cv::VideoCapture: change CAP_PROP_FOURCC to prefer codec_id over codec_tag

modules/videoio/src/cap_ffmpeg_impl.hpp

@@ -1707,14 +1707,36 @@ bool CvCapture_FFMPEG::retrieveHWFrame(cv::OutputArray output)
 #endif
 }
 
+static inline double getCodecTag(const AVCodecID codec_id) {
+    const struct AVCodecTag* fallback_tags[] = {
+        // APIchanges:
+        // 2012-01-31 - dd6d3b0 - lavf 54.01.0
+        //   Add avformat_get_riff_video_tags() and avformat_get_riff_audio_tags().
+        avformat_get_riff_video_tags(),
+#if LIBAVFORMAT_BUILD >= CALC_FFMPEG_VERSION(55, 25, 100) && defined LIBAVFORMAT_VERSION_MICRO && LIBAVFORMAT_VERSION_MICRO >= 100
+        // APIchanges: ffmpeg only
+        // 2014-01-19 - 1a193c4 - lavf 55.25.100 - avformat.h
+        //   Add avformat_get_mov_video_tags() and avformat_get_mov_audio_tags().
+        avformat_get_mov_video_tags(),
+#endif
+        codec_bmp_tags, // fallback for avformat < 54.1
+        NULL };
+    return av_codec_get_tag(fallback_tags, codec_id);
+}
+
+static inline double getCodecIdFourcc(const AVCodecID codec_id)
+{
+    if (codec_id == AV_CODEC_ID_NONE) return -1;
+    const char* codec_fourcc = _opencv_avcodec_get_name(codec_id);
+    if (!codec_fourcc || strcmp(codec_fourcc, "unknown_codec") == 0 || strlen(codec_fourcc) != 4)
+        return getCodecTag(codec_id);
+    return (double)CV_FOURCC(codec_fourcc[0], codec_fourcc[1], codec_fourcc[2], codec_fourcc[3]);
+}
+
 double CvCapture_FFMPEG::getProperty( int property_id ) const
 {
     if( !video_st || !context ) return 0;
 
-    double codec_tag = 0;
-    CV_CODEC_ID codec_id = AV_CODEC_ID_NONE;
-    const char* codec_fourcc = NULL;
-
     switch( property_id )
     {
     case CAP_PROP_POS_MSEC:
@@ -1738,34 +1760,11 @@ double CvCapture_FFMPEG::getProperty( int property_id ) const
     case CAP_PROP_FPS:
         return get_fps();
     case CAP_PROP_FOURCC: {
-        codec_id = video_st->CV_FFMPEG_CODEC_FIELD->codec_id;
+        const double fourcc = getCodecIdFourcc(video_st->CV_FFMPEG_CODEC_FIELD->codec_id);
-        codec_tag = (double) video_st->CV_FFMPEG_CODEC_FIELD->codec_tag;
+        if (fourcc != -1) return fourcc;
-
+        const double codec_tag = (double)video_st->CV_FFMPEG_CODEC_FIELD->codec_tag;
-        if(codec_tag || codec_id == AV_CODEC_ID_NONE)
+        if (codec_tag) return codec_tag;
-        {
+        else return -1;
-            return codec_tag;
-        }
-
-        codec_fourcc = _opencv_avcodec_get_name(codec_id);
-        if (!codec_fourcc || strcmp(codec_fourcc, "unknown_codec") == 0 || strlen(codec_fourcc) != 4)
-        {
-            const struct AVCodecTag* fallback_tags[] = {
-            // APIchanges:
-            // 2012-01-31 - dd6d3b0 - lavf 54.01.0
-            //   Add avformat_get_riff_video_tags() and avformat_get_riff_audio_tags().
-                avformat_get_riff_video_tags(),
-#if LIBAVFORMAT_BUILD >= CALC_FFMPEG_VERSION(55, 25, 100) && defined LIBAVFORMAT_VERSION_MICRO && LIBAVFORMAT_VERSION_MICRO >= 100
-            // APIchanges: ffmpeg only
-            // 2014-01-19 - 1a193c4 - lavf 55.25.100 - avformat.h
-            //   Add avformat_get_mov_video_tags() and avformat_get_mov_audio_tags().
-                avformat_get_mov_video_tags(),
-#endif
-                codec_bmp_tags, // fallback for avformat < 54.1
-                NULL };
-            return av_codec_get_tag(fallback_tags, codec_id);
-        }
-
-        return (double) CV_FOURCC(codec_fourcc[0], codec_fourcc[1], codec_fourcc[2], codec_fourcc[3]);
     }
     case CAP_PROP_SAR_NUM:
         return _opencv_ffmpeg_get_sample_aspect_ratio(ic->streams[video_stream]).num;

modules/videoio/test/test_ffmpeg.cpp

@@ -226,7 +226,11 @@ const videoio_container_params_t videoio_container_params[] =
     videoio_container_params_t(CAP_FFMPEG, "video/big_buck_bunny", "h264", "h264", "h264", "I420"),
     videoio_container_params_t(CAP_FFMPEG, "video/big_buck_bunny", "h265", "h265", "hevc", "I420"),
     videoio_container_params_t(CAP_FFMPEG, "video/big_buck_bunny", "mjpg.avi", "mjpg", "MJPG", "I420"),
+#ifdef _WIN32 // handle old FFmpeg backend - remove when windows shared library is updated
     videoio_container_params_t(CAP_FFMPEG, "video/sample_322x242_15frames.yuv420p.libx264", "mp4", "h264", "avc1", "I420")
+#else
+    videoio_container_params_t(CAP_FFMPEG, "video/sample_322x242_15frames.yuv420p.libx264", "mp4", "h264", "h264", "I420")
+#endif
     //videoio_container_params_t(CAP_FFMPEG, "video/big_buck_bunny", "h264.mkv", "mkv.h264", "h264", "I420"),
     //videoio_container_params_t(CAP_FFMPEG, "video/big_buck_bunny", "h265.mkv", "mkv.h265", "hevc", "I420"),
     //videoio_container_params_t(CAP_FFMPEG, "video/big_buck_bunny", "h264.mp4", "mp4.avc1", "avc1", "I420"),
@@ -448,10 +452,21 @@ TEST_P(ffmpeg_get_fourcc, check_short_codecs)
 const ffmpeg_get_fourcc_param_t ffmpeg_get_fourcc_param[] =
 {
     ffmpeg_get_fourcc_param_t("../cv/tracking/faceocc2/data/faceocc2.webm", "VP80"),
-    ffmpeg_get_fourcc_param_t("video/sample_322x242_15frames.yuv420p.libvpx-vp9.mp4", "vp09"),
-    ffmpeg_get_fourcc_param_t("video/sample_322x242_15frames.yuv420p.libaom-av1.mp4", "av01"),
     ffmpeg_get_fourcc_param_t("video/big_buck_bunny.h265", "hevc"),
-    ffmpeg_get_fourcc_param_t("video/big_buck_bunny.h264", "h264")
+    ffmpeg_get_fourcc_param_t("video/big_buck_bunny.h264", "h264"),
+#ifdef _WIN32 // handle old FFmpeg backend - remove when windows shared library is updated
+    ffmpeg_get_fourcc_param_t("video/sample_322x242_15frames.yuv420p.libvpx-vp9.mp4", "vp09"),
+    ffmpeg_get_fourcc_param_t("video/sample_322x242_15frames.yuv420p.libaom-av1.mp4", "av01")
+#else
+    ffmpeg_get_fourcc_param_t("video/sample_322x242_15frames.yuv420p.libvpx-vp9.mp4", "VP90"),
+    ffmpeg_get_fourcc_param_t("video/sample_322x242_15frames.yuv420p.libaom-av1.mp4", "AV01"),
+    ffmpeg_get_fourcc_param_t("video/big_buck_bunny.mp4", "FMP4"),
+    ffmpeg_get_fourcc_param_t("video/sample_322x242_15frames.yuv420p.mpeg2video.mp4", "mpg2"),
+    ffmpeg_get_fourcc_param_t("video/sample_322x242_15frames.yuv420p.mjpeg.mp4", "MJPG"),
+    ffmpeg_get_fourcc_param_t("video/sample_322x242_15frames.yuv420p.libxvid.mp4", "FMP4"),
+    ffmpeg_get_fourcc_param_t("video/sample_322x242_15frames.yuv420p.libx265.mp4", "hevc"),
+    ffmpeg_get_fourcc_param_t("video/sample_322x242_15frames.yuv420p.libx264.mp4", "h264")
+#endif
 };
 
 INSTANTIATE_TEST_CASE_P(videoio, ffmpeg_get_fourcc, testing::ValuesIn(ffmpeg_get_fourcc_param));