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Modder re-creates Game Boy Advance games using the audio from crash sounds

arstechnica.com

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Re: Modder re-creates Game Boy Advance games using the audio from crash sounds

#51

Post by wegfawefgawefg »

xyzzy_plugh wrote: post #49
nathancahill wrote: post #32

Earlier quoted context omitted.

Good memories. I still have my iPod Classic, I upgraded the battery and added 4 256GB MicroSD cards. I saw a mod recently for adding Bluetooth but it involves swapping the rear case and I don't think I'll go that far. There's something timeless about the design (and about owning copies of music files).

Funny to see this mentioned. I was recently out skiing and was using my phone to listen to music, as I used to do with my 3rd generation iPod. Moments ago I was lamenting to my colleague that while my phone's battery rapidly plummeted in the cold despite being insulated and close to my body (no way even remotely approaching freezing temperatures) my iPod never struggled to play tunes all day. In fact I never recall a…

Was it a difference in battery chemistry?

Re: Modder re-creates Game Boy Advance games using the audio from crash sounds

#52

Post by Dwedit »

jboy55 wrote: post #16
0xC0ncord wrote: post #15

Earlier quoted context omitted.

The author's previous video[1] explains the technical details regarding this behavior. Basically the way GBA sound works is there is a buffer in RAM that the audio is streamed from, and an interrupt is supposed to signal the hardware to begin reading data from the beginning of the buffer again. However, if the interrupt is never fired (such as when the game crashes), the audio stream will go beyond the buffer and rea…

Would this be dependent on the audio file that was being played during the crash to start at address 0 of the ROM? It seems like it'd be highly unlikely you'd be able to get 100% of the ROM. Now if this was a hack where the thought was, "What if we dumped the whole ROM to the audio buffer, could we recover the complete ROM through audio analysis?"

GBA Memory Map:

  02000000-0203FFFF   EWRAM (256 KBytes)
  03000000-03007FFF   IWRAM (32 KBytes)
  06000000-06017FFF   VRAM - Video RAM (96 KBytes)
  08000000-09FFFFFF   Game Cartridge ROM (max 32MB)
The audio buffer will usually live in EWRAM, then you have to wait until about 100,000,000 audio samples have played before it proceeds from EWRAM to Game Cartridge ROM.

Re: Modder re-creates Game Boy Advance games using the audio from crash sounds

#53

Post by Dwedit »

shadowgovt wrote: post #22
peddling-brink wrote: post #8

Why would this happen in the first place? Is it common for these games to dump state to audio? Is it a deliberate debugging tool for the game devs?

It's pretty uncommon and it's not a deliberate debugging tool. In this case, the GBA could, hypothetically, have had a way to "park" the architecture on a game crash, or "watchdog" the system (by tying state update somewhere that should run periodically to a non-maskable interrupt that reboots the machine if that state update stops happening). Simply because it costs more to do those things, the GBA doesn't (Nintendo…

The GBA does have an interrupt that occurs when cartridge is removed.

Re: Modder re-creates Game Boy Advance games using the audio from crash sounds

#55

Post by runnr_az »

taftster wrote: post #26
hifikuno wrote: post #25

Earlier quoted context omitted.

The video was great. I think my favourite part is where he dumps the Chinese knock off version and finds the random ARM code and reverse engineers it. So much cool stuff in there.

Right? This kind of stuff just makes me look silly in what I'm able to achieve. I can only accomplish watching a video of some guy doing bad ass stuff and maybe holding onto a few notional details. People are just super smart sometimes.

It’s especially fun watching super smart people work on somewhat ridiculous projects.

Re: Modder re-creates Game Boy Advance games using the audio from crash sounds

#56

Post by ace2358 »

nathancahill wrote: post #32
Y_Y wrote: post #13

This reminds me of the original iPodLinux hack almost twenty years ago where the fourth-gen firmware was dumped via the piezo speaker - https://web.archive.org/web/20140810083116/http://www.newsci... Coincidentally one of the things this facilitated was playing GBA games on the iPod, though I was happy enough just to play Doom a with the click wheel and watch monochrome videos.

Good memories. I still have my iPod Classic, I upgraded the battery and added 4 256GB MicroSD cards. I saw a mod recently for adding Bluetooth but it involves swapping the rear case and I don't think I'll go that far. There's something timeless about the design (and about owning copies of music files).

Given the ‘super compute in your pocket’ thing we say… super computers turned out to be terrible at playing music files without stopping.

My iPhone will regularly forgot what I was listening to moments ago after I press pause. Insane.

Re: Modder re-creates Game Boy Advance games using the audio from crash sounds

#57

Post by mlyle »

thewakalix wrote: post #9

The issue with long runs of 0x00 is related to "clock recovery". > Some digital data streams, especially high-speed serial data streams (such as the raw stream of data from the magnetic head of a disk drive and serial communication networks such as Ethernet) are sent without an accompanying clock signal. The receiver generates a clock from an approximate frequency reference, and then phase-aligns the clock to the tra…

Another concern is if the waveform is AC coupled somewhere and DC can't pass.

Even if you have a perfectly synchronized clock, all-or-mostly-1's will be the same as all-or-mostly-0's in the long run.

Re: Modder re-creates Game Boy Advance games using the audio from crash sounds

#58

Post by speedgoose »

xyzzy_plugh wrote: post #49
nathancahill wrote: post #32

Earlier quoted context omitted.

Good memories. I still have my iPod Classic, I upgraded the battery and added 4 256GB MicroSD cards. I saw a mod recently for adding Bluetooth but it involves swapping the rear case and I don't think I'll go that far. There's something timeless about the design (and about owning copies of music files).

Funny to see this mentioned. I was recently out skiing and was using my phone to listen to music, as I used to do with my 3rd generation iPod. Moments ago I was lamenting to my colleague that while my phone's battery rapidly plummeted in the cold despite being insulated and close to my body (no way even remotely approaching freezing temperatures) my iPod never struggled to play tunes all day. In fact I never recall a…

Sample size N=1 too but I remember warming up my iPod to get more battery while my iPhone survives pretty well while streaming my GPS coordinates when I go skiing.

Re: Modder re-creates Game Boy Advance games using the audio from crash sounds

#59

Post by sunnybeetroot »

reactordev wrote: post #4

It’s stories like these that remind me I’m stupid and have a lot still to learn. My goodness this is amazing. Up there with audio key logging and things I read about but could never dream would be a real thing. I tip my hat sir. Reminded that I’m a mere mortal in the presence of greatness. The absurdity of recreating a game based on audio crashes sounds like something a mental patient would say but no, here we are in…

You’re not stupid because you don’t know how to reverse engineer a GBA game, unless you work for Nintendo and it’s part of your job description.

Re: Modder re-creates Game Boy Advance games using the audio from crash sounds

#60

Post by andai »

thewakalix wrote: post #9

The issue with long runs of 0x00 is related to "clock recovery". > Some digital data streams, especially high-speed serial data streams (such as the raw stream of data from the magnetic head of a disk drive and serial communication networks such as Ethernet) are sent without an accompanying clock signal. The receiver generates a clock from an approximate frequency reference, and then phase-aligns the clock to the tra…

From this page I found a very interesting article: Wireless Set Number 10

https://en.wikipedia.org/wiki/Wireless_Set_Number_10

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