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Remap Vorbis channels to match SDL channels, and some *UpdateSection() changes. #803

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Merged
icculus merged 3 commits into from
Jan 20, 2026
Merged

Remap Vorbis channels to match SDL channels, and some *UpdateSection() changes. #803

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d476f8d
- Remap channels from vorbis and opus sources to match SDL channels.
Jan 20, 2026
32b024c
Remap and don't discard buffers also on music_ogg_stb backend.
Jan 20, 2026
1b7b90a
Fixed comment.
Jan 20, 2026
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1 change: 1 addition & 0 deletions CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -233,6 +233,7 @@ add_library(SDL2_mixer
src/codecs/music_wav.c
src/codecs/music_wavpack.c
src/codecs/music_xmp.c
src/codecs/remap_channels.c
src/effect_position.c
src/effect_stereoreverse.c
src/effects_internal.c
Expand Down
33 changes: 23 additions & 10 deletions src/codecs/music_ogg.c
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@
#include "SDL_loadso.h"

#include "music_ogg.h"
#include "remap_channels.h"
#include "utils.h"

#define OV_EXCLUDE_STATIC_CALLBACKS
Expand Down Expand Up @@ -195,6 +196,7 @@ static void OGG_Delete(void *context);
static int OGG_UpdateSection(OGG_music *music)
{
vorbis_info *vi;
int new_buffer_size;

vi = vorbis.ov_info(&music->vf, -1);
if (!vi) {
Expand All @@ -206,11 +208,6 @@ static int OGG_UpdateSection(OGG_music *music)
}
SDL_memcpy(&music->vi, vi, sizeof(*vi));

if (music->buffer) {
SDL_free(music->buffer);
music->buffer = NULL;
}

if (music->stream) {
SDL_FreeAudioStream(music->stream);
music->stream = NULL;
Expand All @@ -219,13 +216,25 @@ static int OGG_UpdateSection(OGG_music *music)
music->stream = SDL_NewAudioStream(AUDIO_S16SYS, (Uint8)vi->channels, (int)vi->rate,
music_spec.format, music_spec.channels, music_spec.freq);
if (!music->stream) {
SDL_free(music->buffer);
music->buffer = NULL;
music->buffer_size = 0;
return -1;
}

music->buffer_size = music_spec.samples * (int)sizeof(Sint16) * vi->channels;
music->buffer = (char *)SDL_malloc((size_t)music->buffer_size);
if (!music->buffer) {
return -1;
new_buffer_size = music_spec.samples * (int)sizeof(Sint16) * vi->channels;

/* Note: never shrink the buffer, we just decoded data in there. */
if (new_buffer_size > music->buffer_size) {
char *new_buffer = (char *)SDL_realloc(music->buffer, new_buffer_size);
if (!new_buffer) {
SDL_free(music->buffer);
music->buffer = NULL;
music->buffer_size = 0;
return -1;
}
music->buffer = new_buffer;
music->buffer_size = new_buffer_size;
}
return 0;
}
Expand Down Expand Up @@ -387,7 +396,7 @@ static int OGG_GetSome(void *context, void *data, int bytes, SDL_bool *done)
#ifdef OGG_USE_TREMOR
amount = (int)vorbis.ov_read(&music->vf, music->buffer, music->buffer_size, &section);
#else
amount = (int)vorbis.ov_read(&music->vf, music->buffer, music->buffer_size, SDL_BYTEORDER == SDL_BIG_ENDIAN, 2, 1, &section);
amount = (int)vorbis.ov_read(&music->vf, music->buffer, music->buffer_size, SDL_BYTEORDER == SDL_BIG_ENDIAN, (int)sizeof(Sint16), 1, &section);
#endif
if (amount < 0) {
return set_ov_error("ov_read", amount);
Expand All @@ -400,6 +409,10 @@ static int OGG_GetSome(void *context, void *data, int bytes, SDL_bool *done)
}
}

remap_channels_vorbis_s16((Sint16 *)music->buffer,
amount / (int)sizeof(Sint16),
music->vi.channels);

pcmPos = vorbis.ov_pcm_tell(&music->vf);
if (music->loop && (music->play_count != 1) && (pcmPos >= music->loop_end)) {
amount -= (int)((pcmPos - music->loop_end) * music->vi.channels) * (int)sizeof(Sint16);
Expand Down
60 changes: 34 additions & 26 deletions src/codecs/music_ogg_stb.c
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@
/* This file supports Ogg Vorbis music streams using a modified stb_vorbis module */

#include "music_ogg.h"
#include "remap_channels.h"
#include "utils.h"
#include "SDL_assert.h"

Expand Down Expand Up @@ -74,7 +75,6 @@ typedef struct {
int volume;
stb_vorbis *vf;
stb_vorbis_info vi;
int section;
SDL_AudioStream *stream;
char *buffer;
int buffer_size;
Expand Down Expand Up @@ -123,18 +123,15 @@ static void OGG_Delete(void *context);
static int OGG_UpdateSection(OGG_music *music)
{
stb_vorbis_info vi;
int new_buffer_size;

vi = stb_vorbis_get_info(music->vf);

if (vi.channels == music->vi.channels && vi.sample_rate == music->vi.sample_rate) {
return 0;
}
SDL_memcpy(&music->vi, &vi, sizeof(vi));

if (music->buffer) {
SDL_free(music->buffer);
music->buffer = NULL;
}
music->vi = vi;

if (music->stream) {
SDL_FreeAudioStream(music->stream);
Expand All @@ -144,17 +141,30 @@ static int OGG_UpdateSection(OGG_music *music)
music->stream = SDL_NewAudioStream(AUDIO_F32SYS, (Uint8)vi.channels, (int)vi.sample_rate,
music_spec.format, music_spec.channels, music_spec.freq);
if (!music->stream) {
SDL_free(music->buffer);
music->buffer = NULL;
music->buffer_size = 0;
return -1;
}

music->buffer_size = music_spec.samples * (int)sizeof(float) * vi.channels;
if (music->buffer_size <= 0) {
new_buffer_size = music_spec.samples * (int)sizeof(float) * vi.channels;
if (new_buffer_size <= 0) {
music->buffer = NULL;
music->buffer_size = 0;
return -1;
}

music->buffer = (char *)SDL_malloc((size_t)music->buffer_size);
if (!music->buffer) {
return -1;
/* Note: never shrink the buffer, we just decoded data in there. */
if (new_buffer_size > music->buffer_size) {
char *new_buffer = (char *)SDL_realloc(music->buffer, new_buffer_size);
if (!new_buffer) {
SDL_free(music->buffer);
music->buffer = NULL;
music->buffer_size = 0;
return -1;
}
music->buffer = new_buffer;
music->buffer_size = new_buffer_size;
}
return 0;
}
Expand All @@ -175,7 +185,6 @@ static void *OGG_CreateFromRW(SDL_RWops *src, int freesrc)
}
music->src = src;
music->volume = MIX_MAX_VOLUME;
music->section = -1;

music->vf = stb_vorbis_open_rwops(src, 0, &error, NULL);

Expand Down Expand Up @@ -308,8 +317,7 @@ static int OGG_GetSome(void *context, void *data, int bytes, SDL_bool *done)
{
OGG_music *music = (OGG_music *)context;
SDL_bool looped = SDL_FALSE;
int filled, amount, result;
int section;
int filled, amount, samples, result;
Sint64 pcmPos;

filled = SDL_AudioStreamGet(music->stream, data, bytes);
Expand All @@ -323,21 +331,21 @@ static int OGG_GetSome(void *context, void *data, int bytes, SDL_bool *done)
return 0;
}

section = music->section;
amount = stb_vorbis_get_samples_float_interleaved(music->vf,
music->vi.channels,
(float *)music->buffer,
music_spec.samples * music->vi.channels);
samples = stb_vorbis_get_samples_float_interleaved(music->vf,
music->vi.channels,
(float *)music->buffer,
music->buffer_size / (int)sizeof(float));

amount *= music->vi.channels * sizeof(float);

if (section != music->section) {
music->section = section;
if (OGG_UpdateSection(music) < 0) {
return -1;
}
if (OGG_UpdateSection(music) < 0) {
return -1;
}

amount = samples * music->vi.channels * sizeof(float);

remap_channels_vorbis_flt((float *)music->buffer,
samples * music->vi.channels,
music->vi.channels);

pcmPos = stb_vorbis_get_playback_sample_offset(music->vf);
if (music->loop && (music->play_count != 1) && (pcmPos >= music->loop_end)) {
amount -= (int)((pcmPos - music->loop_end) * music->vi.channels) * (int)sizeof(float);
Expand Down
33 changes: 24 additions & 9 deletions src/codecs/music_opus.c
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@
#include "SDL_loadso.h"

#include "music_opus.h"
#include "remap_channels.h"
#include "utils.h"

#ifdef OPUSFILE_HEADER
Expand Down Expand Up @@ -169,6 +170,7 @@ static void OPUS_Delete(void*);
static int OPUS_UpdateSection(OPUS_music *music)
{
const OpusHead *op_info;
int new_buffer_size;

op_info = opus.op_head(music->of, -1);
if (!op_info) {
Expand All @@ -180,11 +182,6 @@ static int OPUS_UpdateSection(OPUS_music *music)
}
music->op_info = op_info;

if (music->buffer) {
SDL_free(music->buffer);
music->buffer = NULL;
}

if (music->stream) {
SDL_FreeAudioStream(music->stream);
music->stream = NULL;
Expand All @@ -193,13 +190,25 @@ static int OPUS_UpdateSection(OPUS_music *music)
music->stream = SDL_NewAudioStream(AUDIO_S16SYS, (Uint8)op_info->channel_count, 48000,
music_spec.format, music_spec.channels, music_spec.freq);
if (!music->stream) {
SDL_free(music->buffer);
music->buffer = NULL;
music->buffer_size = 0;
return -1;
}

music->buffer_size = (int)music_spec.samples * (int)sizeof(opus_int16) * op_info->channel_count;
music->buffer = (char *)SDL_malloc((size_t)music->buffer_size);
if (!music->buffer) {
return -1;
new_buffer_size = (int)music_spec.samples * (int)sizeof(opus_int16) * op_info->channel_count;

/* Note: never shrink the buffer, we just decoded data in there. */
if (new_buffer_size > music->buffer_size) {
char *new_buffer = (char *)SDL_realloc(music->buffer, (size_t)new_buffer_size);
if (!new_buffer) {
SDL_free(music->buffer);
music->buffer = NULL;
music->buffer_size = 0;
return -1;
}
music->buffer = new_buffer;
music->buffer_size = new_buffer_size;
}
return 0;
}
Expand Down Expand Up @@ -378,6 +387,12 @@ static int OPUS_GetSome(void *context, void *data, int bytes, SDL_bool *done)
}
}

if (music->op_info->mapping_family == 1) {
remap_channels_vorbis_s16((Sint16 *)music->buffer,
samples * music->op_info->channel_count,
music->op_info->channel_count);
}

pcmPos = opus.op_pcm_tell(music->of);
if (music->loop && (music->play_count != 1) && (pcmPos >= music->loop_end)) {
samples -= (int)((pcmPos - music->loop_end) * music->op_info->channel_count) * (int)sizeof(Sint16);
Expand Down
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