I'm stuck about smps limits

Discussion in 'Discussion & Q&A' started by Ashuro, Apr 8, 2017.

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  1. Ashuro

    Ashuro Well-Known Member Member

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    Hello guys.

    I'm currently on the "final editing part" of Sonic & Ashuro 4.00: i'm making custom songs everywhere. The midi are good, i'm using a sequencer named "Sekaiju", and i use the "Ultimate Megadrive Soundfont" with "Coolsoft VirtualMIDISynth, then i can create my midis with a direct preview of what i'm doing, and of the song like if he was played with the megadrive instruments. :)

    But, the problem is, i have:
    _FM1 (channel 1) for the bass
    _FM2 & FM3 (channel 2 & 3) for the leads
    _FM4 & FM5 (channel 4 & 5) for some additionnal leads or instruments.
    _PSG1 (channel 11) for the Square Wave/Saw Wave instrument
    _PSG2 (channel 12) like PSG1 but, i don't use it because... you'll see.
    _PSG3 (channel 13) same as above.
    _DAC (channel 10) drums.

    I don't know exactly how to use these channels with the good instrument, and i want to know what channels are muted by rings and collapsing platforms. It's a little bit frustrating 'cause i have the impression that i can just hear FM1, FM2 and drums correclty in-game.
    The impression that it's no use, to edit the channel 3/4/5 -_-

    Please, someone to guide me?
    Thanks.. :/
     
  2. MarkeyJester

    MarkeyJester ! % # @ Member

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    FM Channels 3, 4 and 5, and PSG Channels, 1, 2 and 3, are subjected to interruptions by the SFX. DIfferent SFX will use different channels, depending on what the initial sound engineers decided.

    FM Channels 1 and 2, and the DAC will never be interrupted by SFX.

    I do however have an optimised SFX pack, which forces the SFX to use as little channels as possible whilst still sounding the same, you can download them here. Not all of the SFX in that pack have been optimised, only the ones that could. But I've included all of the SFX, because I forget which ones I optimised, and which ones I could not.
     
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  3. Ashuro

    Ashuro Well-Known Member Member

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    Thank you MJ!!
     
  4. LuigiXHero

    LuigiXHero Well-Known Member Member

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    You should put the leads onto FM 1 and 2 and put stuff like bass and backing tracks on the other FM channels. IIRC PSG 2 actually get's less interrupted then PSG 1 however.
     
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  5. Natsumi

    Natsumi Phoenix egg Member

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    Usually if the lead channels are almost the same, putting one into FM3 or FM4 and the bass track into FM1/FM2 can be also good. Many musics use this, to try to keep the bass keeping the melody going. It all depends on the track you have, and how important what track is to the melody, and how noticeable any track is if its stopped suddenly.
     
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  6. nineko

    nineko I am the Holy Cat Member

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    It's not an exact science, even I made some songs with a suboptimal channel layout in my early days, and I'm not saying that my later ones were all perfect, either. You already received some good advices, and you should practice until you're satisfied with what you hear (and don't hear). I'll share my experience as well, so you have one more theory to try out.

    Aside from a few exceptions, I usually put the main lead on FM1, and the bass on FM2, which are never muted as already stated above. FM4 and FM5 are the most interrupted, because they host the ring sounds, so they should get the least important stuff, such as two notes from a chord. FM3 is somewhere in the middle, since there are fewer sfxs that mute it (e.g. the collapsing platforms in GHZ and SBZ), but there are still some, so you should use it for a somewhat important (but not very important) channel, such as a secondary lead, or simply as another note of a chord along with FM4 and FM5. If you use a 0703 layout, you can use FM6 instead of the DAC channel, which is good and all, since it's never muted by sound effects, but beware: the original driver doesn't restore the FM6 status if something else enables the DAC mode (e.g. the 1-up jingle). I did this with the bonus stage song in my hack (the "Slide" theme from Super Mario 64), in which I put the whistle on FM6 since it's important and I didn't want it to be muted, just to find out that it goes away forever as soon as you get a 1-up. Modified smps driver which fix this problem exist, however. As for PSG channels, I'm going from memory because a lot of time has passed and I don't have my hacking stuff readily here, but I seem to remember that PSG1 gets muted much more than PSG2 (iirc, PSG1 gets the jump sfx, which you're likely to hear a lot during gameplay), so PSG2 should be used for important things (one sfx which mutes PSG2 is the braking sound, still iirc, don't believe me on that). As for the noise channel, you don't have much of a choice there: if you want to use it for hi-hats or something, you really just have to use it. Some sfxs such as explosions temporarily mute it, but it's unavoidable since it's the only noise channel you have. The good thing is that if you use PSG3 in your song instead of the noise channel, the driver will let you do that just fine (unlike the FM6/DAC issue), if anything because PSG3 and the noise PSG are actually two different channels in the SN76489, and the 3+0/2+1 limit is actually soft imposed by smps, since the chip itself is capable of 3+1 (but, as explained elsewhere, limiting to 3+0/2+1 isn't necessarily a bad thing, but that's besides the point).

    Also, all of this applies to Sonic 1. I seem to remember that someone once mentioned that the Sonic 3 driver behaves a bit differently, in particular when it comes to FM6 and PSG3, but I never used the Sonic 3 driver, so I won't say anything, I don't want to be wrong.

    Good luck with your conversions!
     
    Last edited: Apr 9, 2017
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  7. Ashuro

    Ashuro Well-Known Member Member

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    Thank you all so much!

    Nineko, it's exactly what i wanted to know!

    Last question: How can i use the PSG3 for the hit-hat? Because i can't have 2 drum channel in my midi, no? Yes?
    I have to put the kick/snare/clap/timpani into the DAC channel and the hats into PSG3 but how?

    Oh and sorry, but if i correctly understand, i can use FM6 for the drums instead of the DAC channel, and use the DAC channel for any other instrument?
    The FM6 is only stopped by the 1-up jingle (removed of my hack)?
     
    Last edited: Apr 9, 2017
  8. Natsumi

    Natsumi Phoenix egg Member

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    6th channel in YM2612 is either FM, or DAC. You can not use both of them at the same time, and the driver does not support switching between FM and DAC either. Simply, you must choose either DAC or just another FM channel.
     
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  9. Ashuro

    Ashuro Well-Known Member Member

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    Ok!
    Thank you!
     
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