VideoCDs (a question that takes this site back to its roots)

[Simon_Haddad]

Anybody here ever get the subtitles from one of the commercial VideoCDs put out by Philips for the Dutch or Swedish markets to work in cdiemu? If so, how?

[dannyboy48888]

Following, knew subs were in the spec but never actually seen a disc with them.

[Simon_Haddad]

Subs are in three specs, three ways.

The first one I learned about was page 9 of Philips Video CD on CD-i Release 4.1 (https://www.icdia.co.uk/docs_sw/vcd_on_cdi_41.pdf) way back [checks archive] in January 2002.

Twenty-three years later I learned about page 11 of Philips Video CD on CD-i Release 3.11 (https://www.icdia.co.uk/docs_sw/vcd_on_cdi_311.pdf). This is the version that Philips used in commercial VideoCDs in Swedish and Dutch.

And I finally found VideoCD Specification 2.0: the White Book standard (https://dn720002.ca.archive.org/0/items/video-cd-specification-version-2.0-white-book/...%20Book%29.pdf) which, it turns out, supports the real CEA-608 closed captions that North American TVs display.

[dannyboy48888]

So would they go on line 21 still or a separate file? With only 240 line to work with curious I am

[Simon_Haddad]

So would they go on line 21 still or a separate file...

Two different ways, believe it or not. Encoded in the "user data" which I thought didn't exist until mpeg-2 and SVCDs and DVDs, or in a caption file in the /EXT folder. I have a python script that’ll compile/decompile *.scc files to CEA-608 Closed Captions for VideoCD (and vice versa) that I'll attach here.

usage: python SCC_to_VCD_608.py [-t TRACK] [-v VERSION] input.scc [output.DAT]

This script takes a SMPTE30- or SMPTE30DF-timecode Scenarist Closed Caption *.scc text file and generates a Closed Caption for VideoCD *.DAT binary file.

By default it generates one for the first video track, for a VideoCD version 2.0 disk, in the same directory as the originating scc file, with the filename "CAPT01.DAT".

The file must be added to the /EXT directory of the VideoCD.

Changing the track number (video track, not overall track) with, for example, -t 2, will set the intended video track number of the caption file internally and change the default output filename to, following our example, "CAPT02.DAT", matching the video "AVSEQ02.DAT".

Changing the target VideoCD version number (you'll might never need this) with, for example, -v 1.1, will change the target version number of the file internally to, following our example, 1.1. I don't have access to the White Book 1.1 standard, so I don't know if captioning in this manner is meant to work on 1.1 or any other versions besides 2.0.

This script builds a binary closed caption file according to the White Book 2.0 standard, page III-25 (https://dn720002.ca.archive.org/0/items/video-cd-specification-version-2.0-white-book/...k).pdf#page=49). Closed Captioning in this particular way does not rely on any specific CD-i app and should work with any device compliant with the specification and hooked up to a Closed-Caption-capable NTSC television via composite or S-Video. This includes North American NTSC CD-i, VCD, DVD and maybe even some older Blu-Ray players.


I’m trying at the moment to use Philips VideoCD 2.0 Toolkit (on a DosBox installation of Windows 3.1) to add the file using the guide at https://www.icdia.co.uk/cdprosupport/vcd/vcd2x/other_files.htm but I'm running into some trouble. Toolkit's backend for disc image generation VCDMASTR.DLL generates /EXT and its contents on the fly, and if I add /EXT to the filesystem a second one is generated in the disc image and only one is presumably recognized by the player. I opened VCDMASTR.DLL in Notepad++ and found the strings "line_21_data_pre" and "line_21_data_pres" three times apiece, so I know there's a capability somewhere, but the documentation seems to be lost to the ages.

It might be easier with VCDImager or one of its derivatives, but I haven't tried yet.

[dannyboy48888]

Mpeg-1: the ghost that never dies. Thanks for the info and scripts

[Simon_Haddad]

So would they go on line 21 still or a separate file?

they would go onto line 21 as the signal is sent to the TV, above the viewing area, and the TV would decode line 21 as usual. They wouldn't take any resolution away from the stored video

[dannyboy48888]

Is live 21 "wide" enough in 352x240? It would be cool if it was but I can see a lower character limit is all. Just makes my inner geek tingle with questions is all.

[Simon_Haddad]

I assume it’s applied after the video is upscaled and then sent to the TV. It doesn’t need to be, though, closed caption bandwidth is only two bytes (two characters max) per frame. According to this site (https://nootropicdesign.com/projectlab/2011/03/20/decoding-closed-captioning/) there's room on the screen for about five more bits. As long as the video is at least (coincidentally) 21 pixels wide there’s room for closed captioning.

Line 21 is usually covered up by the TVs bezel; you’d need to mess with the vertical hold to see it.

[dannyboy48888]

Nice, so the cc line is broken up over multiple frames. Thanks for the info and trip down memory lane. I still mess with vcds and the kvcd matrix for nostalgia reasons. Oddly even though blu-ray players (the Walmart onn model is a exception) won't play them any more my Sony uhd player does as well as every no name DVD player. Just fun to show how far tech has come and how simple it use to be.