Apple-2-Tools/bradgrantham-apple2e
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Use two 16-bit channels

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This commit is contained in:
Brad Grantham 2017-01-04 23:19:27 -08:00
parent 442faa4677
commit 4477878011
1 changed files with 15 additions and 13 deletions
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28
testsdl.cpp
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@ -14,26 +14,30 @@
#define BUF_SIZE 4096
unsigned long long audio_pos;
unsigned char buf[32768];
unsigned long long audio_pos = 0;
unsigned short buf[2048];
const int freq = 440;
float freq1 = 440;
float freq2 = 410;
const int rate = 44100;
/* The audio function callback takes the following parameters:
stream: A pointer to the audio buffer to be filled
len: The length (in bytes) of the audio buffer
*/
void fill_audio(void *udata, Uint8 *stream, int len)
void fill_audio(void *userdata, Uint8 *stream, int len)
{
for (int i = 0; i < len; i++) {
buf[i] = (int)(0.75 * 128.0 *
sin(2 * M_PI * freq * ((float) (audio_pos + i)/rate)));
printf("fill audio %d\n", len);
for (int i = 0; i < len / 4; i++) {
buf[i * 2 + 0] = (int)(0.75 * 32768.0 *
sin(2 * M_PI * freq1 * ((float) (audio_pos + i)/rate)));
buf[i * 2 + 1] = (int)(0.75 * 32768.0 *
sin(2 * M_PI * freq2 * ((float) (audio_pos + i)/rate)));
}
/* Mix as much data as possible */
SDL_MixAudio(stream, buf, len, SDL_MIX_MAXVOLUME);
audio_pos += len;
SDL_MixAudio(stream, (unsigned char *)buf, len, SDL_MIX_MAXVOLUME);
audio_pos += len / 4;
}
time_t now;
@ -56,8 +60,8 @@ extern "C" int main(int argc, char **argv)
/* Set the audio format */
wanted.freq = rate;
wanted.format = AUDIO_S8;
wanted.channels = 1; /* 1 = mono, 2 = stereo */
wanted.format = AUDIO_S16;
wanted.channels = 2; /* 1 = mono, 2 = stereo */
wanted.samples = 1024; /* Good low-latency value for callback */
wanted.callback = fill_audio;
wanted.userdata = NULL;
@ -69,8 +73,6 @@ extern "C" int main(int argc, char **argv)
}
printf("opened audio\n");
audio_pos = 0;
/* Let the callback function play the audio chunk */
SDL_PauseAudio(0);
printf("unpaused audio, playing...\n");