encounter
/
SDL
mirror of https://github.com/encounter/SDL.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

fix mixing of U16 audio

This commit is contained in:
pionere 2022-01-08 12:22:28 +01:00 committed by Ryan C. Gordon
parent 905e2e22ef
commit bf66720a4d
1 changed files with 15 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
src/audio/SDL_mixer.c
View File

@ -84,6 +84,7 @@ static const Uint8 mix8[] = {
/* The volume ranges from 0 - 128 */ /* The volume ranges from 0 - 128 */
#define ADJUST_VOLUME(s, v) (s = (s*v)/SDL_MIX_MAXVOLUME) #define ADJUST_VOLUME(s, v) (s = (s*v)/SDL_MIX_MAXVOLUME)
#define ADJUST_VOLUME_U8(s, v) (s = (((s-128)*v)/SDL_MIX_MAXVOLUME)+128) #define ADJUST_VOLUME_U8(s, v) (s = (((s-128)*v)/SDL_MIX_MAXVOLUME)+128)
#define ADJUST_VOLUME_U16(s, v) (s = (((s-32768)*v)/SDL_MIX_MAXVOLUME)+32768)
void void
@ -190,18 +191,22 @@ SDL_MixAudioFormat(Uint8 * dst, const Uint8 * src, SDL_AudioFormat format,
{ {
Uint16 src1, src2; Uint16 src1, src2;
int dst_sample; int dst_sample;
const int max_audioval = SDL_MAX_UINT16; const int max_audioval = SDL_MAX_SINT16;
const int min_audioval = SDL_MIN_SINT16;
len /= 2; len /= 2;
while (len--) { while (len--) {
src1 = SDL_SwapLE16(*(Uint16 *)src); src1 = SDL_SwapLE16(*(Uint16 *)src);
ADJUST_VOLUME(src1, volume); ADJUST_VOLUME_U16(src1, volume);
src2 = SDL_SwapLE16(*(Uint16 *)dst); src2 = SDL_SwapLE16(*(Uint16 *)dst);
src += 2; src += 2;
dst_sample = src1 + src2; dst_sample = src1 + src2 - 32768 * 2;
if (dst_sample > max_audioval) { if (dst_sample > max_audioval) {
dst_sample = max_audioval; dst_sample = max_audioval;
} else if (dst_sample < min_audioval) {
dst_sample = min_audioval;
} }
dst_sample += 32768;
*(Uint16 *)dst = SDL_SwapLE16(dst_sample); *(Uint16 *)dst = SDL_SwapLE16(dst_sample);
dst += 2; dst += 2;
} }
@ -212,18 +217,22 @@ SDL_MixAudioFormat(Uint8 * dst, const Uint8 * src, SDL_AudioFormat format,
{ {
Uint16 src1, src2; Uint16 src1, src2;
int dst_sample; int dst_sample;
const int max_audioval = SDL_MAX_UINT16; const int max_audioval = SDL_MAX_SINT16;
const int min_audioval = SDL_MIN_SINT16;
len /= 2; len /= 2;
while (len--) { while (len--) {
src1 = SDL_SwapBE16(*(Uint16 *)src); src1 = SDL_SwapBE16(*(Uint16 *)src);
ADJUST_VOLUME(src1, volume); ADJUST_VOLUME_U16(src1, volume);
src2 = SDL_SwapBE16(*(Uint16 *)dst); src2 = SDL_SwapBE16(*(Uint16 *)dst);
src += 2; src += 2;
dst_sample = src1 + src2; dst_sample = src1 + src2 - 32768 * 2;
if (dst_sample > max_audioval) { if (dst_sample > max_audioval) {
dst_sample = max_audioval; dst_sample = max_audioval;
} else if (dst_sample < min_audioval) {
dst_sample = min_audioval;
} }
dst_sample += 32768;
*(Uint16 *)dst = SDL_SwapBE16(dst_sample); *(Uint16 *)dst = SDL_SwapBE16(dst_sample);
dst += 2; dst += 2;
} }