From 11e4861082941fdefd26aac7b087130e88ed775e Mon Sep 17 00:00:00 2001
From: study-faraphel <raphael.caron@etud.u-picardie.fr>
Date: Thu, 14 Nov 2024 13:24:49 +0100
Subject: [PATCH] improved latency before playing an audio prevented playing
 packets that are too old to avoid offset

---
 CMakeLists.txt                              |  2 ++
 README.md                                   |  5 ++++-
 source/behavior/events/audio/AudioEvent.cpp |  9 ++++++++-
 source/behavior/tasks/server/ServerTask.cpp | 19 +++++++++----------
 source/utils/audio.cpp                      | 14 ++++++++++++++
 source/utils/audio.hpp                      |  7 +++++++
 source/utils/time/Chrony.cpp                |  1 +
 source/utils/time/Chrony.hpp                | 12 ++++++++++++
 8 files changed, 57 insertions(+), 12 deletions(-)
 create mode 100644 source/utils/time/Chrony.cpp
 create mode 100644 source/utils/time/Chrony.hpp

diff --git a/CMakeLists.txt b/CMakeLists.txt
index bdec8c3..17b4dd1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -57,6 +57,8 @@ add_executable(M2-PT-DRP
         source/packets/base/SecurityMode.hpp
         source/packets/base/PacketData.hpp
         source/packets/info/InfoPacketData.hpp
+        source/utils/time/Chrony.cpp
+        source/utils/time/Chrony.hpp
 )
 target_include_directories(M2-PT-DRP PRIVATE
         source
diff --git a/README.md b/README.md
index 820598d..50c3e07 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,9 @@
 
 Debian
 ```bash
+# Pre-requires
+sudo apt install chrony
+
 # Download
 sudo apt install -y git
 git clone https://git.faraphel.fr/study-faraphel/M2-PT-DRP
@@ -17,6 +20,6 @@ cmake --build build
 cd build
 
 # Run
-./M2-PT-DRP --host ff02::1 --ipv6
+sudo ./M2-PT-DRP --host ff02::1 --ipv6
 ```
 
diff --git a/source/behavior/events/audio/AudioEvent.cpp b/source/behavior/events/audio/AudioEvent.cpp
index 93a8884..6a187be 100644
--- a/source/behavior/events/audio/AudioEvent.cpp
+++ b/source/behavior/events/audio/AudioEvent.cpp
@@ -5,6 +5,7 @@
 
 #include "packets/audio/AudioPacketData.hpp"
 #include "packets/base/PacketData.hpp"
+#include "utils/audio.hpp"
 
 
 namespace drp::event {
@@ -90,6 +91,12 @@ void AudioEvent::loopPlay() {
         // get the most recent audio chunk
         const auto audioPacket = this->audioQueue.top();
 
+        // if the packet should have started playing before, skip it
+        if (audioPacket.timePlay < std::chrono::high_resolution_clock::now()) {
+            this->audioQueue.pop();
+            continue;
+        }
+
         // update the stream with the new audio settings
         this->updateAudioStream(
             audioPacket.channels,
@@ -137,4 +144,4 @@ void AudioEvent::loopPlay() {
 }
 
 
-}
\ No newline at end of file
+}
diff --git a/source/behavior/tasks/server/ServerTask.cpp b/source/behavior/tasks/server/ServerTask.cpp
index 46baf61..77f2142 100644
--- a/source/behavior/tasks/server/ServerTask.cpp
+++ b/source/behavior/tasks/server/ServerTask.cpp
@@ -57,10 +57,8 @@ ServerTask::~ServerTask() {
 void ServerTask::handle(Context& context) {
     // TODO(Faraphel): create a chrony server
 
-    // allow anybody to connect as a chrony client
-    FILE* chronyProcess = popen("chronyc allow all 2>&1", "r");
-    if (pclose(chronyProcess) == -1)
-        std::cerr << "Could not allow chrony connection." << std::endl;
+    // get the time of the start of the processing
+    const auto startProcessingTime = std::chrono::high_resolution_clock::now();
 
     // prepare the packet structure
     packet::base::Packet packet {};
@@ -116,12 +114,13 @@ void ServerTask::handle(Context& context) {
 
     std::cout << "[Task - Server] Sent: " << done << " bytes" << std::endl;
 
-    // wait for the duration of the audio chunk
-    std::this_thread::sleep_for(std::chrono::milliseconds(static_cast<std::uint64_t>(
-        (1 / static_cast<double>(this->sampleRate * this->channels * mpg123_encsize(this->encoding))) *
-        1000 *
-        static_cast<double>(done)
-    )));
+    // wait for the duration of the audio chunk, since the start of the processing
+    std::this_thread::sleep_until(startProcessingTime + util::get_audio_chunk_duration(
+        this->sampleRate,
+        this->channels,
+        mpg123_encsize(this->encoding),
+        done
+    ));
 }
 
 
diff --git a/source/utils/audio.cpp b/source/utils/audio.cpp
index 75e4053..a811108 100644
--- a/source/utils/audio.cpp
+++ b/source/utils/audio.cpp
@@ -1,5 +1,6 @@
 #include "audio.hpp"
 
+#include <chrono>
 #include <stdexcept>
 
 #include <fmt123.h>
@@ -30,4 +31,17 @@ std::uint32_t encoding_mpg123_to_PulseAudio(const int encoding_mpg123) {
 }
 
 
+std::chrono::milliseconds get_audio_chunk_duration(
+    const long sampleRate,
+    const int channels,
+    const int encodingSize,
+    const std::size_t length
+) {
+    return std::chrono::milliseconds(static_cast<std::uint64_t>(
+        (1 / static_cast<double>(sampleRate * channels * encodingSize)) *
+        1000 * static_cast<double>(length)
+    ));
+}
+
+
 }
\ No newline at end of file
diff --git a/source/utils/audio.hpp b/source/utils/audio.hpp
index a5e7ac4..d4ae37e 100644
--- a/source/utils/audio.hpp
+++ b/source/utils/audio.hpp
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <chrono>
 #include <cstdint>
 
 
@@ -8,5 +9,11 @@ namespace drp::util {
 
 std::uint32_t encoding_mpg123_to_PulseAudio(int encoding_mpg123);
 
+std::chrono::milliseconds get_audio_chunk_duration(
+    long sampleRate,
+    int channels,
+    int encodingSize,
+    std::size_t length
+);
 
 }
\ No newline at end of file
diff --git a/source/utils/time/Chrony.cpp b/source/utils/time/Chrony.cpp
new file mode 100644
index 0000000..9ec6aae
--- /dev/null
+++ b/source/utils/time/Chrony.cpp
@@ -0,0 +1 @@
+#include "Chrony.hpp"
diff --git a/source/utils/time/Chrony.hpp b/source/utils/time/Chrony.hpp
new file mode 100644
index 0000000..40fe00f
--- /dev/null
+++ b/source/utils/time/Chrony.hpp
@@ -0,0 +1,12 @@
+#pragma once
+
+
+namespace drp::util::time {
+
+
+class Chrony {
+
+};
+
+
+}
\ No newline at end of file