I did a search, what you think of this?

Interesting, but the conversion / porting would be difficult for some (or all :-( ) libraries.
It seems you use the size of the archive - this may be irrelevant, because some libraries include huge autoconf scripts which we do not use, contrariwise sources are good to be compressed so compilation may produce bigger result than compressing.

SD card would NOT help, because you cannot run code from SD card. But you can run code from flash, which is 1.5 MB.

It probably depends. I know a full WAV song around 5 minutes long takes roughly 60 MB of space, and if it's converted to 22 KHz it's 30 MB. Not sure if changing it from 16 bits to 8 halves the size once more, though. On the 84+SE we roughly had the same sound quality and we could store around 1 minute of audio in 1.54 MB.

It probably depends. I know a full WAV song around 5 minutes long takes roughly 60 MB of space, and if it's converted to 22 KHz it's 30 MB. Not sure if changing it from 16 bits to 8 halves the size once more, though. On the 84+SE we roughly had the same sound quality and we could store around 1 minute of audio in 1.54 MB.

I just did some measurement by winamp. Have music file 8:15 of length.
22KHz, 8bit (format for fxplayer) - 10,929,955 B
11KHz, 8bit - 5,465,000 B
8 KHz, 8bit - 3,965,932 B, but sound quality is like from analog telephone

The fxplayer uses only 5 bits so we can go to 11 KHz, 4 bit - 2732500 B (not tested)

How much music can be stored on 16MB?

So 16 MB storage would hold 5.85x more -> 48 minutes

BTW: why do you ask for 16 MB storage ?
9860 has 1.5 MB and SD card can be up to 2 GB (for the models where fxplayer works)

I'm glad you allow multiple qualities actually. On the 84+SE if you use a 8 KHz file, it plays 3 times faster or so.

I'm afraid it was some misunderstanding. The fxPlayer supports only 1 format - 22 KHz, 8bit. My previous post was only about different wav formats and sizes.

But support for 11 KHz should be easy, 8 KHz can be supported only approximately.