DCP verification player

[Cantar4]

OK, I will. Do you know the name of the subtitle format used by dcp-o-matic ?

a request if I may, please send me the full commandl line you wrote to get this insert.

[Anders M Olsson]

I don't know if there's an official name for the subtitle format, but it's usually referred to as "SMPTE 2010". If anyone has a better answer, do tell.

As for the full command line, it's exactly the same as the one you used. I only substituted some of the file names for my own.
ffmpeg -i j2c_162c742a-65fc-47f2-a935-91f6d9670fb6.mxf -i pcm_219493bd-fb6f-493f-ae1b-8178f435ee63.mxf -i sarah.srt -c:v libx264 -pix_fmt yuv420p -preset slow -crf 21 -ac 2 -c:s mov_text Sarah5fps.mp4

[Cantar4]

thank you Anders, here is the post sent to the FFmpeg forum: http://ffmpeg.gusari.org/viewtopic.php?f=11&t=3112.

[Cantar4]

Among 4000 films the Grenoble Open Air festival selects ninety short-form films per year.
They should be delivered as 'conform' to DCP rules but in practice, because of improper subtitles
or sync+level+dispatch audio problems, 20% of them must be corrected and re-encoded.
Dcp-o-matic is heavily used for these corrections, and the Sony 4K SRX-R320 projector of the Cinémathèque
is used for the realtime verifications.(kind of an overkill isn't?)
To avoid this I asked VLC (HandBrake wiil follow) if they can add a faster than realtime "DCP light playback"
option, by using two simple methods (A) lower temporal sampling, and (B) lower resolution,
to eliminate the looong j2k conversion which shokes slow-CPU laptops :

(A) convert only one frame every three and repeat it 3 times on the display side;
This makes for an 8 samples per sec film which projected at 24fps shows realtime movements
smooth enough** to allow the verification of audio/subtitle sync.

(B) do not convert the upper tiles of the jpg2000 images, only use the low level tiles, e.g. 0.5k,
to produce SD images with more than enough resolution for the 15" screens we use for DCP verification
(focus-puller swiftness and precision is not our job here...)

Would this 'light playback' be acceptable for those of you in charge of cinema festivals DCP control?

**In 1969 at Eclair Corp of America we made an experiment with non warned cinemagoers in LA.
We projected at 24fps three similar sequences of a film about Tango dance respectively shot
at 24, 12 and 8sps. Nobody could see any artifacts on the 12sps shots, only a few people felt something
weird on the 8sps shots. We had to show them the Oude-Delft modified 16mm projector
before a second passage to make them more scrutinizing... and amazed by the plasticity of their brain

[Carsten]

Lower resolution is more acceptable than lower frame rate.

Doremi (now Dolby) Cineplayer offers this option.

However, as a festival, I would invest into NeoDCP Player.

I would prefer Handbrake to have DCP conversion capability instead of a mediocre playback option.


- Carsten

[Cantar4]

Lower resolution is more acceptable than lower frame rate.

On a 15" screen, the j2k decoding "lowres-1" (1kpixel/line) is more than enough,
2kpixel resolution is a waste. On the temporal resolution side I can show you 8sps and 12sps
tests proving that 24sps (samples per sec.) are not necessary for a 24fps realtime verification
of audio and subtitles.

Doremi (now Dolby) Cineplayer offers this option.
However, as a festival, I would invest into NeoDCP Player.

Was Cineplayer working on MacBooks? ...anyway Doremi being ingested, it is no longer available.
Consider the cost in license fees to install three desks with these '"Public screening
allowed" Kakadu based softwares only used three to five weeks a year.
Small festivals and cinemathèques don't have the budget of the FID and Berlinade.

I would prefer Handbrake to have DCP conversion capability instead of a mediocre playback option.

I am not talking about mediocre performances, I am talking about fitted to the purpose performances.
VLC (Yves Kempf) was promising you to work on a 'normal machine' DCP player in July 2015...
one year later he said you can now build it yourself (no kidding !).
The cursor is running realtime but images are all black... be patient.
Under Andres Olsson advice I tried the latest VLC v3.O to get subtitles out of our home made mp4s-from-DCPs...
their nightlybuild does not even approach Quicktime's color rendering, and the subtitles must be re-activated
by hand after each play start ! be very patient.

As for Handbrake I don't know why they do not use the FFmpeg's ffmpeg xyz-to-rgb color space converter
that Libav can't accomplish, the fact is they still are unable (in 2016 !)
to decode a single jpeg2000 image... be very very patient !

[Carsten]

The problem with skipping frames during playback is that broken frames/frame sequences may not be seen. I have seen this happening often when people used image sequences or weird codecs. On the contrary, a broken J2K that does not show in certain resolution levels is highly unlikely.

Yes, Cineplayer is working on Macs, nice performance even on very old machines, as you can scale down the resolution levels and enable/disable xyz-rgb. It also has a multichannel VU meter. I don't like what Dolby is doing now, but the product is too expensive for this application anyway.

The NeoDCP people are quite flexible with their pricing. Just ask them. I mean, powerful machines for playback cost money, too...

VLC actually does a proper xyz->RGB if you use the snapshot feature. I do use VLC for some DCP QC when a single frame is all I need. The conversion is decent. Other than that, importing a DCP into DOM usually gives faster playback, though without sound so far. May be at some point Aaron Boxer will finally get a kick an add/contribute more of his optimized code for faster playback.

- Carsten

[Cantar4]

[Carsten"] broken frames/frame sequences may not be seen. \..\ happening
often when people used image sequences or weird codecs

I would like to see how such an event is seen on the [2x(1/2)] process; would you send me
the j2c_video.mxf file of +/- two sec each side of a break ? jp à aatium point com

Cineplayer is working on Macs, nice performance even on very old machines,

pity the DCP hog killed it. no more versions somewhere on the net ?

VLC actually does a proper xyz->RGB if you use the snapshot feature.

ONE pict !!!... Do they have broken legs?, everybody and his dog can do this now.
With FFmpeg libraries and Oliver Trenouth instructions
https://olitee.com/2014/02/ffmpeg-conve ... quicktime/ , you can even convert
DCPs (wyz) to mp4s (rgb/yuv). Very useful for fast forward/reverse inspections

contribute more of his optimized code for faster playback.

Tell me, when do we launch a subscription like the one which gave us the MacOS version of DCP-o-matic?

[Carsten]

I have both Mac and Win versions of Cineplayer Demo stored away.

The problem is not to have free or low cost playback option, because they exist. The issue is to have the right feature pack for festival signal QC, and currently I only see this with NeoDCP.

- Carsten

[Cantar4]

The issue is to have the right feature pack for festival signal QC, currently I only see this with NeoDCP.

Following your advice I bought the NeoDCP basic player for 77€ per year.
It is limited to non-encrypted DCPs, private screening, and Windows only, but it performs
QC operations and works on my low power MacBook-Air laptop. I am very happy.
Forgetting the ackward Windows10 old-fashioned GUI, the real problem is that 'Bootcamp'
needs to reboot the Mac to activate it ; I should install ‘Parallel’ to keep permanent Windows accessibility.
Is there somebody on this forum to tell me if NeoDCP still performs realtime playback
once Windows is virtualised?

PS: The Neodcp creator says his application is so bound to Windows low level functionality that using Qt to support macOS would equal the development of a new Player.