DCP vs HDCAM vs Blu-ray

[Greg M]

generally a DCP and a BluRay are played on different projectors and the difference is visible. But if the festival requires DCP or HDCAM and won't accept BluRay then why does it matter?

 

[Christopher*Seguine]

What nobody has mentioned is that the DCI projector is probably calibrated reasonably well for DCP playback, Bluray probably not.

Bluray uses an ancillary input on the projector, this is almost never calibrated and is just set to a generic rec709 setting. There may be a mismatch between video range/full range settings, audio is a problem as most theaters just cheap out with just dolby digital connection to their processor and dont bother with DTS-MA or lossless audio routing. If its a 4k projector, the scaling for bluray is very basic and not very good. Bluray could look very good, but there is no consistency that you get from a DCP, and most of the time it sucks.

HDCAM is 1440x1080 8-bit YUV 4:2:2 with a maximum bitrate of 140Mbps. A jpeg2000 DCP should preserve image quality a whole lot better than that, in resolution, compression ratio and bit-depth. HDCAM SR is an entirely different beast in terms of image quality and could outperform a 2k DCP.

HDCAM is actually 3:1:1, SR has multiple formats and could be 880mbs 4:4:4, but a DCI projector can not easily accommodate a Dual link SDI video input that is required, for one offs and festivals they usually use the aux input and a SDI to HDMI converter for simplicity so your back to 8bit video. Almost always a 12bit DCP will be better.

I've never seen a feature bigger than 200GB. Period.

The best (by far) DCP's are made by ARRI Munich.
They use compression algorithms that allow them to put a 150 minute feature below 100 GB.

The primary DCP for our last film is 1.2TB

4k 5.5 hours @ 500mb/sec + 8chan 96khz sound
Most DCI projectors with a built in media block will support 500mbs rate - Christie and Barco at least.
250 mb/sec limit was really designed for 2k, you can definitely see the difference on a 40' screen - its wavelet like R3ds, so things just get soft at higher compression.

The normal 4k 250mbs DCP for our film 600 GB, the 2k DCP is 500 GB - J2k will only use more bits when its needs it so that should tell you that the 4k version is starved for bits.

Arri just uses a Clipster, no special magic there.

In the US at least, distributors really push for the smallest possible DCP, so its cheaper for them to send via satellite to the multiplex hordes. So while the DCP sizes you are seeing for features is the norm, its definitely not best practice.

 

[Marc Wielage]

generally a DCP and a BluRay are played on different projectors and the difference is visible. But if the festival requires DCP or HDCAM and won't accept BluRay then why does it matter?

It will matter if it's not the same color space. DCPs are always in P3/XYZ color space, and -- generally -- HDCam-SR is in Rec709 color space. Rec709 images are generally not intended for theatrical brightness levels, which are roughly half the brightness of flatscreen displays. So you can't necessarily switch between DCPs and HD-Cam tapes unless there's also a corresponding switch in color & gamma space.

 

[Greg M]

It will matter if it's not the same color space. DCPs are always in P3/XYZ color space, and -- generally -- HDCam-SR is in Rec709 color space. Rec709 images are generally not intended for theatrical brightness levels, which are roughly half the brightness of flatscreen displays. So you can't necessarily switch between DCPs and HD-Cam tapes unless there's also a corresponding switch in color & gamma space.

I think you misunderstood. I understand the difference between a DCP and HD-Cam.
"why does it matter?" was for the OP...why does all this matter if the festival in question won't take a Blu Ray?

 

[Marc Wielage]

I think you misunderstood. I understand the difference between a DCP and HD-Cam. "why does it matter?" was for the OP...why does all this matter if the festival in question won't take a Blu Ray?

Blu-ray was not part of my answer. I've never seen an HDCam-SR tape set up for P3. It's primarily a broadcast format. If the projector is set up for P3, it's not going to look good with a Rec709 videotape.

 

[Carsten Schuffert]

Hi all,
besides the discussion which does not reflect the major difference of above formats in codec, compression, color space, number of sound channels, framerate options, security (all big topics where one could write essays) no-one seems to be interested in the fact that amongst the 3 formats DCP, HDCAM(-SR), Blu-ray only the DCP can perform 4k ! As the DCP encoding is a wavelet function the container includes both 4k and 2k, and all DCP-Servers are able to play 4k DCP even if the projector would only be 2k. As a REDuser we should be interested in higher resolution than 2k, no ?
Correct is that a perfectly mastered Blu-ray which is projected on a well colourimetered DCI- Projector looks very close to a DCP, IF (!!!!) content is not going to its limits in terms of contrast, brightness, motion, colors etc. Anyway: There is a quality reason, why a typical DCP is around 200-300 GB (depending on the compression (which is 250 mbit max). Also sound on a DCP is 24 bit, 48 kHz uncompressed WAV, so the best choice you can have.
Moreover the DCP presentation is the only format that allows proper automation in terms of screen masking, safety on playback (hash value checksums) etc., so everything you want to make the screening of you movie the best possible performance
If you are a filmmaker who wants to screen in cinemas, you always should go for this distribution format.

BTW:Let me know if I can help in any way on your DCPs, I really have a lot experience with this format as we did more than 1000 feature film encodings for distributors all over Europe.
best
Carsten