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SDL2: Implement SDL_GetDefaultAudioInfo() on the ALSA backend.

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(cherry picked from commit 8d5984464e)
This commit is contained in:
vanfanel
2025-07-07 09:00:44 +02:00
committed by Sam Lantinga
parent ab9f59e59a
commit 28f2944947
1 changed files with 64 additions and 0 deletions
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64
src/audio/alsa/SDL_alsa_audio.c
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@@ -83,6 +83,12 @@ static int (*ALSA_snd_device_name_hint)(int, const char *, void ***);
static char *(*ALSA_snd_device_name_get_hint)(const void *, const char *);
static int (*ALSA_snd_device_name_free_hint)(void **);
static snd_pcm_sframes_t (*ALSA_snd_pcm_avail)(snd_pcm_t *);
static int (*ALSA_snd_pcm_info)(snd_pcm_t *, snd_pcm_info_t *);
static const char *(*ALSA_snd_pcm_info_get_name)(const snd_pcm_info_t *);
static int (*ALSA_snd_pcm_info_get_card)(const snd_pcm_info_t *);
static int (*ALSA_snd_card_get_name)(int, char **);
static int (*ALSA_snd_pcm_info_malloc)(snd_pcm_info_t **);
static int (*ALSA_snd_pcm_info_free)(snd_pcm_info_t *);
#ifdef SND_CHMAP_API_VERSION
static snd_pcm_chmap_t *(*ALSA_snd_pcm_get_chmap)(snd_pcm_t *);
static int (*ALSA_snd_pcm_chmap_print)(const snd_pcm_chmap_t *map, size_t maxlen, char *buf);
@@ -152,6 +158,11 @@ static int load_alsa_syms(void)
SDL_ALSA_SYM(snd_device_name_get_hint);
SDL_ALSA_SYM(snd_device_name_free_hint);
SDL_ALSA_SYM(snd_pcm_avail);
SDL_ALSA_SYM(snd_pcm_info);
SDL_ALSA_SYM(snd_pcm_info_get_card);
SDL_ALSA_SYM(snd_card_get_name);
SDL_ALSA_SYM(snd_pcm_info_malloc);
SDL_ALSA_SYM(snd_pcm_info_free);
#ifdef SND_CHMAP_API_VERSION
SDL_ALSA_SYM(snd_pcm_get_chmap);
SDL_ALSA_SYM(snd_pcm_chmap_print);
@@ -466,6 +477,58 @@ static void ALSA_CloseDevice(_THIS)
SDL_free(this->hidden);
}
static int ALSA_GetDefaultAudioInfo(char **name, SDL_AudioSpec *spec, int iscapture)
{
const char *device = "default";
snd_pcm_t *pcm_handle;
snd_pcm_info_t *pcm_info;
snd_pcm_stream_t stream;
int card_index;
const char *dev_name;
char *card_name = NULL;
char final_name[256];
SDL_zero(final_name);
stream = iscapture ? SND_PCM_STREAM_CAPTURE : SND_PCM_STREAM_PLAYBACK;
if (ALSA_snd_pcm_open(&pcm_handle, device, stream, SND_PCM_NONBLOCK) < 0) {
return SDL_SetError("ALSA: Couldn't open default device");
}
if (ALSA_snd_pcm_info_malloc(&pcm_info) < 0) {
ALSA_snd_pcm_close(pcm_handle);
return SDL_SetError("ALSA: Couldn't allocate pcm_info");
}
if (ALSA_snd_pcm_info(pcm_handle, pcm_info) < 0) {
ALSA_snd_pcm_info_free(pcm_info);
ALSA_snd_pcm_close(pcm_handle);
return SDL_SetError("ALSA: Couldn't get PCM info");
}
card_index = ALSA_snd_pcm_info_get_card(pcm_info);
dev_name = ALSA_snd_pcm_info_get_name(pcm_info);
if (card_index >= 0 && ALSA_snd_card_get_name(card_index, &card_name) >= 0) {
SDL_snprintf(final_name, sizeof(final_name), "%s, %s", card_name, dev_name);
*name = SDL_strdup(final_name);
} else {
*name = SDL_strdup(dev_name ? dev_name : "Unknown ALSA Device");
}
if (spec) {
SDL_zero(*spec);
spec->freq = 48000;
spec->format = AUDIO_S16SYS;
spec->channels = 2;
spec->samples = 512;
}
ALSA_snd_pcm_info_free(pcm_info);
ALSA_snd_pcm_close(pcm_handle);
return 0;
}
static int ALSA_set_buffer_size(_THIS, snd_pcm_hw_params_t *params)
{
int status;
@@ -975,6 +1038,7 @@ static SDL_bool ALSA_Init(SDL_AudioDriverImpl *impl)
impl->Deinitialize = ALSA_Deinitialize;
impl->CaptureFromDevice = ALSA_CaptureFromDevice;
impl->FlushCapture = ALSA_FlushCapture;
impl->GetDefaultAudioInfo = ALSA_GetDefaultAudioInfo;
impl->HasCaptureSupport = SDL_TRUE;
impl->SupportsNonPow2Samples = SDL_TRUE;