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Resolve easyDCP - strange behaviour while working with animation

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Marek Dudzik
Resolve easyDCP - strange behaviour while working with animation
on Jul 12, 2016 at 11:34:11 am

Hello all,

Actually the thing I need the most is the confirmation that I am not wrong.

Yesterday I created 2K SCOPE DCP with easyDCP plugin for Resolve out of 2048x858 TIFF sq containing 2D animation (ca 30min if it's important).

In a first try I set maximum bitrate to 160Mbps - the final j2c mxf was ~34Mbps according to MediaInfo.
In a second, I moved it to 250Mbps but bitrate of outputted file have not changed.

I assume that as long as I am working with 2D animation there is no need to use standard DCI bitrates (150Mbps+), because it would only be generation of "empty bytes"?

On the other hand, I tried to do the same thing with dcp-o-matic, which uses OpenJPEG encoder and final bitrate was much higher (as desired)....

So I am a bit confused.
Probably the best way would be to watch both (easyDCP and dcp-o-matic) versions on the screen and compare quality, but I will not be able to do that in next few days.

Thanks in advance for your feedback!\
best
Marek


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HiKO Geldanlegehuegel
Re: Resolve easyDCP - strange behaviour while working with animation
on Jul 13, 2016 at 12:37:23 pm

Hi Marek

I am involved in the easyDCP development - just to make that clear.

The behaviour you mentioned is normal. It seems that your source material does not carry enough information in order to reach the maximum bit-rate. That is also normal when working with animated content. The JPEG 2000 encoder is smart enough to detect, whether it makes sense to put more data into the images or not.

There are many ways how you can configure JPEG 2000, so the other tool you mentioned seems to follow another approach. From my experience I can tell, that we received this question many times and at the beginning of our development, we compared packages compiled with other solutions and packages compiled with easyDCP. The quality of the easyDCP packages was at least as good as the quality of the other packages. Most of the time we had the feeling, that the quality of the easyDCP-packages was a little bit better. It was not a big difference at all - more tiny details in certain areas of the images we used.

A couple of years ago we made another test that was also very interesting. We made a DCP with easyDCP - as sources we used DPX files. The DCP had an average bit rate of 100 - 120MBit/s. Then we used another DCP-solution to re-compile the existing DCP. That means it decodes the JPEG 2000 files and encodes them again. We ended with a new DCP comprising an average bit rate of 180 MBit/s. Of course, that makes no sense, since JPEG 2000 de- and encoding won't add new information to the images, right?

If you are more interested in this topic you may want to read about VBR (Variable Bit Rate) and CBR (Constant Bit Rate) Coding.

Regards
HiKO


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