Closed Captioning

[Solace]

Hello all, I had a quick question.

Is there any reason that closed captioning on a videotape master (any format, that is, BetaSP, 1", mini-DV, VHS) would NOT transfer over when a video is captured and encoded for DVD authoring? I was told by a customer of mine who chose another DVD authoring company, that they could not pull the closed captioning over when they captured and encoded her video and manipulated it with their authoring software (DVD Studio Pro.) She was forced to have him re-type in all of the text manually for the closed captions.

Any help is much appreciated. Thanks!

[Cornucopia]

Good question!

For NTSC Closed Captioning, the code is embedded in the video in the vertical interval (for analog systems) or in a user data stream (for digital systems). Getting it from there to DVD's requires:

1. Digitizing with a card that can not only capture all the lines needed (esp. Lines 21 & 22--many don't), but that create a side channel of data from an "OCR-like" conversion of those lines. This will preserve the CC data in the QT/AVI file and give you an auxilliary data/text file that is needed for authoring systems.

2. Editors & Encoders that don't crop/discard the top lines from a picture, and don't re-encode to a compressed intermediary file--until it's time to compress to MPEG for authoring.

3. Authoring systems that explicitly support CC (many don't). Need an asset manager that associates the Line21/22 text/data file with it's corresponding MPEG video file.

..........

If one's capture card DOESN'T save the line 21 data separately, you can go the circuitous route and "extract" it from the digitized video file with McPoodle's SCC Tools (do a google search). Tread carefully.


Alternately, you could use a DVD Recorder that correctly encodes the CC's directly (my Pioneer PRV-1900 does! 8) ) and then rip the MPEG files off of that and extract the CC data, etc.

-or-

You could send it to a CC house and have them output a MPEG and text/data file for you.

HTH,

Scott

[Solace]

Wow, great anwser. Thank you very much!

[handyguy]

Some machines won't recognize the captioning so they won't send it along. It's just a matter of using equipment that does.

[Wile_E]

I have a Canopus ADVC. Does this capture the VBI Line 21?

[Cornucopia]

Wile_E--
Try this:

1. Confirm that you have a master tape with CC coded on it. BetaSP masters, or labeled and non-Macrovisioned VHS tapes would be a good start. Play that out of the VCR and directly to your TV monitor. Enable the CC display on the monitor. Do you see the captions? Yes, then...

2. Connect the VCR to the Canopus ADVC box, and that to your computer. Capture a couple of minutes worth (where you know there should be some CC's).

3. Connect the analog Output of the Canopus to the monitor this time. "Play back" or output the DV file to the monitor.

Does it show CC's NOW?

If yes, then it obviously captures AND saves them.

If no, then it could be that it captures them, be may not pass through on the way out...

But that's a start.

Scott

[mikiem]

Just general info FWIW...

" I was told by a customer...that they could not pull the closed captioning over when they captured and encoded her video and manipulated it with their authoring software...She was forced to have him re-type in all of the text manually for the closed captions. "

Maybe correct *strictly speaking IF* they cut up the video during editing, as CC's more like a sub track then say audio in an avi. More likely though, considering text was re-typed, bunch of #@$%!!! morons [as a member of the hearing challenged community, think I can get away with that ]

"Digitizing with a card that can not only capture all the lines needed (esp. Lines 21 & 22--many don't), but that create a side channel of data from an "OCR-like" conversion of those lines. This will preserve the CC data in the QT/AVI file and give you an auxilliary data/text file that is needed for authoring systems."

My understanding is that the CC data is a signal formated for the CC display portion every (US at least) TV has to have, carried in the vbi portion of the video signal. Regardless how it's carried in the stream to the destination, has to be in that signal to the TV (or VCR) by law. Some PC-based TV hardware also decodes and displays the CC or line 21 data -- line 22 is usually alternate language. No OCR involved, though realize that might just have been a comparison. For capture the CC stream can be written to binary file, as decoded text, or saved along with the video -- mpg2 is common because the user data area can easily contain the added CC. From there it can be stripped using 1 of a few tools, or at the very least using graphedit. There's not a lot of tools available for this because CC are normally copyrighted, and frankly there's less interest in CC then in other things video.

"Editors & Encoders that don't crop/discard the top lines from a picture, and don't re-encode to a compressed intermediary file--until it's time to compress to MPEG for authoring"

The CC data is maintained in analog formats like tape if the vbi data is maintained. When it comes to digital, it's a separate data stream (like audio & vid) that can be embedded, usually in a user defined area of the file, assuming there's a place in the file to contain it, & a decoder to pull it back out. With avi files it's kind of like multiple audio tracks &/or some non-standard audio formats, where you can easily stick it in there, but getting it out is more of a challenge. As there's no real standard about how/where to store the CC data, editing is risky and re-encoding normally drops it -- DVD mpg2 is almost an exception, but my understanding is by common practice rather then standard, and encoders we're likely to see/use drop CC as well. DVB I *think* makes a lot of progress on this, but still has a few options.

Muxing a CC stream into mpg2 is costly -- haven't seen any good software solutions really, though one of the SCC Tools will do it slowly. OTOH with DVDs popular, adding CC as subs is an easy, somewhat common option. And anywhere else subs are used you have an alternative.

Captureing CC can normally be done with Graphedit if your hardware will display CC. SCC Tools makes the conversion to text sub files quick and easy, so the big hassle is if you have to record CC live -- it takes 2 hours for 2 hours of video -- but at least it's a way to keep your vcr from getting rusty. If the video file contains the CC stream, besides SCC Tools I think there are a couple of other specialized options to strip out the CC data -- I think there was work on a tool to strip CC out of WinMediaCntr recordings for example. And again, always have Graphedit.

"Some machines won't recognize the captioning so they won't send it along. It's just a matter of using equipment that does."

Very true, but more often, IMO anyway, many folks don't have any interest so at best they're unfamiliar with tools and methods.

As a starting point, you should be able to work with CC if you can display captions on your PC using a TV &/or capture app (with whatever input: co-ax, s-vid etc. assuming it contains CC). To find out if it's included in a captured file, 1st place to look is with any capture hardware bundled software players, ie. ATI's file player is required for their captures. And as I've said, there's always graphedit.

In graphedit you need a way to open the file 1st: ATI vcr files use the TimeShiftReader -- their newer 9.13 mpg2 uses file open. Then a splitter, followed by a video decoder -- ATI Timeshiftsplitter or the one in Windows for mpg2, & ATI mpg2 decoder in both cases (as it's the only thing that knows where exactly to look). To strip the CC data would use the Dump filter, but to find if it's there, connect the video pin to the Video 9 Mixing Renderer, connect the cc pin to the line21 decoder 2, & that to the 2nd pin on the renderer. Play and hopefully watch your captions.

Vsrip works with some mpg2 files containing CC, but, half the time you're better off running the raw, binary file thru SCC Tools. However you get your CC data, spec calls for all caps, though you'll see some lower case stuff (usually off mpg2 based material as on dig cable). Subtitle Workshop will convert case with better then nothing results.

For more info, including how to make money typing CC , just google -- there's a lot of info, but not all that much so you'll get buried before you find anything.

[SLK001]

Most capture cards do NOT capture any of the VBI lines (it is NOT needed for the video). However, a proper GRAPHEDIT graph can capture any closed captions while the video is being captured.

[handyguy]

ATI cards capture captions to a few formats, DOC, Txt, html.

Being Deaf, I have an old telecaption II box, it has a caption out. So, you take closed captioned video, run it through this box, it can output to permanent OPEN captions.

[ktnwin]

I have not tried to capture VHS tapes (with CC) to DVD using my Pan-E85H recorder. Have anyone with a Panasonic DVD recorder tried this ?
However, when I capture TV shows (or movies) with CC, then the resulting DVD-R contains CC in it and that's a very nice feature to have.

[handyguy]

The panasonics capture CCs.....