implement encoding a part of the host video

conv/block_stego.cc

@@ -36,6 +36,15 @@ ValueFlag<int32_t> bh {
 ValueFlag<int32_t> utime {
   parser, "10", "duration of each feature (frame)", {"utime"}, 10,
 };
+ValueFlag<int32_t> dur {
+  parser, "0", "number of features to be extracted (ut)", {"dur"}, 0,
+};
+ValueFlag<int32_t> offset {
+  parser, "0", "number of offset frames to start extraction", {"offset"}, 0,
+};
+Flag only_body {
+  parser, "only-body", "cut off head and tail that no feature is embedded", {"only-body"},
+};
 
 Flag uvfix {
   parser, "uvfix", "fix UV values in feature", {"uvfix"},
@@ -94,6 +103,8 @@ static void Exec() {
   const auto bw     = args::get(param::bw);
   const auto bh     = args::get(param::bh);
   const auto ut     = args::get(param::utime);
+  const auto dur    = args::get(param::dur);
+  const auto offset = args::get(param::offset);
   Enforce(bw > 0 && bh > 0, "block size must be greater than 0");
   Enforce(ut > 0, "utime must be greater than 0");
 
@@ -151,10 +162,10 @@ static void Exec() {
 
   // calc params
   const auto tscale = tra.timescale;
-  const auto dur    =
+  const auto dur_t  =
       (static_cast<uint64_t>(tra.duration_hi) << 32) |
       static_cast<uint64_t>(tra.duration_lo);
-  const auto dursec = static_cast<float>(dur)/static_cast<float>(tscale);
+  const auto dursec = static_cast<float>(dur_t)/static_cast<float>(tscale);
 
   const float   fps  = static_cast<float>(tra.sample_count)/dursec;
   const auto    fps9 = static_cast<int>(90000/fps);
@@ -218,10 +229,10 @@ static void Exec() {
 
   // decode frame
   Frame bf = {};
-  int32_t t = 0;
+  int32_t fidx = 0;
   for (size_t si = 0; si < tra.sample_count; ++si) {
-    unsigned fsz, time, dur;
+    unsigned fsz, ftime, fdur;
-    const auto off = MP4D_frame_offset(&dem, ti, si, &fsz, &time, &dur);
+    const auto off = MP4D_frame_offset(&dem, ti, si, &fsz, &ftime, &fdur);
 
     srcst.seekg(off);
     Enforce(!!srcst, "NAL seek failure");
@@ -247,13 +258,23 @@ static void Exec() {
 
       // handle decoded frame
       if (frame.iBufferStatus) {
+        bool encode_frame = !param::only_body;
+        bool keep_frame   = false;
+
         // alter the frame if it's not the first
         Frame cf = {yuv, frame};
-        if (t%ut > 0) {
+        if (offset <= fidx && (dur == 0 || fidx-offset < dur*ut)) {
-          Embed(t/ut, cf, bf);
+          const auto t  = (fidx-offset)/ut;
+          const auto tf = (fidx-offset)%ut;
+          if (tf > 0) {
+            Embed(t, cf, bf);
+          }
+          encode_frame = true;
+          keep_frame   = (tf == 0);
         }
 
         // encode
+        if (encode_frame) {
           SFrameBSInfo   info;
           SSourcePicture pic = cf.GetSourcePic();
           Enforce(cmResultSuccess == enc->EncodeFrame(&pic, &info),
@@ -272,12 +293,13 @@ static void Exec() {
               }
             }
           }
+        }
 
         // save the frame if it's the first
-        if (t%ut == 0) {
+        if (keep_frame) {
           bf = std::move(cf);
         }
-        ++t;
+        ++fidx;
       }
       i += sz;
     }

conv/stego_aprob.cc

@@ -35,6 +35,12 @@ ValueFlag<int32_t> bh {
 ValueFlag<int32_t> utime {
   parser, "10", "duration of each feature (frame)", {"utime"}, 10,
 };
+ValueFlag<int32_t> dur {
+  parser, "0", "number of features to be extracted (ut)", {"dur"}, 0,
+};
+ValueFlag<int32_t> offset {
+  parser, "0", "number of offset frames to start extraction", {"offset"}, 0,
+};
 
 ValueFlag<int32_t> bmix {
   parser, "8", "x interval of blockmatch (px)", {"bm-ix"}, 8,
@@ -187,6 +193,8 @@ static void Exec() {
   const auto bw     = args::get(param::bw);
   const auto bh     = args::get(param::bh);
   const auto ut     = args::get(param::utime);
+  const auto dur    = args::get(param::dur);
+  const auto offset = args::get(param::offset);
   Enforce(bw > 0 && bh > 0, "block size must be greater than 0");
   Enforce(ut > 0, "utime must be greater than 0");
 
@@ -265,10 +273,10 @@ static void Exec() {
 
   // decode frame
   Frame pf = {};
-  size_t t = 0;
+  int32_t fidx = 0;
   for (size_t si = 0; si < tra.sample_count; ++si) {
-    unsigned fsz, time, dur;
+    unsigned fsz, ftime, fdur;
-    const auto off = MP4D_frame_offset(&dem, ti, si, &fsz, &time, &dur);
+    const auto off = MP4D_frame_offset(&dem, ti, si, &fsz, &ftime, &fdur);
 
     vst.seekg(off);
     Enforce(!!vst, "NAL seek failure");
@@ -291,16 +299,17 @@ static void Exec() {
       Enforce(ret == 0, "frame decode failure");
       i += sz;
 
+      if (offset <= fidx && (dur == 0 || fidx-offset < dur*ut)) {
         Frame cf = {yuv, frame};
         if (cf.w == 0 || cf.h == 0) continue;
 
-      const auto utf = t%ut;
+        const auto tf = (fidx-offset)%ut;
-      if (utf > 0) {
+        if (tf > 0) {
-        EachFrame(utf, cf, pf);
+          EachFrame(tf, cf, pf);
         }
         pf = std::move(cf);
-
+      }
-      ++t;
+      ++fidx;
     }
   }
 }