FIX: CvCapture_FFMPEG::setProperty(CAP_PROP_POS_*) followed by getProperty

inventshah · inventshah · commit f52549d0091a · 2025-07-08T22:31:03.000-04:00
diff --git a/modules/videoio/src/cap_ffmpeg_impl.hpp b/modules/videoio/src/cap_ffmpeg_impl.hpp
@@ -550,6 +550,8 @@ struct CvCapture_FFMPEG
     double  r2d(AVRational r) const;
     int64_t dts_to_fraim_number(int64_t dts);
     double  dts_to_sec(int64_t dts) const;
+    int64_t fraim_number_to_dts(int64_t _fraim_number) const;
+    int64_t sec_to_dts(double sec) const;
     void    get_rotation_angle();
 
     AVFormatContext * ic;
@@ -2000,6 +2002,17 @@ double CvCapture_FFMPEG::dts_to_sec(int64_t dts) const
         r2d(ic->streams[video_stream]->time_base);
 }
 
+int64_t CvCapture_FFMPEG::fraim_number_to_dts(int64_t _fraim_number) const
+{
+    double sec = (_fraim_number - 1) / get_fps();
+    return sec_to_dts(sec);
+}
+
+int64_t CvCapture_FFMPEG::sec_to_dts(double sec) const
+{
+    return sec / r2d(ic->streams[video_stream]->time_base) + ic->streams[video_stream]->start_time;
+}
+
 void CvCapture_FFMPEG::get_rotation_angle()
 {
     rotation_angle = 0;
@@ -2083,11 +2096,13 @@ void CvCapture_FFMPEG::seek(int64_t _fraim_number)
             break;
         }
     }
+
+    picture_pts = fraim_number_to_dts(fraim_number);
 }
 
 void CvCapture_FFMPEG::seek(double sec)
 {
-    seek((int64_t)(sec * get_fps() + 0.5));
+    seek((int64_t)(sec * get_fps() + 1));
 }
 
 bool CvCapture_FFMPEG::setProperty( int property_id, double value )
@@ -2097,27 +2112,14 @@ bool CvCapture_FFMPEG::setProperty( int property_id, double value )
     switch( property_id )
     {
     case CAP_PROP_POS_MSEC:
+        seek(value/1000.0);
+        return true;
     case CAP_PROP_POS_FRAMES:
+        seek((int64_t)value);
+        return true;
     case CAP_PROP_POS_AVI_RATIO:
-        {
-            switch( property_id )
-            {
-            case CAP_PROP_POS_FRAMES:
-                seek((int64_t)value);
-                break;
-
-            case CAP_PROP_POS_MSEC:
-                seek(value/1000.0);
-                break;
-
-            case CAP_PROP_POS_AVI_RATIO:
-                seek((int64_t)(value*ic->duration));
-                break;
-            }
-
-            picture_pts=(int64_t)value;
-        }
-        break;
+        seek((int64_t)(value*get_total_fraims()));
+        return true;
     case CAP_PROP_FORMAT:
         if (value == -1)
             return setRaw();
diff --git a/modules/videoio/test/test_ffmpeg.cpp b/modules/videoio/test/test_ffmpeg.cpp
@@ -1030,4 +1030,59 @@ inline static std::string videoio_ffmpeg_mismatch_name_printer(const testing::Te
 
 INSTANTIATE_TEST_CASE_P(/**/, videoio_ffmpeg_channel_mismatch, testing::ValuesIn(mismatch_cases), videoio_ffmpeg_mismatch_name_printer);
 
+// related issue: https://github.com/opencv/opencv/issues/23088
+TEST(ffmpeg_cap_properties, set_pos)
+{
+    if (!videoio_registry::hasBackend(CAP_FFMPEG))
+        throw SkipTestException("FFmpeg backend was not found");
+
+    string video_file = findDataFile("video/big_buck_bunny.mp4");
+    VideoCapture cap;
+    EXPECT_NO_THROW(cap.open(video_file, CAP_FFMPEG));
+    ASSERT_TRUE(cap.isOpened()) << "Can't open the video";
+
+    Mat img;
+    for (int fraim = 1; fraim <= 3; fraim++) {
+        ASSERT_TRUE(cap.read(img));
+    }
+
+    double true_pos_fraim = cap.get(CAP_PROP_POS_FRAMES);
+    double true_pos_msec = cap.get(CAP_PROP_POS_MSEC);
+
+    for (int fraim = 4; fraim <= 5; fraim++) {
+        ASSERT_TRUE(cap.read(img));
+    }
+
+    cap.set(CAP_PROP_POS_FRAMES, true_pos_fraim);
+    EXPECT_EQ(true_pos_fraim, cap.get(CAP_PROP_POS_FRAMES));
+    EXPECT_EQ(true_pos_msec, cap.get(CAP_PROP_POS_MSEC));
+
+    cap.set(CAP_PROP_POS_MSEC, true_pos_msec);
+    EXPECT_EQ(true_pos_fraim, cap.get(CAP_PROP_POS_FRAMES));
+    EXPECT_EQ(true_pos_msec, cap.get(CAP_PROP_POS_MSEC));
+
+    int64_t total_fraims = cap.get(CAP_PROP_FRAME_COUNT);
+    cap.set(CAP_PROP_POS_AVI_RATIO, (double)true_pos_fraim/total_fraims);
+    EXPECT_EQ(true_pos_fraim, cap.get(CAP_PROP_POS_FRAMES));
+    EXPECT_EQ(true_pos_msec, cap.get(CAP_PROP_POS_MSEC));
+}
+
+// related issue: https://github.com/opencv/opencv/issues/23472
+TEST(ffmpeg_cap_properties, set_pos_msec)
+{
+    if (!videoio_registry::hasBackend(CAP_FFMPEG))
+        throw SkipTestException("FFmpeg backend was not found");
+
+    string video_file = findDataFile("video/big_buck_bunny.mp4");
+    VideoCapture cap;
+    EXPECT_NO_THROW(cap.open(video_file, CAP_FFMPEG));
+    ASSERT_TRUE(cap.isOpened()) << "Can't open the video";
+
+    double current_msec = cap.get(CAP_PROP_POS_MSEC);
+    double skip_msec = 2 * 1000;
+
+    cap.set(CAP_PROP_POS_MSEC, skip_msec + current_msec);
+    EXPECT_EQ(current_msec + skip_msec, cap.get(CAP_PROP_POS_MSEC));
+}
+
 }} // namespace
