JPEG2000 bandwidth setting for commercial cinema

[swirfelt]

That update seems to have done the trick!
Thank You!

[Carsten]

Hi carsten

Which servers do not handle 250?

Hi Marco,

specifically I meant classic Doremi ('Dolphin based') servers. It is not easy to give a precise number when they fail, as the data throughput naturally varies per frame for typical content, and even a single frame may crash the decoder. Also, different J2K encoders deal differently with bandwidth variations.

My recommendation comes from reports that DOM (OpenJPEG) encoded DCPs at 250MBit/s spec setting crashed Doremis on some occasions. So, as the added 30-50MBit/s simply don't cut it, I would use a 200-220MBit/s setting for general applications (that is: as DOM default) and only change the value under the DCP tab temporarily for specific work. There are so many of those Dolphin Doremis in the field that I wouldn't risk it for such a minor/questionable increase in image quality.

- Carsten

[marcogiustini]

Hi Carsten

Yes, I am aware too that Doremi's cannot cope with anything more than 250 - but AFAIK they can deal with 250. My experience was that out of XX frames the encoder would go slightly over 250 every now and then and the Doremi decoder simply cannot cope with that and you get a green flash on screen.
I agree that keeping the bandwidth a little lower is an acceptable safety margin but if someone wants to use 250, I guess that it should suffice to check the size of each J2C frame to confirm that none is over the maximum bandwidth (250Mbit should be 1333.33KByte per frame at 24fps if I'm not mistaken). This is just for conversation's sake - I'm not questioning that using 230Mbit is a bad idea!