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ws
Registered: Apr 2012
Posts: 229 |
SID Interlaced Chord question
On a SID, musicians use the effect of playing chords on one channel by quickly altering the frequency of the note by playing for example C E G in rapid succession, mainly via a table/command. (Are they called arps, arpeggios?)
Is the interlace/arp being done by the driver in 50/3 hz? Or is it actually slower for some reason?
Are Tracks like the Armalyte Title tune using 50hz/3 speed chords or is the frequency of the note alteration actually slower? Is there perhaps a SID-side reason why a maximum speed of playing interlaced chords cannot be exceeded, or is the limit just cpu speed?
Did anyone yet make a driver that uses gliding arps/interlaced notes? Any Examples?
Do you have any outstanding/groundbreaking examples for songs that use unusual high chord note interlace rates, like a 3x speed Tune that achieves 50 hz or higher "interlaced" chords?
Thank you for any helpful insight!
[If this has already been covered in another thread please excuse, i didn't know what to search for due to my lack of knowledge of terminology]
ps.: can one of you coders make a demo where the axes of the sprite multiplexer are rotating? |
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Martin Piper
Registered: Nov 2007
Posts: 645 |
Usually, but not always, music update routines are called once per frame, or at 50/60 Hz. Obviously this limits the speed at which SID can be updated. The update speed is a trade-off, between raster time and sound quality.
However there are some music routines that can be called more than once per frame, perhaps on a title screen where time is less of a concern, and these can vary the frequency faster.
My MusicStudio allows table based customisation of ARPs: https://martin-piper.itch.io/musicstudio |
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ws
Registered: Apr 2012
Posts: 229 |
Thank you, that was my guess. Any examples for deviations? |
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Frantic
Registered: Mar 2003
Posts: 1629 |
Yes, arpeggios are usually updated once per frame, for single speed tunes. Sometimes slower than that, like every second frame, if it happens to sound nice. Quicker updates also creates a different sound, but requires 2x-speed player or higher, obviously.
Hubbard sometimes used a trick of alternating between fixed notes and a sliding note, which is one of the many components of his "sound".
There are many tunes with quicker arps. Check Automatas by Goto80 for example, which is 8x-speed I think. |
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Martin Piper
Registered: Nov 2007
Posts: 645 |
Thanks for this, it reminded me that I need to add variable speed playback and voice update flags. |
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Oswald
Registered: Apr 2002
Posts: 5028 |
Quote: Thank you, that was my guess. Any examples for deviations?
here is what SID sounds like when updated multiple times per frame
https://www.youtube.com/watch?v=UrPFVHc55KU
(not sure sid is updated here 8 or 16 times more frequent than 50hz) |
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tlr
Registered: Sep 2003
Posts: 1725 |
Quoting wsAre Tracks like the Armalyte Title tune using 50hz/3 speed chords or is the frequency of the note alteration actually slower? Is there perhaps a SID-side reason why a maximum speed of playing interlaced chords cannot be exceeded, or is the limit just cpu speed?
There is a _physical_ limitation if you want to still hear this as a chord. When the switching speed approaches a significant proportion of the frequency of the individual notes you will get frequency modulation effects which may not be what you want.
Assuming you only change the frequency this effect will be less and less prominent the higher the notes in the chord are. |
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ws
Registered: Apr 2012
Posts: 229 |
@ everyone - thanks for the input, very interesting!
@ oswald - thanks for pointing me to that tune, which actually gave me real goosebumps! |
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chatGPZ
Registered: Dec 2001
Posts: 11147 |
Quote:not sure sid is updated here 8 or 16 times more frequent than 50hz
8-speed - just read the scroller =) |
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Bansai
Registered: Feb 2023
Posts: 34 |
Quoting Frantic
Hubbard sometimes used a trick of alternating between fixed notes and a sliding note, which is one of the many components of his "sound".
The tricks various musicians did in their drivers to get their "sound" are interesting, especially when the trick used was quite simple. Russell Lieblich would use an incrementing sliding frequency detune of V1+=2/V2-=2/V3+=2 per frame that switched direction every 128 frames in order to get that twangy sound of his, for example, in Activision's Aliens and Transformers. |
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ws
Registered: Apr 2012
Posts: 229 |
@Bansai: nice detail! I was never fully aware of that - now i can actually "hear it". Cool.
What i find also notable/interesting is how the arps/chords in Tigermission Subtune 3 stagger sometimes. I wonder why that is (actually some "staggering" is pretty prominent throughout the entire SID).
Accidentally triggered late sometimes? Could that easily be fixed? |
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