h264parse: Include `interlace-mode` in caps

Those are the rules:

In the SPS:
  * if frame_mbs_only_flag=1 => all frame progressive
  * if frame_mbs_only_flag=0 => field_pic_flag defines if each frame is
    progressive or interlaced, thus the mode is 'mixed' in GStreamer
    terms.

https://bugzilla.gnome.org/show_bug.cgi?id=779309

1 files changed, 8 insertions, 0 deletions

diff --git a/gst/videoparsers/gsth264parse.c b/gst/videoparsers/gsth264parse.c
index 3153c2bc5..aaf4c39ac 100644
--- a/gst/videoparsers/gsth264parse.c
+++ b/gst/videoparsers/gsth264parse.c
@@ -1791,6 +1791,7 @@ gst_h264_parse_update_src_caps (GstH264Parse * h264parse, GstCaps * caps)
     }
 
     if (G_UNLIKELY (modified || h264parse->update_caps)) {
+      GstVideoInterlaceMode imode = GST_VIDEO_INTERLACE_MODE_PROGRESSIVE;
       gint width, height;
       GstClockTime latency;
 
@@ -1864,7 +1865,14 @@ gst_h264_parse_update_src_caps (GstH264Parse * h264parse, GstCaps * caps)
           gst_base_parse_set_latency (GST_BASE_PARSE (h264parse), latency,
               latency);
         }
+
       }
+      if (sps->frame_mbs_only_flag == 0)
+        imode = GST_VIDEO_INTERLACE_MODE_MIXED;
+
+      if (s && !gst_structure_has_field (s, "interlace-mode"))
+        gst_caps_set_simple (caps, "interlace-mode", G_TYPE_STRING,
+            gst_video_interlace_mode_to_string (imode), NULL);
     }
   }