From e0f175c6baac157305a9841d90aa0817b5b18dd1 Mon Sep 17 00:00:00 2001
From: falsycat <me@falsy.cat>
Date: Tue, 6 Sep 2022 21:22:28 +0900
Subject: [PATCH] add new converter: cprob -> code

---
 conv/CMakeLists.txt |   3 +
 conv/bidx_video.cc  |  21 +------
 conv/common.hh      |  14 +++++
 conv/cprob_code.cc  | 150 ++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 170 insertions(+), 18 deletions(-)
 create mode 100644 conv/cprob_code.cc

diff --git a/conv/CMakeLists.txt b/conv/CMakeLists.txt
index 0a466cd..c207ab6 100644
--- a/conv/CMakeLists.txt
+++ b/conv/CMakeLists.txt
@@ -5,3 +5,6 @@ target_link_libraries(bidx_video PRIVATE args minimp4 openh264)
 
 add_executable(video_fprob common.hh video_fprob.cc)
 target_link_libraries(video_fprob PRIVATE args minimp4 openh264)
+
+add_executable(cprob_code common.hh cprob_code.cc)
+target_link_libraries(cprob_code PRIVATE args minimp4 openh264)
diff --git a/conv/bidx_video.cc b/conv/bidx_video.cc
index 493b2b1..34bf6d3 100644
--- a/conv/bidx_video.cc
+++ b/conv/bidx_video.cc
@@ -54,9 +54,6 @@ std::vector<std::vector<int32_t>> indices;
 }  // namespace param
 
 
-// util
-static std::vector<std::vector<int32_t>> ReadIndices(std::istream&) noexcept;
-
 static void Embed(int32_t t, Frame& dst, const Frame& base) {
   const auto bw  = args::get(param::bw);
   const auto bh  = args::get(param::bw);
@@ -68,6 +65,8 @@ static void Embed(int32_t t, Frame& dst, const Frame& base) {
 
   t = t%param::indices.size();
   for (auto idx : param::indices[t]) {
+    Enforce(idx >= 0, "block index underflow");
+
     const auto bx = idx%bx_cnt;
     const auto by = idx/bx_cnt;
     Enforce(by < by_cnt, "block index overflow");
@@ -99,7 +98,7 @@ static void Exec() {
   Enforce(ut > 0, "utime must be greater than 0");
 
   // read indices
-  param::indices = ReadIndices(std::cin);
+  param::indices = ReadMatrix<int32_t>(std::cin);
   Enforce(param::indices.size() > 0, "empty indices");
 
   // open source video stream
@@ -301,17 +300,3 @@ try {
   std::cerr << e.what() << std::endl;
   return EXIT_FAILURE;
 }
-
-
-
-static std::vector<std::vector<int32_t>> ReadIndices(std::istream& st) noexcept {
-  std::vector<std::vector<int32_t>> ret;
-
-  std::string line;
-  while (std::getline(st, line)) {
-    std::istringstream sst {line};
-    ret.emplace_back(std::istream_iterator<int32_t> {sst},
-                     std::istream_iterator<int32_t> {});
-  }
-  return ret;
-}
diff --git a/conv/common.hh b/conv/common.hh
index c7e5346..cce68bf 100644
--- a/conv/common.hh
+++ b/conv/common.hh
@@ -3,6 +3,7 @@
 #include <cstdint>
 #include <cstring>
 #include <stdexcept>
+#include <sstream>
 #include <string>
 #include <vector>
 
@@ -15,6 +16,19 @@ inline void Enforce(bool eval, const std::string& msg) {
   }
 }
 
+template <typename T>
+std::vector<std::vector<T>> ReadMatrix(std::istream& st) noexcept {
+  std::vector<std::vector<T>> ret;
+
+  std::string line;
+  while (std::getline(st, line)) {
+    std::istringstream sst {line};
+    ret.emplace_back(std::istream_iterator<T> {sst},
+                     std::istream_iterator<T> {});
+  }
+  return ret;
+}
+
 
 // ---- MP4 utilities
 inline void CopyNal(std::vector<uint8_t>& v, const uint8_t* buf, size_t sz) noexcept {
diff --git a/conv/cprob_code.cc b/conv/cprob_code.cc
new file mode 100644
index 0000000..75c371d
--- /dev/null
+++ b/conv/cprob_code.cc
@@ -0,0 +1,150 @@
+#include <cmath>
+#include <cstdint>
+#include <cstdlib>
+#include <cstring>
+#include <fstream>
+#include <sstream>
+#include <stdexcept>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include <args.hxx>
+#include <minimp4.h>
+
+#include <codec/api/wels/codec_api.h>
+
+#include "conv/common.hh"
+
+
+namespace param {
+using namespace ::args;
+
+ArgumentParser parser {
+  "converter: code probability matrix -> code"
+};
+HelpFlag help {
+  parser, "help", "display this menu", {'h', "help"},
+};
+
+enum StepAlgo {
+  kIncrement,
+};
+const std::unordered_map<std::string, StepAlgo> kStepAlgo = {
+  {"inc", kIncrement},
+};
+MapFlag<std::string, StepAlgo> algo {
+  parser, "inc", "step algorithm (inc)", {"algorithm", "algo"}, kStepAlgo,
+};
+
+Group inc {
+  parser, "increment algorithm parameters"
+};
+ValueFlag<uint32_t> inc_min {
+  inc, "1", "max stride of increment algorithm", {"inc-min"}, 1,
+};
+ValueFlag<uint32_t> inc_max {
+  inc, "1", "max stride of increment algorithm", {"inc-max"}, 1,
+};
+
+Flag output_prob {
+  parser, "output-prob", "prints path probability at last", {"output-prob", "prob"},
+};
+
+}  // namespace param
+
+
+static auto GenerateLegalStepMap(size_t dur, size_t n) {
+  const auto inc_max = args::get(param::inc_max);
+  const auto inc_min = args::get(param::inc_min);
+  Enforce(0 <= inc_min && inc_min <= inc_max, "invalid increment stride");
+
+  std::vector<std::vector<int32_t>> ret;
+  ret.resize(dur*n);
+  auto legals = &ret[0];
+
+  for (size_t t = 0; t < dur; ++t) {
+    for (size_t i = 0; i < n; ++i) {
+      switch (args::get(param::algo)) {
+      case param::kIncrement:
+        legals->reserve(inc_max-inc_min+1);
+        for (uint32_t j = inc_min; j <= inc_max; ++j) {
+          legals->push_back(static_cast<int32_t>((i+j)%n));
+        }
+        break;
+      }
+      ++legals;
+    }
+  }
+  return ret;
+}
+
+static void Exec() {
+  const auto cprobs = ReadMatrix<double>(std::cin);
+  Enforce(cprobs.size() > 0 && cprobs[0].size() > 0, "empty matrix");
+
+  const auto dur = cprobs.size();
+  const auto n   = cprobs[0].size();
+
+  const auto lmap = GenerateLegalStepMap(dur, n);
+
+  struct Step {
+    double prob = -1;
+    size_t from = 0;
+  };
+  std::vector<Step> steps((dur+1)*n);
+  for (size_t i = 0; i < n; ++i) {
+    steps[i].prob = cprobs[0][i];
+  }
+  for (size_t t = 1; t < dur; ++t) {
+    Enforce(cprobs[t].size() == n, "ill-formed matrix");
+    for (size_t i = 0; i < n; ++i) {
+      const auto& cur = steps[(t-1)*n + i];
+      for (auto j : lmap[t*n+i]) {
+        auto& next = steps[t*n + j];
+
+        const auto sum = cur.prob + cprobs[t][j];
+        if (next.prob < sum) {
+          next.prob = sum;
+          next.from = i;
+        }
+      }
+    }
+  }
+
+  double max_prob = -1;
+  size_t max_idx  = 0;
+  for (size_t i = 0; i < n; ++i) {
+    const auto& step = steps[(dur-1)*n + i];
+    if (max_prob < step.prob) {
+      max_prob = step.prob;
+      max_idx  = i;
+    }
+  }
+
+  std::vector<size_t> path = {max_idx};
+  path.reserve(dur);
+  for (size_t t = dur-1; t > 0; --t) {
+    path.push_back(steps[t*n + path.back()].from);
+  }
+  for (auto itr = path.rbegin(); itr < path.rend(); ++itr) {
+    std::cout << *itr << '\n';
+  }
+  if (param::output_prob) {
+    std::cout << max_prob/static_cast<double>(path.size())*100 << "%" << std::endl;
+  }
+}
+
+int main(int argc, char** argv)
+try {
+  param::parser.ParseCLI(argc, argv);
+  Exec();
+  return EXIT_SUCCESS;
+} catch (const args::Help&) {
+  std::cout << param::parser << std::endl;
+  return EXIT_SUCCESS;
+} catch (const std::exception& e) {
+  std::cerr << e.what() << std::endl;
+  return EXIT_FAILURE;
+}
+