RTL subtitles

[Alex Asp]

I created an .srt Hebrew Unicode subtitle file (right-to-left) and then used it to create a SMPTE compliant DCP with DCP-O-Matic.

I tested the DCP on a DOLBY DSS200 server, and the subtitles were displayed in a horizontal mirrored order. I suppose it is a problem with Lynux OS, that doesn’t have right-to-left script installed (most cinemas servers are like that) .

In other words what should be on screen as סרטו של אקירה קורוסאווה
was displayed on screen as הוואסורוק הריקא לש וסרט


I hope you can see the difference.

I presume that if DCP-O-MATIC is fed a reversed RTL text, it would appear in a correct order on the screen. The question is, however, can it be done by DCP-O-MATIC.

Attached is the Hebrew .srt file if you need one.

KAKUSHI_TORIDE_NO_SAN_AKUNIN.txt

The other problem seems to be that the text is displayed properly in DoM preview, but the punctuation marks are all in wrong places as displayed.
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[Alex Asp]

I suppose that same problems would plague any user working in RTL language: Arabic, Farsi and Urdu come to mind.

[Carsten]

Alex, I have never seen or shown a DCP with RTL subtitles, but I am willing to test a DCP containing them on our Sony and Barco system.

I can see no reason why DOM shouldn't simply ignore the text flow direction and leave the titles in reverse.
As a matter of fact, I do not even understand how the RTL is actually signaled to the projector? Should it actually recognize the hebrew charset/font and reverse? Please ignore my ignorance I will read it up.


DOM makes subtitle testing very easy - you do not need image or audio for it. Just load an SRT or XML file, set your DCP audio channels to 2, hit 'make DCP', and you are done. DOM creates a 'real' DCP with only black frames and the timed-text subtitles, and two silent audio channels. Because of the all black frames and silent audio, it will compress nicely and you can even send it though email.

Just create a DCP with a few lines, and send it over or attach to this thread.

Bear in mind, there are different ways how subtitles are rendered in the cinema. Some systems render on the projector, some are set to render though the server. Both methods could yield different results, even when using the same equipment. If you want to be absolutely sure about proper rendering, you have to test a DCP on many/most common systems, or, burn in the subtitles. Having a single common system doing it wrong like you experienced, would be reason enough for me to burn in the subtitles.

- Carsten

[Alex Asp]

Hi Carsten and thanks for your reply.

I will post here a short dcp with Hebrew text on screen and 6 different VF versions that have same text as the text onscreen. The text comes in all variations like Unicode corrected or Plain Reversed. So you could actually see and compare the look of the subtitles and see which version works correctly.

The text encoding I used for subtitle files is Unicode UTF-8

Here's the links for the files:
https://www.sendspace.com/pro/dl/cies7s

https://www.sendspace.com/pro/dl/zjz49l

https://www.sendspace.com/pro/dl/pad2ui

https://www.sendspace.com/pro/dl/qclpo9

https://www.sendspace.com/pro/dl/6hl7l5

https://www.sendspace.com/pro/dl/gh2ae9

[Carsten]

Wow, 1GB, at first I thought a simpler test with your own burnt-in titles would be more appropriate. But when I looked at the footage, I understood that RTL is not just the opposite of LTR, but establishes are very different screen design and viewing culture.

Now, let me transport this to our machines and I will see.

But still, for now I am nearly sure that theatrical DCPs in RTL countries will nearly always have the RTL titles/captions burnt in to be on the safe side.

- Carsten

[Alex Asp]

Actually the common practice is that they are not burned in, but rather a specific form of Interop DCP is employed, that uses a png file for each subtitle plus xml script that describes time code and position of each png file which is then overlayed on top of the picture by the projector. Most RTL DCPs that I have seen use this method, as SMPTE standard does not use graphic rendering. Still it would be a great addition to DOM and to the whole community to finally tackle a proper RTL SMPTE DCP.

While my primary concern now is Hebrew subtitled DCP, you should note the differences between Hebrew and Arabic scripts In Hebrew the numerals use regular Arabic numbers (actually the numbers used in most European languages and are rendered in LTR manner as would be in English or French). In Farcsi, Arabic and Urdu the numerals are Farsi and rendered in the same RTL order as the rest of the text. In Other words 500 in Arabic would be written 005 or ٠٠٥ .. Usually Unicode aware word processing applications know how to handle the script, but cinema servers are totally different animals.

[carl]

There is a flag in SMPTE DCPs to get RTL text; we could test that to see if it works in common playback servers.

[Alex Asp]

That would be great

[Carsten]

It is certainly right to equip DOM to do it properly. BUT - you can never be sure what happens on the projection system. Bear in mind, the usual way to render subtitles is not in the server, but in the projector. These projectors receive fewer softwareupdates than servers. Plus, DLP/Cinecanvas subtitling has a spec by TI, but the implementations in the projectors are poor. I wouldn't know which projectors can actually render RTL. Then there is series I and series II projectors, plus Sony.

I talked with Carl about implementing PNG subtitles before, I guess it wouldn't be too complicated. I just discussed PNG with some people with a greater knowledge (actually, I talked to the guy who wrote the original TI DLP Cinecanvas spec). In Interop, PNG is restricted to 2k. 4k PNGs are possible in Interop, but give very different results (from no subtitle, to normal display, to subtitles render to big or too small).

For 2k features, 2k PNGs seem to be safe, but don't mix 2k and 4k.

I think ISDCF should issue RTL test material.

- Carsten

[Alex Asp]

So far all Christy projectors are capable of rendering RTL subtitles. Both series I and Series II. The most problematic projectors seem to be first generation Kinotons, but there are very few installations of those.