GBA FLAC Demo

Video preview

Usage notes

If you run this in something other than a hardware GBA, DS, or 3DS+open_gba_firm, be sure to enable the interframe blending feature in the settings, to simulate the LCD ghosting that occurs on the portables' hardware, which this demo requires for its visual effects.

• In the official GameBoy Player Start-up Disc, that's Z Button : Options|Sharpness|Soft
• In GameBoyInterface, that's --filter=blend in the .dol+cli arguments.
• In mGBA, that's Audio/Video|:heavy_check_mark:Interframe blending. You may also need to disable Tools|Settings...|BIOS|:white_large_square:Use BIOS file if found to avoid a crash whose cause I have yet to determine. Press the Select button after enabling Info logging (Tools|View logs...|:ballot_box_with_check:Info) to view licenses of third-party runtime dependency crates which require a copyright message to be reproduced in binary distributions.
• In VisualBoyAdvance-M, that's Options|Video|Change interframe blending; select that option until the status bar (Options|Video|Status bar) says "Using interframe blending #2". Note that despite having a workaround baked into the demo to prevent flickering, there will still be some visible inaccuracy in the textbox rendering.
• No$GBA and NanoboyAdvance do not seem to have an interframe blending feature, but otherwise render correctly.
• While normally an accurate emulator, I currently can't recommend higan for this demo in particular, as it struggles with rendering the scanline effects properly (without flickering), and I don't yet have a way of detecting when the demo is running in higan to enable workarounds. But for completeness / in case the problem gets fixed after this writing, it's Settings|Video...|:ballot_box_with_check:Interframe Blending

Caveat for developers

The quality of a lot of the code here isn't what I'd call production-grade, or even idiomatic Rust; this was primarily a demo thrown together to demonstrate to myself that Rust was viable at all for targetting GBA hardware with a nontrivial workload (that is, more than just drawing three pixels to a framebuffer). There were already growing pains in the codebase by the time I finished this (particularly the mutable static global used for interfacing with the hardware in ways that completely neglect a lot of what Rust brings to the table in terms of Fearless Concurrency:tm:)

Development setup

Either clone this repo with git clone --recurse-submodules or use git submodule update --init --recursive to get all the dependencies.

Install youtube-dl, clang++, auto{conf,make}, libtool, pkg-config, gettext, ffmpeg, mgba-qt, SDL2-devel, SDL2_image-devel, and arm-none-eabi-{as,gcc,ld,objcopy} wherever Unix packages are sold. (If a cross-compile GCC toolchain for arm-none-eabi isn't packaged for your distribution, you may choose to simply use the one included in devkitARM from devkitPro, but devkitPro is not required)

You'll need at least the nightly-2021-01-15 (or so) Rust toolchain.

rustup toolchain install nightly
rustup component add --toolchain nightly rust-src

If you're on Windows, you'll probably want to try doing all this in WSL or LxSS or whatever they're calling it these days. It might work!

Build and run

cargo run --release

Make ROM for hardware

(Or just for non-development-oriented emulators)

You'll need gbafix from either cargo (cargo install gbafix) or devkitPro.

make

You'll find the built ROM at target/flac-demo-release.gba.

Acknowledgements

Thanks to Lokathor & other contributors to rust-console/gba.

Thanks to Nayuki for the accessible example of FLAC decoding.

Thanks to Leonarth for the VBA-detection trick.

Thanks to endrift for mGBA, without which development would be a huge pain.