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Modder re-creates Game Boy Advance games using the audio from crash sounds
41–50 of 89 posts
Re: Modder re-creates Game Boy Advance games using the audio from crash sounds
#42[deleted]
Re: Modder re-creates Game Boy Advance games using the audio from crash sounds
#43Earlier quoted context omitted.
A sprinkle of entropy improves everything
They do a similar thing for GPS data recovery. It is so far below the noise floor that normally speaking the signal is not recoverable. But then you inject some (known) noise and suddenly the noise modulated by the (unknown) signal starts to drown out the noise in the rest of the system and that in turn allows you to recover bits from the signal.
It's not only below the noise floor, but all satellites transmit the code on the same frequencies, so it's several signals all at once below the noise floor. Which makes the known noise unique to each satellite, and you dredge out the same frequency repeatedly with different sets of known noise to recover multiple signals.
Gold sequences are really neat, which is precisely the same pseudorandom scrambling technique, but where each sequence is selected to have low correlation with all other sequences in use, which is what enables the frequency sharing property of the system.
Re: Modder re-creates Game Boy Advance games using the audio from crash sounds
#44Earlier 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?"
the sounds aren’t read directly from the rom - the buffer is in a fixed place in ram, and sounds from the rom get copied into there
remember that it’s not like the music is just there as raw audio, the raw audio is just the sounds of the different instruments
Re: Modder re-creates Game Boy Advance games using the audio from crash sounds
#45Earlier quoted context omitted.
A sprinkle of entropy improves everything
They do a similar thing for GPS data recovery. It is so far below the noise floor that normally speaking the signal is not recoverable. But then you inject some (known) noise and suddenly the noise modulated by the (unknown) signal starts to drown out the noise in the rest of the system and that in turn allows you to recover bits from the signal.
This thread brings back fond memories from electronics and digital signal processing.
Re: Modder re-creates Game Boy Advance games using the audio from crash sounds
#46This 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).
Every music file I have in iTunes and on my iPhone is a DRM-less MP3 or AAC file.
Re: Modder re-creates Game Boy Advance games using the audio from crash sounds
#47Earlier quoted context omitted.
I love how we used to use a bunch of very clever "code book" systems like 8b/10b which did a lot of careful work with small runs of bits to ensure the clock was recoverable and to avoid line capacitance issues. Then we just moved to things like 64/66b which takes a giant chunk of bits, adds a short header to guarantee a clock transition, then runs everything through a pseudorandom scrambler.
A sprinkle of entropy improves everything
QR codes do this too, as explained by yesterday’s front page post about decoding QR codes by hand.
Re: Modder re-creates Game Boy Advance games using the audio from crash sounds
#48Does anyone know what's going on when the TheZZAZZGlitch's emulator reports that the game tries to jump to an invalid address? I'm not so familiar with the ARM7 processor used in the GameBoy Advance, but I can't imagine how it would be possible to construct a jump call with an invalid value. Additionally, what would happen if one of TheZZAZZGlitch's incorrectly reconstructed ROMs was run on a real GameBoy?
It is likely that the emulator only emulates accessing valid parts of the GBA's memory map, and throws that error if invalid parts are accessed. As to what happens on real hardware.. who knows? :)
Re: Modder re-creates Game Boy Advance games using the audio from crash sounds
#49This 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).
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 any noticeable difference in battery performance in cold temperatures despite daily use for years.
And yet my phone gets a bit chilly and gives up the ghost.
I use Bluetooth otherwise I'd have dug out the 3rd gen for the next ski day.
Re: Modder re-creates Game Boy Advance games using the audio from crash sounds
#50The 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…
I love how we used to use a bunch of very clever "code book" systems like 8b/10b which did a lot of careful work with small runs of bits to ensure the clock was recoverable and to avoid line capacitance issues. Then we just moved to things like 64/66b which takes a giant chunk of bits, adds a short header to guarantee a clock transition, then runs everything through a pseudorandom scrambler.
Against adversaries, scrambling schemes can produce some very perplexing behaviour. See the "weak sectors" used for CD copy protection for one infamous example.