Sometimes audio files are too short and does not match the length of the video files
Instead of making another reel with a silent soundtrack you can add some silence to the audio files using Sox.
To make a 48 khz 24 bit 10 second silent wav file with sox: sox -n -r 48000 -b24 silent10sec.wav trim 0.0 10.0
To add this to the end of another 48 khz 24 bit sound file with sox: sox film.LFE.wav silent10sec.wav film2.LFE.wav
Should the DCI/SMPTE 431 digital cinema standards be updated for RGB LASER projectors?
Higher contrast ratio
The SMPTE RP 431-2:2011 digital cinema standard document describes the reference projector viewing environments used in DCI digital cinemas.
–SMPTE 431 Review room 14 fL, 100:1 Intra frame contrast, 1500:1 Sequential contrast
–SMPTE 431 Cinema Theatre 14 fL, 100:1 Intra frame contrast, 1200:1 Sequential contrast
Most cinemas will see an improvement of contrast ratio and light levels with an upgrade to RGB Laser projectors.
This improvement will be noticeable on the DCPs used today.
Rec 2020 color space
New digital cinema projectors uses red, green and blue lasers as their light sources. They can (almost) reach the REC 2020 color space.
The RGB laser projectors also have better contrast ratio and can reach higher light levels without ruining the black level.
The DCI-P3 color space and 1200:1 contrast ratio in SMPTE RP 431-2 are based on what you can achieve with a Xenon lamp projector.
REC2020 covers 99.9 percent of pointer’s gamut, while DCI-P3 cover 91.4 percent. Source
This means that REC 2020 can do all the primary saturated colors, while DCI-P3 is more limited. DCI-P3 lacks Cyan.
Cinemas are also limited to colors that can be achieved with 14 fL.
It would be difficult to use an automatic algorithm to map some of these colors to DCI-P3 without changing the artistic expression of the film.
The Alexa SXT camera that is used on many films is compatible with REC2020
Barco White paper “What are ‘better pixels’?”
This Barco white paper from 1. february 2016 looks at REC.2020 and higher contrast ratio in cinemas with RGB laser projectors. They also recommend keeping the optical light path clean.
In practice, it turns out that some effort in reducing the auditorium reflectivity and lens glare (by e.g. keeping the lens and port hole clean of dust) can yield the same or better results than moving to HDR projection.
Dolby Vision and Imax Digital
You can watch RGB laser projection with (almost) REC 2020 color space and higher contrast ratios in Dolby Vision and IMAX Laser cinemas.
These cinemas can reach higher light levels and use bright colors that are not possible in ordinary cinemas.
Read a review of both here.
A LASER IMAX system demonstration used an intra frame contrast checkerboard test image to show the intra frame contrast of their dual LASER projectors. They said in the demonstration that they changed the furnishing and changed the screen to get better contrast ratio.
A combination of peak brightness and black level either:
More than 1000 nits peak brightness and less than 0.05 nits black level OR
More than 540 nits peak brightness and less than 0.0005 nits black level
Apple is moving prosumer displays to the DCI-P3 color space. The first product is the Ipad Pro. Source wikipedia.
Dual inventory of DCPs?
I think you can have two kinds of DCPs until all cinemas get RGB Laser or similar projectors:
RP 431-2:2011 DCPs for Xenon/UHP and Phosphor Laser projectors
RP 431-2:RGBLASER DCPs for RGB Laser projectors.
Dual inventory of DCPs is not a big problem.
DCP delivery services that uses fast internet to distribute DCPs to cinemas send the 3D DCP to the 3D cinemas and the 2D DCP to the 2D cinemas. In the future if a venue have a RGB laser projector, it would be easy to send them the RGB laser DCP instead of the xenon DCP.
RP 431-2:RGB LASER REC 2020 could possibly use:
-REC 2020 color space,
-and higher contrast ratio
inside the 12 bit 2.6 gamma X`Y`Z` JPEG 2000 250 mbit encoding used in today’s DCPs.
Or use the SMPTE ST2084 EOTF standard to be able to use higher light levels.
Upgrading the light path
Changing screen and furnishing to get good intra frame contrast is essential to good projection.
If the intra frame contrast is bad you could try to:
– Clean the port glass and optics.
– Avoid spill light from projection booth.
– Use matte black seats and furnishing.
– Install an iris in the projector.
– Upgrade to a laser projector.
A laser projector will be better at reaching today´s 3D light levels with just one projector and better at reaching today’s standard contrast ratio. 6P Laser projectors can use 3D with matte white screens and one projector.
A new RGB Laser standard could keep today’s light levels and contrast ratios and just add REC2020 color space. Or the standard could go beyond today’s values. RGB Laser projectors could manage higher values. But in a dark viewing environment higher luminance values can seem very bright.
The higher contrast ratio you could get with a laser projector could be ruined by reflective furnishing in the auditorium and other factors like old silver screens.
There should be a certification that cinemas could get to show that they are RP 431-2:2011(Xenon) or (future) RP 431-2:RGBLASER certified and have the correct intra frame contrast ratio and light levels.
Or they could get a certification that say they reach the correct light levels in 2D and 3D. (The cinemas should be able to reach these levels also when the lamp/lasers gets older.)
This way the public would know that kind of cinemas they can choose between.
Here are some tips on downloading and uploading DCPs and other large files like prores quicktime files:
-I recommended using a fast wired internet connection. (20/20-50/50 mbit/s). (Use a good network cable/router)
-I recommend using a download manager like Free download manager (Windows/mac) that support resume and multi-part downloading. Free Download will allocate disk space in the start of the transfer and then the download speed will increase.
-I recommend using Cyberduck if you want to download from filemail via FTP.
-I recommended using a fast wired internet connection. (20/20-50/50 mbit/s). (Use a good network cable/router)
-I recommend a reboot of the computer or at least a restart of chrome before uploading large files (100 GB) in a web uploader.
I have used filemail to receive files on many film festivals I have worked on.
-On filemail.com you can send 30 GB files for free. With a Filemail Pro or Business account you can send and receive 100-200 GB files.
-I have used the filemail html5 uploader on many 100 gb files. You can also use the html5 uploader to send folders. The Desktop filemail app also works well on 100 gb files and can be used to auto download all incoming files.
-With a Filemail business account you will have access to the files for longer and people can use a branded upload web page. You can also enable the md5 hash value. Filemail now has an option for permanent storage.
Filemail md5 hash check
Filemail shows the md5 checksum on the download page if you enable it in the settings for the business download page.
This way you can check if the uploaded file is correct if the client sends you the original md5 checksum. You can ask for the md5 checksum as info on the upload page. This way you and the client can verify that the file is correct.
You also use the command md5 "file" in a terminal on a Mac to generate a md5 file hash value. The Terminal app is in Applications – Utilities. You can type md5 and push space, then drag the file from a finder window and push enter.
You can use the command certutil -hashfile "file" md5 on a Windows 7, 8, 10 computer in a command prompt (CMD)
You can use md5sum "file" in a terminal on a linux computer.
-If the sender sends a 7z archive, the receiver will know when unpacking if the file fails the 7z checksum test.
-When sending prores quicktime files it is important that the sender include a md5 checksum to enable verification of the file.
-DCPs have the checksums in the XML files that can be verified with easydcp player or using this command openssl sha1 -binary "FILE_NAME" | openssl base64
-If you want to send a uncompressed quicktime file, TIFF or DPX image sequences or wav files I suggest using 7z with normal compression. A uncompressed quicktime file will be reduced to half the size after 7z compression.
-I recommend Keka on mac or 7zip on Windows.
-7z archives can be protected with encryption and a password and have a built in hash check.
-In Keka, choose 7z and store for no compression or normal for normal compression, then drag the folder to the Keka window.
-You can also split the archive in parts and upload the file in parts. Example 20 GB. If one of the parts is corrupted you only need to upload that part again.
Use a PAR2 recovery file as backup
-You can use a PAR 2 file as an additional backup solution if there is no time to upload/download the corrupt files again . I have tried both MultiPar and MacPAR Deluxe to generate PAR 2 1 percent redundancy files. PAR 2 files with 1 percent redundancy are 1 percent of the size of original file. If the downloaded file is 0,5 percent corrupted, you can use the 1 percent PAR 2 recovery file to recover the file instead of downloading again. I have tried this and it works.
Amazon S3 can be used to deliver and receive big files on the internet.
-You can use the s3 web uploader or use Cyberduck and similar programs to upload to S3. It uses integrity checks when uploading so you will know the uploaded file is working.
-After uploading you can make the link accessible (public) and give the clients the S3 download link.
-S3 storage is very reliable and scalable. You pay for each download.
-If you want a client to upload a file to a s3 upload bucket you can make an upload user in https://console.aws.amazon.com/iam/home#users with a policy that enables the user to upload to that upload bucket.
– then give the client the access key and secret key and directory for the upload user. (with this policy the user will need to add the directory to be able to upload.)
-You can give out the access key and secret key and directory for clients who will be downloading via Cyberduck
I have used Aspera Cloud on many DCP transfers. It is used by many film festivals and post-production services. It is very fast.
I have downloaded many DCP with free download manager from Google Drive. It is fast.
I have downloaded many DCP with free download manager from Dropbox. I had no problems.
DCP and quicktime specific advice
-When downloading a DCP folder in Filezilla from a FTP server it is important to change Transfer – transfer type – binary. It should not be ascii or auto, this way the XML files will pass the checksum test.
-Ask people who submit DCPs to ether upload the folder or the archive format 7z instead of zip. This way you can avoid the (large) Mac OS archive utility zip files that can only be opened by the Mac OS archive zip utility. Both Keka and 7-Zip can make 7z archives.
-I recommend checking DCPs in Easydcp player. The trial version will let you know if the DCP fails some checks. You can also run a file hash check.
You should also make a DCP quality checklist that may include:
-Is the DCP named correctly?
Is it in the correct scope or flat format? The DCP should have a correct digital naming convention name. Example: The DCP is called Dcpname_SHR_S but is actually Dcpname_SHR_F because the subtitles are burned in too low and will be cropped at a scope preset in your cinema.
-Is the DCP in the correct language/subtitle language?
-Will the DCP play at your venue. Example: You may have a server with old firmware that can play 25 SMPTE DCPs with burned in subtitles, but not SMPTE 2010 subtitles. (all film festivals should have updated firmware/software).
-If you have downloaded a DCP folder archive like DCP.7z on a mac and want to ingest in on a digital cinema media block/server/player you can extract it to a DX115 hard drive or similar.
-If you get an error message extracting a zip file in Keka that says error code 2 using p7zip, you probably need to extract the zip file with mac os archive utility.