Studio Bandwidth FAQ: Viewer

How much bandwidth is required for a viewer to join a Studio webcast?

This varies, depending on a variety of factors that impact the overall quality level of the webcast. In general, in order to have a quality experience viewing a video webcast, a user needs an internet connection with at least 500 Kbps of available bandwidth. We recommend a connection of 1 Mbps or higher. Also note that Studio uses adaptive bitrate streaming to ensure a quality experience for users with bandwidth constraints.

What factors impact the amount of bandwidth required for a webcast?

Bandwidth (expressed in bitrate), video size and quality of the video are directly related. Increasing the bitrate of a webcasts will increase the video quality. And increasing the video size will also increase the bitrate demands of a webcast.

Are webcast hosts in control of these factors?

Yes. When configuring a Studio webcasts, webcasts hosts can adjust the video size and target bitrate for a webcast. INXPO provides recommendations for these settings.

How do PowerPoint slides affect bandwidth consumption?

There are two components that impact the amount of bandwidth consumed by an attendee in webcast: the audio/video stream and the PowerPoint slides. These two elements are delivered in very different manners, so the patterns of bandwidth consumption for the two will be different.

The video or audio component of a webcast is delivered in a single, continuous stream. By default, an audio webcast media stream is delivered at 128 Kbps. For video webcasts, the bitrate is automatically calculated by the Studio engine and varies depending on the frame size and frame rate defined in the Settings (for a deeper dive into video bitrates click here). Over the course of a live webcast, the consumption of bandwidth by the media stream will remain steady with only minor variations.

Slides, on the other hand, are not delivered as a stream. When slides are uploaded into Studio, the slides deck is converted to an HTML page. This HTML page includes all the graphical assets used in the slide deck. As a result, when slides are loaded, the bandwidth consumption will resemble loading a large web page, rather than a continuous stream. The initial load of the first slide will lead to a spike in bandwidth consumption as the converted ppt file is being downloaded. As additional slides are pushed, smaller spikes in consumption will occur as the new slides are loaded for each user. If a welcome slide is used in the presentation, slides will begin to load when a user enters the webcast, whether the webcast has started or not. If a welcome slide is not used, all users will download the slide content at the same time, when the webcast begins. As a best practice, if you are running a webcast inside a network with bandwidth limitations, a welcome slide can greatly soften the bandwidth drain on the network due to the slide content. Additionally, since slide content is delivered via HTTP as regular HTML content with PNG images, this content will be cached by proxy servers or caching appliances installed on the network.

How do screen sharing and video slides impact the amount of bandwidth required for a webcast?

Screen sharing and video slides are additional video streams; when a video presenter is sharing a video slide, users are receiving two video streams at the same time. Because of this, the use of screen sharing and video slides can potentially double the amount of bandwidth required for a webcast.

How does using picture-in-picture mode impact the amount of bandwidth consumed by a webcast?

Picture-in-picture mode helps conserve bandwidth by blending live and pre-recorded media elements (including videos and screen sharing) into a single video stream. When using PiP mode, the final stream video stream the user receives is not affected by adding video sources.

How does adaptive bitrate work?

Adaptive bitrate helps ensure that users with bandwidth constraints are able to have a quality experience viewing a webcast. INXPO’s cloud-based application creates multiple quality streams for a single webcast, with the lowest quality version being audio only. During the webcast, Studio identifies the bandwidth each viewer has available in real time, and then sends them the highest quality stream their system can receive. For viewers, this means that the quality of the webcast will adjust in real time, based upon their connection speed. This behavior is familiar to users of other streaming applications, including Netflix.

What settings are available for adjusting the bitrate of a stream?

The main factors that impact the bitrate of a stream for attendees are the size of the video window and the quality of the stream. Studio also allows webcasts hosts to adjust the target bitrates of a webcast.

How do network bandwidth requirements change for multiple viewers in a single location?

In general, bandwidth requirements increase linearly based upon number of users. For example, if three users are watching a 500 Kbps stream, the network will require at least 1500 Kbps (or 1.5 Mbps) of available bandwidth.

Are there any options for lowering the amount of bandwidth required for multiple viewers in a single location?

Yes. INXPO does offer a solution that will alleviate bandwidth constraints on networks with a large number of users. Contact your INXPO representative for more information about Amplify.

Can I send higher-quality video to specific users?

Yes. Studio can generate separate output streams and target specific groups of users to receive a specific bandwidth. This is an advanced option, so contact your INXPO representative for more information.