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spa: alsa: Read and expose channel count and position from ELD

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The next step will be to propagate this to the correct node.
This commit is contained in:
Arun Raghavan 2025-10-08 16:38:51 -07:00 • committed by Wim Taymans
parent d268b6e104
commit 91e2f184e2
4 changed files with 90 additions and 3 deletions
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69
spa/plugins/alsa/acp/acp.c
View file

@ -10,6 +10,7 @@
#include <spa/utils/json.h>
#include <spa/utils/cleanup.h>
#include <spa/param/audio/iec958-types.h>
#include <spa/param/audio/raw.h>
int _acp_log_level = 1;
acp_log_func _acp_log_func;
@ -1064,8 +1065,8 @@ static int hdmi_eld_changed(snd_mixer_elem_t *melem, unsigned int mask)
{
pa_card *impl = snd_mixer_elem_get_callback_private(melem);
snd_hctl_elem_t **_elem = snd_mixer_elem_get_private(melem), *elem;
int device, i;
const char *old_monitor_name, *old_iec958_codec_list;
int device;
const char *old_monitor_name, *old_iec958_codec_list, *old_channels, *old_position;
pa_device_port *p;
pa_hdmi_eld eld;
bool changed = false;
@ -1087,7 +1088,7 @@ static int hdmi_eld_changed(snd_mixer_elem_t *melem, unsigned int mask)
memset(&eld, 0, sizeof(eld));
// Strip trailing whitespace from monitor_name (primarily an NVidia driver bug for now)
for (i = strlen(eld.monitor_name) - 1; i >= 0; i--) {
for (int i = strlen(eld.monitor_name) - 1; i >= 0; i--) {
if (eld.monitor_name[i] == '\n' || eld.monitor_name[i] == '\r' || eld.monitor_name[i] == '\t' ||
eld.monitor_name[i] == ' ')
eld.monitor_name[i] = 0;
@ -1115,6 +1116,68 @@ static int hdmi_eld_changed(snd_mixer_elem_t *melem, unsigned int mask)
pa_proplist_sets(p->proplist, ACP_KEY_IEC958_CODECS_DETECTED, codecs);
}
old_channels = pa_proplist_gets(p->proplist, ACP_KEY_AUDIO_CHANNELS_DETECTED);
if (eld.lpcm_channels == 0) {
changed |= old_channels != NULL;
pa_proplist_unset(p->proplist, ACP_KEY_AUDIO_CHANNELS_DETECTED);
} else {
char channels[4];
snprintf(channels, sizeof(channels), "%u", eld.lpcm_channels);
changed |= (old_channels == NULL) || (!spa_streq(old_channels, channels));
pa_proplist_sets(p->proplist, ACP_KEY_AUDIO_CHANNELS_DETECTED, channels);
}
old_position = pa_proplist_gets(p->proplist, ACP_KEY_AUDIO_POSITION_DETECTED);
if (eld.speakers == 0) {
changed |= old_position != NULL;
pa_proplist_unset(p->proplist, ACP_KEY_AUDIO_POSITION_DETECTED);
} else {
uint32_t positions[eld.lpcm_channels];
char position[64];
int i = 0, pos = 0;
if (eld.speakers & 0x01) {
positions[i++] = ACP_CHANNEL_FL;
positions[i++] = ACP_CHANNEL_FR;
}
if (eld.speakers & 0x02) {
positions[i++] = ACP_CHANNEL_LFE;
}
if (eld.speakers & 0x04) {
positions[i++] = ACP_CHANNEL_FC;
}
if (eld.speakers & 0x08) {
positions[i++] = ACP_CHANNEL_RL;
positions[i++] = ACP_CHANNEL_RR;
}
/* The rest are out of order in order of what channels we would prefer to use/expose first */
if (eld.speakers & 0x40) {
/* Use SL/SR instead of RLC/RRC */
positions[i++] = ACP_CHANNEL_SL;
positions[i++] = ACP_CHANNEL_SR;
}
if (eld.speakers & 0x20) {
positions[i++] = ACP_CHANNEL_RLC;
positions[i++] = ACP_CHANNEL_RRC;
}
if (eld.speakers & 0x10) {
positions[i++] = ACP_CHANNEL_RC;
}
while (i < eld.lpcm_channels)
positions[i++] = ACP_CHANNEL_UNKNOWN;
for (i = 0, pos = 0; i < eld.lpcm_channels; i++) {
pos += snprintf(&position[pos], sizeof(position) - pos, "%s,", channel_names[positions[i]]);
}
/* Overwrite trailing , */
position[pos - 1] = 0;
changed |= (old_position == NULL) || (!spa_streq(old_position, position));
pa_proplist_sets(p->proplist, ACP_KEY_AUDIO_POSITION_DETECTED, position);
}
pa_proplist_as_dict(p->proplist, &p->port.props);
if (changed && mask != 0 && impl->events && impl->events->props_changed)

12
spa/plugins/alsa/acp/acp.h
View file

@ -153,6 +153,18 @@ const char *acp_available_str(enum acp_available status);
* values may be incorrect and/or might change, e.g. when external devices such
* as receivers are powered on or off.
*/
#define ACP_KEY_AUDIO_CHANNELS_DETECTED "audio.channels.detected"
/**< The number of channels detected detected via EDID-like data read from a device
* connected via HDMI/DisplayPort. This only serves as a hint, as the auto-detected
* values may be incorrect and/or might change, e.g. when external devices such
* as receivers are powered on or off.
*/
#define ACP_KEY_AUDIO_POSITION_DETECTED "audio.position.detected"
/**< The channel positions detected detected via EDID-like data read from a device
* connected via HDMI/DisplayPort. This only serves as a hint, as the auto-detected
* values may be incorrect and/or might change, e.g. when external devices such
* as receivers are powered on or off.
*/
struct acp_device;

10
spa/plugins/alsa/acp/alsa-util.c
View file

@ -2020,14 +2020,24 @@ int pa_alsa_get_hdmi_eld(snd_hctl_elem_t *elem, pa_hdmi_eld *eld) {
sad_count = 0;
}
/* Look up speaker presence in Speaker Allocation Data Block */
eld->speakers = elddata[7] & 0x7f;
eld->lpcm_channels = 0;
eld->iec958_codecs = 0;
for (unsigned i = 0; i < sad_count; i++) {
uint8_t *sad = &elddata[20 + mnl + 3 * i];
uint8_t lpcm_channels;
/* https://en.wikipedia.org/wiki/Extended_Display_Identification_Data#Audio_Data_Blocks */
switch ((sad[0] & 0x78) >> 3) {
case 1:
eld->iec958_codecs |= 1ULL << SPA_AUDIO_IEC958_CODEC_PCM;
/* Lowest 3 bits are channel count - 1 */
lpcm_channels = (sad[0] & 0x07) + 1;
if (lpcm_channels > eld->lpcm_channels)
eld->lpcm_channels = lpcm_channels;
break;
case 2:
eld->iec958_codecs |= 1ULL << SPA_AUDIO_IEC958_CODEC_AC3;

2
spa/plugins/alsa/acp/alsa-util.h
View file

@ -175,7 +175,9 @@ void pa_alsa_mixer_free(pa_alsa_mixer *mixer);
typedef struct pa_hdmi_eld pa_hdmi_eld;
struct pa_hdmi_eld {
char monitor_name[17];
uint8_t speakers;
uint64_t iec958_codecs;
uint8_t lpcm_channels;
};
int pa_alsa_get_hdmi_eld(snd_hctl_elem_t *elem, pa_hdmi_eld *eld);