From d8a2cef3608d21af5a13d3ff95b6bb23602dd583 Mon Sep 17 00:00:00 2001
From: Colin Leroy <colin@colino.net>
Date: Sun, 17 Sep 2017 20:46:49 +0200
Subject: [PATCH] RAOP: Announce real latency

Use predefined values depending on the server, and make it configurable.
AirPlay is supposed to have 2s of latency. With my hardware, this is
more 2.352 seconds after numerous tests.
Switch from pausing/resuming the smoother to resetting it because the
smoother got stuck returning the same value after an idle/running cycle,
making latency calculation wrong.
---
 src/modules/raop/module-raop-discover.c | 46 +++++++++++++++++++++++--
 src/modules/raop/module-raop-sink.c     |  4 ++-
 src/modules/raop/raop-sink.c            | 15 ++++++--
 src/modules/raop/raop-util.h            |  2 ++
 4 files changed, 62 insertions(+), 5 deletions(-)

diff --git a/src/modules/raop/module-raop-discover.c b/src/modules/raop/module-raop-discover.c
index d65615b26..8b7ba49b1 100644
--- a/src/modules/raop/module-raop-discover.c
+++ b/src/modules/raop/module-raop-discover.c
@@ -44,11 +44,14 @@
 #include <pulsecore/avahi-wrap.h>
 
 #include "module-raop-discover-symdef.h"
+#include "raop-util.h"
 
 PA_MODULE_AUTHOR("Colin Guthrie");
 PA_MODULE_DESCRIPTION("mDNS/DNS-SD Service Discovery of RAOP devices");
 PA_MODULE_VERSION(PACKAGE_VERSION);
 PA_MODULE_LOAD_ONCE(true);
+PA_MODULE_USAGE(
+        "latency_msec=<audio latency - applies to all devices> ");
 
 #define SERVICE_TYPE_SINK "_raop._tcp"
 
@@ -61,9 +64,13 @@ struct userdata {
     AvahiServiceBrowser *sink_browser;
 
     pa_hashmap *tunnels;
+
+    bool latency_set;
+    uint32_t latency;
 };
 
 static const char* const valid_modargs[] = {
+    "latency_msec",
     NULL
 };
 
@@ -127,6 +134,23 @@ static void tunnel_free(struct tunnel *t) {
     pa_xfree(t);
 }
 
+/* This functions returns RAOP audio latency as guessed by the
+ * device model header.
+ * Feel free to complete the possible values after testing with
+ * your hardware.
+ */
+static uint32_t guess_latency_from_device(const char *model) {
+    uint32_t default_latency = RAOP_DEFAULT_LATENCY;
+
+    if (pa_streq(model, "PIONEER,1")) {
+        /* Pioneer N-30 */
+        default_latency = 2352;
+    }
+
+    pa_log_debug("Default latency is %u ms for device model %s.", default_latency, model);
+    return default_latency;
+}
+
 static void resolver_cb(
         AvahiServiceResolver *r,
         AvahiIfIndex interface, AvahiProtocol protocol,
@@ -145,6 +169,7 @@ static void resolver_cb(
     char at[AVAHI_ADDRESS_STR_MAX];
     AvahiStringList *l;
     pa_module *m;
+    uint32_t latency = RAOP_DEFAULT_LATENCY;
 
     pa_assert(u);
 
@@ -226,6 +251,9 @@ static void resolver_cb(
             /* Sample rate */
             pa_xfree(sr);
             sr = pa_xstrdup(value);
+        } else if (pa_streq(key, "am")) {
+            /* Device model */
+            latency = guess_latency_from_device(value);
         }
 
         avahi_free(key);
@@ -308,6 +336,13 @@ static void resolver_cb(
         pa_xfree(t);
     }
 
+    if (u->latency_set)
+        latency = u->latency;
+
+    t = args;
+    args = pa_sprintf_malloc("%s latency_msec=%u", args, latency);
+    pa_xfree(t);
+
     pa_log_debug("Loading module-raop-sink with arguments '%s'", args);
 
     if (pa_module_load(&m, u->core, "module-raop-sink", args) >= 0) {
@@ -432,10 +467,17 @@ int pa__init(pa_module *m) {
         goto fail;
     }
 
-    m->userdata = u = pa_xnew(struct userdata, 1);
+    m->userdata = u = pa_xnew0(struct userdata, 1);
     u->core = m->core;
     u->module = m;
-    u->sink_browser = NULL;
+
+    if (pa_modargs_get_value(ma, "latency_msec", NULL) != NULL) {
+        u->latency_set = true;
+        if (pa_modargs_get_value_u32(ma, "latency_msec", &u->latency) < 0) {
+            pa_log("Failed to parse latency_msec argument.");
+            goto fail;
+        }
+    }
 
     u->tunnels = pa_hashmap_new(tunnel_hash, tunnel_compare);
 
diff --git a/src/modules/raop/module-raop-sink.c b/src/modules/raop/module-raop-sink.c
index 82fa48d95..d6826572d 100644
--- a/src/modules/raop/module-raop-sink.c
+++ b/src/modules/raop/module-raop-sink.c
@@ -46,7 +46,8 @@ PA_MODULE_USAGE(
         "rate=<sample rate> "
         "channels=<number of channels> "
         "username=<authentication user name, default: \"iTunes\"> "
-        "password=<authentication password>");
+        "password=<authentication password> "
+        "latency_msec=<audio latency>");
 
 static const char* const valid_modargs[] = {
     "name",
@@ -61,6 +62,7 @@ static const char* const valid_modargs[] = {
     "channels",
     "username",
     "password",
+    "latency_msec",
     NULL
 };
 
diff --git a/src/modules/raop/raop-sink.c b/src/modules/raop/raop-sink.c
index 4d13927fc..cd90e3d95 100644
--- a/src/modules/raop/raop-sink.c
+++ b/src/modules/raop/raop-sink.c
@@ -63,6 +63,7 @@
 
 #include "raop-sink.h"
 #include "raop-client.h"
+#include "raop-util.h"
 
 struct userdata {
     pa_core *core;
@@ -87,6 +88,8 @@ struct userdata {
     pa_usec_t start;
     pa_smoother *smoother;
     uint64_t write_count;
+
+    uint32_t latency;
 };
 
 enum {
@@ -119,6 +122,9 @@ static int64_t sink_get_latency(const struct userdata *u) {
 
     latency = pa_bytes_to_usec(u->write_count, &u->sink->sample_spec) - (int64_t) now;
 
+    /* RAOP default latency */
+    latency += u->latency * PA_USEC_PER_MSEC;
+
     return latency;
 }
 
@@ -136,7 +142,6 @@ static int sink_process_msg(pa_msgobject *o, int code, void *data, int64_t offse
 
                     pa_assert(PA_SINK_IS_OPENED(u->sink->thread_info.state));
 
-                    pa_smoother_pause(u->smoother, pa_rtclock_now());
                     /* Issue a TEARDOWN if we are still connected */
                     if (pa_raop_client_is_alive(u->raop)) {
                         pa_raop_client_teardown(u->raop);
@@ -163,7 +168,7 @@ static int sink_process_msg(pa_msgobject *o, int code, void *data, int64_t offse
                     pa_log_debug("RAOP: RUNNING");
 
                     now = pa_rtclock_now();
-                    pa_smoother_resume(u->smoother, now, true);
+                    pa_smoother_reset(u->smoother, now, false);
 
                     if (!pa_raop_client_is_alive(u->raop)) {
                         /* Connecting will trigger a RECORD and start steaming */
@@ -494,6 +499,12 @@ pa_sink* pa_raop_sink_new(pa_module *m, pa_modargs *ma, const char *driver) {
     u->thread = NULL;
     u->rtpoll = pa_rtpoll_new();
     u->rtpoll_item = NULL;
+    u->latency = RAOP_DEFAULT_LATENCY;
+
+    if (pa_modargs_get_value_u32(ma, "latency_msec", &u->latency) < 0) {
+        pa_log("Failed to parse latency_msec argument");
+        goto fail;
+    }
 
     if (pa_thread_mq_init(&u->thread_mq, m->core->mainloop, u->rtpoll) < 0) {
         pa_log("pa_thread_mq_init() failed.");
diff --git a/src/modules/raop/raop-util.h b/src/modules/raop/raop-util.h
index d3f756661..7c25e5cab 100644
--- a/src/modules/raop/raop-util.h
+++ b/src/modules/raop/raop-util.h
@@ -27,6 +27,8 @@
   Kungliga Tekniska högskolan.
 ***/
 
+#define RAOP_DEFAULT_LATENCY 2000 /* msec */
+
 int pa_raop_base64_encode(const void *data, int len, char **str);
 int pa_raop_base64_decode(const char *str, void *data);