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ALSA: Try improving native channel count detection heuristics.

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This commit is contained in:
David Reid
2026-01-10 12:41:19 +10:00
parent 999c16d834
commit 280c118dfd
1 changed files with 45 additions and 3 deletions
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miniaudio.h
+45 -3
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@@ -27754,6 +27754,10 @@ available in old versions of Linux anyway.
#include <poll.h> /* poll(), struct pollfd */
#include <sys/eventfd.h> /* eventfd() */
#ifndef MA_ALSA_MAX_NATIVE_CHANNELS
#define MA_ALSA_MAX_NATIVE_CHANNELS 64
#endif
#ifdef MA_NO_RUNTIME_LINKING
/* asoundlib.h marks some functions with "inline" which isn't always supported. Need to emulate it. */
@@ -27784,6 +27788,10 @@ typedef snd_pcm_info_t ma_snd_pcm_info_t;
typedef snd_pcm_channel_area_t ma_snd_pcm_channel_area_t;
typedef snd_pcm_chmap_t ma_snd_pcm_chmap_t;
typedef snd_pcm_state_t ma_snd_pcm_state_t;
typedef snd_pcm_type_t ma_snd_pcm_type_t;
/* snd_pcm_type_t */
#define MA_SND_PCM_TYPE_HW SND_PCM_TYPE_HW
/* snd_pcm_state_t */
#define MA_SND_PCM_STATE_XRUN SND_PCM_STATE_XRUN
@@ -27869,6 +27877,7 @@ typedef int ma_snd_pcm_stream_t;
typedef int ma_snd_pcm_format_t;
typedef int ma_snd_pcm_access_t;
typedef int ma_snd_pcm_state_t;
typedef int ma_snd_pcm_type_t;
typedef struct ma_snd_pcm_t ma_snd_pcm_t;
typedef struct ma_snd_pcm_hw_params_t ma_snd_pcm_hw_params_t;
typedef struct ma_snd_pcm_sw_params_t ma_snd_pcm_sw_params_t;
@@ -27886,6 +27895,9 @@ typedef struct
unsigned int pos[1];
} ma_snd_pcm_chmap_t;
/* snd_pcm_type_t */
#define MA_SND_PCM_TYPE_HW 0
/* snd_pcm_state_t */
#define MA_SND_PCM_STATE_OPEN 0
#define MA_SND_PCM_STATE_SETUP 1
@@ -28022,6 +28034,7 @@ typedef size_t (* ma_snd_pcm_format_mask_sizeof_proc) (
typedef int (* ma_snd_pcm_format_mask_test_proc) (const ma_snd_pcm_format_mask_t *mask, ma_snd_pcm_format_t val);
typedef ma_snd_pcm_chmap_t * (* ma_snd_pcm_get_chmap_proc) (ma_snd_pcm_t *pcm);
typedef ma_snd_pcm_state_t (* ma_snd_pcm_state_proc) (ma_snd_pcm_t *pcm);
typedef ma_snd_pcm_type_t (* ma_snd_pcm_type_proc) (ma_snd_pcm_t *pcm);
typedef int (* ma_snd_pcm_prepare_proc) (ma_snd_pcm_t *pcm);
typedef int (* ma_snd_pcm_start_proc) (ma_snd_pcm_t *pcm);
typedef int (* ma_snd_pcm_drop_proc) (ma_snd_pcm_t *pcm);
@@ -28118,6 +28131,7 @@ typedef struct ma_context_state_alsa
ma_snd_pcm_format_mask_test_proc snd_pcm_format_mask_test;
ma_snd_pcm_get_chmap_proc snd_pcm_get_chmap;
ma_snd_pcm_state_proc snd_pcm_state;
ma_snd_pcm_type_proc snd_pcm_type;
ma_snd_pcm_prepare_proc snd_pcm_prepare;
ma_snd_pcm_start_proc snd_pcm_start;
ma_snd_pcm_drop_proc snd_pcm_drop;
@@ -28550,6 +28564,7 @@ static ma_result ma_context_init__alsa(ma_context* pContext, const void* pContex
pContextStateALSA->snd_pcm_format_mask_test = (ma_snd_pcm_format_mask_test_proc )ma_dlsym(pLog, pContextStateALSA->asoundSO, "snd_pcm_format_mask_test");
pContextStateALSA->snd_pcm_get_chmap = (ma_snd_pcm_get_chmap_proc )ma_dlsym(pLog, pContextStateALSA->asoundSO, "snd_pcm_get_chmap");
pContextStateALSA->snd_pcm_state = (ma_snd_pcm_state_proc )ma_dlsym(pLog, pContextStateALSA->asoundSO, "snd_pcm_state");
pContextStateALSA->snd_pcm_type = (ma_snd_pcm_type_proc )ma_dlsym(pLog, pContextStateALSA->asoundSO, "snd_pcm_type");
pContextStateALSA->snd_pcm_prepare = (ma_snd_pcm_prepare_proc )ma_dlsym(pLog, pContextStateALSA->asoundSO, "snd_pcm_prepare");
pContextStateALSA->snd_pcm_start = (ma_snd_pcm_start_proc )ma_dlsym(pLog, pContextStateALSA->asoundSO, "snd_pcm_start");
pContextStateALSA->snd_pcm_drop = (ma_snd_pcm_drop_proc )ma_dlsym(pLog, pContextStateALSA->asoundSO, "snd_pcm_drop");
@@ -28625,6 +28640,7 @@ static ma_result ma_context_init__alsa(ma_context* pContext, const void* pContex
ma_snd_pcm_format_mask_test_proc _snd_pcm_format_mask_test = snd_pcm_format_mask_test;
ma_snd_pcm_get_chmap_proc _snd_pcm_get_chmap = snd_pcm_get_chmap;
ma_snd_pcm_state_proc _snd_pcm_state = snd_pcm_state;
ma_snd_pcm_type_proc _snd_pcm_type = snd_pcm_type;
ma_snd_pcm_prepare_proc _snd_pcm_prepare = snd_pcm_prepare;
ma_snd_pcm_start_proc _snd_pcm_start = snd_pcm_start;
ma_snd_pcm_drop_proc _snd_pcm_drop = snd_pcm_drop;
@@ -28697,6 +28713,7 @@ static ma_result ma_context_init__alsa(ma_context* pContext, const void* pContex
pContextStateALSA->snd_pcm_format_mask_test = _snd_pcm_format_mask_test;
pContextStateALSA->snd_pcm_get_chmap = _snd_pcm_get_chmap;
pContextStateALSA->snd_pcm_state = _snd_pcm_state;
pContextStateALSA->snd_pcm_type = _snd_pcm_type;
pContextStateALSA->snd_pcm_prepare = _snd_pcm_prepare;
pContextStateALSA->snd_pcm_start = _snd_pcm_start;
pContextStateALSA->snd_pcm_drop = _snd_pcm_drop;
@@ -28968,8 +28985,8 @@ static ma_result ma_context_enumerate_devices__alsa(ma_context* pContext, ma_enu
/* Test the format first. If this fails it means the format is not supported and we can skip it. */
if (pContextStateALSA->snd_pcm_hw_params_test_format(pPCM, pHWParams, ma_convert_ma_format_to_alsa_format(format)) == 0) {
/* The format is supported. */
unsigned int minChannels;
unsigned int maxChannels;
unsigned int minChannels = 0;
unsigned int maxChannels = 0;
/*
The configuration space needs to be restricted to this format so we can get an accurate
@@ -29255,7 +29272,32 @@ static ma_result ma_device_init_by_type__alsa(ma_context* pContext, ma_context_s
/* Fallback to set_channels_near() if we couldn't set the exact channel count. */
if (resultALSA < 0) {
if (channels == 0) {
channels = MA_DEFAULT_CHANNELS;
/*
Gettting here means we want to use the "native" channel count. There's no good way that I can tell
to retrieve this because a device can support multiple channel counts. It's tempting to use the
maximum channel count, but that cannot be used generically because many virtual devices will report
unpractical counts like 64, or even 10000 which I've seen in the wild.
However, I think a good compromise might be to check if we're opening an actual hardware device, and
if so accept the maximum channel count in that case. Otherwise we'll just use stereo as the default.
*/
ma_snd_pcm_type_t pcmType = pContextStateALSA->snd_pcm_type(pPCM);
if (pcmType == MA_SND_PCM_TYPE_HW) {
/* Hardware device. Just use the maximum count available. */
resultALSA = pContextStateALSA->snd_pcm_hw_params_get_channels_max(pHWParams, &channels);
if (resultALSA < 0) {
channels = MA_DEFAULT_CHANNELS;
ma_log_postf(ma_context_get_log(pContext), MA_LOG_LEVEL_WARNING, "[ALSA] Trying to open hardware device \"%s\", but requesting the maximum channel count failed. Defaulting to stereo.", pDeviceName);
} else {
if (channels > MA_ALSA_MAX_NATIVE_CHANNELS) {
channels = MA_ALSA_MAX_NATIVE_CHANNELS;
ma_log_postf(ma_context_get_log(pContext), MA_LOG_LEVEL_WARNING, "[ALSA] Native channel count of %u for hardware device \"%s\" exceeds maximum supported by miniaudio's ALSA backend of %d. Clamping channels to %d.", channels, pDeviceName, MA_ALSA_MAX_NATIVE_CHANNELS, MA_ALSA_MAX_NATIVE_CHANNELS);
}
}
} else {
/* Not a hardware device. No way to determine an appropriate native channel count so just default to stereo. */
channels = MA_DEFAULT_CHANNELS;
}
}
resultALSA = pContextStateALSA->snd_pcm_hw_params_set_channels_near(pPCM, pHWParams, &channels);