Feb 2, 2020 | 7 min read
What is Live Streaming
Live streaming is a method of distributing video to viewers, so they all watch it simultaneously.
To create a live video stream, the video is processed and made available for viewers soon after it is captured from the source. In actual conditions, depending on various factors, there is a delay of 1 second to 60 seconds until viewers can view the captured video.
Why is Live Streaming Important?
Live streaming is important and has become popular because it enables participants to view the event with other participants and interact with the speakers and with each other based on current happenings.
How Live Streaming Works
With the tools available today, live event streaming is easier than ever.
Step 1 - Video Capture
First, we need to capture to content to broadcast. The content to broadcast includes on-stage happenings, presentations, screens, remote speakers, and possibly other recorded videos that are part of a live lecture. Multiple cameras and microphones can be used to capture on-stage motion and sounds from different directions. Screen captures and remote speakers are captured by computers on the local network.
All captured content is routed to a central video mixing device, usually through cables (HDMI cables or SDI cables) or a local network.
Audio quality
With a focus on video quality, sometimes, the audio quality does not get enough attention, but good audio quality is critical for most live events. Clear audio makes it easier to understand speakers and enjoy live music.
Ways to improve audio quality
- Test the microphone and audio quality before going live.
- Use an external microphone (like a Lavalier microphone) if possible.
- Reduce background sounds. Close doors and windows in the room.
Step 2. Mix and Edit
Captured content video is fed to a video switch device or software, also called a video mixer. Each feed is an input channel in the video mixer. Using a basic video mixer, the operator can monitor the incoming channels and direct one to the device output.
Using a more advanced video mixer or a PC with live video editing software allows creating more engaging videos by mixing multiple media sources and adding graphics and special effects.
Video editing options opened by using a live video editing or video mixer:
- Switch between onsite camera, remote speakers, recorded content, static images, and presentations
- Compose a composite scene with multiple speakers speaking from different locations
- Add subtitles
- Add graphic overlays
- Add titles and information over the video
- Add live background or virtual studio backgrounds
- Combine two video sources using chroma key
Video mixer hardware and software solution specification include:
- Number and type of input channels
- Number and type of output channels
- Resolution and frame rate
- Transitions effects
- Picture in Picture templates
- Supported video effects
- Chroma key support
- Built-in media player
- Streaming support - Ability to upload a video to a remote server
- Recording
Live video editing
Some of the most common live video tools available are
- OBS Studio
- Open Broadcaster Software. Free, open-source, and cross-platform software for capturing and editing live video broadcasts.
- vMix
- vMix is a video mixer and live production software for Windows with free to $1200 versions. vMix includes "vMix Call", a feature that allows operators to bring in live video from remote guests.
- Wirecast
- Wirecast is a popular live production software for Mac and Windows that is available for $599 to $799.
3. Upload
The video stream created by the video mixer is sent over the internet to a remote server for additional processing. To do that, the mixer uses an internet connection upload link. There are several standard protocols that streaming servers support for receiving video streams, the most common protocol is RTMP. RTMP is supported by almost all video streaming providers, including YouTube Live, Facebook, and Twitch
Sending the video to multiple steaming services
Most video switches can send the video simultaneously to more than one streaming service. Sending the video to multiple streaming services is useful to create a backup for important broadcasts. It is also helpful if the event organizers want to show the content to multiple outlets such as an Event app, Facebook, and YouTube.
To send the video stream to the server, the mixer uses an internet connection. How much bandwidth is required to transmit video to the server depends on video resolution, and other parameters such as compression level, the dynamics of the footage itself. For example, uploading video steam of a fixed position camera requires less bandwidth than a video from a moving camera.
Bandwidth requirements
| Resolution | Resolution | Bandwidth | |
|---|---|---|---|
| 360p | 640x360 | 1 Mbps | Good for smartphones |
| 480p | 854x480 | 2 Mbps | Standard definition widescreen |
| 720p 30fps | 1280x720 | 4 Mbps | HD minimum |
| 1080p 30fps | 1920x1080 | 6 Mbps | Full HD |
| 4K 30fps | 3840x2160 | 34 Mbps | UHD |
Available upload bandwidth is affected by all the local network users. Always ensure you have extra bandwidth above the minimum required. Some internet providers do not guarantee they will provide the specified bandwidth all the time. For example, a 5MB upload link sometimes means 5MB maximum. The actual upload bandwidth is not guaranteed.
Step 4 - Video Encoding
A server receives the video and converts it to a format suitable for delivery to a large audience over the internet. To optimize the experience for viewers with limited bandwidth and different screen resolutions, the video encoding process usually includes creating multiple versions of the content in different resolutions.
The encoded video format and method of packaging and delivering the content must be compatible with the application the viewer is using to view the content. Over the years, multiple delivery methods where used. As of 2022, two main video delivery methods are used: HLS and MPEG-DASH.
MPEG-DASH is newer and has potential quality and bandwidth benefits, but MPEG-DASH is also a little more complex and more impotently not natively supported on Apple devices. The DASH quality advantage over HLS, together with the lack of Apple iOS / iPhone support, are the main reasons HLS is still more popular.
The most common video delivery methods are:
- HLS
-
HLS is the most common internet video streaming method for live video and VOD. HLS is based on widely supported protocols such as HTTP / HTTPS - the basic web data transfer protocol and MPEG / H.264 / H.265 - a standard and widely supported video compression format.
HLS was originally designed by Apple but it is supported on virtually all platforms yet, HLS is not an official standard. HLS is reliable, fault-tolerant, and can easily support millions of simulations viewers.
- DASH
-
DASH is a video streaming method that is an international standard and a published ISO standard. DASH is based on HTTP and video compression standards. DASH is similar to HLS but allows more flexibility in video compression formats.
DASH is used by YouTube and Netflix, and other large video streaming services. The downside of DASH is that not natively supported on Apple products.
Step 5. Video Distribution
Distributing a large amount of data to a massive audience requires resources. Sometimes one server can not handle it alone. The solution is a network of servers that share the load of delivering the video content to end-users. In addition, physically locating those servers in proximity to the end-user may improve performance and reduce latency.
A single server has limited CPU power and bandwidth so it is limited in the number of viewers it can serve simultaneously. To overcome this limit and deliver video thounds of viewers spread across the globe, a network of servers called Content Delivery Network (CDN) is used.
Instead of one server, a network of servers spread across the globe that share the load. Those servers face the viewers and deliver the video. To do that, the servers download a copy of the video from the video encoding and store it locally for a short period. This period is enough for other viewers connected to the same server to download it.
The servers that make the video distribution network are strategically located in different geographical locations to shorten the geographical and internet distance between the viewers and the content. This helps minimize latency and buffering time and ensures that the stream's source or origin server is not overwhelmed with requests.
Step 6. Video Players
A video player is a software component that displays the video stream on the user screen. To do that, the player has to download the video and play it. The video player is integrated into the event application or event website. Basic video players allow users to view the video and listen to the audio. However, most video players also allow the users to pause the video, mute and unmute the audio, select the video quality, select the video resolution, and resize the video.