avfilter/idet: add current frame classification to metadata

Fixes ticket 3832
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

doc/filters.texi

@@ -5577,9 +5577,17 @@ Detect video interlacing type.
 This filter tries to detect if the input is interlaced or progressive,
 top or bottom field first.
 
+Single frame detection considers only immediately adjacent frames when classifying each frame.
+Multiple frame detection incorporates the classification history of previous frames.
+
 The filter will log these metadata values:
 
 @table @option
+@item single.current_frame
+Detected type of current frame using single-frame detection. One of:
+``tff'' (top field first), ``bff'' (bottom field first),
+``progressive'', or ``undetermined''
+
 @item single.tff
 Cumulative number of frames detected as top field first using single-frame detection.
 
@@ -5589,6 +5597,11 @@ Cumulative number of frames detected as top field first using multiple-frame det
 @item single.bff
 Cumulative number of frames detected as bottom field first using single-frame detection.
 
+@item multiple.current_frame
+Detected type of current frame using multiple-frame detection. One of:
+``tff'' (top field first), ``bff'' (bottom field first),
+``progressive'', or ``undetermined''
+
 @item multiple.bff
 Cumulative number of frames detected as bottom field first using multiple-frame detection.
 

libavfilter/vf_idet.c

@@ -40,10 +40,10 @@ AVFILTER_DEFINE_CLASS(idet);
 static const char *type2str(Type type)
 {
     switch(type) {
-        case TFF          : return "Top Field First   ";
-        case BFF          : return "Bottom Field First";
-        case PROGRESSIVE  : return "Progressive       ";
-        case UNDETERMINED : return "Undetermined      ";
+        case TFF          : return "tff";
+        case BFF          : return "bff";
+        case PROGRESSIVE  : return "progressive";
+        case UNDETERMINED : return "undetermined";
     }
     return NULL;
 }
@@ -149,13 +149,15 @@ static void filter(AVFilterContext *ctx)
     idet->prestat [           type] ++;
     idet->poststat[idet->last_type] ++;
 
-    av_log(ctx, AV_LOG_DEBUG, "Single frame:%s, Multi frame:%s\n", type2str(type), type2str(idet->last_type));
+    av_log(ctx, AV_LOG_DEBUG, "Single frame:%12s, Multi frame:%12s\n", type2str(type), type2str(idet->last_type));
 
+    av_dict_set    (metadata, "lavfi.idet.single.current_frame", type2str(type), 0);
     av_dict_set_int(metadata, "lavfi.idet.single.tff", idet->prestat[TFF], 0);
     av_dict_set_int(metadata, "lavfi.idet.single.bff", idet->prestat[BFF], 0);
     av_dict_set_int(metadata, "lavfi.idet.single.progressive", idet->prestat[PROGRESSIVE], 0);
     av_dict_set_int(metadata, "lavfi.idet.single.undetermined", idet->prestat[UNDETERMINED], 0);
 
+    av_dict_set    (metadata, "lavfi.idet.multiple.current_frame", type2str(idet->last_type), 0);
     av_dict_set_int(metadata, "lavfi.idet.multiple.tff", idet->poststat[TFF], 0);
     av_dict_set_int(metadata, "lavfi.idet.multiple.bff", idet->poststat[BFF], 0);
     av_dict_set_int(metadata, "lavfi.idet.multiple.progressive", idet->poststat[PROGRESSIVE], 0);