NES DLC idea

[lidnariq]

That's interesting. I found Zapper schematics, and it is way more complex than the one found in clones, it has a demodulating IC or something (no resonators are seen, though). Sega Master System also had very complex schematics with six transistors. The clones had only R2, R4 and Q1 from the Zapper schematics, with photosensor connected to the base of the transistor.

Yeah, ok, "resonator" is a bit of a misnomer; it's a demodulator comparable to the ones mentioned for LIRC's homebrew IR receivers

[tepples]

What I've been calling a "resonator" is in that IC, and it's underclocked from the typical 35.75 or 37.92 kHz. Essentially what the photodiode picks up is a stream of scanline height values, pulse position modulated with a 50 or 60.1 Hz carrier, and further amplitude shift keyed with a 15.7 kHz carrier. The IC decodes the ASK, and software such as the "zapkernels" in Zap Ruder decodes the PPM.

[infiniteneslives]

The zapper either sees white or black, it'd be a trivial test I'm surprised no one (including myself) has actually done it yet... There might be an additional limit based on how fast these monitors can switch black/white but that issue would only slow the transfer rate.

That's an interesting way to try to download data. But I don't think the light from a modern digital TV (LCD and Plasma) works with the zapper. The light from a CRT is more intense. Newer lightguns actually have more complex logic behind how they function. The NES Zapper is pretty simple.

The reason games don't work on LCD/plasmas is due to timing delay these displays have from what I understand. The delay wouldn't affect a download because it'd be synced up from the source. In fact I'd bet you could even make a homebrew that'd work with a LCD/plasma TV if you 'calibrated' your sensing code to the delay that exists on that specific TV in the beginning of the game.

[MottZilla]

Well that's true, digital display are delayed versus good old analog CRTs. But the qualities of the light matter too.

[infiniteneslives]

Well that's true, digital display are delayed versus good old analog CRTs. But the qualities of the light matter too.

Yes but we're only talking about a threshold of intensity here really. Blacks are certainly more dark on LED/plasma TVs compared to CRT. If whites are as bright/brighter then you we should be good.

And for the speed thing... LEDs switch on and off *DRASTICALLY* faster than phosphor gains/loses it's light. I don't know about plasma but phosphor is still damn slow, and PC are usually LED anyways. The argument of speed doesn't really make much sense to me anymore assuming you can get a video frame rate close 60hz or as fast monitor refresh (>=60Hz).

[Shiru]

The so called 'LED displays' in modern TVs and computer monitors are still the same LCD displays with the same old technology limitations (switch delays), only with LED backlight, which is constantly turned on.

[MottZilla]

Well remember how people complain about eye strain when staring at a CRT for a long time but not so much compared to LCDs? I'm sure more light beams out of a CRT than a LCD. How bright does the light going into the barrel of the zapper have to be to register properly? More importantly, is anyone going to try this data transfer out? I don't know that a youtube video would work since video encoding and performance issues could disrupt your perfect video that you planned.

[Shiru]

People complained about CRT TVs because there was 50/60 Hz flicker, quite noticeable. There is no flicker at LCDs.

As we see brightness/contrast ratio/colors on a LCD display very close to a CRT, wavelengths, spectrum, and amount of energy in the light is roughly the same.

YouTube encoding certainly will hurt the video, though, that's for sure, as it can't properly display videos with high framerate. I uploaded a number of 60 FPS videos at YouTube that were perfectly smooth, and they all look jerky after upload.

[Nioreh]

Youtube encoding is 30fps max, but that's ok. I don't think the encoding should hurt a video just switching from all black to all white and back. That should be very easy to compress.

[rainwarrior]

Well, you're also lucky if you can get YouTube to play back at a reliable 30fps. It is generally a bit unstable and will skip frames here and there.

[Dwedit]

Sounds like you guys are reinventing ROB!

[Sik]

Yeah, the encoding will hurt the video - even if what you upload is correct it will get hurt by the reencoding YouTube does. There's also the framerate issue, not only YouTube would need to have perfect vsync, but also the refresh rate of the monitor needs to be a multiple of 30Hz or it won't work (for 60Hz that'd be OK, but what about 85Hz?). Not to mention, such a video would be a massive cause of seizures and there are chances Google may decide to take down such videos for that reason.

Entering passwords seems a better idea at this rate XD

[Nioreh]

Yeah, the encoding will hurt the video - even if what you upload is correct it will get hurt by the reencoding YouTube does. There's also the framerate issue, not only YouTube would need to have perfect vsync, but also the refresh rate of the monitor needs to be a multiple of 30Hz or it won't work (for 60Hz that'd be OK, but what about 85Hz?). Not to mention, such a video would be a massive cause of seizures and there are chances Google may decide to take down such videos for that reason.

Entering passwords seems a better idea at this rate XD

I guess you could easily tell the difference between the length of one frame over two frames. No need for perfect sync.

[rainwarrior]

The problem is worse than that; video in browsers is not generally vsynched at all. In addition there is no way to guarantee that every frame is displayed, let alone every second frame (skips often come in bursts). YouTube is like the UDP of video.

Also it's kind of useless unless the video encoding can even DO alternating single-colour frames. I haven't tried that kinda thing, but am not sure if it would turn out properly at all with normal video encoding algorithms.

[Nioreh]

Skipped frames would be an issue. I will do some tests. I guess one could also release extra content as a small video file for download on a website using a codec that would work better and let the user play it in a nice vsynced environment like VLC. You could even release it as a little app that flickers the data over to the zapper. Youtube was an example just because it would be a nice easy way to upload stuff.