⚙️Media specs and encoding

Looking Glass Hololuminescent Displays ship with an included Raspberry Pi based media player. This media player is intended to allow customers to quickly preview content on the HLD displays and is not meant for full large-scale installations. To encode content on your HLD please see the following instructions.

Specification
Resolution	2160 x 3840
Aspect Ratio	9:16
Frame Rate	30fps or 60fps
Codec	HEVC/H265
Color space	bt709

Safe Areas

For a 4K video (2160x3840) we recommend leaving 355 pixels on the top, 100 pixels on the bottom, and 108 pixels on either side (~9% on the top, ~3% on the bottom, and ~3% on either side). You can preview this safe area in our templates.

Masking

Content for HLD systems does not need an alpha channel. The display itself handles the blending between the video and the holographic volume built into the display. The effect is similar to a multiply blend mode like you'd see in photo or video editing tools. Content should be "pre-matted" with the desired background color.

Encoding

Looking Glass provides a utility called HLD Author, a small application designed to encode video for proper playback on the HLD systems. Generally, this tool will handle all the encoding specs necessary for you to have your content playback properly. If you need to change settings or add custom encoding options, please ensure your content meets the following criteria. If you're unable to use HLD Author, please ensure that the content is rotated counterclockwise by 90 degrees. The result would be that your video appears sideways. This is necessary to get the most performance out of embedded media playback systems.

Should you wish to encode in your own pipeline, the standard FFmpeg command we use for our content is the following:

ffmpeg -i input.mp4 -c:v libx265 -crf 18 -pix_fmt yuv420p -tag:v hvc1 -c:a aac -ar 48000 output.mp4