Bad Apple but It's Played Inside Super Mario Bros

I share the full assembly code in the tasvideos writeup: https://tasvideos.org/8991S#HereSTheAsmCode

To summarize what I put in the writeup, the 7-bit PCM audio was streamed in at approximately 25 Khz, (reading from the controller and writing to address $4011 every 71 CPU cycles.) while occasionally dipping to 9 Khz while streaming in the graphics data.

They use a modified ROM to set the memory state, but that could be done with SMB3 manually, apparently.

This is a video of it running on a console, though I'm uncertain how the inputs were provided

There's online forums for posting speed-running accomplishments and challenging others' accomplishments.

I'n this case, someone used the tools for automated speed running, to execute a glitch in SMB that allows for arbitrary code execution, then entered and ran a program that plays a Bad Apple music video, all with controller input. This is posted as a speed run with an accomplishment of playing the video.

A custom cartridge could be made to make a Bad Apple music video, but this is showing off a way to play the video using only SMB cartridges.

The data has to fit into RAM, which is much smaller than a tricky cartridge ROM. The music and graphic data is streamed as controller inputs, but the rest is done in RAM, using some data already in the SMB cartridge for video output, due to the low bitrate of controller input but also because the video processor can't display directly from RAM.

Controller inputs, same as if you were playing SMB yourself. This "just" presses buttons a lot faster and with more precision.

For a bit more background, this type of thing originally grew out of the game speedrunning community. Some people were interested in how much faster a speedrun could become if a "perfect" human with complete knowledge of the game state and perfect execution ran a game, and they modified games/created tools to mimic what such a run would look like, resulting in tool-assisted speedruns.

Because of this goal of showing off what might be theoretically possible, TASes are nearly universally restricted to ~the same input methods that humans would use. Where TASes differ is in how they're created, as they make use of external tools such as memory inspection (e.g., to observe RNG, player/enemy positions/speeds, etc.), frame advance/programmed input (for perfectly precise/reproducible inputs), and save states (so sections can be tried over and over again to correct mistakes, try different RNG, etc.).

> Why does it involve playing part of SMB to start with?

This is also tied to TASes showing off what is theoretically possible. Because of this, TASes pretty much always start from some "normal" state - game power-on (the normal start state for TASes submitted to tasvideos.org), a game state that is reachable by a normal human (e.g., done for one of the Ocarina of Time showcases at one of the Games Done Quick events IIRC), etc.

> Besides the sprites used, what does this have to do with SMB at all?

One of the "holy grails" of TASes is arbitrary code execution (ACE), where you manipulate a game into a state where you can get it to execute arbitrary code. This TAS shows that only using controller inputs it's possible to manipulate SMB and the game hardware into a state where ACE is possible.

> How is this different from just a custom ROM that would play this music video?

The difference is in the journey, not the destination. An analogy might be installing "plain" malware on a computer vs. finding/writing a RCE chain that gets you the same capabilities. The latter might be considered more technically impressive/interesting to certain communities.

> Could you even fit this much data into a ROM?

Not as-is in this case. Here the data is streamed in, sort of as if the controllers were serving as extended memory.

> And the "objectives" list at the top isn't helping ("1. Do a little tomfoolery 2. Execute arbitrary code..."). What are the actual parameters of this challenge, to understand what is actually being achieved?

TASes submitted to tasvideos.org come with a submitter-chosen list of objectives for the TAS since different TASes for the same game may aim to do different things. One TAS may try to finish a game as fast as possible using any possible method, another TAS may try to finish a game as fast as possible while restricting the use of some approaches, some TASes may try to finish a game as fast as possible while also getting a "true" ending or "full" completion, some TASes may just try to be entertaining without trying to be as fast as possible, etc.

Not all objectives are deemed worthwhile of official publication by tasvideos.org, but IIRC there aren't any hard-and-fast rules about what is acceptable and what isn't.

This particular TAS was submitted on April Fool's, so there's a bit of additional silliness involved.

This video is done by hand and explains a bit more about how and why it works: https://www.youtube.com/watch?v=hB6eY73sLV0

You could in theory perform this on the original SNES hardware with the original SMB game cartridge, if you can press the buttons on the gamepad fast enough and with the right timing.

a good video that makes this tech more understandable (with explanations at the beginnimg and an amazing demo at the end) https://www.youtube.com/watch?v=PNbkv_DJ0f0

and some background https://tasvideos.org/ArbitraryCodeExecutionHowTo