From 7894b8c1e8b286e5a5f7f6b90376e434d6a565d3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jo=C3=A3o=20Magalh=C3=A3es?= <joamag@gmail.com>
Date: Tue, 28 Feb 2023 00:27:36 +0000
Subject: [PATCH] feat: initial support for audio in the web front-end There
are a series of hacks involved in making a constant stream of audio data to
work OK with web audio.
---
frontends/web/ts/gb.ts | 81 +++++++++++++++++++++++++++++++++++++++---
src/gb.rs | 8 +++--
2 files changed, 83 insertions(+), 6 deletions(-)
diff --git a/frontends/web/ts/gb.ts b/frontends/web/ts/gb.ts
index 3dec704e..277ab156 100644
--- a/frontends/web/ts/gb.ts
+++ b/frontends/web/ts/gb.ts
@@ -80,6 +80,13 @@ const KEYS_NAME: Record<string, number> = {
const ROM_PATH = require("../../../res/roms/pocket.gb");
+// @TODO: check if this is the right place for this struct
+type AudioChunk = {
+ source: AudioBufferSourceNode;
+ playTime: number;
+ duration: number;
+};
+
/**
* Top level class that controls the emulator behaviour
* and "joins" all the elements together to bring input/output
@@ -115,6 +122,13 @@ export class GameboyEmulator extends EmulatorBase implements Emulator {
private romSize = 0;
private cartridge: Cartridge | null = null;
+ // @TODO: try to think where does this belong
+ private audioContext = new AudioContext({
+ sampleRate: 44100
+ });
+ private audioChunks: AudioChunk[] = [];
+ private nextPlayTime = 0.0;
+
/**
* Associative map for extra settings to be used in
* opaque local storage operations, associated setting
@@ -226,6 +240,10 @@ export class GameboyEmulator extends EmulatorBase implements Emulator {
}
tick(currentTime: number, pending: number, cycles = 70224) {
+ // in case the reference to the system is not set then
+ // returns the control flow immediately (not possible to tick)
+ if (!this.gameBoy) return pending;
+
// in case the time to draw the next frame has not been
// reached the flush of the "tick" logic is skipped
if (currentTime < this.nextTickTime) return pending;
@@ -245,19 +263,19 @@ export class GameboyEmulator extends EmulatorBase implements Emulator {
// runs the Game Boy clock, this operations should
// include the advance of both the CPU and the PPU
- const tickCycles = this.gameBoy?.clock() ?? 0;
+ const tickCycles = this.gameBoy.clock();
counterCycles += tickCycles;
// in case the current PPU mode is VBlank and the
// frame is different from the previously rendered
// one then it's time to update the canvas
if (
- this.gameBoy?.ppu_mode() === PpuMode.VBlank &&
- this.gameBoy?.ppu_frame() !== lastFrame
+ this.gameBoy.ppu_mode() === PpuMode.VBlank &&
+ this.gameBoy.ppu_frame() !== lastFrame
) {
// updates the reference to the last frame index
// to be used for comparison in the next tick
- lastFrame = this.gameBoy?.ppu_frame();
+ lastFrame = this.gameBoy.ppu_frame();
// triggers the frame event indicating that
// a new frame is now available for drawing
@@ -304,6 +322,61 @@ export class GameboyEmulator extends EmulatorBase implements Emulator {
);
ticks = Math.max(ticks, 1);
+ // --- START OF THE AUDIO CODE
+
+ const channels = 2;
+ const internalBuffer = this.gameBoy.audio_buffer_eager(true);
+ const audioBuffer = this.audioContext.createBuffer(
+ channels,
+ internalBuffer.length,
+ 44100
+ );
+
+ for (let channel = 0; channel < channels; channel++) {
+ const channelBuffer = audioBuffer.getChannelData(channel);
+ for (let index = 0; index < internalBuffer.length; index++) {
+ channelBuffer[index] = internalBuffer[index] / 100.0;
+ }
+ }
+
+ // @todo check this code so see if it makes sense
+
+ // makes sure that we're not too far away from the audio
+ // and if that's the case drops some of the audio to regain
+ // some sync, this is required because of time hogging
+ const audioCurrentTime = this.audioContext.currentTime;
+ if (
+ this.nextPlayTime > audioCurrentTime + 0.05 ||
+ this.nextPlayTime < audioCurrentTime
+ ) {
+ // @TODO: this is tricky as it cancels most of the code
+ this.audioChunks.forEach((chunk) => {
+ chunk.source.disconnect(this.audioContext.destination);
+ chunk.source.stop();
+ });
+ this.audioChunks = [];
+ this.nextPlayTime = audioCurrentTime;
+ }
+
+ const source = this.audioContext.createBufferSource();
+ source.buffer = audioBuffer;
+ source.connect(this.audioContext.destination);
+
+ this.nextPlayTime = this.nextPlayTime || audioCurrentTime;
+
+ const chunk: AudioChunk = {
+ source: source,
+ playTime: this.nextPlayTime,
+ duration: audioBuffer.length / 44100.0
+ };
+
+ source.start(chunk.playTime);
+ this.nextPlayTime += chunk.duration;
+
+ this.audioChunks.push(chunk);
+
+ // ---- END OF THE AUDIO CODE
+
// updates the next update time according to the number of ticks
// that have elapsed since the last operation, this way this value
// can better be used to control the game loop
diff --git a/src/gb.rs b/src/gb.rs
index 015f0c92..7cbafab9 100644
--- a/src/gb.rs
+++ b/src/gb.rs
@@ -164,8 +164,12 @@ impl GameBoy {
self.frame_buffer().to_vec()
}
- pub fn audio_buffer_eager(&mut self) -> Vec<u8> {
- self.audio_buffer().to_vec()
+ pub fn audio_buffer_eager(&mut self, clear: bool) -> Vec<u8> {
+ let buffer = self.audio_buffer().to_vec();
+ if clear {
+ self.clear_audio_buffer();
+ }
+ buffer
}
pub fn cartridge_eager(&mut self) -> Cartridge {
--
GitLab