Been searching google for such features. But seems like it doesn't exist.<p>I am surprised podcast apps don't support closed captioning of podcast audio. Plus such features are also useful for music files for lyrics.<p>It would help those who are hard of hearing... also it would make podcast easier to search and index as well!
The HTML audio tag is quite limited, hence a million solutions to the problem.<p>However the video tag supports WebVTT subtitles (and plain audio tracks) which is quite close to SRT, so it should be possible without any kind of proprietary/custom solution.
It should be possible to create an MKV file like this but I don't know what media player support is like. If it doesn't work then I guess you're stuck with the stupidly common dummy video thing (where the video content is just black or a single image like the album cover).<p>I seem to remember old iPods having a feature where you could switch to the lyrics but it wasn't in time with the song.