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Retronitus - Noise from the past! - Page 10 — Parallax Forums

Retronitus - Noise from the past!

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  • And here's the other Spintris one rendered:


    One may also find source for both of these on GitLab...
  • Nice tune! I like the claps too.

  • Here's another original tune:


    "Stepping through a dusty archway into halls unseen for centuries..."

    I whipped this tune up pretty quick, so it's not perfect, but I've been doing this long enough to know that trying to fiddle it to perfection doesn't work and is a waste of time, so say it with me: **Ehhhh**....

    As always, source is on GitLab.

  • PublisonPublison Posts: 11,860
    edited 2020-10-23 21:30
    Stellar! !!
  • New tune time:


    "And so a journey begins..."

    There. A Field theme. It works and is long enough to not get old too quick. I took way too long to make this, mostly spent on fruitlessly trying to make new parts to make it longer/more varied.
  • Wuerfel_21Wuerfel_21 Posts: 1,404
    edited 2020-11-30 02:03
    So here's a thing:

    I tried my hand at adding an NES-style DPCM channel type. Seems to work fine and doesn't even consume as many cog resources as I'd initially had thought it would (the samples themselves are of course huge...)



    The noise is mostly due to my sub-optimal sample here. If I take the one from, say, Journey to Silius, it's a lot less noisy, but very detuned instead (since we need different sample rates than NES DPCM would)

    The code is in GitLab right now. It's a bit tricky to use, just look at the example or ask me if that doesn't help.

    How to create an untuned sample (drums and stuff):
    - Find/record a sample
    - Decide on a sampling rate - ideally, choose 32000,16000, etc, since these will not suffer aliasing
    - Resample the sample to that rate and export as mono WAV
    - Open the WAV in a hex editor and change the sample rate (at offset 18h) to 33144
    - Open the modified WAV in RJDMC and save out a DMC file (leave the settings alone!)
    - Done, include the sample in your tune and play it at your chosen frequency!

    How to create a tuned sample (i.e. any pitched instrument):
    - Find/record a sample and take note of which note it is
    - The sample rate must be the same note as your sample, but in a higher octave. Note that the highest note Retronitus supports is B10 (OCTAVE*0 NOTE*11).
    - Resample the sample to that rate and export as mono WAV
    - Open the WAV in a hex editor and change the sample rate (at offset 18h) to 33144
    - Open the modified WAV in RJDMC and save out a DMC file (leave the settings alone!)
    - Done, include the sample in your tune - make sure the notes are shifted up enough octaves!
  • I recently pushed a minor enhancement to Retronitus DX: The amplification of Sawtooth channels is now configurable

    Also, attached you may find another tune I did. It's for the game and I think it's too short and simple for a video. It uses the new DPCM stuff, which is cool, too.
  • Wuerfel_21Wuerfel_21 Posts: 1,404
    edited 2021-01-02 22:38
    Here's a fun thing: MAKE SURE WHICH COG YOU LOAD RETRONITUS (or any other audio cog, for that matter) INTO

    I've spent a couple hours today tracking this bug down, so please, for all that is good, DO NOT LOAD RETRONITUS INTO COG 7 LIKE I DID, IT WILL MAKE YOU SAD.

    So, after having vented my frustration, here's the problem:

    Image21.png
    Pictured: grahphic from section 8.5 of the P8X32A datasheet

    When generated by a cog far away from the audio pins (usually 11 and 10), the very high-frequency modulated audio signal gets distorted by all the OR gates in the path. As you may see, cog 7 is furthest from pins 0 through 15.

    This is what that does to the signal:
    wiggle.png

    Top traces are Retronitus DX in cog 2 (running standalone with a *_main.spin file, as in the repo),
    bottom traces are Retronitus DX in cog 7 (running inside my game).

    This distorion manifests in a highly irritating sound.

    I've attached some zipped FLACs to illustrate that point. They are all the same length and content, so you can compare them. The *_game ones have a lot higher noise floor due to the video pins having a rave next door.


    940 x 439 - 34K
    1680 x 1010 - 116K
  • Because someone kinda asked for it, here's a video that shows the sawtooth modulation in action:

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