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FamiTracker > General > Show Off Your Work > Path of the Ninja (VRC6) Owner: graypesoda

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RE: ANOTHER Update!!! Posted: 2015-04-18 06:58

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wispybowl

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#68233

ollaxe wrote:

I noticed that in song 18, frame 04, row 16-1E, you can clearly hear the "plop"-sound that the built in squarewave channels make when they slide over certain frequencies. One way to fix it is to change the last number on the 4xx effect to something lower until you can't hear the plop anymore. Make sure you do this on the echo too! Smile

And also the loop for song 2 is a little abrupt, don't you think? It goes from everything to nothing instantly.

This is still "helt fantastiskt!", as we say in sweden. It means "Totally awesome"

Is there a specific reason the square waves do this? Is it a bug?

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Posted: 2015-04-18 10:37 (Last Edited: 2015-04-18 10:38)

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Alexander283

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#68235

Yeah, there actually is. You see, the frequency is a 24 Bit number. Since the NES is an 8 Bit System, this number is split into 3 bytes. Because of the internal structure, if the highest Byte changes during a pitch-slide, the tone generator resets resulting in a small "plop"-Sound. Not as significant as a DPCM 0->7F - plop, but still noticable - especially if you do a vibrato going "2FF - 300 - 2FF - 200 - ..." (just a random example). In this case, there will be one plop every frame.

Another example is attached below - go to "Tracker -> View Register State" to see that the frequency register changes between being more or less than $300 causing this sound.

Also, I wanna use the chance to congratulate Graypesoda on creating such a magnificent soundtrack :D
Keep going - this is only getting better ^^

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Posted: 2015-04-18 11:38

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za909

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#68236

Well other than the bit-depth (which is actually 11-bit) you got that right. The VRC6 for example has 12-bits, which adds an extra octave.
The Master System only has 10 bits, that's why it's so bad at doing bass notes.

These systems always take an input frequency and then divide it by the number you specify, this is how the output frequency is produced.

The pop doesn't seem to be as much of a bug once you understand the built-in hardware functions. The two pulses and the noise can use an automated volume slide, (similar to the hardware sweeps, but for volume) often called "envelope" or "hardware decay". The official Famitracker does not support this currently. In this mode, the volume acts as a speed setting and not a real volume. The channel automatically goes from volume 15 to 0 at the rate you told it to.
It can also operate at 240Hz, so the fastest speed will decrease the volume 4 times every frame. This is impossible with software control if you don't choose 240Hz for engine speed.

Then there is the length counter, which is an optional automatic countdown to silence a certain channel after a certain amount of time without the program having to silence it manually. This is not very useful because it doesn't do anything you can't do manually (operates at 60Hz).

When a program writes the high 3 bits of the frequency (when it crosses a frequency boundary) this also has the side-effect of restarting the length counter if it's enabled (it isn't in Famitracker), the envelope if it's enabled and resets the wave generator. It's supposed to be like a trigger, when you hit a key on a piano.

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