static boolean ExpandSoundData_SRC(sfxinfo_t *sfxinfo,
byte *data,
int samplerate,
int length)
{
SRC_DATA src_data;
uint32_t i, abuf_index=0, clipped=0;
uint32_t alen;
int retn;
int16_t *expanded;
Mix_Chunk *chunk;
src_data.input_frames = length;
src_data.data_in = malloc(length * sizeof(float));
src_data.src_ratio = (double)mixer_freq / samplerate;
// We include some extra space here in case of rounding-up.
src_data.output_frames = src_data.src_ratio * length + (mixer_freq / 4);
src_data.data_out = malloc(src_data.output_frames * sizeof(float));
assert(src_data.data_in != NULL && src_data.data_out != NULL);
// Convert input data to floats
for (i=0; i<length; ++i)
{
// Unclear whether 128 should be interpreted as "zero" or whether a
// symmetrical range should be assumed. The following assumes a
// symmetrical range.
src_data.data_in[i] = data[i] / 127.5 - 1;
}
// Do the sound conversion
retn = src_simple(&src_data, SRC_ConversionMode(), 1);
assert(retn == 0);
// Allocate the new chunk.
alen = src_data.output_frames_gen * 4;
chunk = AllocateSound(sfxinfo, src_data.output_frames_gen * 4);
if (chunk == NULL)
{
return false;
}
expanded = (int16_t *) chunk->abuf;
// Convert the result back into 16-bit integers.
for (i=0; i<src_data.output_frames_gen; ++i)
{
// libsamplerate does not limit itself to the -1.0 .. 1.0 range on
// output, so a multiplier less than INT16_MAX (32767) is required
// to avoid overflows or clipping. However, the smaller the
// multiplier, the quieter the sound effects get, and the more you
// have to turn down the music to keep it in balance.
// 22265 is the largest multiplier that can be used to resample all
// of the Vanilla DOOM sound effects to 48 kHz without clipping
// using SRC_SINC_BEST_QUALITY. It is close enough (only slightly
// too conservative) for SRC_SINC_MEDIUM_QUALITY and
// SRC_SINC_FASTEST. PWADs with interestingly different sound
// effects or target rates other than 48 kHz might still result in
// clipping--I don't know if there's a limit to it.
// As the number of clipped samples increases, the signal is
// gradually overtaken by noise, with the loudest parts going first.
// However, a moderate amount of clipping is often tolerated in the
// quest for the loudest possible sound overall. The results of
// using INT16_MAX as the multiplier are not all that bad, but
// artifacts are noticeable during the loudest parts.
float cvtval_f =
src_data.data_out[i] * libsamplerate_scale * INT16_MAX;
int32_t cvtval_i = cvtval_f + (cvtval_f < 0 ? -0.5 : 0.5);
// Asymmetrical sound worries me, so we won't use -32768.
if (cvtval_i < -INT16_MAX)
{
cvtval_i = -INT16_MAX;
++clipped;
}
else if (cvtval_i > INT16_MAX)
{
cvtval_i = INT16_MAX;
++clipped;
}
// Left and right channels
expanded[abuf_index++] = cvtval_i;
expanded[abuf_index++] = cvtval_i;
}
free(src_data.data_in);
free(src_data.data_out);
if (clipped > 0)
{
fprintf(stderr, "Sound '%s': clipped %u samples (%0.2f %%)\n",
sfxinfo->name, clipped,
400.0 * clipped / chunk->alen);
}
return true;
}
static boolean I_SDL_InitSound(boolean _use_sfx_prefix)
{
int i;
use_sfx_prefix = _use_sfx_prefix;
// No sounds yet
for (i=0; i<NUM_CHANNELS; ++i)
{
channels_playing[i] = NULL;
}
if (SDL_Init(SDL_INIT_AUDIO) < 0)
{
fprintf(stderr, "Unable to set up sound.\n");
return false;
}
if (Mix_OpenAudio(snd_samplerate, AUDIO_S16SYS, 2, GetSliceSize()) < 0)
{
fprintf(stderr, "Error initialising SDL_mixer: %s\n", Mix_GetError());
return false;
}
ExpandSoundData = ExpandSoundData_SDL;
Mix_QuerySpec(&mixer_freq, &mixer_format, &mixer_channels);
#ifdef HAVE_LIBSAMPLERATE
if (use_libsamplerate != 0)
{
if (SRC_ConversionMode() < 0)
{
I_Error("I_SDL_InitSound: Invalid value for use_libsamplerate: %i",
use_libsamplerate);
}
ExpandSoundData = ExpandSoundData_SRC;
}
#else
if (use_libsamplerate != 0)
{
fprintf(stderr, "I_SDL_InitSound: use_libsamplerate=%i, but "
"libsamplerate support not compiled in.\n",
use_libsamplerate);
}
#endif
// SDL_mixer version 1.2.8 and earlier has a bug in the Mix_SetPanning
// function that can cause the game to lock up. If we're using an old
// version, we need to apply a workaround. But the workaround has its
// own drawbacks ...
{
const SDL_version *mixer_version;
int v;
mixer_version = Mix_Linked_Version();
v = SDL_VERSIONNUM(mixer_version->major,
mixer_version->minor,
mixer_version->patch);
if (v <= SDL_VERSIONNUM(1, 2, 8))
{
setpanning_workaround = true;
fprintf(stderr, "\n"
"ATTENTION: You are using an old version of SDL_mixer!\n"
" This version has a bug that may cause "
"your sound to stutter.\n"
" Please upgrade to a newer version!\n"
"\n");
}
}
Mix_AllocateChannels(NUM_CHANNELS);
SDL_PauseAudio(0);
sound_initialized = true;
return true;
}
static boolean I_SDL_InitSound(boolean _use_sfx_prefix)
{
int i;
// SDL 2.0.6 has a bug that makes it unusable.
if (SDL_COMPILEDVERSION == SDL_VERSIONNUM(2, 0, 6))
{
I_Error(
"I_SDL_InitSound: "
"You are trying to launch with SDL 2.0.6 which has a known bug "
"that makes the game crash. Please either downgrade to "
"SDL 2.0.5 or upgrade to 2.0.7. See the following bug for some "
"additional context:\n"
"<https://github.com/chocolate-doom/chocolate-doom/issues/945>");
}
use_sfx_prefix = _use_sfx_prefix;
// No sounds yet
for (i=0; i<NUM_CHANNELS; ++i)
{
channels_playing[i] = NULL;
}
if (SDL_Init(SDL_INIT_AUDIO) < 0)
{
fprintf(stderr, "Unable to set up sound.\n");
return false;
}
if (Mix_OpenAudio(snd_samplerate, AUDIO_S16SYS, 2, GetSliceSize()) < 0)
{
fprintf(stderr, "Error initialising SDL_mixer: %s\n", Mix_GetError());
return false;
}
ExpandSoundData = ExpandSoundData_SDL;
Mix_QuerySpec(&mixer_freq, &mixer_format, &mixer_channels);
#ifdef HAVE_LIBSAMPLERATE
if (use_libsamplerate != 0)
{
if (SRC_ConversionMode() < 0)
{
I_Error("I_SDL_InitSound: Invalid value for use_libsamplerate: %i",
use_libsamplerate);
}
ExpandSoundData = ExpandSoundData_SRC;
}
#else
if (use_libsamplerate != 0)
{
fprintf(stderr, "I_SDL_InitSound: use_libsamplerate=%i, but "
"libsamplerate support not compiled in.\n",
use_libsamplerate);
}
#endif
Mix_AllocateChannels(NUM_CHANNELS);
SDL_PauseAudio(0);
sound_initialized = true;
return true;
}
