAM: 16 GB DDR3-1600 RAM
  • Capture Card: AVerMedia C985
Setup Explanation
You should follow the diagram above as a guide for setting up your computers. If you have two computers of varying strengths, you are recommended to use the stronger PC as the streaming PC, but, it is up to you to choose what is most comfortable for you. Streaming requires a strong CPU but not a strong GPU, so many people will to use their old graphics card in the streaming PC and their new graphics card in the gaming PC.

Start by installing the capture card into your streaming PC and then connecting the HDMI cable from the capture card to the graphics card on your gaming PC. You can then plug your headphones and microphone into your gaming PC. If you have a webcam, plug it into your streaming PC.

The HDMI cable will deliver both the video and the audio from your gaming PC to your streaming PC for use on your stream. All we need to do now is set up the software to make that happen. 

Step by Step Guide

Step 1: Send the video from your gaming PC to your streaming PC
In your display options, you should be able to locate a setting that duplicates your desktop onto multiple displays. On a PC you can do this by going to Control Panel > All Control Panel Items > Display > Screen Resolution. 

Your monitor(s) will show up as displays, and your capture card will show up as a display as well. Use the duplicate display setting to duplicate your main desktop onto your capture card. The screenshot below shows two monitors and one capture card. The monitors are displays 1 and 3, and the capture card is display 2. Notice that you are able to duplicate the desktop on display 1 and display 2.

Step 2: Set your capture card to "listen" to your microphone
Setting your capture card to "listen" to your microphone will allow you to use the microphone for all of your gaming PC needs while transmitting the microphone audio to your streaming PC. This means that you will be able to use your microphone for in-game voice chat or third party software like Skype and TeamSpeak, while also using it to talk to your stream. 

Right click the volume control options in your system tray and choose "Recording Options". Find your microphone, right click it, and go to "Properties". Under the "Listen" tab, check the box titled "Listen to this device". Then, in the drop-down list for "Playback through this device", choose your capture card. In the example screenshot below, you will notice that AverMedia capture card is chosen. 

Step 3: Repeat your gaming PC audio for your capture card
The last thing you need to do is to send over is the audio from your gaming PC. This will allow you to listen to game sounds, music, and more while transferring all of that over to your capture card. This walkthrough will show you how to use a piece of free software called Audio Repeater, but you can use a number of different programs to do this.

Install Audio Repeater on your gaming PC. When you open Audio Repeater, there will a lot of settings that you can tweak, but the recommended settings are as follows: set your sample rate to 48000, use 16 bits per sample, set your channel config to "Stereo", and set your priority to "High". Most importantly, you will set your "wave in" as your default audio device, and your "wave out" as your capture card. This is what delivers the audio from your gaming PC to your capture card.

Lastly, you need to adjust your "Total Buffer" based on the audio delay. This is going to be different for everyone, but this setting controls the audio buffer and directly affects the audio delay between your gaming PC and your streaming PC. You should play around with this setting to sync up the game audio with the video. Read more about audio syncing in-depth later on in the walkthrough.

Press "Start" and you'll be good to go!

Step 4: Set up the capture card with your streaming program of choice (Xsplit, OBS, Gameshow, etc.)
You can use a capture card with any major streaming software, but the following example shows how to set it up with Open Broadcaster Software (OBS) for this guide. In your scene, add a video source and select your capture card from the drop-down menu. Under audio, select "Use Device Audio". You can choose to output audio to your desktop or to your stream only -- it is up to you. If you choose to output it to the stream only, you will get an additional option for assisting you with synchronizing the audio with the video.

Step 5: Balance your sound levels
All of your sound sources are easily balanced using your gaming PC, since that is the computer that controls all of the audio inputs. Right click on your volume control options in your system tray and choose "Open Volume Mixer". From here, you can balance the sound levels of your various devices. Choose your default audio device to balance the sound levels of your applications, which are sent to the capture card via the Audio Repeater. Under device, you can also select your capture card and balance your microphone and the output level of the Audio Repeater.

Step 6: Synchronize your sound with your video devices
The sound will likely be out of sync across your various devices, so you will need to make some tweaks to get everything to look and sound great. You will need to synchronize your game sounds with your game, and if you are using a webcam, you will have to synchronize your microphone with your webcam. 

First you should start by synchronizing your microphone with your webcam. In the "Advanced" tab of your OBS settings, check the box under Audio titled "Force desktop audio to use video timestamps as a base for audio time" and adjust the Global Audio Sync Offset to get your webcam to match up with your microphone. 

Once that is matching, you need to get your game sounds to match up to your video. In your Audio Repeater settings, adjust the "Total Buffer" to get that to sync up (see Step 3).

NOTE: You will not need to use the offset found in the "Audio" tab unless you plug your microphone directly into your streaming PC. In this setup guide, your microphone is plugged into the gaming PC and all sounds are coming from the gaming PC (including your microphone). OBS will not detect that you are using a microphone unless you plug it into the streaming PC.

Step 7: Make any changes to your video settings
You may not have any issues with your video quality while streaming, but many users report seeing screen tearing on their streams. If you are running into issues, you may want to check to see if you are using resolution downscaling. Resolution downscaling adds one more step to the process and may create some graphical issues with your capture card. You should downscale using your capture card, and then choose to not use resolution downscaling through OBS.

For example, when running a gaming PC in 1920x1080 resolution, choose to capture it in 1280x720 at 60FPS on the capture card. In the OBS video settings, choose the "None" option for resolution downscale and set the FPS to 60.

There is also another option that you can use to reduce screen tearing when using an Nvidia graphics card. In your Nvidia control panel under “Manage 3D Settings” there is an option to set “maximum prerendered frames”. The default is usually 3, but many people will set it to 1 to reduce input lag. I’ve found that increasing the maximum number of prerendered frames can actually reduce screen tearing so I’ve set this to 4 on my personal setup. You may see some increased input lag, but it shouldn’t be too noticeable.

The final option is to try turning on vertical sync (Vsync) for your game. This is usually the last option for competitive gamers since Vsync is known to cause noticeable amounts of input lag. Although input lag is less than ideal, it can be worth it to try using Vsync to improve the video quality for your stream.

Step 8: Advanced settings and encoding speeds
This is where all of the magic happens. In simple terms, you can make your computer work harder and compress the data better, increasing video quality. Using two computers, it is theoretically possible to make a 3500 bitrate stream look better than a one-computer setup at 3500 bitrate.

For you technical folks, the main benefit of a two-PC setup is being able to handle the encoding on a separate PC, reducing the load on your gaming PC. However, if you have a very strong streaming PC, you can increase the load on it by choosing a slower-than-normal encoding speed. This will result in compression efficiency -- the slower the preset is, the better the optimizations will be and the better your video quality will be. However, the slower the encoding speed, the more computation time it will take. You will need a very strong computer to be able to quickly process the slower encoding speeds.

To change this setting, look under your advanced settings for "x264 CPU Preset". If you are on a one-computer setup, you will likely choose the "veryfast" setting, as it provides a good balance between quality and performance. If you have a stronger computer, feel free to choose a slower preset. Be aware that if the preset you choose is too slow, it will affect your stream quality.

Final Tips

It is definitely not required to purchase a second PC for streaming, but if you are interested in using one for streaming, this is definitely one of the easiest ways to set it up. 

The biggest issue that people run into is screen tearing. Capture cards are notorious for screen tearing issues, and you should to do some proper research into this topic to figure out which cards are good and which cards are not. If you have already purchased your capture card and are running into issues when using this guide, check your resolution downscale settings. In addition, if your Streaming PC is not strong enough, this may also cause screen tearing issues (especially if you are using a laptop or an older machine). Some users will be a bit too ambitious and choose a x264 CPU Preset that is too slow, and this may also have an adverse effect on your video quality. If you have already tried all of these troubleshooting techniques, you may opt to upgrade your machine or overclock your current machine.

Good luck and happy streaming!