Prepping your master before anyone makes a DCP.

Most bad DCPs were made from bad masters. The encoder did exactly what it was told, and what it was told was wrong.

A DCP is a translation. Your master goes in, and a cinema-standard package comes out. Clean up the source and the translation is easy. Hand over something ambiguous and the tool or the tech has to guess, and guesses are how dialogue ends up in the left surround.

So far this series has covered what a DCP is, when you need one and what it costs. This week is the homework that makes the rest go smoothly.

Lock everything first.

The DCP is the last file you make. Picture locked, color final, mix final, credits proofed. Every change after the DCP means another DCP, and last week showed what remakes cost.

Proofread the credits one more time. Credits are the most common reason a finished film gets reopened.

Pick the best source you have.

Give the encoder the highest-quality master available:

• ProRes 4444 or ProRes 422 HQ QuickTime, or

• A 16-bit TIFF image sequence plus separate audio files.

Avoid building a DCP from an H.264 or H.265 file made for streaming. Those files already threw information away, and JPEG 2000 compression at cinema bitrates will show it on a 40-foot screen.

Frame rate: the 23.976 problem.

Most indie films are shot and edited at 23.976 frames per second, because that’s what cameras and editing software default to. DCPs don’t use 23.976. The frame rate that works in every cinema is 24.

DCP-o-matic’s manual is direct about it: “The only rates that are guaranteed to work on all DCI projectors are 24 frames per second (fps) for video and 48kHz for audio.” Other rates like 25 and 30 are often supported, but only 24 is certain. The Academy accepts only 24 or 48.

So your 23.976 film will play at 24. The picture runs 0.1% faster, which nobody can see. The sound has to keep up. Good DCP tools handle this by resampling the audio so it stays in sync, and DCP-o-matic warns that the result “will sound slightly different.” In practice the shift is tiny, but a careful sound mixer may prefer to conform the audio to 24 themselves.

What you must not do is let picture and sound drift apart. Brad Fox, VP of Postproduction at CineSend, describes the failure: “If frame rate conversion is handled incorrectly, you can end up with choppy motion, blurry playback, or audio that slowly drifts out of sync over the course of the film.”

If you shot 29.97 or 25 for a reason, talk to whoever makes the DCP before anything else.

Aspect ratio: pick a container.

A DCP has two standard shapes, called containers:

• Flat, 1.85:1. 1998 × 1080 pixels at 2K.

• Scope, 2.39:1. 2048 × 858 pixels at 2K.

Your film goes inside one of them. If you cut in 16:9 HD (1920 × 1080, about 1.78:1), it fits in flat with a thin black bar on each side. If you framed for 2.39, use scope, so the theater can mask the screen correctly. If you framed for 2.39 but letterboxed it inside a 16:9 master, crop the bars off before you make a scope DCP. Otherwise the black bars get baked in and the audience sees a small picture floating in a big box.

Never stretch. Scaling to fit is fine. Distorting the image isn’t.

Color: know what you’re handing over.

Your colorist almost certainly graded on a monitor calibrated to Rec. 709, the HD television standard. Cinema projection uses a different color space and a different gamma, which week eight explains. The DCP encoder converts one to the other. For the conversion to be right, it needs to know what it’s converting from.

Three things to confirm with your colorist:

• The color space of the master, usually Rec. 709, sometimes P3 if the grade was done for theatrical.

• Video range or full range. Get this wrong and the blacks go gray and milky, or crush to nothing.

• Whether a separate theatrical grade exists. If you graded in a projection suite for P3, use that master.

Then write it down and hand it to whoever makes the DCP. This one note prevents the most common “why does it look washed out?” complaint.

Audio: discrete channels, cinema levels.

A DCP carries uncompressed audio, 24-bit at 48 kHz, one channel per speaker. Give the encoder discrete mono WAV files, or a single multichannel WAV with the channel order written down:

• 5.1: Left, Right, Center, LFE, Left surround, Right surround.

• Stereo: Left, Right.

Ask your mixer whether the mix was made for a cinema. A mix built for streaming or TV will play in a theater, but it was balanced for a living room. Week nine covers why theaters turn films down and how to avoid being one of them.

Clean the head and tail.

Take out bars and tone, slates, countdown leaders and any watermark from your screener workflow. Start the film on picture or a beat of black, and end the same way. Leave a second or two of black at each end so the projectionist has room.

The handoff checklist.

Whether you make the DCP yourself or hire it out, gather this in one folder:

• Picture. ProRes 4444, 422 HQ or TIFF sequence, with resolution, frame rate and color space noted.

• Audio. 48 kHz, 24-bit WAVs with the channel layout noted.

• Subtitles or captions, as timed files, if needed.

• Runtime and first-frame-of-action timecode.

• Title, exactly as it should appear in the DCP name.

• The venue’s delivery requirements, printed out.

That folder is what our DCP service asks for, and it’s what any good house will ask for. Next week we use it to build a DCP ourselves, with free software, start to finish.