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wave: SDL_LoadWAV now supports 24-bit audio.

This commit is contained in:
Ryan C. Gordon 2017-09-07 10:56:08 -04:00
parent fb28393200
commit ca15c7d67f
1 changed files with 47 additions and 0 deletions
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47
src/audio/SDL_wave.c
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@ -403,6 +403,43 @@ IMA_ADPCM_decode(Uint8 ** audio_buf, Uint32 * audio_len)
return (0);
}
static int
ConvertSint24ToSint32(Uint8 ** audio_buf, Uint32 * audio_len)
{
const double DIVBY8388608 = 0.00000011920928955078125;
const Uint32 original_len = *audio_len;
const Uint32 samples = original_len / 3;
const Uint32 expanded_len = samples * sizeof (Uint32);
Uint8 *ptr = (Uint8 *) SDL_realloc(*audio_buf, expanded_len);
const Uint8 *src;
Uint32 *dst;
Uint32 i;
if (!ptr) {
return SDL_OutOfMemory();
}
*audio_buf = ptr;
*audio_len = expanded_len;
/* work from end to start, since we're expanding in-place. */
src = (ptr + original_len) - 3;
dst = ((Uint32 *) (ptr + expanded_len)) - 1;
for (i = 0; i < samples; i++) {
/* There's probably a faster way to do all this. */
const Sint32 converted = ((Sint32) ( (((Uint32) src[2]) << 24) |
(((Uint32) src[1]) << 16) |
(((Uint32) src[0]) << 8) )) >> 8;
const double scaled = (((double) converted) * DIVBY8388608);
src -= 3;
*(dst--) = (Sint32) (scaled * 2147483647.0);
}
return 0;
}
/* GUIDs that are used by WAVE_FORMAT_EXTENSIBLE */
static const Uint8 extensible_pcm_guid[16] = { 1, 0, 0, 0, 0, 0, 16, 0, 128, 0, 0, 170, 0, 56, 155, 113 };
static const Uint8 extensible_ieee_guid[16] = { 3, 0, 0, 0, 0, 0, 16, 0, 128, 0, 0, 170, 0, 56, 155, 113 };
@ -551,6 +588,9 @@ SDL_LoadWAV_RW(SDL_RWops * src, int freesrc,
case 16:
spec->format = AUDIO_S16;
break;
case 24: /* convert this. */
spec->format = AUDIO_S32;
break;
case 32:
spec->format = AUDIO_S32;
break;
@ -598,6 +638,13 @@ SDL_LoadWAV_RW(SDL_RWops * src, int freesrc,
}
}
if (SDL_SwapLE16(format->bitspersample) == 24) {
if (ConvertSint24ToSint32(audio_buf, audio_len) < 0) {
was_error = 1;
goto done;
}
}
/* Don't return a buffer that isn't a multiple of samplesize */
samplesize = ((SDL_AUDIO_BITSIZE(spec->format)) / 8) * spec->channels;
*audio_len &= ~(samplesize - 1);