Add support to explicitly set segment duration.

Adds a flag to sample muxer to copy input file's duration.

BUG=https://bugs.chromium.org/p/webm/issues/detail?id=1100

Change-Id: I9138f0301fa5c9f467c802d75e6ba32db156ae4f

mkvmuxer/mkvmuxer.cc

@@ -3047,6 +3047,7 @@ Segment::Segment()
       size_position_(0),
       doc_type_version_(kDefaultDocTypeVersion),
       doc_type_version_written_(0),
+      duration_(0.0),
       writer_cluster_(NULL),
       writer_cues_(NULL),
       writer_header_(NULL) {
@@ -3220,21 +3221,25 @@ bool Segment::Finalize() {
     double duration =
         (static_cast<double>(last_timestamp_) + last_block_duration_) /
         segment_info_.timecode_scale();
-    if (last_block_duration_ == 0 && estimate_file_duration_) {
-      const int num_tracks = static_cast<int>(tracks_.track_entries_size());
-      for (int i = 0; i < num_tracks; ++i) {
-        if (track_frames_written_[i] < 2)
-          continue;
+    if (duration_ > 0.0) {
+      duration = duration_;
+    } else {
+      if (last_block_duration_ == 0 && estimate_file_duration_) {
+        const int num_tracks = static_cast<int>(tracks_.track_entries_size());
+        for (int i = 0; i < num_tracks; ++i) {
+          if (track_frames_written_[i] < 2)
+            continue;
 
-        // Estimate the duration for the last block of a Track.
-        const double nano_per_frame =
-            static_cast<double>(last_track_timestamp_[i]) /
-            (track_frames_written_[i] - 1);
-        const double track_duration =
-            (last_track_timestamp_[i] + nano_per_frame) /
-            segment_info_.timecode_scale();
-        if (track_duration > duration)
-          duration = track_duration;
+          // Estimate the duration for the last block of a Track.
+          const double nano_per_frame =
+              static_cast<double>(last_track_timestamp_[i]) /
+              (track_frames_written_[i] - 1);
+          const double track_duration =
+              (last_track_timestamp_[i] + nano_per_frame) /
+              segment_info_.timecode_scale();
+          if (track_duration > duration)
+            duration = track_duration;
+        }
       }
     }
     segment_info_.set_duration(duration);

mkvmuxer/mkvmuxer.h

@@ -1688,6 +1688,8 @@ class Segment {
   }
   bool estimate_file_duration() const { return estimate_file_duration_; }
   const SegmentInfo* segment_info() const { return &segment_info_; }
+  void set_duration(double duration) { duration_ = duration; }
+  double duration() const { return duration_; }
 
   // Returns true when codec IDs are valid for WebM.
   bool DocTypeIsWebm() const;
@@ -1897,6 +1899,9 @@ class Segment {
   uint32_t doc_type_version_;
   uint32_t doc_type_version_written_;
 
+  // If |duration_| is > 0, then explicitly set the duration of the segment.
+  double duration_;
+
   // Pointer to the writer objects. Not owned by this class.
   IMkvWriter* writer_cluster_;
   IMkvWriter* writer_cues_;

mkvmuxer_sample.cc

@@ -54,6 +54,7 @@ void Usage() {
   printf(">0 Writes the last frame in each cluster with Duration\n");
   printf("  -fixed_size_cluster_timecode <int> ");
   printf(">0 Writes the cluster timecode using exactly 8 bytes\n");
+  printf("  -copy_input_duration        >0 Copies the input duration\n");
   printf("\n");
   printf("Video options:\n");
   printf("  -display_width <int>        Display width in pixels\n");
@@ -170,6 +171,7 @@ int main(int argc, char* argv[]) {
   const char* chunk_name = NULL;
   bool accurate_cluster_duration = false;
   bool fixed_size_cluster_timecode = false;
+  bool copy_input_duration = false;
 
   bool output_cues_block_number = true;
 
@@ -234,6 +236,8 @@ int main(int argc, char* argv[]) {
                i < argc_check) {
       fixed_size_cluster_timecode =
           strtol(argv[++i], &end, 10) == 0 ? false : true;
+    } else if (!strcmp("-copy_input_duration", argv[i]) && i < argc_check) {
+      copy_input_duration = strtol(argv[++i], &end, 10) == 0 ? false : true;
     } else if (!strcmp("-display_width", argv[i]) && i < argc_check) {
       display_width = strtol(argv[++i], &end, 10);
     } else if (!strcmp("-display_height", argv[i]) && i < argc_check) {
@@ -655,6 +659,12 @@ int main(int argc, char* argv[]) {
   if (!metadata.Write(-1))
     return EXIT_FAILURE;
 
+  if (copy_input_duration) {
+    const double input_duration =
+        static_cast<double>(segment_info->GetDuration()) / timeCodeScale;
+    muxer_segment.set_duration(input_duration);
+  }
+
   if (!muxer_segment.Finalize()) {
     printf("Finalization of segment failed.\n");
     return EXIT_FAILURE;

testing/mkvmuxer_tests.cc

@@ -409,6 +409,22 @@ TEST_F(MuxerTest, SegmentDurationComputation) {
       CompareFiles(GetTestFilePath("segment_duration.webm"), filename_));
 }
 
+TEST_F(MuxerTest, SetSegmentDuration) {
+  EXPECT_TRUE(SegmentInit(false, false, false));
+  AddVideoTrack();
+  EXPECT_TRUE(segment_.AddFrame(dummy_data_, kFrameLength, kVideoTrackNumber, 0,
+                                false));
+  EXPECT_TRUE(segment_.AddFrame(dummy_data_, kFrameLength, kVideoTrackNumber,
+                                2000000, false));
+
+  segment_.set_duration(10500.0);
+  segment_.Finalize();
+  CloseWriter();
+
+  EXPECT_TRUE(
+      CompareFiles(GetTestFilePath("set_segment_duration.webm"), filename_));
+}
+
 TEST_F(MuxerTest, ForceNewCluster) {
   EXPECT_TRUE(SegmentInit(false, false, false));
   segment_.set_estimate_file_duration(false);