Realfun 3

Wow!

Very very impressive!

Can we have some technical details about this achievement?

The voice uses only one SCC channel with a wavetable updated every 60 Hz frame?
What is the size of the file containing the music?
Do you know what percentage of the frame is used by the replayer?

Basically, I would like to figure if it's more or less possible to use this technique in a game.

EDIT: CPU meter show about 70% usage; classic MSX or turbo R?

The 70% you see isn't the CPU load for the player. It can work safely on the ISR within a game.

The voice track is ripped from the original song using the free online ai splitter, and cut in 15 parts. Worked on some of these a bit using low /high pass and noise filters to try to get some of the music out... Encoded the voices using ARTRAG's voice encoder. Did some manual tweaking in the Realfun 3 wave editor. So quite some work, which I imagine would be easier if you can work with clean voice tracks.

As ARTRAG already pointed out it is possible to play this in-game on Z80, though you may need a large(r) ROM.

When converted to Realfun 3 (z80) re-player format I get the following numbers (uncompressed):

- ISR sample data: 76.050 bytes (15 samples, each less than 8kb)
- ISR sample headers: 60 bytes (15 samples)
- Song data: 15.649 bytes (default mode) or 15.356 bytes (on-the-fly mode)
- Wave data: 4.640 bytes

For this song I used 60 Hz samples, because it is slightly better quality. For games it might be better to switch to 50 Hz (note that the sample data will reduce accordingly 74.3 kb vs. 62 kb).

In principle you can expect the same CPU usage numbers as reported on page 9. The ISR sample playback normally adds only very little overhead compared to regular instruments. Only in case "on-the-fly" mode is selected during conversion then the sample play back becomes quite a bit more demanding, but only in case when pitch shifting is required (which does happen once or twice in this song). On the plus side the song data size will reduce a bit.
Further detail on this is given in the Realfun 3 manual.

Thank you very much GhostwriterP for these detailed explanations.

I was able to get the example ROM of the 0.53 replayer working. I will play with it a bit to understand the code better before I start converting it to sdasz80 to make it SDCC compatible. I'll add it to MSXgl if you agreee, but then it will easily be used with Fusion-C (or any other SDCC based C programs).