Over the past few years, livestreaming has exploded in popularity, thanks to a combination of social media channels and networks like Twitch and YouTube, better phones and cameras and faster internet and cellular speeds. Lately, producers and YouTubers have seen a sharp increase in the demand for livestreaming, but it isn’t as simple as pulling out an iPhone and starting a stream.
To properly livestream, there are several things you must consider, including:
- Video bitrate
- Video resolution
- Internet upload speed
- Internet protocols
- Different requirements of each streaming platform
When just one or more of those technical aspects aren’t right, the livestream will be negatively affected — the video stutters and the sound goes out of sync — and viewers stop watching.
What exactly is video bitrate, and why is it important to understand it when it comes to your livestream settings? Bitrate is essentially the transfer of video from one source to another. In this case, through a pipeline across the internet to viewers watching. It’s measured most commonly in kilobits per second (Kbps), Megabits per second (Mbps) and Gigabits per second (Gbps). For our purposes, we’ll use Mbps.
On average, a bitrate of 4.5 to 6 Mbps is great for 1080p video, depending on the frame rate. If you stream at 30 fps, about 4.5 Mbps is ideal. At 60 fps, the bitrate should be at 6 Mbps. 4K requires higher bitrates and a faster connection.
In addition, there are hardware encoders available from companies like the Blackmagic Design ATEM Mini Pro and the NewTek TriCaster. Plus software like the popular and free OBS Studio is great for streaming on Windows, macOS, or Linus.
The video resolution chosen plays a big part in livestream settings. so much so that the bitrate depends on both resolution and frame rate. Streaming at 1080p30 works best, especially since many viewers watch on devices that won’t get the full benefit of a 4K livestream.
When you start your livestream, the video and audio are encoded and sent out for the world to watch live. 1080p30 and lower are the best resolutions, but that doesn’t mean you can’t do a 4K livestream. However, it’s limited to where it can be done (YouTube), and if the upload speed can handle that kind of data.
What it comes down to is this — the higher the resolution, the more bandwidth is needed. YouTube supports 4K 3840 x 2160p livestreaming, but you need a bitrate range of 13 Mbps to 34 Mbps for 30 fps, and 20 Mbps to 51 Mbps for 60 fps.
Internet upload speed
Internet upload speed is perhaps as important as the bitrate settings. Many internet providers offer incredibly fast download speed options, but a mere fraction when it comes to uploading. For example, one popular provider offers 300-400 Mbps of download speed but limits the upload to 20 Mbps. However, 20 Mbps is an excellent option for livestreaming video resolutions up to 1080p.
A good rule of thumb is to take your internet upload speed and cut that number in half for what should be considered the maximum bitrate. In this case, the highest bitrate should be set to 10 Mbps for an upload connection of 20 Mbps.
Having a fast, dedicated connection is important. However, it also depends on what devices are connected. Run a speed test early in the morning on one device. You may see that 300-400 Mbps download speed you pay for.
Try again in the evening when you and your family are on their devices. That number quickly drops, perhaps as low as 70 Mbps. In fact, there may be a greater slowdown in upload and download speeds as your neighbors also jump online.
Depending on where you live, different internet providers offer up to 1 GB of download and even upload speed. In some cases, you may need a business account. The price of these services varies widely. Some newer providers offer a steep discount the first year, while others charge upwards of $200 to $300 a month. However, if livestreaming is how you make a living, it’s a small price to pay.
One thing to always remember — not all of your viewers have fast and consistent download speed. This affects their viewing. That’s why 1080p at 30 fps works best.
There are many different livestreaming protocols, some going back many years (RTMP), but still tried and true. Real-time messaging protocol, or RTMP, continues this day and helped the Flash player take off nearly 20 years ago. Flash may be dead, but RTMP is still going strong, helping to ‘transport’ livestream video and audio across the web.
RTMP supports many different video and audio codecs, but the most common ones are H.264 and AAC. YouTube still recommends RTMP for livestreaming. Other protocols include HLS, MPEG-DASH, WebRTC and more.
Different platforms, different requirements
YouTube breaks down settings on their site for the various resolutions and frame rates. These include 4K at 60 fps all the way down to 240p, which recalls the early days of streaming. What’s important to remember is they require RTMP streaming, CBR bitrate encoding, H.264 for video, frame rates up to 60 fps, AAC or MP3 for audio and a recommended 2 seconds for keyframe frequency (no more than 4 seconds).
YouTube allows streamers to choose three different options for a livestream. These include normal latency (10 Mbps max), low-latency (7 Mbps max) and ultra low-latency (5.5 Mbps max).
When it comes to Twitch, without an official partnership, you can’t effectively livestream unless the resolution is 720p and a bitrate of no greater than 3.5 Mbps. With a partnership, 1080p at 6 Mbps works great for a livestream, and some experts agree not to exceed 6 Mbps.
Interestingly, Twitch breaks down recommended livestream settings based on the type of system handling the stream. Having a powerful GPU works better with a livestream, just as it is with video editing or graphics software.
Facebook’s recommended livestream settings include a max bitrate of 4 Mbps, 720p resolution (1280 x 720), no more than 30 fps, H.264 and AAC video and audio, and an I-frame must be sent every two seconds. As many streamers know, this past summer Microsoft shut down Mixer, and moved accounts over to Facebook.
Once you learn the required livestream settings of each of the livestreaming platforms, experiment within those parameters to improve your streams without compromising the overall quality of sound and picture. A great livestream helps to grow and keep an audience. Keep all the technical requirements in mind when starting out.