iPod touch video with switchable subtitles

[txporter]

I got an iPod touch for Christmas and my wife got an iPad. Up to this point, I have always burned my subs into my videos since we play back on our Tivo at home (most of the time). Now that we have our new toys, I am curious to test out switchable subtitles rather than burned in.

What is the correct way to do this for iPod video? I tried what I thought was the logical approach. I converted a clip with x264 and then tried to mux the subtitle into the container with mp4box. The subs were switchable in VLC, but not on the iPod. What do I need to do different?

[Baldrick]

It must be a special kind of subs(ttxt). Try srtiphone.

[txporter]

Thanks, Baldrick. I will give it a whirl. Not exactly what I was hoping for though. I like to use CLI tools if possible to use with batch files.

Just looked through the mp4box documentation again. Perhaps I need to use the -ttxt string to convert the srt file for use with ipod? I vaguely remember reading something about that in the past, but I guess that I haven't tried it.

-ttxt Converts input subtitle to GPAC TTXT format
-ttxt TrackID Dumps Text track to GPAC TTXT format

I maybe I just need to use the -ipod string to write the container in whatever magic format that the iPod wants to see. Guess I have more tinkering to do.

[Baldrick]

Probably. srtiphone uses mp4box so it should be possible.

[txporter]

Just to report back, it was just the -ipod flag that I needed when muxing. If you use -add video.srt with mp4box, it automatically converts them to ttext. The "magic" all seems to be with whatever is done with the -ipod flag.

[Baldrick]

Thanks for posting back. It might help others.