Subtitles and font size limit in 2024?

[Schmidt]

Today a standard font like Arial or Microsoft Sans Serif exceeds the 640kb size.
(not by a big margin, but still over 640)

Reading specs from Deluxe and Netflix, they still specify the font size not to exceed 640kb.
But from a practical standpoint, it also means that an older version of the Arial.ttf font
(as example) needs to be used in order to fully comply.

So my question: Is the Font Size limit of 640kb still applicable? And if yes, is the best way to ensure
compatibility to simply use an older and smaller version of the .ttf font?

[Carsten]

So my question: Is the Font Size limit of 640kb still applicable? And if yes, is the best way to ensure
compatibility to simply use an older and smaller version of the .ttf font?

Yes and Yes.

+ there are other font options than Arial. For instance, DCP-o-matics default font.

[Schmidt]

Thanks!

[IoannisSyrogiannis]

Texas Instruments, the ICP of which is the main culprit for that limitation, had the DLP Cinema Font Compression Application (for Windows).
I quote:
"This application will reduce a TrueType font file by removing the glyphs that are not used by a particular DLP Cinema(tm) Subtitle XML file."

It also "removes large optional tables such as the embedded bitmap tables, the PCL printer tables, and the horizontal and vertical device metrics tables."

Look it up! I just found (again) on TI the forum thread that lead to the archived installation file.

Professional subtitling programs like EZTitles would also offer to "compress" the fonts used for each reel.
(Be careful, though. I have seen missing characters on subtitles, because there was a mix-up between fonts. Or should I write "I haven't seen"?)

[Carsten]

I once talked to Carl about implementing Font Compressor as an optional process in DCP-o-matic.

Wondering wether it would be allowed to have font compressor as an additional download on DCP-o-matic.com


- Carsten

[carl]

Does the font compressor just remove unused glyphs from the font, do we know?

[Schmidt]

I did some more research and it seems like a Font under < 10mb should be fine for SMPTE 429-2 and up.

For IOP it's still 640kb, but for those cases - perhaps using older versions of the common fonts or the default
DOM font Liberation-Sans is the answer.

Edit:
I also found this discussion. Looks like the limit is XML (if it is Closed Caption) below 256kb, Font Size below 10mb, wrapped MXF 115mb.

https://dcpomatic.com/mantis/view.php?id=2505

[Carsten]

I believe there is still a limit in place of 640KByte per reel for font AND XML combined. This may only apply to series 1 projection systems, but they are still around in serious numbers.

[IoannisSyrogiannis]

Does the font compressor just remove unused glyphs from the font, do we know?

Yes. That is exactly what it does.
The quoted text I used was out of the Texas Instruments' description of the program.
I will reiterate that one can find and download it from the internet archives. "Gary S" is providing the link here. One may download the Windows program (zip file) and some literature on the subtitles' subject.