ChanServ changed the topic of ##yamahasynths to: Channel dedicated to questions and discussion of Yamaha FM Synthesizer internals and corresponding REing. Discussion of synthesis methods similar to the Yamaha line of chips, Sound Blasters + clones, PCM chips like RF5C68, and CD theory of operation are also on-topic. Channel logs: https://freenode.irclog.whitequark.org/~h~yamahasynths
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<cr1901_modern>
wb superctr and emily
<emily>
rip irccloud
<cr1901_modern>
If someone's bouncer dies, I will sometimes gently let them know. But only after sufficient time has passed.
* cr1901_modern
fun fact: I don't use a bouncer. I just leave my damn laptop on all the time
<emily>
both my irccloud and matrix connections were broken for different reasons :')
<cr1901_modern>
The matrix channels I'm on were nice enough to add IRC bridges, so I can keep using the IRC client for now.
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<emily>
I mean my matrix freenode bridge
<cr1901_modern>
Ahhh I see... which connection are you using right now to chat here?
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<doppler>
evidently not a very reliable one
<cr1901_modern>
:(
<cr1901_modern>
IRC seems to be having a stroke for other ppl too
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<andlabs>
IRC is great, it's a decentralized network that anyone[netsplit]
<andlabs>
afk
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<cr1901_modern>
TIL that there are at least _two_ published standards for NTSC... I have no idea where to download RS-170A
<ej5>
RS-170 was the original B&W standard. the 'A' version added color and became NTSC
<ej5>
the sync timings for B&W vs color are close but not exactly the same.
<ej5>
for color they adjusted the sync rates just slightly. vertical went from 60hz to 59.94hz
<cr1901_modern>
yea, there's something about peaks at multiples of 60Hz that screw things up in color
<ej5>
you can go through the math, but basically they wanted to derive everything from integer ratios of 3.579545hz
<cr1901_modern>
What was special about 3579545 Hz?
<ej5>
the reason for 60hz was to reduce interference from the AC line
<ej5>
3.5795454545454545... was derived from the adjusted sync rates
<ej5>
let me see if i can find the explanation...
<cr1901_modern>
oh good at least its a rational number
<ej5>
hmm, so it's because the chroma freq (3.579545) is an n+0.5 multiple of the line frequency while the audio subcarrier is an integer multiple of the line frequency
<ej5>
basically to reduce interference
<ej5>
so the old standard you have 4.5MHz/15.75KHz = 285.71. in NTSC they rounded up the relationship to 286
<cr1901_modern>
oooh 286
<ej5>
(4.5mhz is the audio subcarrier frequency)
<ej5>
so 4.5MHz/386=15.734KHz
<ej5>
*286 lol
<ej5>
and since there are 262.5 lines per field, the field rate is therefore 59.94005994005994...
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<ej5>
so how to get to the 3.579545MHz signal? well...
<ej5>
remember they wanted a chroma freq that is an n+0.5 multiple of the line frequency
<ej5>
so 15.734KHz * 227.5 = 3.57954545...
<cr1901_modern>
Nice
<cr1901_modern>
I'm sure I just asked you to explain something you tweeted about before, but thanks!
<ej5>
i haven't tweeted that. hmm.
<ej5>
so anyway the reason for the n+0.5 factor is so that, if intermod distortion happens to the broadcast signal, the beat frequency of the color subcarrier and the audio subcarrier will alternate in phase each line
<ej5>
visually, the interference cancels out mostly
<ej5>
otherwise you'd get a dot crawl pattern.
<cr1901_modern>
ej5: It was doctoranalog, whoops
<ej5>
hmm, he hasn't tweeted this year at all
<cr1901_modern>
It was a while ago. And I'm sure he's fine- taking a break. Like anyone who isn't too Internet-poisoned should do.
<ej5>
4 years ago lol.
<cr1901_modern>
System Essentially Contrary to the American System, or SECAM
<ej5>
i have a multiformat VCR that can generate SECAM
<ej5>
turns out most modern LCD monitors with composite video inputs can handle SECAM, PAL, and so on
<ej5>
but on the oscilloscope, SECAM looks like crap.
<cr1901_modern>
lmao
<cr1901_modern>
Unrelated: Did you know that if you play a Beta tape in a VHS VCR, the video will be garbled, but the audio will work fine?
<ej5>
how'd you figure that out
<cr1901_modern>
It's a secret :3
<cr1901_modern>
(I watched someone else on YouTube do it)