Can't get audio mixer to work

[junewunder]

as title says: I have been trying to get the audio mixer to work. I have followed the documentation and tried just using the example code mixer_basic.rs but I have not been able to get any audio output (from an emulator or the actual gba). I'm not sure how to debug this one any further but here is the example program I'm trying to run from the repository. I have copied the wav file to my own project.

#![no_std]
#![no_main]
#![cfg_attr(test, feature(custom_test_frameworks))]
#![cfg_attr(test, reexport_test_harness_main = "test_main")]
#![cfg_attr(test, test_runner(agb::test_runner::test_runner))]

extern crate alloc;

mod sfx;

use agb::{
    println,
    sound::mixer::{SoundChannel, Frequency}
};

pub const PURPLE_NIGHT: &[u8] = agb::include_wav!("sfx/01 - The Purple Night (Main Loop).wav");

#[agb::entry]
fn main(mut gba: agb::Gba) -> ! {
    let vblank = agb::interrupt::VBlank::get();
    vblank.wait_for_vblank();

    let mut mixer = gba.mixer.mixer(Frequency::Hz18157);
    mixer.enable();

    let mut song_pos: agb::fixnum::Num<usize, 8> = 0.into();

    let mut channel = SoundChannel::new_high_priority(PURPLE_NIGHT);
    channel.stereo().should_loop();
    let bgm = mixer.play_sound(channel);

    println!("init");
    println!("purple night len: {}", sfx::PURPLE_NIGHT.len());

    loop {
        if let Some(ref bgm) = bgm {
            song_pos = mixer.channel(bgm).expect("expected music to be playing").pos();
            println!("pos: {}", song_pos.to_raw());
        }

        mixer.frame();
        vblank.wait_for_vblank();
    }
}

update: it seems like it gets a little bit into the audio file and just pauses

[junewunder]

the problem was I was using 0.12.2 instead of 0.13, no idea what that was causing but that fixed it

[gwilymk]

Yeah, we changed the way audio was done in 0.13 to remove the need to call mixer.after_vblank() immediately after vblank.

So the examples will be in 0.13 where that method doesn't exist, but with 0.12 you needed that extra call. It would still compile but make no noise if you forget that call.

https://docs.rs/agb/0.12.2/agb/sound/mixer/index.html

Glad you got it working! And hopefully this explanation makes sense.

[junewunder]

thank you yes that does make sense, I'll be careful about versions in the future, it makes sense things are changing quickly