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alsa: hook up latencyOffsetNsec in ALSA sink/source

Browse source 
This property is exposed on the device Route and forwarded to the
nodes. It then configured the process_latency.ns field, which
influences the reported port latency.

This makes it possible to change the internal port latency on the
sink and source with pavucontrol and tweak the synchronization to
compensate for internal latencies in the device.
This commit is contained in:
Wim Taymans 2021-08-17 11:57:12 +02:00
parent 391465d1cd
commit c39d374ca8
4 changed files with 125 additions and 18 deletions
Download patch file Download diff file Expand all files Collapse all files

43
spa/plugins/alsa/alsa-acp-device.c
View file

@ -460,6 +460,9 @@ static struct spa_pod *build_route(struct spa_pod_builder *b, uint32_t id,
spa_pod_builder_array(b, sizeof(float), SPA_TYPE_Float,
channels, soft_volumes);
spa_pod_builder_prop(b, SPA_PROP_latencyOffsetNsec, 0);
spa_pod_builder_long(b, dev->latency_ns);
spa_pod_builder_pop(b, &f[1]);
}
spa_pod_builder_prop(b, SPA_PARAM_ROUTE_devices, 0);
@ -574,6 +577,32 @@ static int impl_enum_params(void *object, int seq,
return 0;
}
static void on_latency_changed(void *data, struct acp_device *dev)
{
struct impl *this = data;
struct spa_event *event;
uint8_t buffer[4096];
struct spa_pod_builder b = { 0 };
struct spa_pod_frame f[1];
spa_log_info(this->log, "device %s latency changed", dev->name);
this->info.change_mask |= SPA_DEVICE_CHANGE_MASK_PARAMS;
this->params[IDX_Route].user++;
spa_pod_builder_init(&b, buffer, sizeof(buffer));
spa_pod_builder_push_object(&b, &f[0],
SPA_TYPE_EVENT_Device, SPA_DEVICE_EVENT_ObjectConfig);
spa_pod_builder_prop(&b, SPA_EVENT_DEVICE_Object, 0);
spa_pod_builder_int(&b, dev->index);
spa_pod_builder_prop(&b, SPA_EVENT_DEVICE_Props, 0);
spa_pod_builder_add_object(&b,
SPA_TYPE_OBJECT_Props, SPA_EVENT_DEVICE_Props,
SPA_PROP_latencyOffsetNsec, SPA_POD_Long(dev->latency_ns));
event = spa_pod_builder_pop(&b, &f[0]);
spa_device_emit_event(&this->hooks, event);
}
static int apply_device_props(struct impl *this, struct acp_device *dev, struct spa_pod *props)
{
float volume = 0;
@ -614,6 +643,20 @@ static int apply_device_props(struct impl *this, struct acp_device *dev, struct
changed++;
}
break;
case SPA_PROP_latencyOffsetNsec:
{
int64_t latency_ns;
if (spa_pod_get_long(&prop->value, &latency_ns) == 0) {
if (dev->latency_ns != latency_ns) {
dev->latency_ns = latency_ns;
on_latency_changed(this, dev);
changed++;
}
}
break;
}
default:
break;
}
}
if (n_volumes > 0)