Why are Swiffy files incapable of sound on iPads?

What are these podcast sound files with image and text?

• I have a walkman NWZ-E443 and I have saved some podcasts, and on the screen I can see an image, text and I can listen to the mp3 file. On windows I can open the device and all i can see are mp3 files which I thought were only sound files. What kind of files are these? How can i create such a file with sound, image and text that works on a walkman? To answer my own question, I found you can get software to rename sound files based on the tag and file information, and to add an image, (album art). I can use the categories of information, nominally called title, artist, album, genre, etc, to show any kind of information. In my case I wanted to make foreign vocabulary flash cards. Also i found a suggestion to make image files using text and save as .jpg files to a picture file on the device. Although this doesn't have sound it is quite easy. Really now I am wondering if there isn't a card maker for mp3 files working from lists?

• Answer:

  They are just animating files in the folder.... Good luck!