Change Aspect Ratio

When the aspect ratio of the source video is not the same as the desired output aspect ratio, the following advice will help you to get the best result. The points below are specifically for changing landscape video into portrait, but similar advice applies to changing portrait into landscape.

In general, transcoding or other processing should be kept to a minimum as each transcode will result in some quality loss as well as increased latency.

If at all possible, crop the source content prior to Phenix ingest. This is by far the best outcome for preserving quality and latency.

If it is not possible to crop the content prior to ingest, the content published to Phenix MUST include black bars on the side (pillarbox). Black bars use a minimal amount of bits for the part of the video that is going to cropped off, which saves CPU as well as network bandwidth.

When ingesting a video without black bars, the video bitrate must be increased. For example, 16x9 cropped to 9x16 means losing 2 x 9/16 of the content, which is about 31%. That means to have the same quality on the ingest the bitrate must be at least 30% higher than what would be needed for 9x16 ingest.

When video is cropped by the Phenix platform, the effect only impacts the real-time feed. Any VOD assets will not have the aspect-ratio capability applied.

Phenix does not currently support cropping of DASH/HLS. If this is needed, the real-time output can be forked to a new Channel and archived from that stream.