Could be both right? Your podcast app could generate captions on the server (assuming, as mentioned above, that on-device hardware limitations prevent doing so

Could be both right? Your podcast app could generate captions on the server (assuming, as mentioned above, that on-device hardware limitations prevent doing so on the phone itself) as a file that you download along with the mp3. They'd only have to generate one file for every episode of every podcast that anyone subscribes to, which doesn't seem like it'd take much hardware. There arent' THAT many. Could even be one third party service they all use, like how all the audio players used to use CDDB for cover art, track names, etc. Apple's podcast app is probably the biggest impediment to podcast technology, but no reason 3rd party apps couldn't all do this.