To describe it another way I shall try putting it like this:
Using the Arduino - with display and buttons - I would like to make something which you could call a juke box.
It displays the songs/tracks available, allows you to select them and play them, or just plays them randomly.
It can exclude songs from this random selection and all sorts of things to do with the play list.
The volume is controlled by the Arduino - though the user has control via buttons.
I've seen it and still not sure if it does what I require.
I shall look at it again and do more digging.
What does concern me is that it plays MP3 files, but they have to be sampled at a certain sample rate.
Now: MP3 standard says it should not matter the sample rate.
I am not an MP3 master, but I don't know what rates my MP3 files are sampled. It would be annoying to buy it only to find that all my samples wouldn't play.
Yeah, ok, I would check before buying.... but......
We're going to need a file to play, so find an MP3 file on your computer. Make sure the MP3 is encoded at 192kbps. To do this, right click on the file, then select "Properties," and then the "Summary" tab. Scroll to the bottom until you can see "Bit Rate." If this rate is anything other than 192kbps, the file won't play correctly with our example firmware, and you should either choose a different file or convert the existing one.
The "problem" with one of the shields you mentioned is WAV format.
Most of my stuff is MP3 and I don't want to have to change their format to WAV to suite the card.
Yes, I am thinking of hacking an older MP3 player.
I've actually got one and am thinking of it.
Why I am not too keen on that is that the file names are not "visible" to the user.
And some of the players/shields want the names to be (for instance) 0001.mp3 0002.mp3 0004.mp3 and so on.
Yeah, workable, but not really handy to the person if you are displaying the file names to know what is playing.
Am trying to read that other thread you posted/mentioned. It is long.