> For the complete documentation index, see [llms.txt](https://hlddocs.lookingglassfactory.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hlddocs.lookingglassfactory.com/resources/media-specs-and-encoding.md).

# Media specs and encoding

Looking Glass Hololuminescent Displays ship with an included [Demo Media Player](/managing-content/using-the-demo-media-player.md). 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 Demo Media Player, please see the following instructions.

| Demo Media Player target | Resolution | Source aspect ratio | Codec      | Output orientation                  |
| ------------------------ | ---------- | ------------------- | ---------- | ----------------------------------- |
| HLD 16"                  | 1080p      | 9:16                | HEVC/H.265 | Rotated 90 degrees counterclockwise |
| HLD 27"                  | 4K         | 9:16                | HEVC/H.265 | Rotated 90 degrees counterclockwise |
| HLD 86"                  | 4K         | 9:16                | HEVC/H.265 | Rotated 90 degrees counterclockwise |

Use a frame rate of 30 fps or 60 fps and the `bt709` color space. HLD Author selects the target resolution, orientation, and codec automatically.

#### 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 [HLD Author](/apps-and-tools/hld-author.md), a browser-based tool for importing videos, images, and 3D media; adjusting and previewing the content; and exporting an MP4 for the selected playback destination. When exporting for the [HLD Demo Media Player](/managing-content/using-the-demo-media-player.md), choose the exact HLD target and HLD Author will apply its required resolution, rotation, and HEVC codec. BrightSign and General exports use standard portrait H.264 instead. If you use a custom encoding pipeline, follow the specifications for your playback target.\
\
If you're unable to use [HLD Author](/apps-and-tools/hld-author.md), Demo Media Player content must be rotated counterclockwise by 90 degrees (via an FFmpeg command like `-vf transpose=2`) and encoded to the resolution and HEVC profile required by the target HLD. This means the video will appear sideways if viewed normally. Do not apply this rotation to BrightSign or General playback files.

For an HLD 27" or HLD 86" 4K source, the standard FFmpeg command is:

`ffmpeg -i input.mp4 -vf transpose=2 -c:v libkvazaar -crf 18 -pix_fmt yuv420p -tag:v hvc1 -c:a aac -ar 48000 output.mp4`

Or, if you're using a GPL version of FFmpeg, you can run the following command:

`ffmpeg -i input.mp4 -vf transpose=2 -c:v libx265 -crf 18 -pix_fmt yuv420p -tag:v hvc1 -c:a aac -ar 48000 output.mp4`

Note that this includes the transpose step, which means it's assuming we're starting with a portrait-oriented video.