From b0534c65d1797b871b5c796a1761011f5015acff Mon Sep 17 00:00:00 2001
From: Doug Nazar <nazard@nazar.ca>
Date: Wed, 7 Aug 2019 10:01:34 -0400
Subject: [PATCH] matroska: Handle interlaced field order

---
 gst/matroska/matroska-demux.c | 45 ++++++++++++++++++++++++++++++++++-
 gst/matroska/matroska-ids.c   |  1 +
 gst/matroska/matroska-ids.h   |  2 ++
 gst/matroska/matroska-parse.c | 38 +++++++++++++++++++++++++++++
 4 files changed, 85 insertions(+), 1 deletion(-)

diff --git a/gst/matroska/matroska-demux.c b/gst/matroska/matroska-demux.c
index 5878f38449..e39965baf5 100644
--- a/gst/matroska/matroska-demux.c
+++ b/gst/matroska/matroska-demux.c
@@ -974,6 +974,44 @@ gst_matroska_demux_parse_stream (GstMatroskaDemux * demux, GstEbmlRead * ebml,
               break;
             }
 
+              /* interlaced field order */
+            case GST_MATROSKA_ID_VIDEOFIELDORDER:{
+              guint64 num;
+
+              if ((ret = gst_ebml_read_uint (ebml, &id, &num)) != GST_FLOW_OK)
+                break;
+
+              if (videocontext->interlace_mode !=
+                  GST_MATROSKA_INTERLACE_MODE_INTERLACED) {
+                GST_WARNING_OBJECT (demux,
+                    "FieldOrder element when not interlaced - ignoring");
+                break;
+              }
+
+              if (num == 0)
+                /* turns out we're actually progressive */
+                videocontext->interlace_mode =
+                    GST_MATROSKA_INTERLACE_MODE_PROGRESSIVE;
+              else if (num == 2)
+                videocontext->field_order = GST_VIDEO_FIELD_ORDER_UNKNOWN;
+              else if (num == 9)
+                videocontext->field_order =
+                    GST_VIDEO_FIELD_ORDER_TOP_FIELD_FIRST;
+              else if (num == 14)
+                videocontext->field_order =
+                    GST_VIDEO_FIELD_ORDER_BOTTOM_FIELD_FIRST;
+              else {
+                GST_FIXME_OBJECT (demux,
+                    "Unknown or unsupported FieldOrder %" G_GUINT64_FORMAT,
+                    num);
+                videocontext->field_order = GST_VIDEO_FIELD_ORDER_UNKNOWN;
+              }
+
+              GST_DEBUG_OBJECT (demux, "video track field order: %d",
+                  videocontext->field_order);
+              break;
+            }
+
               /* aspect ratio behaviour */
             case GST_MATROSKA_ID_VIDEOASPECTRATIOTYPE:{
               guint64 num;
@@ -6437,7 +6475,12 @@ gst_matroska_demux_video_caps (GstMatroskaTrackVideoContext *
           break;
         case GST_MATROSKA_INTERLACE_MODE_INTERLACED:
           gst_structure_set (structure,
-              "interlace-mode", G_TYPE_STRING, "mixed", NULL);
+              "interlace-mode", G_TYPE_STRING, "interleaved", NULL);
+
+          if (videocontext->field_order != GST_VIDEO_FIELD_ORDER_UNKNOWN)
+            gst_structure_set (structure, "field-order", G_TYPE_STRING,
+                gst_video_field_order_to_string (videocontext->field_order),
+                NULL);
           break;
         default:
           break;
diff --git a/gst/matroska/matroska-ids.c b/gst/matroska/matroska-ids.c
index b3c51309b6..3722822b19 100644
--- a/gst/matroska/matroska-ids.c
+++ b/gst/matroska/matroska-ids.c
@@ -59,6 +59,7 @@ gst_matroska_track_init_video_context (GstMatroskaTrackContext ** p_context)
   video_context->fourcc = 0;
   video_context->default_fps = 0.0;
   video_context->interlace_mode = GST_MATROSKA_INTERLACE_MODE_UNKNOWN;
+  video_context->field_order = GST_VIDEO_FIELD_ORDER_UNKNOWN;
   video_context->earliest_time = GST_CLOCK_TIME_NONE;
   video_context->dirac_unit = NULL;
   video_context->earliest_time = GST_CLOCK_TIME_NONE;
diff --git a/gst/matroska/matroska-ids.h b/gst/matroska/matroska-ids.h
index ab74ed2897..429213f778 100644
--- a/gst/matroska/matroska-ids.h
+++ b/gst/matroska/matroska-ids.h
@@ -132,6 +132,7 @@
 #define GST_MATROSKA_ID_VIDEOPIXELCROPLEFT         0x54CC
 #define GST_MATROSKA_ID_VIDEOPIXELCROPRIGHT        0x54DD
 #define GST_MATROSKA_ID_VIDEOFLAGINTERLACED        0x9A
+#define GST_MATROSKA_ID_VIDEOFIELDORDER            0x9D
 /* semi-draft */
 #define GST_MATROSKA_ID_VIDEOSTEREOMODE            0x53B8
 #define GST_MATROSKA_ID_VIDEOASPECTRATIOTYPE       0x54B3
@@ -632,6 +633,7 @@ typedef struct _GstMatroskaTrackVideoContext {
   guint32       fourcc;
 
   GstMatroskaInterlaceMode interlace_mode;
+  GstVideoFieldOrder field_order;
 
   GstVideoMultiviewMode multiview_mode;
   GstVideoMultiviewFlags multiview_flags;
diff --git a/gst/matroska/matroska-parse.c b/gst/matroska/matroska-parse.c
index b34817ffb4..594cd9a137 100644
--- a/gst/matroska/matroska-parse.c
+++ b/gst/matroska/matroska-parse.c
@@ -557,6 +557,44 @@ gst_matroska_parse_add_stream (GstMatroskaParse * parse, GstEbmlRead * ebml)
               break;
             }
 
+              /* interlaced field order */
+            case GST_MATROSKA_ID_VIDEOFIELDORDER:{
+              guint64 num;
+
+              if ((ret = gst_ebml_read_uint (ebml, &id, &num)) != GST_FLOW_OK)
+                break;
+
+              if (videocontext->interlace_mode !=
+                  GST_MATROSKA_INTERLACE_MODE_INTERLACED) {
+                GST_WARNING_OBJECT (parse,
+                    "FieldOrder element when not interlaced - ignoring");
+                break;
+              }
+
+              if (num == 0)
+                /* turns out we're actually progressive */
+                videocontext->interlace_mode =
+                    GST_MATROSKA_INTERLACE_MODE_PROGRESSIVE;
+              else if (num == 2)
+                videocontext->field_order = GST_VIDEO_FIELD_ORDER_UNKNOWN;
+              else if (num == 9)
+                videocontext->field_order =
+                    GST_VIDEO_FIELD_ORDER_TOP_FIELD_FIRST;
+              else if (num == 14)
+                videocontext->field_order =
+                    GST_VIDEO_FIELD_ORDER_BOTTOM_FIELD_FIRST;
+              else {
+                GST_FIXME_OBJECT (parse,
+                    "Unknown or unsupported FieldOrder %" G_GUINT64_FORMAT,
+                    num);
+                videocontext->field_order = GST_VIDEO_FIELD_ORDER_UNKNOWN;
+              }
+
+              GST_DEBUG_OBJECT (parse, "video track field order: %d",
+                  videocontext->field_order);
+              break;
+            }
+
               /* aspect ratio behaviour */
             case GST_MATROSKA_ID_VIDEOASPECTRATIOTYPE:{
               guint64 num;