encoding closed captions in an .avi file

[jbaber]

Hello. I'm a video producer using Premiere Pro 7 to edit, then burning to BetaSP, adding closed captioning as I burn (process: firewire from editing system to Panasonic AG-DV2500 dv deck, acting as transcoder. S-video out of dv deck to cc encoder, s-video out of cc encoder to video input on BetaSP. Secondary laptop feeding caption text file to cc encoder).

Now, a TV station that airs my program has asked if I can start providing my content as an .avi(dv), .mov, or .mp4 file rather than on tape. To do this I have to find a way to re-encode the captioned tape, maintaining the line 21 caption data, OR, find a way to route the output of the captioning encoder back to a computer to encode the composite video/caption signal to a digital file. I hope to not have to purchase a separate computer with capture card to encode as I output from my existing editing system. If I do, is there a capture card/software available that maintains line 21 data?

Anyone know of a way (within reason price-wise) to capture the output from the cc encoder onto my laptop, keeping the cc data? Or any other ideas?

I've tried a test where I played the beta tape back through the dv deck and captured an avi on my edit system using MS Movie Maker (I know my version of Premiere Pro doesn't capture cc data), but it ignored the cc data, at least when I played the file back from MS MM to my cc monitor.

Thanks for considering.

[usually_quiet]

Did they say what format to use if you supply the closed captions as a separate file?

I play around with N. American closed caption data (from DVDs and ATSC TV captures) using consumer-level software and equipment. As far as I know, MPEG-2 video is the only digital format that supports them in its standard.

[Edit]I found this link that has a bit of information about closed captioning and Quicktime http://documentation.apple.com/en/finalcutstudio/workflows/index.html#chapter=6%26sect...4%26tasks=true So I guess there is a way to put them in .mov files too... Sorry I can't be of more help.

[jbaber]

There was no discussion of supplying a separate caption file. The station is just beginning the transition process from tape format to digital file. It's my understanding that the local affiliate receives programming in various formats, ingests all content to a server, then delivers the files to a parent facility in Atlanta via T1, that then delivers all on-air content by satellite back to the affiliate. The only content the local station actually airs from its own master control is the live news (which is captioned live by an off-site service).

They have been testing with some church programming, which is delivered as an avi, mov, or mp4 on thumb drives, or on pocket drives. However, it's my understanding the church programming isn't required to be closed captioned, so this hasn't been an issue for them yet. I talked to one of their engineering staff today about it, and he didn't have a ready answer. Apparently, when they asked me to start providing a digital file, and I brought up the issue of captioning, it was the first discussion of this subject they've had.

Anyway, the use of Beta tape isn't going away anytime soon, so this isn't a pressing problem, but I would like to find out if and how it can be done. Thanks for the link, it's an interesting read. After submitting my post, I found a site where you can upload your text file, and they can create a "line-21 .mov file" that you download and lay on your editing timeline. ??? It looked more like a cg overlay (subtitle) rather than true captioning, so I've inquired from them an explanation and possible demo download.

[usually_quiet]

The captions in .mov files created using QuicktimePro or other programs are text-based and intended for web video, or for play-back with software video players, iPods, etc. I'm not sure how the TV station would go from QuickTime captions to the type of closed captioning needed for broadcast, but I guess that is something they will have to figure out.

More fun reading for you...
http://www.webaim.org/techniques/captions/quicktime/

This has descriptions for the various closed captioning standards used for TV and DVD (following the comparison chart for the closed captioning features offered by the various products pixeltools makes.) http://www.pixeltools.com/tech_tip_closed_captioning.html

There is a list of more captioning tools here, although some that look particularly useful for QuickTime are Mac only. http://www.captions.org/softlinks.cfm

[Edit]LOL All of the above is irrelevant to your situation. I found something in the Wikipedia closed captioning article that gave me a somewhat better understanding of what you have been doing and what you are going to be doing in the future. I don't know enough about Premiere Pro to say whether it can do what you want, but it sounds like you have found a good resource to help you figure it out.

[handyguy]

I never saw an AVI with CC's. Is it even possible? Assuming that you could do it, what player would read them & even if you could get a player to read them that doesn't mean a TV would display them. You know that DV & HDMI & Component don't display captions right. Only way to get them to display them is if the source has captions turned on & embeds them. Seems a lot of work.

[usually_quiet]

I never saw an AVI with CC's. Is it even possible? Assuming that you could do it, what player would read them & even if you could get a player to read them that doesn't mean a TV would display them. You know that DV & HDMI & Component don't display captions right. Only way to get them to display them is if the source has captions turned on & embeds them. Seems a lot of work.

If you read the Wikipedia article on closed captioning, apparently it is possible to add closed caption data to .mov and .avi files as VAUX data, even if consumer electronics and software players aren't designed to make use of them in that format.

He is doing this so the TV station can conveniently store programs on their servers prior to broadcast. Consumers like you and me are never going to see the avi or .mov files. After the TV station finishes processing the stored files, we'll receive an MPEG-2 transport stream as usual.

[amiga29]

Well, well .... somebody I can talk to about closed captioning for the local TV producer / video editor.

Many older Sony consumer camcorders, both Digi 8 and Mini DV record closed captions correctly and automatically transfer the caption data to the correct place in the DV tape. (I believe it's known as the VANC area ... or something like that.)

I use a Sony DCR-TRV 17 consumer camcorder which records and plays back closed captions fine, but there are many Sony models that work, as well as some small Sony desktop DV / DVCAM desks. (The Sony DVCAM 1100 model does NOT, but I think the Sony DVCAM 2500 series does). When dealing with DV closed captions you will NOT see any white data lines on line 21 of your analogue picture monitor as the captions are recorded in the VANC area and are not viewable until playback on screen.
NOTE: Most Panasonic DV camcorders and decks don't record closed captions UNLESS you have the high end studio models.

Adam Wilt has much info on his website about this: (go down page a ways)
www.adamwilt.com/DV-FAQ-tech.html#ClosedCaptioning


NOTE ALSO: You can firewire DV tape with embedded closed captions into your edit system using Premiere 6, 7 or PP 1.5, PP2, PP CS3, or PP CS4 and do EDIT CUTS (assemble edits) and RE output DV timeline to DV tape again via firewire and the captions will remain with the video, ... BUT, ... IF you re-render ANY DV on the timeline just kiss your captions GOOD BYE !

ALSO .... re rendering any DV video that has closed captions embedded into the VANC area into any MPG format will destroy the closed captioning data during the conversion as the transfer process does not take the VANC captions with it.

So .... If your TV station requires an MPG stream of your show rather than DV, then, you will need to look into capturing your show and the associated closed captions using a different method than starting with DV tape. POSSIBLY you could give your TV station a DVD with captions made by Adobe DVD Encore built into Premiere of your show and they could deal with the conversion ... DVD's don't have embedded captions - it's just another data stream on the disc.

You could use a consumer DV camcorder to record your closed captioned show, then firewire said tape to your DVC Pro deck and the captions will remain as long as it's a pure firewire transfer ... or just give your TV station the Mini DV tape for playback which is what I've done.

This info is mostly from my own personal experiments with trying to deal with closed captioning and local/regional TV programming myself.

Your mileage may vary ... always test your final output product.

Good luck.

[amiga29]

... then there is also the newer Black Magic Decklink capture cards that can capture into MPG format preserving the line 21 embedded closed captions in the stream as long as your doing SD and are using 720x486 resolution.

NOTE: The DV tape format is 720x480 resolution and cuts off line 21 used in captioning and thus the problem with using DV for future conversion later on.

Maybe just recapturing your Beta tape using a Decklink card into MPG format at 720x486 will solve your problem.

[jbaber]

amiga29...Thanks so much for the great info. I'll hit the adamwilt link early next week. Since my original post, the station hasn't brought up the matter anymore, I guess since they themselves can't provide a solution. As always, I continue to submit a BetaSP tape of the show with captioning on line 21. Of the 4 broadcast stations around the state which air my program, only the local (to me) station has inquired about receiving a digital version of the show.

I also work at another local broadcast station on weekends, and all the programs airing there are ingested from tape or DVD to mpeg2 files, which then air from a server (Leightronix Nexxus). The encoding and scheduling software provided by Leightronix (called WinGLX), when encoding from a captioned Beta tape, creates an mpeg2 file with captioning for airing. I may do a trial encoding of my show using that software, then see if the other station can use it on air.

[amiga29]

The way to work with archived files that include captions (as I see it) is to edit your program in 720x486 resolution and use a capture card at that resolution for all outputs to tape and for monitoring playback. That being said, having a Decklink card and editing & archiving shows in digital form using a 720x486 Adobe edit preset will preserve line 21 closed captions. The DV spec cuts off 6 lines of analogue full screen video and thus cuts off analogue line 21 captions as they would normally appear in the vertical interval of video signal, and so, they've developed a work around for some DV decks to capture CC by moving it to another area of the video data signal altogether, but using a DV editing preset doesn't work for an editing environment if you want to have closed captions too.
NOTE: some DV camcorders will capture CC embedded video and will show you the white hash marks at top of screen that make up the CC information, BUT, do not be fooled into thinking that that is where the DV captions are (as I was for a long time) .... what was actually happening was the video window at time of Off-Air test capture was actually being shrunk a little and I could see the white hash marks at top of screen in my Adobe program, but what was actually happening was that my Sony Camcorder was actually encoding the CC by moving it into the hidden area of the DV data stream that stores the CC info and, that is what was really playing out the CC to my monitor.

What I'm gonna be trying soon is to get a Decklink card and just capture a 720x486 black signal passing through my EEG EN470 closed caption encoder using my consumer camcorder as the black video source. Then, I'll put the CC embedded black video on my timeline above my rendered DV program master track (I'll be using a 720x486 edit preset timeline) and crop the program master several lines to allow the CC embedded black to show through and then re-render the program as 720x486 master file ... and then output that to tape using the Decklink card.

I've spent several years trying to find a cheap solution and I believe this will work for me, but, as always .... your mileage may vary.

Good luck.