quote: Bobby Henderson

---

JPEG 2000 isn't very file size efficient when it comes to encoding and compressing imagery meant to view as video.

---

quote: Bobby Henderson

---

If decision makers are going to put more emphasis on shrinking file sizes instead of preserving image quality then they might as well just dump JPEG 2000 for d-cinema use and adopt HEVC H.265 instead.

---

quote: Bobby Henderson

---

It certainly would make sense to data compress a movie more severely to make more efficient use of satellite bandwidth, but it doesn't make any sense if the movie is just being shipped on hard discs.

---

It is entirely possible the hard drive duplication costs are in various brackets based upon the amount of GB put onto them. After all 500GB of data on a hard drive only takes half the time of putting 1000GB of data on that drive to duplicate.
 

---

Posted by Carsten Kurz (Member # 5396) on 01-13-2015, 09:23 AM:
 
Well, first of all, it is in CS AR, that means, less pixel to beginn with. Second, compression ratio of real material depends on the spatial resolution and high-frequency signal components of the source footage. An exceptional soft, monochromatic, dark, etc. movie will 'naturally' compress to smaller file sizes without anyone pulling the strings especially towards that direction.

That said - 93GBytes certainly still seems a bit on the low side.

I would think that normally the only valid decision towards filesize would be made based on the aspect of harddisc single inventory. That is, a typical multi-format package with 2D, language versions, different 3D grades, etc. should fit on the commonly found distribution disks. But with a feature like 'unbroken', this could hardly play a role (first of all, no 3D).

Unfortunately, hard-disk distribution can no longer be considered the norm. As the DCDC takes up pace, I would think that satellite or broadband distribution cost will play a larger role for future features. It is possible that in this case, this was the decision factor.

- Carsten
 

---

Posted by Joe Redifer (Member # 3) on 01-13-2015, 02:41 PM:
 
Even with no compression at all, hard drive duplication costs would be MUCH more cost efficient than than striking a bunch of prints, right? So why are they pinching pennies?
 

---

Posted by John Wilson (Member # 269) on 01-13-2015, 03:32 PM:
 
As a comparison, our 2K version of AMERICAN SNIPER which runs a comparable 132mins is 235GB.

Go figure...
 

---

Posted by Monte L Fullmer (Member # 2797) on 01-15-2015, 06:13 PM:
 
And, you get the count up to 126Gb if you're doing ATMOS 7.1 for the same 4K resolution.
 

---

Posted by Owen Morgan (Member # 7854) on 01-17-2015, 09:35 PM:
 
This topic has me intrigued....

I am in a position to actually ask the people who actually mastered the DCP (UK/EU/Other releases) questions, and I wonder why it is soo small..

I see no real reason other than to save duplication time, digital delivery time (both IP and Satellite based)...

I have a suspicion that the guys who worked on this were simply working with the source materials they had (which may have been source DCP or .j2c files from universal, or uncompressed .tif...) and that decisions based on how much compression to use etc would have been already down the line.

I can but ask..
 

---

Posted by Antonio Casado (Member # 7592) on 01-18-2015, 04:14 AM:
 
I can answer about that, because I professionally make DCPs and I have done a lot of test regarding this...

Well, first of all, the tool you use can be more or less efficient. For example, at the same bitrate, OpenJPEG is more heavy in size, but EasyDCP (kadaku encoder) is less weight.

You can think that less size is less quality. Not in JPEG2000, that have a very optimized algorithm.

I use a tool that use other Jpeg2000 encoder and the results are really amazing.

Second, the bandwidth. The maximum Mbit/sec for DCP is 250 Mbit/sec (including audio tracks). Really, no one make DCPs to that Mbit/sec because is not needed.

In fact, more that 150Mbit/sec is considered garbage and there is NOT difference visually with a 250Mb/sec DCP. When you low to 100 mbit/sec is when you can loss some high frequency textures, so not recommended at all. 25Mbit/sec cause severe degradation in the image, and the image look like plains colors, really funny :-D

Third, the use of VBR Encoding. When you use it, is when you make the "magic". Prior to the use of VBR, you mark a target Mbit/sec and ALL Jpeg2000 files will be compressed at this Mbit/sec. So a black image will size like a full detailed pic. This is a nonsense.

The VBR encoding can lower A LOT the final size, as a black image can be as low as 2Kb, and that is very good.

Also, if the original image is NOT HD (DVD Scaled to HD, for example, or something similar), the size will be much lower, by using VBR encoding (equal pixels surronding will be compressed and the final image will be lower in size, but retaining the original Quality).

I have done a lot of projections of very high frequency images (with a lot of detail), and when you compare a 150Mbit/sec DCP with a 250Mbit/sec DCP, there is NO difference. It´s the same.

Of course, a final cause is the duplication time. It´s not the same copy a 200GB DCP that a 100GB DCP. You can lower the time, and make more copies in the same time. And the quality is the same. So, why to spent useless bytes?.

About H265, I don´t think that H265 will be used in DCP. H265 is a very good codec, I have done test at 4K and using the same bitrate of Bluray at 1080P the quality blow away. Imagine a 1080P H265 Feature weighting only the half of the size but the same quality. Really cool!. This is intended to use for streaming and Digital Download, not Cinema.

But who knows how can be the Digital Projection in 10 or 15 years from now...

I only know that Jpeg2000 is one of the best codecs to use in delivery, much better that anyone other...
 

---

Posted by Steve Guttag (Member # 268) on 01-18-2015, 08:14 AM:
 
Thanks Antonio! Very informative. Do you have a suggested bit-rate when encoding DVDs and Blu-Rays that retain as much quality of the original but without wasting space?
 

---

Posted by Antonio Casado (Member # 7592) on 01-19-2015, 02:04 AM:
 
Thanks Steve!

About Bluray and DVD, as these media is compressed in origin, a 140 Mbit Bitrate will be fine.

The SAME movie in DVD will compress A LOT (because the image need to be scaled and the pixels repeats, so a lot of optimization will occur).

I do not recommend to transfer to DCP from a DVD, it´s really crappy, but I understand that sometimes is the only source, unfortunately.

I receive A LOT of compressed, interlaced, resized, pulldown material, the clients doesn´t know anything about DCinema and thinks that "all is good" to project in DCinema. What a mess!
 

---

Posted by Marco Giustini (Member # 4544) on 01-19-2015, 10:17 AM:
 

quote: Antonio Casado

---

I have done a lot of projections of very high frequency images (with a lot of detail), and when you compare a 150Mbit/sec DCP with a 250Mbit/sec DCP, there is NO difference. It´s the same.

---

Hi Antonio,
May I ask you on what screen size you run your tests?

If I did my calculations right, the CPL we're talking about has been mastered at an average of 92Mbit/S

I believe one of the reasons for the small size is satellite/online delivery. The smaller, the faster/cheaper to transfer. I know of some countries where the satellite version is actually smaller than the DCP counterpart.

Personally I feel that considering the money a feature costs, a little less compression for the big screen is not going to hurt! I trust your observations Antonio, 150Mbit sounds good to me.

Let's say that if you say that 150 is very good, if I were a studio I'd choose 160 to be on the safe side. Not 92!

That said as you noted nobody knows about that stuff and it's likely the higher compression was just a result of random events.
 

---

Posted by Lyle Romer (Member # 1266) on 01-19-2015, 12:00 PM:
 
Antonio,

Thank you for the detailed explanations you have posted. Does your 150 Mbps maximum necessary bitrate apply to 4k? My non-expert thought would be that with 4X the information to start with, it would require a higher bitrate than 2k to get to where you don't notice a difference with more bandwidth. I'm specifically referring to JPEG2000 compression.
 

---

Posted by Antonio Casado (Member # 7592) on 01-19-2015, 12:38 PM:
 
Marco:

I have projected in a 300 meters square screen, so trust me, 150/160Mbits is fine and the quality is very good (but at these levels of screen we need 4K)

92Mbit/sec is really a low low bitrate!. The Scope format also helps to lower the bitrate (as the pixel count is lower that Flat/Full), but that is not the point. I NEVER lower from 125mbit/sec. I use 125mbit/sec for ads, because they are "temporal", but for Features and other things, I set mainly 150/160mbit/sec.

Of course, the final size varies in function of the type of images, I have a rule of 1 min = 1GB, so 90 minutes will size 90GB or more (suggested more, of course)

Lyle:

About 4K, as the maximum bitrate is 250mbits for both format I suggest to up to 170/180 mbits, not more. And even 160Mbits will be fine too, as the "degradation" in a 4K image is less noticeable, and ONLY the very near seats can "see" the true 4K resolution (and you need a reasonably big screen too).

This apply too to 3D and HFR, where the FPS will be doubled and the size of the files are lower too.

That´s because HFR 3D need 500Mbit/sec, to make the really good quality needed, as 250Mbit/sec will be insuficient (but possible!)
 

---

Posted by Carsten Kurz (Member # 5396) on 01-19-2015, 01:13 PM:
 
As I mentioned before, there are some differences between common J2K encoders. The Dolby encoder e,g, manages lower bitrates very well, while OPENJPEG does not.
I talked so someone dealing with DCP mastering and disc & satellite distribution professionally. He did confirm that, though rarely, sometimes the rights owner/distributor do in fact instruct the mastering companies to lower the bitrate in favour of certain distribution channels and cost. Some distribution companies actually charge per GB, so they actually do save with smaller files.

I hope they will not overdo this in the future as more and more satellite and broadband distribution taking over.

J2K/Wavelets deal very well with higher resolution content. That's one of the reasons DCI chose this codec. You can add a lot more detail without having to increase the datarate significantly.

When recompressing DVD or BluRay, J2k as intraframe also does not pile up more motion artifacts as with most other interframe codecs. These would show up badly on the big screen. So, it is relatively easy to conserve at least the original BluRay quality using J2K. BluRay also has only 8Bit 4:2:0. These 'flatter' files will compress a lot higher than DCPs 12Bit 4:4:4 as they contain a lot more redundancy.

Proper color/gamma conversion is more important than bitrate settings when doing DCP conversions - even for DVD.

- Carsten
 

---

Posted by Antonio Casado (Member # 7592) on 01-19-2015, 01:22 PM:
 
I agree with Carsten ;-)
 

---

Posted by Steve Guttag (Member # 268) on 01-19-2015, 01:49 PM:
 
Carsten,

Your rule of thumbs on DVDs and Blu-Ray conversions? I have also heard that for them, particularly DVD...100Mbit/sec is sufficient to not lose anything.

I would presume the path the "ripping" occurred would make some difference as to what colorspace one should select on the DCP conversion. Blu-Ray should be REC709.

In other threads I've heard the discussion on the Gamma...there is the theoretical and what seems to work well in the theatre. Again, Rec 709 stuff is normally in the 2.2-2.3 range but some claim it is a bit too much on the "light" side.
 

---

Posted by Carsten Kurz (Member # 5396) on 01-19-2015, 02:07 PM:
 
Steve,

actually I have set my DCP datarate at 150 and hardly ever touch it. I usually do not care if one of these conversions has a couple of GB more or less. Yes, DVD could probably be set well below 100MBit/s, but I really do not care. You do know that different discs can have very different resolution/quality, so, while you could take an edge with one disc, it may not work with a different one. So I just play safe with 150MBit/s. That would still be sufficient with high quality 4:4:4 10/12Bit source footage.

REC709 is right for both DVD and Bluray. The problem is that there is a strange gamma uncertainty, discussed at various places, claiming that there is not a single gamma setting that fits all media.

http://dcinemaforum.com/forum/index.php?topic=451.0

I have actually seen strange lifted blacks on some BluRay conversions, but not others. I have a hard time to understand why these differences do not show up as drastically in their original intended playback environment - home cinema, etc. I can only advise to keep a close look at the blacks/colored shadows and keep the issue in mind. All DCP converters with support for REC709 should do gamma correction from 2.4 to 2.6 (2.2 to 2.6 for sRGB sources) while converting to xyz color. But sometimes this simple scheme fails. When I did my first full lenght Bluray-DCP conversion two years ago, I only noticed too late that in some scenes there were torn up blocky blacks and strange clipped saturated dark colors. At the time I did not have the time for a new conversion, let alone thorough testing. So I had to adjust the projector settings to fix it. Best of course would be to have an A/B comparion between disc and DCP on the DCI machine. But who has the time to do that for every conversion?

- Carsten
 

---

Posted by Owen Morgan (Member # 7854) on 01-19-2015, 07:02 PM:
 
Hi,

For the record the FR-FR_FR-TL_71_4K has a JP2K bandwidth of 80.90MB/s.

I doubt that they are using any 'open' JP2K encoders..

But that goes a long way to explain the size.
 

---

Posted by Carsten Kurz (Member # 5396) on 01-20-2015, 03:46 AM:
 
If you can, look up the metadata files for any hints on the encoder/mastering system used.

-Carsten
 

---

Posted by Marcel Birgelen (Member # 6801) on 01-20-2015, 04:36 AM:
 

quote: Owen Morgan

---

I doubt that they are using any 'open' JP2K encoders..

---

quote: Carsten Kurz

---

I have actually seen strange lifted blacks on some BluRay conversions, but not others. I have a hard time to understand why these differences do not show up as drastically in their original intended playback environment - home cinema, etc.

---

quote: Antonio Casado

---

Third, the use of VBR Encoding. When you use it, is when you make the "magic". Prior to the use of VBR, you mark a target Mbit/sec and ALL Jpeg2000 files will be compressed at this Mbit/sec. So a black image will size like a full detailed pic. This is a nonsense.

The VBR encoding can lower A LOT the final size, as a black image can be as low as 2Kb, and that is very good.

---

quote: Antonio Casado

---

About 4K, as the maximum bitrate is 250mbits for both format I suggest to up to 170/180 mbits, not more. And even 160Mbits will be fine too, as the "degradation" in a 4K image is less noticeable, and ONLY the very near seats can "see" the true 4K resolution (and you need a reasonably big screen too).

---

quote: Antonio Casado

---

About 4K...well..is long to talk. Better in another thread, really...

---