Hello, I have a problem with my Ipod Nano 7th Gen too. With ffpmeg I am able to write a subtitle file .srt into a mp4 file. Now I can switch to subtitle in my Ipod. But the Ipod shows only a few of these subtitles, and the subtitles that are shown are in thw wrong time in the first 40 seconds of the movie... I have no idea how to fix it and I believe that it is very hard too fix due to its age 😀. If you have any questions how I tried it or tips, please write back ( and sorry for my english)
Tl:dr, You are using the wrong text encoding, use the .srt Macintosh encoding to fix your issue like in the images below. Also use Itunes 9 to sync videos for alternative audio and subtitles, make sure your text encoding is set to Utf-8 in Macintosh in the srt file or it won’t play back properly. (And stay away from handbrake)
(Please make sure to read this entire reply before anyone downloads software or goes looking for programs, don’t use Batch 1.1 use Subtitle edit it has a batch feature that is better than Batch 1.1)
I know what your issue is. The source .srt file needs to be Utf-8, and you also NEED to make sure its in the "Macintosh" format. Look at the screenshot, use Subtitle edit (Free), or Batch 1.1 (Free if your a pirate), and set the "Encoding" to "Macintosh" If your using Japanese subs, you would use the "Japanese - Macintosh" setting in Subtitle edit or Batch 1.1. But as your are using English, just use the "10000: Western European (Mac)" Setting.
Using the wrong text encoding can cause the same errors you are referring too (I used to have them awhile ago). I am attaching a sample .srt file for you to test and see if it works with your ffmpeg process. (Something to take note, you HAVE to use Itunes 9, I think 10 does not work but I didn't try it. I cant remember what versions in Itunes 9 are the working one, I think I used the latest version of itunes 9, so good luck) in order for any most ipods (Not sure about the 7th gen nano) to display the subtitles or have the alternate audio to work. As itunes 9 sets a special quick time atom (that no one on Earth knows about, I had to consult the dead to figure this out, and surpass the illithid grand design, im not kidding. This took way to long to figure out, like 16 years of my life.) on the video file for the ipod classic/nano to read the audio file. I found out how to put the subtitles and alternate, all you have to do is use itunes 9, you can use .mp4s from ffmpeg, subler (mac only, subler is not that good, just use ffmpeg its free the cli interface its not hard to use), or apples compressor and final cut pro. (or anywhere as long as its not handbrake, pro tip avoid handbrake like the plague. It does not let you pass-through video and forces you to re-encode everything wasting time and cpu life, just use subler or ffmpeg (works on Windows 7) if you need to mux mp4/mkv videos.). If you are for some reason wondering out how to use the "608" "line 21" captions, all you need to do is use .scc files. Subtitle edit and Batch 1.1 both support .scc files, also subtitle edit supports batch conversions of subtitle files, making batch 1.1 obsolete. (I only just remembered this feature while writing this so plz dont hate me if you went and tried to find it without reading all the way).
Dont ever use these ".scc Captions" they are not the same thing as the .srt subtitles. After doing some testing and find out why the ipod has 608 support, I got so mad. (The reason why they do its because Steve jobs wanted it on there so bad, even though the 608 standard was garage (and still is), as it was originality made for crt tvs hence the name "Line 21" but in the 90s someone made it its own stream in a .mov file not encoded into the actual video stream. Just use .srt instead) The internal renderer for 608 captions does not work accurately on ipod classics and ipod nanos, as there is some multi second delay after from when they are supposed to go off. They also look way too big on the screen compared to the .srt subtitles. Id post a picture but I cant get itunes 9 to freaking put the quick time atom back correctly anymore when syncing with my nano 5th gen or classic 7th gen, not clue why. Bonus: The 608 captions support color text (the .srt subtitles do not. .ssa/.ass support color and fonts, the ipod classic.nano does not supports .ssa/.ass), white cyan red and yellow (I think thats all of them) there are more colors in the 608 stranded but they are not implemented in the ipods for some reason, I did test this myself this time last year. (Apple needs to fix this in a software update to the ipod classic 5th,6th,7th gen classics, and the 4th~7th nanos). The captions also support something called "forced" lines. Im not sure if srt supports this on the ipod, but I know for a fact the captions do. A cool trick to waste all of your teenage life, is to have the signs and songs into the captions stream, while having the full translation in the .srt portion. So people can understand whats happening, and still be able to turn it off if they want. (But again, captions are poorly made on the classics and nanos, so dont bother) This way you can have English and Japanese audio, and a English translation subtitle stream all in the same .mp4/.mov/.mkv video file.
There is ZERO information about the ipod classic/nano alternate audio and subtitle support. I had to look in the wayback machine for years to figure out how to do any of this. I have wasted what feels like my whole life finding out this issue. I hope that this post contains useful information to the sorry soul that gets entrapped with subtitles and duel audio on the ipod classic. Dont let those mind flayers posses you, its not worth the years of your teenage life they take for the knowledge, you'll regret it I promise you. I only ever log on about two times a year on the mac rumors form, if you want to find me out side of here look for “Jeff__9000” on if. Or “Jeff__100” on steam. Good luck. You’ll need it 4 years from now.