roc-streaminggh-675 Implement reports from RFC 6776 and RFC 6843

- Add support for Delay Metrics XR block (RFC 6843) and
  Measurement Info XR block (RFC 6776)

- Send these blocks from receiver and handle them on sender

This allows to obtain e2e latency on sender and use it for sender-side
clock adjustment, which will be added in future commits.

Currently, receiver doesn't calculate min/max/avg RTT, and just
sends the latest value. This will be fixed in future commits.

src/internal_modules/roc_pipeline/receiver_session.cpp

@@ -298,6 +298,7 @@ void ReceiverSession::generate_reports(const char* report_cname,
 
     if (n_reports > 0 && packet_router_->has_source_id(packet::Packet::FlagAudio)
         && source_meter_->has_metrics()) {
+        const audio::LatencyMonitorMetrics latency_metrics = latency_monitor_->metrics();
         const rtp::LinkMetrics link_metrics = source_meter_->metrics();
 
         rtcp::RecvReport& report = *reports;
@@ -312,6 +313,7 @@ void ReceiverSession::generate_reports(const char* report_cname,
         report.fract_loss = link_metrics.fract_loss;
         report.cum_loss = link_metrics.cum_loss;
         report.jitter = link_metrics.jitter;
+        report.e2e_latency = latency_metrics.e2e_latency;
 
         reports++;
         n_reports--;
@@ -333,6 +335,7 @@ void ReceiverSession::generate_reports(const char* report_cname,
         report.fract_loss = link_metrics.fract_loss;
         report.cum_loss = link_metrics.cum_loss;
         report.jitter = link_metrics.jitter;
+        report.e2e_latency = 0;
 
         reports++;
         n_reports--;

src/internal_modules/roc_rtcp/builder.cpp

@@ -375,6 +375,35 @@ void Builder::end_xr_dlrr() {
         size_t(cur_pkt_slice_.data_end() - (uint8_t*)cur_xr_block_header_));
 }
 
+void Builder::add_xr_measurement_info(
+    const header::XrMeasurementInfoBlock& measurement_info) {
+    roc_panic_if_msg(state_ != XR_HEAD, "rtcp builder: wrong call order");
+
+    header::XrMeasurementInfoBlock* p =
+        (header::XrMeasurementInfoBlock*)add_block_(sizeof(measurement_info));
+    if (!p) {
+        return;
+    }
+    memcpy(p, &measurement_info, sizeof(measurement_info));
+
+    cur_xr_block_header_ = &p->header();
+    cur_xr_block_header_->set_len_bytes(sizeof(measurement_info));
+}
+
+void Builder::add_xr_delay_metrics(const header::XrDelayMetricsBlock& delay_metrics) {
+    roc_panic_if_msg(state_ != XR_HEAD, "rtcp builder: wrong call order");
+
+    header::XrDelayMetricsBlock* p =
+        (header::XrDelayMetricsBlock*)add_block_(sizeof(delay_metrics));
+    if (!p) {
+        return;
+    }
+    memcpy(p, &delay_metrics, sizeof(delay_metrics));
+
+    cur_xr_block_header_ = &p->header();
+    cur_xr_block_header_->set_len_bytes(sizeof(delay_metrics));
+}
+
 void Builder::end_xr() {
     roc_panic_if_msg(state_ != XR_HEAD, "rtcp builder: wrong call order");
 

src/internal_modules/roc_rtcp/builder.h

@@ -92,6 +92,12 @@ class Builder : public core::NonCopyable<> {
     //! Add DLRR report to current DLRR block.
     void add_xr_dlrr_report(const header::XrDlrrSubblock& report);
 
+    //! Add measurement info block.to current XR packet.
+    void add_xr_measurement_info(const header::XrMeasurementInfoBlock& measurement_info);
+
+    //! Add delay metrics block.to current XR packet.
+    void add_xr_delay_metrics(const header::XrDelayMetricsBlock& delay_metrics);
+
     //! Finish current DLRR block.
     void end_xr_dlrr();