Before going live with your first town hall or virtual event, there are some factors to consider. A successful live stream has a few key ingredients: bandwidth to distribute content, audio and video inputs, hardware or software used to push out the stream, and the proper settings such as frame rate to ensure the best viewing experience for your audience.
In this article, we’ll dive into some of the common questions around frame rates and FPS for live streaming.
What is frame rate?
This is the most important question when it comes to fps for live streaming. Frame rate is the frequency at which a series of distinct, consecutive images is captured or displayed in a given time frame. When put together it creates a sense of motion.
What is FPS (frames per second)?
Technically, the FPS or frames per second refers to the unit of measurement of frame rate.
It's the quantity of unique images captured or displayed in any given second. For example, if you were to take one second of video captured at 30 FPS, you would have 30 unique images. The same goes for one second of video captured at 60 FPS, which would include 60 unique images.
That's how video is constructed: it’s a collection of images that our brain perceives as motion.
The eye and the brain interpret motion at different times. For example, the brain has the capacity to distinguish twelve images before it begins to perceive consecutive images as motion.
The easier analogy to FPS is a flip book. Imagine thumbing a flip book with a series of illustrations that show a horse galloping on a race track. Each consecutive image in the flip book is slightly different from the last one. When you look at the individual images, you can’t perceive them as different. But when you flip the flip book, you see the motion. That’s a more approachable way to think about frame rate and FPS.
Are frame rate and Hz (hertz) different?
Hertz or HZ are somewhat interchangeable with frame rate. However, hertz is related to displaying content versus capturing or streaming it.
Why does FPS matter for live streaming?
The biggest reason frame rate and FPS matter for live streaming is because it affects how your content is both captured and interpreted by viewers. To the average person who doesn’t watch a lot of film or broadcast television, the difference between 24 FPS and 60 FPS may be unnoticeable.
However, if you watch a film or a news broadcast, they have a different feel. A film with a lower frame rate conveys a more cinematic or artistic feel. A news broadcast or a sports broadcast usually has a higher frame rate offering more "in-between the moment" details and thus has a different feel.
The frame rate and FPS contribute to how your content is perceived by the viewer. A video can potentially feel more cinematic or more news-worthy depending on whether you capture video at a low or high frame rate. This also impacts the storytelling aspect of your live streams, so it's important to know what
At Vimeo, 30 FPS is the standard for our live streams. There might be occasions where 24 FPS make more sense for more cinematic or creative content. However, for internal events like town halls or external events like conferences or virtual events, 30 FPS is the go to.
What’s the difference between 24 FPS, 25 FPS, 30 FPS, 50 FPS, and 60 FPS?
Remember: the individual values (24,30,60, etc) determine the quantity of images or frames that are depicted per second in a video.
When sound film was first developed around the 1920s-1930s, 24 FPS became the standard form film. The number 24 FPS was mainly chosen because filmmakers at the time wanted to limit the money and resources that went into the physical film. At a higher frame rate, you are exposing more frames and you need more film. So 24 FPS became the standard and stayed the standard for film specifically. If someone uses 24 FPS in a broadcast environment, it’s likely an intentional, creative choice.
30 FPS is the most common in live streaming. Vimeo uses it universally for all our live streams. With six more frames than 24 FPS, 30 FPS doesn’t have as much of a cinematic feel.
60 FPS is the third most common rate and typically used for fast motion like sports live streaming. You’re working with a lot more frames and capturing twice as much data as 30 FPS.
If you capture a fast pace sport in 30 FPS, you might capture more motion blur and stuttering because you’re capturing movement with thirty still images as opposed to sixty still images. At 60 FPS, you’re able to capture the in-between moments with a more fluid motion.
25 FPS and 50 FPS are specific to European standards of capture.
How do you choose the right FPS for your live streaming video?
There are a variety of factors when considering the appropriate frame rate for live streaming video. I would say it's largely dependent on the type of content you are streaming and the requirements to make that content look best to your viewers.
As a best practice, plan to stream your video in the same FPS that the video is captured. So if you shoot a video at 30 FPS you should broadcast it in 30 FPS.
It’s also important to acknowledge the resources you have available, including bandwidth and the processing capabilities on your encoder. 30 FPS will typically suffice for simple content.
FPS and encoders
An encoder is a vital tool when delivering your content to an online audience.
Whether your encoder is software-based, like our industry-leading Livestream Studio 6 software, or hardware based, like the NewTek's TriCaster, an encoder will interpret and translate a video signal into a digital format in order to make it compatible for the platform that is delivering the content. Besides an encoder, it's also important to understand the platform you'll be delivering your stream to in addition to its capabilities or limitations.
Understanding frame rates is important here. Specific encoders may require you to manually configure encoder settings, including frames per second. It's best to arrange for your encoder FPS setting to match your camera FPS setting. If you're using Vimeo, the Livestream Studio 6 software is great at optimizing the frame rate based on your selected project format.
What are the recommended encoder settings?
Regardless of what encoder you plan to use, we do have recommended settings listed below:
- Codec H.264
- Output resolution of 1920 x 1080 (maximum)
- Frame rate of 60 fps (maximum)
- Key frame interval of 2 seconds
If you're using encoding software on a Mac or Windows PC, we recommend keeping your encoding software on a separate machine from any other tasks you may need to do during your event, such as previewing and monitoring your stream or moderating chat. Using one machine for all streaming tasks can cause CPU percentages to spike and impact the quality of your live stream.
If you're planning a live stream to Vimeo, we have a couple software and hardware encoders you can consider:
- Livestream Studio
- Wirecast
- SlingStudio
- Open Broadcaster Software
- Teradek encoders
- NewTek Tricaster
- Epiphan Pearl and Pearl 2
For details on how to live stream to Vimeo using each encoder, check out our in-depth guide in the Vimeo help center.
FPS for live streaming FAQ
- What is the best FPS for live streaming?
- We recommend 30 FPS for most live streams. That frame rate can handle basic motion and doesn’t require a significant amount of bandwidth. It’s a happy medium where your stream is guaranteed to look great without taking up too many resources.
- Does live streaming decrease FPS?
- There is the possibility of frames being dropped if you don’t have the resources to push out your target frame rate. Those resources are a combination of your internet bandwidth, upload speed, and processing power on your machine. If you don’t have the resources required to push out your desired frame rate than technically the live stream could decrease the FPS in order to keep up with delivery of the stream under specific constraints.
- Can I stream in 60 FPS?
- The short answer is yes, you can stream in 60 FPS.
- However, there are two important factors to consider when streaming at 60 FPS. One is your available resources for streaming in 60 FPS and the second is making sure the platform you plan to push your stream can handle 60 FPS.
- 60 FPS is common for fast paced sports content, because that frame rate is ideal high-motion content. Gamers on Twitch like to stream at 60 FPS because the type of content they are streaming is fast paced and benefits from the additional frames.
- Make sure you have the right resources and are conscientious about making the decision to stream at 60 FPS. Identify what resources you have available and how your viewer’s experience will look like. For any basic content, 30 FPS is more than ideal.
- What is the bitrate for 1080p 30 FPS?
- I’d say 5,000 kbps (kilobit per second) = 5 mbps (megabit per second) is the ideal if you’re looking to push out at 1080p 30 FPS stream. However, there is range. You can find anywhere from 3,000 kbps - 6,000 kbps
- In a production environment, it’s important to run a speed test. Whether you are live streaming from a full production studio, remotely, or in the field, a speed test can help you identify what you’re working with.
- Even on a 20 mbps connection, you still need to consider if there is other traffic on that network. It’s important to understand both your bandwidth constraints and other obstacles that might impact your live stream.
- The rule of thumb is to have double the upload speed of the maximum stream quality that you are pushing out. So if your maximum stream quality is 1080p at 30 FPS, which would be 5 mbps, at minimum you want a 10 mbps upload speed for additional wiggle room. You want your connection to be more than the bitrate at which you are pushing out your stream.
Wrap up
The great thing about live streaming content is that the sky is really the limit.
To create an amazing experience for your viewers, it's first important to understand what type of content you're trying to stream, the tools you have at hand to stream, and the environment and bandwidth you have available to push out your content.
If you have a live streaming idea that's a small production or looking to broadcast a full production, reach out to learn how our production team can help you go live.
Learn more about Vimeo's live production team
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