Make EDI fragment interleaver less bursty

3 files changed, 21 insertions, 3 deletions

diff --git a/src/DabMultiplexer.cpp b/src/DabMultiplexer.cpp
index 97336d1..a86a1c7 100644
--- a/src/DabMultiplexer.cpp
+++ b/src/DabMultiplexer.cpp
@@ -716,6 +716,11 @@ void DabMultiplexer::mux_frame(std::vector<std::shared_ptr<DabOutput> >& outputs
             // Apply PFT layer to AF Packet (Reed Solomon FEC and Fragmentation)
             vector<edi::PFTFragment> edi_fragments = edi_pft.Assemble(edi_afpacket);
 
+            if (edi_conf.verbose) {
+                fprintf(stderr, "EDI number of PFT fragment before interleaver %zu\n",
+                        edi_fragments.size());
+            }
+
             if (edi_conf.interleaver_enabled()) {
                 edi_fragments = edi_interleaver.Interleave(edi_fragments);
             }
diff --git a/src/dabOutput/edi/Interleaver.cpp b/src/dabOutput/edi/Interleaver.cpp
index 810e76f..e31326b 100644
--- a/src/dabOutput/edi/Interleaver.cpp
+++ b/src/dabOutput/edi/Interleaver.cpp
@@ -64,8 +64,6 @@ Interleaver::fragment_vec Interleaver::Interleave(fragment_vec &fragments)
 
     fragments.clear();
 
-    std::vector<PFTFragment> interleaved_frags;
-
     while ( not m_buffer.empty() and
             (m_buffer.front().size() >= m_fragment_count * m_latency)) {
 
@@ -89,7 +87,7 @@ Interleaver::fragment_vec Interleaver::Interleave(fragment_vec &fragments)
 
         for (size_t i = 0; i < m_fragment_count; i++) {
             const size_t ix = m_interleave_offset + m_fragment_count * m_stride;
-            interleaved_frags.push_back(first_buffer.at(ix));
+            m_interleaved_fragments.push_back(first_buffer.at(ix));
 
             m_stride += 1;
             if (m_stride >= m_latency) {
@@ -105,6 +103,16 @@ Interleaver::fragment_vec Interleaver::Interleave(fragment_vec &fragments)
         }
     }
 
+    std::vector<PFTFragment> interleaved_frags;
+
+    const size_t n = std::min(m_fragment_count, m_interleaved_fragments.size());
+    std::move(m_interleaved_fragments.begin(),
+              m_interleaved_fragments.begin() + n,
+              std::back_inserter(interleaved_frags));
+    m_interleaved_fragments.erase(
+              m_interleaved_fragments.begin(),
+              m_interleaved_fragments.begin() + n);
+
     return interleaved_frags;
 }
 
diff --git a/src/dabOutput/edi/Interleaver.h b/src/dabOutput/edi/Interleaver.h
index f94219e..f1cff30 100644
--- a/src/dabOutput/edi/Interleaver.h
+++ b/src/dabOutput/edi/Interleaver.h
@@ -64,6 +64,11 @@ class Interleaver {
 
         /* Buffer that accumulates enough fragments to interleave */
         std::deque<fragment_vec> m_buffer;
+
+        /* Buffer that contains fragments that have been interleaved,
+         * to avoid that the interleaver output is too bursty
+         */
+        std::deque<PFTFragment> m_interleaved_fragments;
 };
 
 }