Question how to extract Closed Captions (cc) from VCR tape

[jimdagys]

I know how to extract the Closed Captions (cc) from a DVD, but I need to do this for a VCR tape. I know that I will first play the tape into the computer in real time to capture the movie into a 4 GB mpeg2 file. But what do I do next?

[jagabo]

On video tape the CC text is encoded as part of the picture -- those flashing white lines at the top of the frame. I don't know if there's any software to decode it but be sure you don't crop or mask that data.

[Nelson37]

Don't use an image stabilizer, either. Most and I know for certain the Sima Copy Master strip out the CC info.

Don't have a link but McPoodle's web page has all the tools for CC extraction. Raw2SCC is the main one.

Some capture cards apparently do not capture this information, you may need to do a 2-pass capture using Graphedit to get the info.

[Vidd]

My ATI capture card and ATI capture software (pre AMD) has an option to save the closed captions to a text file with timestamps. There is also a hidden binary file called ATI-SBE.cc that contains a raw dump of the closed captions. This works for both TV broadcasts and VHS tapes.


You need to have both a capture card and software that supports closed captions.

[jimdagys]

I looked at that McPoodle link and I can see that there is no 1, 2 or 3 click solution to this problem. May need to use "command line" (never been successful to do this) and 250mb (ouch) software. Could someone please look at this captured mpeg2 video clip link (10mb, 15 seconds) and tell me if it is possible to extract (or just view) the closed caption? If it is possible, then I can try to go from there.
Video clip link:
http://rapidshare.com/files/259523040/cctest.mpg

[jagabo]

There's no CC text in that MPG file. You would see flickering white lines at the top of the frame if there was.

[mh2360]

I'm pretty sure that Subrip can capture hard coded subs from video files using OCR.

[Ai Haibara]

...but we're talking about extracting closed-captioning data from a video, not text burned into the video. The closed captioning would have to be enabled and the text part of the video for Subrip, wouldn't it? (No, I'm curious. I didn't think Subrip could detect closed-captioning if it was present but not enabled... wasn't that line 21 data? I'll have to look it up.)

Ah, yes. From Wikipedia (I know, I know...):

For all types of NTSC programming, captions are "encoded" into Line 21 of the vertical blanking interval – a part of the TV picture that sits just above the visible portion and is usually unseen. For ATSC (digital television) programming, three streams are encoded in the video: two are backward compatible Line 21 captions, and the third is a set of up to 63 additional caption streams encoded in EIA-708 format.[7]

Captioning is transmitted and stored differently in PAL and SECAM countries, where teletext is used rather than Line 21, but the methods of preparation are similar. For home videotapes, a variation of the Line 21 system is used in PAL countries. Teletext captions can't be stored on a standard VHS tape (due to limited bandwidth), although they are available on S-VHS tapes and DVDs.

[mh2360]

What I was suggesting is that if no other way could found to extract the CC data, a temporary capture might be created with the captions displayed. Subrip could extract the captions from that file.