@saimo

If anyone is interested, I've written this extensive article on LinkedIn that explains the music engine.

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RETREAM - retro dreams for Amiga, Commodore 64 and PC

@saimo

thanks! totally above my head but very interesting reading

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@saimo

Interesting read. From my own experiments with (lossy) delta compression, I have to ask, did you consider applying delta to the original 16 bit data? Using a lossy encoding like adpcm I've had pretty good results in the past.

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@klx300r

Quote:

thanks! totally above my head but very interesting reading

It's no rocket science, but there are so many concepts that it's understandable that, despite my efforts to simplify, who isn't familiar with them will find the whole picture obscure.
Thanks for the feedback, though

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RETREAM - retro dreams for Amiga, Commodore 64 and PC

@Karlos

Quote:

Interesting read. From my own experiments with (lossy) delta compression, I have to ask, did you consider applying delta to the original 16 bit data? Using a lossy encoding like adpcm I've had pretty good results in the past.

No, I didn't because I started directly with the idea of separating the high and low bytes in order to make things easier for the 68020. I don't think the result would be much different or better:
* if the bytes were separated after calculating the deltas, the result would be similar (i.e. the high bytes of the deltas would not be much different from the 8 bit deltas, as the idea of "being close" doesn't apply to the low bits);
* if the bytes were not separated at all, an 8 bit encoding wouldn't be very effective (because the low bits are noise); on the other hand, a 14 bit encoding would be more complicated and heavier on the CPU.

Your observation reminded me that I forgot to include in the article a comparison with FLAC. I have fixed that now. Here's the revised part.

The overall result is pretty good. For example, the title screen music consists in a loop that lasts 4.592 seconds; its raw size is 810022 bytes; after the quality reduction, the size becomes 231973 bytes (132556 bytes for the upper 8 bit data plus 132556*0.75 = 99417 bytes for the lower 6 bit data); the upper 8 bit data compresses to 79115 bytes (with a gain of 40.3%), giving a total size of 79115+99417 = 178532 bytes (for comparison, the same 16 bit 28867 Hz mono file, when compressed with the best FLAC method, shrinks to 203078 bytes; given that FLAC preserved all the bits, it is also necessary to compare its result with the sum of the compressed upper 8 bit data and the unmodified lower 8 bit data, i.e. 79115+132556 = 211671 bytes, which, being not much more than the size of the FLAC-compressed data, is a testimony of the effectiveness of the compression applied to the upper 8 bit data).

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RETREAM - retro dreams for Amiga, Commodore 64 and PC

Finally also the in-game music is ready!

The gameplay idea is that when the Notes Cell is caught, music starts playing and all the cells become bonuses (maluses have no effect anymore and award points, and the Controls Swap Cells always fix controls); then, when music ends, the game returns to normal.

This video shows how it works (although, as usual, YouTube just can't cope with the scrolling layers and thus totally destroyed it): https://www.youtube.com/watch?v=6sDg0zni9ac&vq=hd1080

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RETREAM - retro dreams for Amiga, Commodore 64 and PC

Regarding the SkillGrid music, I've been asked if, besides the guitars, I have played also the drums and the bass. Well, the answer is no: I made the music, quite fittingly, the Amiga way, i.e. I used a tracker, namely MilkyTracker (although the game itself doesn't use the tracker module, but uses the alternative solution illustrated in this article on LinkedIn).

http://www.youtube.com/watch?v=ESdTO2-xGkk

This is the procedure followed for the Music Mode music:
1. on guitar, I composed the two chords progressions the music is built on;
2. on guitar, I adapted those progressions for the crunchy rhythm guitar and the clean rhythm guitar;
3. in the tracker, I composed a minimal drum loop;
4. while the tracker was playing the drum loop, I played and recorded the crunchy rhythm guitar;
5. in the tracker, I added to the music the guitar track just recorded;
6. in the tracker, I gave the drums some more structure;
7. while the tracker was playing the music, I played and recorded the clean rhythm guitar;
8. in the tracker, I added to the music the guitar track just recorded;
9. in the tracker, I refined the drums further, until they were about 80% done;
10. while the tracker was playing the music, I played and recorded the various solo guitars;
11. in the tracker, I progressively added to the music the solo guitar tracks as I was recording them;
12. in the tracker, I (almost) finished the drums;
13. while the tracker was playing the music, I composed the bassline on the guitar;
14. in the tracker, I programmed the bassline according to what I had just found;
15. while the tracker was playing the music, I composed the C64 sounds fills/melody on the guitar;
16. in the tracker, I programmed the C64 sounds fills/melody according to what I had just found;
17. I recorded my voice counting down from 3 to 1;
18. I added lots of reverb to the voice samples;
19. in the tracker, I added the voice samples at the end of the music;
20. in the tracker, I did the final polish work: I refined the drums, fixed the timings, improved the panning of the instruments, composed the coda, etc.

As the video shows, the music uses 10 tracks, allocated this way:
* tracks 1-3: drumkit;
* track 4: crunchy rhythm guitar;
* track 5: (almost) clean rhythm guitar;
* track 6: solo guitar A (neck single-coil pickup);
* track 7: solo guitar B (brigde humbucker pickup);
* track 8: bass;
* track 9-10: C64 sound and voice samples.

Fun facts:
* I decided to add the spoken countdown because, besides adding a little extra dimension to the music, it warns the player that the Music Mode is about to end;
* making the coda was a pain: the rest of the music had already reached almost 30 seconds, and that was a limit I couldn't go much beyond due to memory constraints (see the article on LinkedIn); eventually I came up with something decent that keeps the music slightly below 31 seconds.

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RETREAM - retro dreams for Amiga, Commodore 64 and PC

Development was suspended for a few weeks due to another project (a book not related to computers), but then it resumed with these changes:
* added spaceship tilting when it moves sideways;
* improved music;
* saved some RAM by replacing general-purpose routines with game-specific ones;
* drawn boss;
* made the game run from (2) floppies;
* written manual;
* written installer;
* drawn icons.

There is enough RAM left to add bossfights, more UFO types, and dynamic generation of the scrolling middle layer (and possibly improving the quality of some sound samples). The biggest issue will be stuffing everything into the 2 floppies (at the moment there are less than 110 kB free).
By the way, of all the icons shown in the picture, only the ones surrounded by squares, which are in the old 4-color format, will be used, precisely to use as little floppy disk space as possible.

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RETREAM - retro dreams for Amiga, Commodore 64 and PC

@saimo

looking good

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c64-2sids, A1000, A1200T-060@50(finally working!),A4000-CSMKIII
! My Master Miggies- Amiga 1000 & AmigaOne X1000 !
mancave-ramblings
X1000 I BELIEVE

@saimo

Another Milkytracker user :)

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Thanx for the videos and explenation regarding how you do the music.

Milkytracker is nice. I'm doing a tune there that is half way finished :)

@klx300r

Quote:

looking good

Thanks!


@saimon69

Quote:

Another Milkytracker user :)

Well, not much of a user, I must say: since 2008, all I've done with it is just a few tunes for BOH, (maybe) MeMO, and SkillGrid :p


@nikosidis

Quote:

Thanx for the videos and explenation regarding how you do the music.

You're welcome.
By the way, I've touched up the music further.


@all

I'm fiddling with procedural generation of the middle layer: I have tried many alternatives, but their visual outcome doesn't really convinces me so far...

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@saimo

Quote:

[...] The biggest issue will be stuffing everything into the 2 floppies (at the moment there are less than 110 kB free) [...] [img]

Why not aiming at a 3 Disks release, then (Just asking)?

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@ErikBauer

Or make HDD/whdload version ;) like Giana Sisters SE

@ErikBauer

Quote:

Quote: [...] The biggest issue will be stuffing everything into the 2 floppies (at the moment there are less than 110 kB free) [...] [img] Why not aiming at a 3 Disks release, then (Just asking)?

Why going for 3 if it can be 2
Philosophy aside, if one day the game gets a physical release (not planned for now, but still), one disk less will make the product less expensive.

BTW, the dynamic generation of the middle layer freed some 30 kB on disk, so now there 138 kB free. I'm thinking I might do the same for the bottom layer, but I haven't decided yet.

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@Paulthetall

Quote:

Or make HDD/whdload version ;) like Giana Sisters SE

The game does run from HD as well, and it will be possible to unpack it anywhere from an .lha archive or to install it from floppies - it's all already done.

Last edited by saimo on 10-Sep-2018 at 03:12 PM.

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RETREAM - retro dreams for Amiga, Commodore 64 and PC

@saimo

Quote:

saimo wrote: Why going for 3 if it can be 2 Philosophy aside, if one day the game gets a physical release (not planned for now, but still), one disk less will make the product less expensive. BTW, the dynamic generation of the middle layer freed some 30 kB on disk, so now there 138 kB free. I'm thinking I might do the same for the bottom layer, but I haven't decided yet.

Well, that's an excellent reason

Last edited by ErikBauer on 10-Sep-2018 at 03:31 PM.

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God created Paula so that Allister Brimble and Dave Whittaker could do music

Check my Amiga gameplays (ITA)!

@ErikBauer

Quote:

Well, that's an excellent reason

@all

The dynamic tile-based generation of the middle layer is done. Besides looking cool, it saved about 30 kB of floppy disk space at little CPU cost.
The picture shows various experiments and the final choice (the blue-purple gases/clouds).

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RETREAM - retro dreams for Amiga, Commodore 64 and PC

Video preview #6

https://www.youtube.com/watch?v=nNmP6qFXMvc

This video demonstrates these new features:
* procedural generation of bottom and middle layers;
* new bottom and middle layers graphics;
* spaceship tilting;
* touched up music.

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Development slowed down a bit in the past couple of months, but still a number of (important) changes have been made:
* added bossfights;
* added CHASE cell (the UFOs chase the spaceship for 5 seconds);
* moved HUD icons column to the left side;
* touched up graphics;
* made various improvements/fixes;
* extended/improved manual.

http://www.youtube.com/watch?v=AbdfSSvK8lk

Future:
* the final boss graphics will be totally different;
* the background graphics might change as well;
* there are 47 kB of floppy disk space and 140 kB of RAM left: they will be used to make improvements and/or to add new features.

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RETREAM - retro dreams for Amiga, Commodore 64 and PC