NES Audio: Rob Hubbard DPCM Sawtooth

/ retrogameaudio
In this video, a unique trick for generating a sustained melodic sound from the sample channel is examined.
Example: The Immortal (Rob Hubbard).

[@verbicide4736]

This is a thought that came to my mind a while ago: 'Why don't people just make new wave-forms on the NES by just looping PCM samples?' - Well the answer now is: 'Because you need to be A) Crazy enough or B) Rob Hubbard in order to accomplish this.'

[@ConnorR.mp3]

So, you need to be A) Crazy, or B) Really crazy?

[@verbicide4736]

Yes, I suppose so.

[@ABCDEFGHdumbo]

oh also a real reason is that it can take up precious CPU power

[@quetalsam]

I think they did that on Donkey Kong Country for SNES

[@Sh-hg8kf]

@@quetalsam The snes itself is about wavetable synthesis and sampling waves.

[@vuurniacsquarewave5091]

The thing is, you can even see the waveform at 0:28 it's not a real sawtooth, as a matter of fact, it is impossible to create a perfect saw wave with 1-bit DPCM encoding because a saw wave is made of steps and then the next wave cycle starts at the bottom of the steps again, but DPCM can't suddenly change the output level. The 0 or 1 in a bit tells it to move a bit this or that way.

[@vuurniacsquarewave5091]

***** That has been done before yes, in fact blargg has taken it a lot further: www.slack.net/~ant/misc/nes-saw/ The problem is that if the interrupt to change the level happens during the sprite DMA that HAS to occur once par frame if you want sprites in your game, the interrupt will be delayed and this can introduce distortion to the sound.

[@ABCDEFGHdumbo]

you can sort of do it in famitracker, but it's a lot more limited than if you did indeed just used a different engine

[@nis5e]

Really unique and interesting sound texture (timbre?). The kind of uniqueness that comes from ruthless experimenting, the kind the video game industry was packed with during the earlier home console eras.

[@retrogameaudio]

I just double checked, Metroid does not use this trick. It uses a low pitched pulse wave and triangle wave doubled up. With a bit of dissonance between the two voices, it has a sort of 'buzzing' quality to it that does remind me of the sound here. :)

[@Appleboy78165]

This is kind of like how the "custom waveform" sound channel on the Game Boy works

[@dantescanline]

Another great program is Richard Bannister's Audio Overload. It lets you play back, visualize and selectiely solo individual voices. It also plays back music from like 20 different pieces of hardware!

[@fungo6631]

Actually, it's dookie. The GEP plug in for foobar2000 is much better.

[@dantescanline]

@@fungo6631 hey man i left this comment 8 years ago, thanks for keeping me updated on plugins for an unrelated piece of software

[@fungo6631]

@@dantescanline It's not unrelated with that Plugin. It does the same thing except better.

[@explod2A03]

I did a quick experiment, couldn't get anything good sounding, at least not with this sample. As za909 suggested, I put the song at "speed 1" in famitracker so I could write out an arpeggio effect in the tracker-space. I got a very muddy sound. Playing around with Zxx commands made cool clicky sounds, but nothing helped pronounce it. I'd be interested to hear if someone has managed a decent arp sound from the sample channel. I'm guessing you might need higher pitches, or longer samples...

[@tillerGeneric]

This one was very cool. Your videos are awesome man. Can't wait for the vids about other consoles!

[@CoolDudeClem]

Could someone clarify this for me? So NES DPCM is 1 bit? Does that mean each sample is just a bunch of on/off pulses (like how a ZX Spectrum Beeper or PC Speaker would play back sampled sounds) then smoothed with a low pass filter, or is it something different?

[@BinaryCounter]

The D in DPCM stands for differential. The sample is stored as the difference to the previous sample. So if the previous sample was "32" and the current one is "33" the bit would be 1. If the value was lower it'd be 0. That obviously saves a lot of memory sonce you only need a single bit for each sample, but has a few negatives. First of all, since it's either up or down, you can't encode silence or square waves perfectly. Secondly, the waveform can only rise or fall at a fixed rate, which means that high frequency information is discarded when encoding, making the sound muffled. The waveform is always somewhat triangular, you can even see it in oscilloscope videos.

[@CoolDudeClem]

@@BinaryCounter Ok got it, thanks.

[@explod2A03]

I highly recommend famitracker. It's free software for composing NES music on a windows machine. It's a music "tracker" (a type music sequencer/ composition software that basically runs from top to bottom instead of left to right), so it might take a little getting used to, but it allows you to write real NES music that works on the actual console. If you don't feel like learning the entire program but want to experiment, you can create patches and make sounds with the instrument editor.

[@Whelkman]

I wondered for years why NES composers didn't simply slap a tiny sample or a set of them onto the DPCM channel for additional polyphony, especially the European ones. In the demoscene, in which many of these composers share lineage, utilizing tiny samples is still extremely common when composing tunes to fit in a small file size. With a set of, say, 32 byte samples, one would basically arrive at a 1-bit monophonic wavetable (with some severe limitations, of course). 32 samples in 1k @ 32 bytes.

[@big0bad0brad]

A big problem is related to some quirks of the DPCM playback between the sample length options and playback speeds available. You can only really get one or two notes to sound "correct" for a given sample. If these issues weren't there I think it would be much more common to see.

[@EYTPS]

I'm glad that I'm aware the NES could do so many things

[@OswaldMiyake35]

EYTPS The Bad Part is that Rob doesn't even remenber how he did the Waveform.

[@LuwiigiMaster]

That's because Hubbard is a damn magician. He only did two soundtracks (more if you count the NES ports of other EA games), but I really wish he did more. He would've been among the gods of getting the best sound out of the stock 2A03, and with people like him, what good would sound expansion be?

[@user-ql2re2es9y]

Commodore 64 Master.....

[@RaposaCadela]

Is your name a reference to Bionic Commando's "THIS BASE WILL EXPLOD IN 60 SECONDS."?

[@explod2A03]

Yeah, there's a lot of different stuff I want to cover. :) Although since I started with the NES, I wanted to cover all the main points I can think of before moving on. I'll probably go into Famicom sound expansion before other systems though, so something like the Sega Genesis or Virtual Boy will come a bit later.

[@SantiagoVa1entine]

I will wait for those videos! even tho your last video of the series was 8 years ago :(

[@MrRetrogamingBard]

Ah yes! The Immortal! One of many games I purchased mainly because of the soundtrack :)

[@TheDrunkardHu]

thanks for the recommendation. checking it out right now!

[@ConnorR.mp3]

For anyone who wants the sample, here it is. www.dropbox.com/s/46lgaqbhzhhah66/ripped01.dmc?dl=0

[@Anomalous404]

Do you or anyone else still have the .fti sample posted on your tumblr? Zshare seems to be down or maybe just the link, but i'd really like to get that mapped sample.

[@ConnorR.mp3]

I've just ripped it from the game, if you're still interested. www.dropbox.com/s/46lgaqbhzhhah66/ripped01.dmc?dl=0

[@user-ql2re2es9y]

Tips🔦: Use/load any kinda bass or wave sample you like, click the sample file, click "Edit" to open the sample editor and delete all the excess parts of the waveform, you left with the very beginning offset of the wave. Assign to individual notes and repitch to low notes (C-1 - C-0 pitch), loop every sample assignment and voila!.

[@infinitecanadian]

I heard that it was possible to modify the NES to generate the sawtooth and square waves present in Famicom games such as Akumajo Densetsu 3 and Megami Tensei II, and you could connect a Famicom cartridge using an adapter and play the games with full sound.

[@Nukle0n]

It is possible, you need to wire up some unused pins on the cartridge slot to the sound mixing circuit on the NES. then you also need to modify the adapter a bit.

[@TheDrunkardHu]

is there a contemporary program that i can download that would allow me to experiment with these wonderful sounds? i'm an utter noob when it comes to fami... com... idk, but i love 8 bit game music!

[@user-ql2re2es9y]

w7n did this looped FDS samples on "Hatsune Miku no Shoushitsu", "Luka Luka Night Fever", and "Himitsu Dolls cover from Strawberry Panic ED01".

[@SrivatsanVenkatesh]

So I'm trying to rip some of the samples out of Immortal's NSF, and so far I have the drums, but I can't seem to get the sawtooth/bass sample. Any ideas?

[@AzatronZadrotov]

Good!!!!!!!!

[@clubhappybest]

Does the title music from Metroid employ this as well?

[@arciks11]

Will you cover Skate or Die 2 Title screen music?

[@johnnyselfdestruct]

Anyone know where I could download this for famitracker?

[@filmgbg]

johnny v You could just simply google "famitracker"...

[@johnnyselfdestruct]

I was actually referring to the post from retrogameaudio.tumblr.com/ they had a download for a sample of this for FAMITRACKER but for whatever reason it's dead. I have since become familiar on making it myself. SO thanks for your concern.

[@ConnorR.mp3]

Here's a link! I just ripped it. www.dropbox.com/s/46lgaqbhzhhah66/ripped01.dmc?dl=0

[@ostradiemgi5469]

You should remake the series with better visualisation!

[@Alianger]

So DPCM is pretty much the same as wavetable synthesis?

[@markkoetsier6475]

Somewhat, except with major limitations like only being able to pitch shift an existing sample down, not up. Also, doing so will automatically slow down playback. It's quite primitive. Combine that with a very short (if you want to keep some manner of sound quality) maximum sample length, the fact there's only one channel *and* the NES' lack of cartridge space limiting your amount of samples, and you really don't have anywhere near the kind of versatility you'd have on something like an SNES. Still, when used in a smart way it can really enhance the sound of a typical 2A03 song. There's also a neat trick where you can use the DPCM to modulate the volume of the Triangle channel. That one's otherwise limited to two settings: _on_ and _off_ , it has no volume control of its own. Which obviously kinda sucks.

[@Alianger]

Interesting, thanks.

[@markkoetsier6475]

Sure, no problem!

[@sylvoen]

does this technique work with famitracker?

[@vuurniacsquarewave5091]

+Thr³³ Yes but you only get a usable B major scale on like one and a half octaves. You need to use the Loop function of the channel to sustain the note.

[@johneygd]

It sounds more like a noise channel to mimmick drums.

[@bitchlasagna4720]

its not even a sawtooth wave