Changing aspect ratios

Endpoints send and display video images and presentations in various aspect ratios, most commonly 16:9 and 4:3. If there is a difference between the aspect ratios of the sending and receiving endpoints, then the endpoint and/or Pexip Infinity may crop the image or add black vertical or horizontal mattes (also known as letterboxing and pillarboxing). How and when aspect ratios are changed depends on a number of factors, but the general principles are described below.

Presentations

Pexip Infinity

In general, Pexip Infinity prefers to send presentations as 720p (which has an aspect ratio of 16:9) for calls where the bandwidth is sufficient and the endpoint supports it. But if this is not feasible, all alternative resolutions have an aspect ratio of 4:3.

If a change of aspect ratio is required, Pexip Infinity will add mattes (in order to not remove anything important from the presentation). It will never crop presentations.

This means that depending on circumstances, the presentation may be sent as either 16:9 or 4:3. The decision is made without knowing about the actual display on the endpoint, so in some cases the endpoint may need to change the aspect ratio again.

Endpoints

If the aspect ratio of the presentation image being sent from Pexip Infinity does not match the display aspect ratio on the endpoint screen, the endpoint will typically add another letter/pillarbox to make it fit. Generally endpoints will not crop the image.

Main video

If required, Pexip Infinity will change the aspect ratio of main video by cropping the image (to avoid black bars in the thumbnail images).

If the aspect ratio of the main video image being sent from Pexip Infinity does not match the display aspect ratio on the endpoint screen, the endpoint will typically add another letter/pillarbox to make fit. Generally endpoints will not crop the image.