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Author Topic: Sound in and out of sync with Sony projectors  (Read 554 times)

rconnew

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Sound in and out of sync with Sony projectors
« on: May 23, 2017, 01:24:42 PM »
Folks,
         New ish to DCP's so not entirely sure what I'm doing is right so if anyone could please give me some pointers I'd really appreciate it.

We have an 80 min feature film we made that we are going to premiere in the local VUE cinema at the end of June. To be on the safe side I took a test DCP down today to test it and then I have time to fix any problems. Good news is the picture is perfect, bad news is the sound starts off in sync and then gets more and more out of sync over time. If the film is stopped and restarted at another point in the film it returns to being in sync again and then slowly gets worse. This happens every time you restart it at any different points including start and stop at the same point.

Obvious one was different frame rates but I have double checked and both are 24 plus if one was 23 and one 24 then surely the sync would be out all the way through? Plus the frames would be different numbers on DCP creation as well?

DCP was created as follows
1. Film into DaVinchi Resolve project then output as J2000 files in 2K flat at 230mbs.
2. Use OPEN DCP to create MXF file SMPTE from J2000 files
3. Export from 24fps project in Premiere uncompressed 5.1 wav file
4. Open wav file in Adobe Audition and split into separate 5.1 files
5. Import Right, left, centre etc etc into OPEN DCP and create SMPTE 5.1 MXF sound file
6. Add sound and video MXF files into OPEN DCP and create DCP

When tested on a PC via stereoscopic player (can view and playback dcps as well as 3D) sound in sync and all works well?


Tried the staff at VUE for help or ideas but it seems they only load the films and press buttons these days which isn't much help. The only thing I can think of is to create an MXF Interop DCP and see if with more tolerance that's any better? Anyone any other ideas please? Anything I've not allowed for or forgotten?
Appreciate any help, Thanks

Richard

Terrence Meiczinger

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Re: Sound in and out of sync with Sony projectors
« Reply #1 on: May 23, 2017, 04:32:32 PM »
1. Do you know the make/model of the digital server?
2. Your bandwidth is way higher than you need and some servers (especially older DoRemi's) can have issues with that. You only need around 75mb/s for 2K 24fps. This is the most common source of sync issues that I have seen.
3. DaVinci Resolve may not be creating DCI compliant J2K images.
« Last Edit: May 23, 2017, 04:34:44 PM by Terrence Meiczinger »

rconnew

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Re: Sound in and out of sync with Sony projectors
« Reply #2 on: May 24, 2017, 01:39:59 AM »
Thanks I'd just assumed a maximum of 250mbs as the limit. The sound did seem to be ahead of the picture so possibly it was taking longer to process the picture. The projectors are supposed to be the latest having been updated last year see https://www.sony.co.uk/pro/press/pr-sony-4k-projectors-at-vue-entertainment
The footage is 10bit with some really extensive colour grading and as such what I didn't want to see was blocky bits on the screen by compressing it too much so that's why I went for 230. I did notice the picture stop go black at one part then restart so you may very well have a good point. May even be slow disks on the server? I'll go for 50% and try 125 and see if that works. Picture was really really good no artefacts or banding anywhere not even in very dark scenes so I wouldn't want to introduce it now. Others have used Resolve successfully for DCP's (and it does have easy dcp built in but at a cost!) so I'm fairly sure that isn't the issue and it makes the process a lot quicker plus I'm more sure about the colours being right as that was where the film was graded.
Much appreciated.

Richard

Terrence Meiczinger

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Re: Sound in and out of sync with Sony projectors
« Reply #3 on: May 24, 2017, 09:35:03 AM »
I seem to recall (from a few years ago) the standard JPEG2000 export in Resolve does not use EasyDCP and is not DCI compliant. This may not be the case anymore, but something to consider.

rconnew

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Re: Sound in and out of sync with Sony projectors
« Reply #4 on: May 26, 2017, 02:53:49 AM »
Thanks I have another test opportunity next week so I'll add a test file with J2000 from another source just to be sure.

rconnew

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Re: Sound in and out of sync with Sony projectors
« Reply #5 on: May 26, 2017, 03:05:30 AM »
Seems the non compliant was with the size of the J2000's as they were being output over 250 even though the system said 250. There didn't use to be a means of changing the J2000 size in Resolve away from 250 but there is now in 12.5 and the new 14. Someone told me to set it to 230 hence why I did but without really understanding why that would be a problem. So I'll do a 175 and a 125 version and check the files sizes to make sure they are indeed smaller and go from there. Think this may be the problem thank you.

rconnew

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Re: Sound in and out of sync with Sony projectors
« Reply #6 on: June 20, 2017, 06:20:19 AM »
Ok finally I have I believe found the answer. J2000's from Resolve don't work well on SONY projectors if they work at all, but they do seem to work on other projectors providing the bitrate is 180 or lower - tried one at 180 and it just about worked. SONY projection system doesn't like any blank bits at all in the name it must all be filled in. Again other projectors seem to be ok with the odd blank.

Solution work flow.

Resolve output master file to TIFF XYZ at 16bit uncompressed. An observation I made was with cineform avi files you must select video levels as auto makes the blacks appear crushed which I suspect is due to the gamma level it thinks its at or not as the case may be. Didn't try it with other forms as I'm working with a cineform 3D avi master albeit split into separate L and R for this but its something to look out for if you get that problem.

OPEN DCP - Convert to J2000 - bitrate 180 - 230 seemed to work best - noted the higher the bitrate the richer the colours appeared to me on screen. XYZ Transform and DPX Log unchecked. Make MXF as normal. Works great and more importantly looks great Tried it at 230 and no problems with picture or sound sync at all!

dcinemaforum.com

Re: Sound in and out of sync with Sony projectors
« Reply #6 on: June 20, 2017, 06:20:19 AM »