From 2c045d4c730335ab38d48b5d3af97629fed0189d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jonas=20R=C3=B6ger?= <jonas.roeger@tu-dortmund.de>
Date: Sun, 23 Nov 2025 21:04:53 +0100
Subject: [PATCH] feat(mm2): smear frames

---
 app/mosh-me-2.cpp | 81 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 80 insertions(+), 1 deletion(-)

diff --git a/app/mosh-me-2.cpp b/app/mosh-me-2.cpp
index a3ae6aa..891c911 100644
--- a/app/mosh-me-2.cpp
+++ b/app/mosh-me-2.cpp
@@ -1,3 +1,82 @@
+#include <avcpp/av.h>
+#include <avcpp/avtime.h>
+#include <avcpp/format.h>
+#include <avcpp/formatcontext.h>
 #include <spdlog/spdlog.h>
+#include <vector>
 
-int main() { spdlog::info("MM2"); }
+int main(int argc, char *argv[]) {
+
+  if (argc < 4) {
+    spdlog::error("Usage: {} <input-file> <output-file> <smear-frames>",
+                  argv[0]);
+    return 1;
+  }
+
+  const char *input_file = argv[1];
+  const char *output_file = argv[2];
+  int smear_frames = atoi(argv[3]);
+
+  av::init();
+
+  av::FormatContext ictx;
+  av::FormatContext octx;
+  ictx.openInput(input_file);
+  ictx.findStreamInfo();
+
+  std::vector<off_t> stream_map(ictx.streamsCount());
+
+  off_t oix = 0;
+  for (size_t i = 0; i < stream_map.size(); i++) {
+    auto istream = ictx.stream(i);
+
+    if (istream.codecParameters().codecType() != AVMEDIA_TYPE_AUDIO ||
+        istream.codecParameters().codecType() != AVMEDIA_TYPE_VIDEO ||
+        istream.codecParameters().codecType() != AVMEDIA_TYPE_SUBTITLE) {
+      stream_map[i] = -1;
+    }
+
+    auto ostream = octx.addStream();
+    ostream.setCodecParameters(istream.codecParameters());
+    ostream.codecParameters().codecTag(0);
+    stream_map[i] = oix++;
+  }
+
+  octx.openOutput(output_file);
+  octx.writeHeader();
+
+  av::Packet packet_buffer;
+
+  for (;;) {
+    auto pkt = ictx.readPacket();
+
+    if (pkt.isNull()) {
+      break;
+    }
+
+    auto istream = ictx.stream(pkt.streamIndex());
+
+    if (pkt.streamIndex() >= stream_map.size() ||
+        stream_map[pkt.streamIndex()] < 0 || pkt.isKeyPacket()) {
+      continue;
+    }
+
+    pkt.setStreamIndex(stream_map[pkt.streamIndex()]);
+
+    if (auto ts = pkt.pts().timestamp(); ts % smear_frames == 0) {
+      packet_buffer = pkt;
+    } else {
+      auto dts = pkt.dts();
+      auto pts = pkt.pts();
+      auto dur = pkt.duration();
+      pkt = packet_buffer;
+      pkt.setDts(dts);
+      pkt.setPts(pts);
+      pkt.setDuration(dur);
+    }
+
+    octx.writePacket(pkt);
+  }
+
+  octx.writeTrailer();
+}