What to Ask Before You Render for a Media Server

Show files aren't web videos. They have to play back perfectly, in sync, at huge sizes, on a machine someone else set up. The cheapest time to find out what that machine wants is before you render, so ask the operator these five things.

1. What is the exact canvas?

Ask for the pixel map, not the aspect ratio. Walls are built from panels, so the real canvas is rarely a round number, and it may be split across outputs. Your pixel pitch decides how many pixels there are.

2. Which codec?

Show playback usually runs on codecs built for fast decoding rather than small files.

• HAP has the lowest data rate of its family. HAP Alpha adds an alpha channel at the same quality, and HAP Q improves quality at larger file sizes.
• NotchLC is GPU-accelerated with the equivalent of 10-bit accuracy and compression of 8:1 to 4:1.
• DXV is GPU-accelerated only inside Resolume, so it's only a good choice if you know that's what's running.

The server may add rules of its own. disguise accepts .mov files in HAP, HAP Alpha, HAP-Q, NotchLC and other codecs up to 16384x16384, and it needs a keyframe on every frame, because delta frames aren't supported. Its codec overview suggests HAP above HD, and notes that HAP-Q takes twice the bandwidth.

Also, HAP's own guide says chunks should never exceed the playback machine's CPU core count. That's a detail you can only get right by asking.

3. Do you need alpha?

If titles sit over a live feed or a separate background, you need transparency, and that decides the codec. It also makes later changes cheaper, which is why we prefer it for content that has to survive a rehearsal.

4. What frame rate does the output run at?

TouchDesigner's playback guide explains why this matters: movie frame rates should divide evenly into the refresh rate. Render 29.97 for a 60Hz output and you get a regular repeated frame, which is easy to see in a slow pan on a very big screen.

5. Can I send a test file today?

This matters most. Send ten seconds with your finest line, your smallest type and a slow pan. Ask for a photo or a video of it on the real wall, if it's up. A test file takes an hour, and it answers all of the other questions for certain.

Put the answers at the top of the cue sheet, so the next person doesn't have to ask. For more on our show work, see live events.