TiVo to Mac to Apple TV — Part II, Capturing Captions

In TiVo to Mac to Apple TV — Part I, Moving Movies I showed how to make Apple TV videos out of TiVo recordings of old movies shown on the Turner Classic Movies HD channel — or, for that matter, of any TV shows your TiVo has recorded and that you have downloaded to your Mac.

The workflow I gave there works miracles, but one miracle it cannot work is adding subtitles to an Apple TV-compatible video file.

TCM HD shows its movies — the vast majority of them — with closed captioning for the hearing-impaired, of whom I am one. When I, using kmttg, download one of these TCM HD recordings to my Mac, the closed captions come along for the ride. They're embedded in the digital video stream.

Let's say, for example, that I download a recording of the 1956 movie The Searchers from my TiVo Premiere to my Mac. A copy of the recording appears on my Mac in a file called The Searchers.TiVo. (The actual The Searchers ________.TiVo filename as saved by kmttg would contain the date of the original recording in place of the ________, but I'll ignore the inclusion of the date in the filename for purposes of this post.) I can then tell VideoReDo TV Suite version 4 with H.264 (VRD) to trim off the unwanted extra material at the beginning and end, and to save the result in a new Mac file. (To use VRD on a Mac, you also have to employ the likes of Parallels Desktop 6 for Mac to let the Mac run Windows.)

If I used the previous post's workflow, I would save the final result as The Searchers.mp4, a video "container" or "wrapper" file in the MPEG-4 format. That file would house an H.264 video stream along with an AAC audio stream. It could in fact be added to my iTunes movie library and played successfully on my Apple TV. The only problem is, VRD isn't presently capable of turning the closed captions in the original MPEG-2 file into subtitles in the MPEG-4/H.264 output file, the one that would be given an .mp4 filename extension.

That's a shame, because the Apple TV is perfectly capable of rendering subtitles that are contained in .mp4 files. An especially nice feature of the way it does so is that the user can turn subtitle rendering on and off for any particular video file at any moment in time, on the fly, while viewing the video on the TV to which the Apple TV connects.

When subtitles can be turned on and off at the whim of the user, they're called "soft" subtitles. When a video's subtitles can't be turned off and on — they're "burned into" the image, so to speak, and they're always "on," and so the video player (the Apple TV, in this case) simply can't turn them off — they're "hard" subtitles.

That's the difference between "hard" and "soft" subtitles. Now, how can I give my .mp4 files soft subtitles?

Step 1

The first step I do is to tell VRD to create a The Searchers Trimmed.mpg output file containing my trimmed selection of video material. The filename extension is now .mpg instead of .mp4. That means the VRD output file is an MPEG-2 "container" file that houses, basically, the selected swath of the original video ... and this time it's not going to be re-encoded to a different format, i.e., MPEG-4/H.264.

When you start VRD, you'll see this window. Click on the "Open Video" button ...

You see an "Open" dialog. Navigate to the (in this example) The Searchers.Tivo file and open it ...

Now, use VRD's editing tools to select a swath of the input video to save. Then, click on the "Save As" button ...

Clicking on the "Save As" button brings up another dialog. If "Save as type:" is not already set to "MPEG2 Program Stream (*.mpg)" click the V button to get ...

In the drop-down menu, select "MPEG2 Program Stream (*.mpg)". After the drop-down menu disappears, click on "Save" in the "Save As" dialog ...

The VRD window will shrink to become a small window with a progress bar while the "Fast Frame Copy" is happening. When it's done, the small window will replaced with one confirming the completion of the output operation. When you click "OK," the main VRD window reappears. You can close it at this point.

Step 1 goes pretty fast — about half an hour for a two-hour movie — because VRD is doing a "fast frame copy" instead of a major re-encoding of the video.

This way of doing things means the closed captioning embedded in the original video gets passed to the output The Searchers Trimmed.mpg video file absolutely intact.

Step 2

Next, I pass The Searchers Trimmed.mpg as input to CCExtractor, an application I run on my Mac from the command line in Terminal.

Drag the CCExtractor icon from the Desktop and drop it on a new Terminal window ...

Now, drag the (in this example) The Searchers Trimmed.mpg file from Step 1 and drop it on the Terminal window, and press Return ...

CCExtractor will begin extracting the closed captions from the The Searchers Trimmed.mpg file ...

When CCExtractor is done, the Terminal window looks like this. A file called The Searchers.srt will now be in the same folder as The Searchers.mpg is in. You can quit the Terminal application.  

CCExtractor creates, over a period of perhaps ten minutes, a text file called The Searchers.srt that contains the closed captions themselves, along with timing information to show when and for how long each caption should be displayed.

Step 3

Now I use HandBrake — specifically, I use the Mac GUI version — to re-encode The Searchers Trimmed.mpg, the output file I made when I used VRD in Step 1, as The Searchers Trimmed.m4v. The .m4v extension indicates an MPEG-4/H.264 video file that is internally constructed in a format that is specifically compatible with QuickTime, iTunes, and Apple TV. In other words, it's not a "generic" MPEG-4/H.264 video file; if it were, it would have an .mp4 filename extension instead.

Here, I have selected The Searchers Trimmed.mpg as the input file to HandBrake. The output file will be called The Searchers Trimmed.m4v. For purposes of re-encoding the input file, I'm using a group of video and audio parameters called "My Apple TV 2 960x544," which I have previously defined. 

I've clicked on the Subtitles tab, then on the "Add External SRT ..." button, to get the following file selection dialog ...

I choose The Searchers Trimmed.srt ...

... and I see this. Notice that I have not clicked the "Burned In" checkbox, although I've clicked the "Default" checkbox so that these will be the default subtitles to be used during playback. (Actually, they're the only subtitles I've specified, but it's theoretically possible to specify more than one set.) Now I'm ready to begin creating my The Searchers Trimmed.m4v output file, so I click on the "Start" button near the upper left corner, and pretty soon I see ... 

The progress bar at the bottom of the window may crawl along for several hours.

That's how I use HandBrake's GUI interface to tell it that, in re-encoding the original The Searchers Trimmed.mpg file as The Searchers Trimmed.m4v, it should use an external SRT file as a source of subtitles. This external file is, of course, The Searchers Trimmed.srt, as output earlier by CCExtractor. By expressly telling HandBrake not to burn these subtitles in, I in effect order it to produce soft, rather than hard, subtitles in its The Searchers Trimmed.m4v output file.

I also tell HandBrake to use my own specially constructed "My Apple TV 2 960x544" preset, which yields an .m4v output file that has 960x544-pixel video resolution at 29.97 frames per second. That resolution is exactly half of the input's in both the horizontal and vertical directions, while the frame rate of the output is the same as that of the input. I expressly tell HandBrake to do no cropping of the original image, so any black bars in the original will show up unchanged in the copy. (Purists will hate that, but I believe HandBrake operates more quickly this way, since cropping necessitates that it compute non-square, anamorphic pixels from the input's square, non-anamorphic ones.) I'm using HandBrake's RF 20 "constant quality" video quality setting, which I feel gives me perfectly acceptable video quality all through the movie.

Fair warning: This step can take a long time — up to six hours or so for a two-hour movie, depending on how slow your Mac is. Re-encoding a two-hour .mpg file as an .m4v can be a lengthy process, and adding soft subtitles makes it even longer.

Step 4

Finally, after the long wait for Step 3 to finish is over, I can add The Searchers Trimmed.m4v to my iTunes movies library. Before I do so, in its Finder window I'm going to rename it The Searchers (SS).m4v so that I'll remember from here on out that it contains soft subtitles. When I add it to my iTunes movies library, it will have the iTunes-internal name The Searchers (SS).

It is my custom to, at this juncture, type Command-I to bring up iTunes' Get Info window on the newly added movie and add poster art via the Artwork tab. (I find the poster images in Google Images by Googling, for instance, "the searchers" poster.) I add information under other tabs as well — usually, Description, under the Video tab, and Year, under the Info tab.

These informational nuggets I obtain by opening The Searchers.TiVo.txt in TextEdit. The Searchers.TiVo.txt is a file that gets created by kmttg way back in Step 1, by virtue of having that application's Metadata option checked at the time I download The Searchers.TiVo from my TiVo to my Mac. The Searchers.TiVo.txt contains such "metadata" items as title, seriesTitle, description, time, mpaaRating, movieYear, and so forth and so on, for each movie that the TCM HD channel shows.

I also employ a little trick, while I'm editing the movie's Get Info window in iTunes: I set it's Genre to the first letter of its name! In the case of The Searchers (SS), I set Genre to "S." Doing this lets me, when I'm looking at my movies library on my Apple TV, select the Apple TV's View by Genre tab and then see, in effect, an alphabetical index into my movies library!

Here's what it all looks like in the main iTunes window on my Mac (click on the image to enlarge it):

At this point, I am able to play The Searchers (SS) in iTunes on my Mac, which I can tell to show the "English" subtitles during playback ...

... or not, as the mood strikes me.

I can likewise play The Searchers (SS).m4v in QuickTime Player, or in VLC ... or, via iTunes on my Mac, on my Apple TV. In each of those players, optionally turning on the "English" subtitles lets me view text that originally started out as closed captioning in the TCM HD cablecast stream.

And that's it! There are no more steps ...

... however, I should add that it's OK to delete:

• The The Searchers.TiVo file that was downloaded by kmttg
• The The Searchers Trimmed.mpg file that was output by VideoReDo
• The The Searchers Trimmed.srt file that was output by CCExtractor

The only file you absolutely need to keep is The Searchers Trimmed.m4v. (I also tend to keep The Searchers.TiVo.txt, because it has other uses that I won't detail here.)

You may nevertheless choose to keep both The Searchers Trimmed.mpg and The Searchers Trimmed.srt, if (see Apple's New AirPlay Comes to Air Video) you want to be able to use the Air Video iPad/iPhone/iPod Touch app to send Air Video playback of (in this example) The Searchers Trimmed.mpg from the handheld mobile device to a big TV screen in your home, using Apple's new AirPlay/Home Sharing capability. In this Air Video/AirPlay scenario, your Apple TV is again used as an intermediary device.

If you also save the The Searchers Trimmed.srt file, Air Video will optionally (when doing a "Live Conversion") superimpose subtitles from it over top of the video on the touchscreen of the handheld iPad/iPhone/iPod Touch device ... and also over top of the video on the large HDTV screen to which the video + audio playback is being routed via AirPlay.

Still and all, it's not really necessary to keep The Searchers Trimmed.mpg and The Searchers Trimmed.srt as a means of being able to view subtitles during Air Video/AirPlay playback, since The Searchers Trimmed.m4v can reproduce its soft subtitles during Air Video play as well as during the more direct scenario of play via iTunes.