add opus audio support

.gitignore

@@ -23,3 +23,4 @@ minecraft/gen/map.txt
 test.pack
 pack_main
 .gdb_history
+*.pcm

Makefile

@@ -22,8 +22,12 @@ CFLAGS += -DREAD_PACK_FILE
 endif
 CFLAGS += -I./include
 CFLAGS += -I../SDL3-dist/include
+CFLAGS += -I../opus-dist/include
 
 LDFLAGS += -lm
+ifeq ($(shell uname),Linux)
+LDFLAGS += -Wl,-z noexecstack
+endif
 
 MINECRAFT_OBJS = \
 	minecraft/love2dworld/inthash.o \
@@ -58,6 +62,7 @@ OBJS = \
 	src/lua_api.o \
 	src/pixel_line_art.o \
 	src/flame.o \
+	src/audio.o \
 	data/scenes/ship20/ship20.o \
 	data/scenes/noodle/noodle.o \
 	data/scenes/shadow_test/shadow_test.o \
@@ -83,13 +88,10 @@ test.pack: pack_main $(PACK_FILENAMES)
 test.pack.o: test.pack
 	$(OBJCOPY) -I binary -O $(OBJARCH) $< $@
 
-test.so: $(OBJS)
-	$(CC) $(ARCH) $(OPT) -Wl,-z noexecstack -shared $(DEBUG) $^ -o $@ -lSDL3
-
 test.dll: $(OBJS)
 	$(CXX) $(ARCH) $(OPT) -mthreads -static -mdll -static-libstdc++ -static-libgcc $(DEBUG) $^ -o $@ -L. -lSDL3 $(WINDOWS)
 
-main: $(OBJS) src/main.o ../SDL3-dist/lib64/libSDL3.a
+main: $(OBJS) src/main.o ../SDL3-dist/lib64/libSDL3.a ../opus-dist/lib/libopus.a
 	$(CC) $(ARCH) $(LDFLAGS) $(OPT) $(DEBUG) $^ -o $@
 
 clean:

filenames.txt

@@ -55,3 +55,4 @@ data/scenes/book/book.idx
 shader/flame.vert
 shader/flame.frag
 minecraft/flame.data
+audio/Suite.opus.bin

include/audio.h

@@ -0,0 +1,7 @@
+#pragma once
+
+namespace audio {
+  void init();
+  void load();
+  void update();
+}

sdl3-build.sh

@@ -1,3 +1,9 @@
 cmake ../SDL3-3.4.2/ -DBUILD_SHARED_LIBS=OFF -DCMAKE_BUILD_TYPE=Debug -DCMAKE_INSTALL_PREFIX=../SDL3-dist
 cmake --build . --config Debug
 cmake --install . --config Debug
+
+
+# opus
+../opus-1.6.1/configure LDFLAGS="-static" CFLAGS="-march=x86-64-v3 -O2 -pipe" --prefix=../opus-dist
+make
+make install

src/audio.cpp

@@ -0,0 +1,123 @@
+#include <assert.h>
+#include <stdint.h>
+#include <stdio.h>
+
+#include <opus/opus.h>
+#include <SDL3/SDL.h>
+
+#include "file.h"
+#include "audio.h"
+
+namespace audio {
+
+  int const frame_samples = 960; // 20 milliseconds @ 48kHz
+  int const sample_rate = 48000;
+  int const channels = 2;
+  int const sample_size = (sizeof (int16_t));
+
+  int const max_frame_size = 960 * 3; // 20ms at 48kHz
+  int const max_packet_size = 1275;
+
+  //
+
+  SDL_AudioStream * audio_stream;
+  SDL_AudioSpec audio_spec;
+  void const * audio_buf;
+  int audio_size;
+  int audio_samples_total;
+  int audio_offset;
+  int audio_samples_decoded;
+
+  OpusDecoder * opus_decoder;
+
+  void init()
+  {
+    audio_spec.channels = channels;
+    audio_spec.format = SDL_AUDIO_S16LE;
+    audio_spec.freq = sample_rate;
+    audio_stream = SDL_OpenAudioDeviceStream(SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK, &audio_spec, NULL, NULL);
+    assert(audio_stream);
+    SDL_ResumeAudioStreamDevice(audio_stream);
+
+    int err;
+    opus_decoder = opus_decoder_create(sample_rate, channels, &err);
+    if (err < 0) {
+      fprintf(stderr, "opus_decoder_create: %s\n", opus_strerror(err));
+      assert(!"opus_decoder_create");
+    }
+  }
+
+  void load()
+  {
+    audio_buf = file::read_file("audio/Suite.opus.bin", &audio_size);
+    assert(audio_buf != nullptr);
+
+    uint8_t const * buf = (uint8_t const *)audio_buf;
+    audio_samples_total
+      = (buf[3] << 24)
+      | (buf[2] << 16)
+      | (buf[1] << 8)
+      | (buf[0] << 0);
+    printf("audio samples total: %d\n", audio_samples_total);
+
+    audio_offset = 4;
+    audio_samples_decoded = 0;
+  }
+
+  inline static int min(int a, int b)
+  {
+    return (a < b) ? a : b;
+  }
+
+  void update()
+  {
+    int half_period_samples = audio_spec.freq / 2;
+    int half_period_size = half_period_samples * sample_size * audio_spec.channels;
+
+    if (SDL_GetAudioStreamQueued(audio_stream) < half_period_size) {
+      int put_samples = half_period_samples;
+
+      while (put_samples > 0) {
+        uint8_t const * buf = (uint8_t const *)audio_buf;
+
+        assert(audio_offset <= audio_size);
+        if (audio_offset == audio_size) {
+          assert(audio_samples_decoded == audio_samples_total);
+          audio_offset = 4;
+          audio_samples_decoded = 0;
+
+          int err = opus_decoder_ctl(opus_decoder, OPUS_RESET_STATE);
+          if (err < 0) {
+            fprintf(stderr, "opus_encoder_ctl(OPUS_RESET_STATE): %s\n", opus_strerror(err));
+            assert(!"opus_encoder_ctl");
+          }
+        }
+
+        uint16_t packet_size = (buf[audio_offset + 1] << 8) | (buf[audio_offset + 0] << 0);
+        audio_offset += 2;
+        int16_t decode_buf[max_frame_size * channels];
+        int frame_size = opus_decode(opus_decoder, &buf[audio_offset], packet_size, decode_buf, max_frame_size, 0);
+        if (frame_size < 0) {
+          fprintf(stderr, "opus_decode: %s\n", opus_strerror(frame_size));
+          assert(!"opus_decode\n");
+        }
+        audio_offset += packet_size;
+
+        int max_samples_this_frame = audio_samples_total - audio_samples_decoded;
+        assert(max_samples_this_frame > 0);
+        /*
+        if (frame_size > max_samples_this_frame) {
+          fprintf(stderr, "max samples %d %d\n", frame_size, max_samples_this_frame);
+        }
+        */
+        frame_size = min(max_samples_this_frame, frame_size);
+
+        SDL_PutAudioStreamData(audio_stream,
+                               (void *)decode_buf,
+                               frame_size * channels * sample_size);
+        put_samples -= frame_size;
+        audio_samples_decoded += frame_size;
+      }
+    }
+  }
+}

src/main.cpp

@@ -8,6 +8,7 @@
 #include "test.h"
 #include "window.h"
 #include "view.h"
+#include "audio.h"
 
 static int const max_gamepads = 16;
 static SDL_Gamepad * gamepads[max_gamepads];
@@ -125,6 +126,8 @@ int main()
   }
 
   load(".");
+  audio::init();
+  audio::load();
 
   update_window(1024, 1024);
 
@@ -153,6 +156,8 @@ int main()
     update();
     draw();
 
+    audio::update();
+
     SDL_GL_SwapWindow(window);
   }
 

tool/Makefile

@@ -0,0 +1,5 @@
+OPT = -O2
+CFLAGS = -I../../opus-dist/include
+
+opus_encode: opus_encode.c ../../opus-dist/lib/libopus.a
+	gcc -o $@ $(OPT) $(CFLAGS) -lm $^

tool/opus_encode.c

@@ -0,0 +1,121 @@
+#include <assert.h>
+#include <errno.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <opus/opus.h>
+
+const int frame_size = 960; // 20ms at 48kHz
+const int sample_rate = 48000;
+const int channels = 2;
+const int bitrate = 128000;
+
+const int max_packet_size = 3 * 1275;
+
+int main(int argc, char *argv[])
+{
+  assert(argc == 3);
+  int err;
+
+  OpusEncoder * encoder = opus_encoder_create(sample_rate, channels, OPUS_APPLICATION_AUDIO, &err);
+  if (err < 0) {
+    fprintf(stderr, "opus_encoder_create: %s\n", opus_strerror(err));
+    return 1;
+  }
+
+  err = opus_encoder_ctl(encoder, OPUS_SET_BITRATE(bitrate));
+  if (err < 0) {
+    fprintf(stderr, "opus_encoder_ctl(OPUS_SET_BITRATE): %s\n", opus_strerror(err));
+    return 1;
+  }
+
+  char const * input_filename = argv[1];
+  FILE * input_file = fopen(input_filename, "rb");
+  if (input_file == NULL) {
+    fprintf(stderr, "fopen(%s): %s\n", input_filename, strerror(errno));
+    return 1;
+  }
+
+  char const * output_filename = argv[2];
+  FILE * output_file = fopen(output_filename, "wb");
+  if (input_file == NULL) {
+    fprintf(stderr, "fopen(%s): %s\n", output_filename, strerror(errno));
+    return 1;
+  }
+
+  int16_t input[frame_size * channels];
+  uint8_t input_buf[frame_size * channels * (sizeof (int16_t))];
+  uint8_t encode_buf[max_packet_size];
+
+  int total_samples = 0;
+  size_t header_write_1 = fwrite(&total_samples, 1, (sizeof (int)), output_file);
+  if (header_write_1 != (sizeof (int))) {
+    fprintf(stderr, "fwrite: %s\n", strerror(errno));
+    return 1;
+  }
+
+  bool more_data = true;
+  while (more_data) {
+    size_t samples = fread(input_buf, (sizeof (int16_t)) * channels, frame_size, input_file);
+    if (samples == 0)
+      break;
+
+    total_samples += samples;
+
+    if (samples != frame_size) {
+      printf("padding short frame %ld\n", samples);
+      more_data = false;
+      for (int i = samples * channels; i < frame_size * channels; i++) {
+        input_buf[i * 2 + 0] = 0;
+        input_buf[i * 2 + 1] = 0;
+      }
+    }
+    samples = frame_size;
+
+    for (int i = 0; i < channels * frame_size; i++) {
+      // load little endian
+      input[i] = (input_buf[2 * i + 1] << 8) | (input_buf[2 * i + 0] << 0);
+    }
+
+    int bytes = opus_encode(encoder, input, frame_size, encode_buf, max_packet_size);
+    if (bytes < 0) {
+      fprintf(stderr, "opus_encode: %s\n", opus_strerror(bytes));
+      return 1;
+    }
+    assert(bytes <= 1275);
+
+    int16_t encode_bytes = bytes;
+    size_t bytes_write = fwrite(&encode_bytes, 1, (sizeof (encode_bytes)), output_file);
+    if (bytes_write != (sizeof (encode_bytes))) {
+      fprintf(stderr, "fwrite: %s\n", strerror(errno));
+      return 1;
+    }
+    size_t buf_write = fwrite(encode_buf, 1, bytes, output_file);
+    if (buf_write != bytes) {
+      fprintf(stderr, "fwrite: %s\n", strerror(errno));
+      return 1;
+    }
+  }
+
+  fflush(output_file);
+
+  int ret = fseek(output_file, SEEK_SET, 0);
+  if (ret != 0) {
+    fprintf(stderr, "fseek: %s\n", strerror(errno));
+    return 1;
+  }
+
+  size_t header_write_2 = fwrite(&total_samples, 1, (sizeof (int)), output_file);
+  if (header_write_2 != (sizeof (int))) {
+    fprintf(stderr, "fwrite: %s\n", strerror(errno));
+    return 1;
+  }
+  printf("total_samples: %d\n", total_samples);
+
+  fclose(output_file);
+  fclose(input_file);
+
+  return 0;
+}