Jared Evans Global Microbrand

I got an excellent email that explained more about how one could extract the closed captioning text from a DVD. I have already covered how one could extract the English Subtitles (not the same thing as the closed captioning text) from a DVD.  I didn’t know that there was another deaf software developer out there involved with decoding all this video whatchamacallit.

I had already explained a bit about how one could grab the closed captioning text from DVD here but this person’s email goes into greater details.

This person preferred to remain anonymous:

I stumbled across your blog, I think it was from a reference in the DeafDC blog.  I think we crossed paths at RIT.  I graduated from RIT in ‘94 with a degree in Computer Engineering.  I think I’ve seen you around one of the science/engineering support offices – I was a regular hangout there.

Anyway – I read the section from your blog regarding making subtitles from DVD’s as "open captions" so that it could be ported to portable media players.  If I recall, you only addressed the subpicture method of subtitling on DVD’s, not the line 21 closed captioning method (aka EIA 608).  Since I’ve been looking for a way to burn subtitles onto my videos, your blog worked it all out for me and for that I am grateful!  So, as a thanks, here is a way to get line 21 captions from DVDs to appear as open captions!

Here is a link to a free utility program called mpg2srt (http://www.htpctools.com/mpg2srt/).  I can’t take credit for writing this utility program.  It was written by another deafie by the name of Ian Coggins.  He wrote it because he was frustrated with his DVR software not showing closed captions when playing back the recorded video.  He discovered that the closed captions were embedded the whole time in the MPEG2 video stream, but the DVR software did not display it (not without a hack, anyway).  So, he wrote a program to extract the line 21 closed caption data to an SRT file.  As it so happens, the SRT formatted file is compatible with Subtitle Workshop!

Here is what you have to do to extract captions from a DVD and get them to become open captions:

   1. Extract the files from the DVD using DVD Decryptor.  Use the FILE mode and in the options, turn off splitting the VOB into multiple files.  You want just one VOB to be created as a result (there will also be some IFO and BUP files but you can ignore those).

   2. After the DVD extraction is done, rename the VOB file (or copy it) to a file with an MPG extension.  Guess what!  The VOB was a valid MPEG2 file the whole time.  This format is known as MPEG2 DVD stream.

   3. Run MPG2SRT on the renamed VOB (now MPG) file and wait while it extracts all the captioning data out of it.  It will take a few minutes.  As far as I know, MPG2SRT will work only on MPEG2 DVD streams.  I don’t know if it will handle MPEG2 transport streams or program streams (one of them is used for digital TV so it might be possible to use MPG2SRT to convert closed captions on a captured MPEG2 stream from your digital cable box or OTA HDTV).

   4. Open the video file and the SRT file in Subtitle Workshop.  Adjust/resync the captions (now subtitles) as necessary.  Subtitle workshop will let you resync the captions.  A word of caution, I discovered that for multivolume DVD’s that for 2nd (and maybe 3rd, 4th, etc) that the time code for the captions are off by hours.  For example, volume 2 of a DVD set, I found that the captions were scheduled to appear 2 hours later because it thought it was continuing from the 1st volume.  I had to fix that so it started at time zero.   That’s where Subtitle workshop comes in handy.  Save the subtitles into a substation alpha file and you’re good to go with the VirtualDub and whatever encoding method you prefer (Win Media Encoder, DivX, whatever – this is where your blog entry picks up).

If you already know all this, please accept my thanks for figuring out the sub titling process – I wouldn’t have discovered Subtitle workshop otherwise and worked out how to get line 21 captions working!

On another note, I share the same frustrations you have with the state of closed captioning/subtitling (or lack thereof) of the various video clips found on the net.  It really galls me that episodes that were aired on TV with closed captions are not saved with the captions for inclusion with downloadable clips!  I can’t believe that the sites would throw away all that hard work that went into authoring/transcribing the closed captions in the first place, only to leave it out!   When home broadband networking reaches saturation, the deafies will be the ones holding the short stick for a while.

It’s the same thing with HDTV.  Everyone claims that they have working captions for HDTV.  I have HDTV and it is not without its problems.  My cable company royally screwed up carrying the video streams and corrupted the captioning on several of my channels.  As a consequence, I don’t see captions for all my HDTV channels, and when I try to call the cable company, they want to send a tech to "fix my TV" when you and I know that’s not the problem.  It is really hard to overcome the inertia that many of these corporations have and it will require a critical mass of deaf people to assert and voice their complaints to fix these problems.  Right now, we’re just too few and not worth it to their bottom lines.

Just my 2 cents.  Devalue accordingly…

Thanks!