From 10e2ce9ba46b4b1e720fa6847854854223d97d22 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Sun, 24 Nov 2024 15:05:12 -0500
Subject: [PATCH] examples: Added audio/04-multiple-streams
---
examples/CMakeLists.txt | 1 +
examples/audio/04-multiple-streams/README.txt | 5 +
.../04-multiple-streams/multiple-streams.c | 151 ++++++++++++++++++
3 files changed, 157 insertions(+)
create mode 100644 examples/audio/04-multiple-streams/README.txt
create mode 100644 examples/audio/04-multiple-streams/multiple-streams.c
diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
index b886ba5df8d4c..85621449aa937 100644
--- a/examples/CMakeLists.txt
+++ b/examples/CMakeLists.txt
@@ -139,6 +139,7 @@ add_sdl_example_executable(renderer-debug-text SOURCES renderer/18-debug-text/de
add_sdl_example_executable(audio-simple-playback SOURCES audio/01-simple-playback/simple-playback.c)
add_sdl_example_executable(audio-simple-playback-callback SOURCES audio/02-simple-playback-callback/simple-playback-callback.c)
add_sdl_example_executable(audio-load-wav SOURCES audio/03-load-wav/load-wav.c DATAFILES ${CMAKE_CURRENT_SOURCE_DIR}/../test/sample.wav)
+add_sdl_example_executable(audio-multiple-streams SOURCES audio/04-multiple-streams/multiple-streams.c)
add_sdl_example_executable(camera-read-and-draw SOURCES camera/01-read-and-draw/read-and-draw.c)
add_sdl_example_executable(pen-drawing-lines SOURCES pen/01-drawing-lines/drawing-lines.c)
add_sdl_example_executable(demo-snake SOURCES demo/01-snake/snake.c)
diff --git a/examples/audio/04-multiple-streams/README.txt b/examples/audio/04-multiple-streams/README.txt
new file mode 100644
index 0000000000000..cdbc0202b7b6e
--- /dev/null
+++ b/examples/audio/04-multiple-streams/README.txt
@@ -0,0 +1,5 @@
+This example code loads .wav files dropped onto the app window, puts
+them in an audio stream and binds them for playback. This shows several
+streams mixing into a single playback device.
+
+Drag several files while one is still playing!
diff --git a/examples/audio/04-multiple-streams/multiple-streams.c b/examples/audio/04-multiple-streams/multiple-streams.c
new file mode 100644
index 0000000000000..b2c494f88d544
--- /dev/null
+++ b/examples/audio/04-multiple-streams/multiple-streams.c
@@ -0,0 +1,151 @@
+/*
+ * This example code loads .wav files dropped onto the app window, puts
+ * them in an audio stream and binds them for playback. This shows several
+ * streams mixing into a single playback device.
+ *
+ * This code is public domain. Feel free to use it for any purpose!
+ */
+
+#define SDL_MAIN_USE_CALLBACKS 1 /* use the callbacks instead of main() */
+#include <SDL3/SDL.h>
+#include <SDL3/SDL_main.h>
+
+/* We will use this renderer to draw into this window every frame. */
+static SDL_Window *window = NULL;
+static SDL_Renderer *renderer = NULL;
+static SDL_AudioDeviceID audio_device = 0;
+static SDL_AudioStream **streams = NULL;
+static int num_streams = 0;
+
+/* This function runs once at startup. */
+SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
+{
+ SDL_SetAppMetadata("Example Audio Multiple Streams", "1.0", "com.example.audio-multiple-streams");
+
+ if (!SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO)) {
+ SDL_Log("Couldn't initialize SDL: %s", SDL_GetError());
+ return SDL_APP_FAILURE;
+ }
+
+ if (!SDL_CreateWindowAndRenderer("examples/audio/multiple-streams", 640, 480, 0, &window, &renderer)) {
+ SDL_Log("Couldn't create window/renderer: %s", SDL_GetError());
+ return SDL_APP_FAILURE;
+ }
+
+ /* open the default audio device in whatever format it prefers; our audio streams will adjust to it. */
+ audio_device = SDL_OpenAudioDevice(SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK, NULL);
+ if (audio_device == 0) {
+ SDL_Log("Couldn't open audio device: %s", SDL_GetError());
+ return SDL_APP_FAILURE;
+ }
+
+ return SDL_APP_CONTINUE; /* carry on with the program! */
+}
+
+static void load_wav_file(const char *fname)
+{
+ int idx;
+ SDL_AudioSpec spec;
+ Uint8 *wav_data = NULL;
+ Uint32 wav_data_len = 0;
+
+ /* Find an unused element in the streams array... */
+ for (idx = 0; idx < num_streams; idx++) {
+ if (streams[idx] == NULL) {
+ break;
+ }
+ }
+
+ /* No space? Grow the array. */
+ if (idx == num_streams) {
+ void *ptr = SDL_realloc(streams, (num_streams + 1) * sizeof (*streams));
+ if (!ptr) {
+ SDL_Log("Out of memory!");
+ return; // oh well.
+ }
+ streams = (SDL_AudioStream **) ptr;
+ streams[idx] = NULL;
+ num_streams++;
+ }
+
+ /* Load the new .wav file */
+ if (!SDL_LoadWAV(fname, &spec, &wav_data, &wav_data_len)) {
+ SDL_Log("Failed to load '%s': %s", fname, SDL_GetError());
+ return; // oh well.
+ }
+
+ /* Create an audio stream. Set the source format to the wav's format (what
+ we'll input), leave the dest format NULL here (it'll change to what the
+ device wants once we bind it). */
+ streams[idx] = SDL_CreateAudioStream(&spec, NULL);
+ if (!streams[idx]) {
+ SDL_Log("Couldn't create audio stream: %s", SDL_GetError());
+ } else if (!SDL_BindAudioStream(audio_device, streams[idx])) { /* once bound, it'll start playing when there is data available! */
+ SDL_Log("Failed to bind '%s' stream to device: %s", fname, SDL_GetError());
+ } else if (!SDL_PutAudioStreamData(streams[idx], wav_data, (int) wav_data_len)) {
+ SDL_Log("Failed to put '%s' data into stream: %s", fname, SDL_GetError());
+ } else {
+ /* tell SDL we won't be sending more data to this stream, so don't hold back for resampling. */
+ SDL_FlushAudioStream(streams[idx]);
+ }
+
+ SDL_free(wav_data);
+}
+
+/* This function runs when a new event (mouse input, keypresses, etc) occurs. */
+SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event)
+{
+ if (event->type == SDL_EVENT_QUIT) {
+ return SDL_APP_SUCCESS; /* end the program, reporting success to the OS. */
+ } else if (event->type == SDL_EVENT_DROP_FILE) {
+ load_wav_file(event->drop.data);
+ }
+ return SDL_APP_CONTINUE; /* carry on with the program! */
+}
+
+/* This function runs once per frame, and is the heart of the program. */
+SDL_AppResult SDL_AppIterate(void *appstate)
+{
+ int winw = 640, winh = 480;
+ const char *text = "--> Drag and drop .wav files here <--";
+ float x, y;
+ int i;
+
+ /* see if any streams have finished; destroy them if so. */
+ for (i = 0; i < num_streams; i++) {
+ if (streams[i] && (SDL_GetAudioStreamAvailable(streams[i]) == 0)) {
+ SDL_DestroyAudioStream(streams[i]);
+ streams[i] = NULL;
+ }
+ }
+
+ SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
+ SDL_RenderClear(renderer);
+ SDL_GetWindowSize(window, &winw, &winh);
+ x = (((float) winw) - (SDL_strlen(text) * SDL_DEBUG_TEXT_FONT_CHARACTER_SIZE)) / 2.0f;
+ y = (((float) winh) - SDL_DEBUG_TEXT_FONT_CHARACTER_SIZE) / 2.0f;
+ SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
+ SDL_RenderDebugText(renderer, x, y, text);
+ SDL_RenderPresent(renderer);
+
+ return SDL_APP_CONTINUE; /* carry on with the program! */
+}
+
+/* This function runs once at shutdown. */
+void SDL_AppQuit(void *appstate, SDL_AppResult result)
+{
+ int i;
+
+ SDL_CloseAudioDevice(audio_device);
+
+ /* see if any streams have finished; destroy them if so. */
+ for (i = 0; i < num_streams; i++) {
+ if (streams[i]) {
+ SDL_DestroyAudioStream(streams[i]);
+ }
+ }
+
+ SDL_free(streams);
+
+ /* SDL will clean up the window/renderer for us. */
+}