plugins: preserve framerate when updating src caps video format.

In the current implementation, gst_video_info_set_format() would reset
the whole GstVideoInfo structure first, prior to setting video format
and size. So, coleteral information like framerate or pixel-aspect-
ratio are lost.

Provide and use a unique gst_video_info_change_format() for overcome
this issue, i.e. only have it change the format and video size, and
copy over the rest of the fields.

https://bugzilla.gnome.org/show_bug.cgi?id=734665

gst/vaapi/gstvaapidecode.c

@@ -129,25 +129,6 @@ gst_vaapidecode_update_sink_caps(GstVaapiDecode *decode, GstCaps *caps)
     return TRUE;
 }
 
-#if GST_CHECK_VERSION(1,1,0)
-static void
-gst_vaapidecode_video_info_change_format(GstVideoInfo *info,
-    GstVideoFormat format, guint width, guint height)
-{
-    GstVideoInfo vi = *info;
-
-    gst_video_info_set_format (info, format, width, height);
-
-    info->interlace_mode = vi.interlace_mode;
-    info->flags = vi.flags;
-    info->views = vi.views;
-    info->par_n = vi.par_n;
-    info->par_d = vi.par_d;
-    info->fps_n = vi.fps_n;
-    info->fps_d = vi.fps_d;
-}
-#endif
-
 static gboolean
 gst_vaapidecode_update_src_caps(GstVaapiDecode *decode,
     const GstVideoCodecState *ref_state)
@@ -188,7 +169,7 @@ gst_vaapidecode_update_src_caps(GstVaapiDecode *decode,
     vis = *vi;
     switch (feature) {
     case GST_VAAPI_CAPS_FEATURE_GL_TEXTURE_UPLOAD_META:
-        gst_vaapidecode_video_info_change_format(&vis, GST_VIDEO_FORMAT_RGBA,
+        gst_video_info_change_format(&vis, GST_VIDEO_FORMAT_RGBA,
             GST_VIDEO_INFO_WIDTH(vi), GST_VIDEO_INFO_HEIGHT(vi));
         features = gst_caps_features_new(
             GST_CAPS_FEATURE_META_GST_VIDEO_GL_TEXTURE_UPLOAD_META, NULL);
@@ -199,7 +180,7 @@ gst_vaapidecode_update_src_caps(GstVaapiDecode *decode,
                format=ENCODED + memory:VASurface caps feature are provided.
                Meanwhile, providing a random format here works but this is
                a terribly wrong thing per se. */
-            gst_vaapidecode_video_info_change_format(&vis, out_format,
+            gst_video_info_change_format(&vis, out_format,
                 GST_VIDEO_INFO_WIDTH(vi), GST_VIDEO_INFO_HEIGHT(vi));
 #if GST_CHECK_VERSION(1,5,0)
             if (feature == GST_VAAPI_CAPS_FEATURE_VAAPI_SURFACE)
@@ -544,7 +525,7 @@ gst_vaapidecode_decide_allocation(GstVideoDecoder *vdec, GstQuery *query)
     state = gst_video_decoder_get_output_state(vdec);
     if (!gst_caps_is_always_compatible(caps, state->caps)) {
         if (decode->has_texture_upload_meta)
-            gst_video_info_set_format(&state->info, GST_VIDEO_FORMAT_RGBA,
+            gst_video_info_change_format(&state->info, GST_VIDEO_FORMAT_RGBA,
                 GST_VIDEO_INFO_WIDTH(&state->info),
                 GST_VIDEO_INFO_HEIGHT(&state->info));
         gst_vaapidecode_update_src_caps(decode, state);

gst/vaapi/gstvaapipluginutil.c

@@ -681,3 +681,20 @@ gst_caps_has_vaapi_surface (GstCaps * caps)
 #endif
   return found_caps;
 }
+
+void
+gst_video_info_change_format (GstVideoInfo * vip, GstVideoFormat format,
+    guint width, guint height)
+{
+  GstVideoInfo vi = *vip;
+
+  gst_video_info_set_format (vip, format, width, height);
+
+  vip->interlace_mode = vi.interlace_mode;
+  vip->flags = vi.flags;
+  vip->views = vi.views;
+  vip->par_n = vi.par_n;
+  vip->par_d = vi.par_d;
+  vip->fps_n = vi.fps_n;
+  vip->fps_d = vi.fps_d;
+}

gst/vaapi/gstvaapipluginutil.h

@@ -117,4 +117,9 @@ G_GNUC_INTERNAL
 gboolean
 gst_caps_has_vaapi_surface (GstCaps * caps);
 
+G_GNUC_INTERNAL
+void
+gst_video_info_change_format (GstVideoInfo * vip, GstVideoFormat format,
+    guint width, guint height);
+
 #endif /* GST_VAAPI_PLUGIN_UTIL_H */

gst/vaapi/gstvaapipostproc.c

@@ -1153,7 +1153,7 @@ gst_vaapipostproc_transform_caps_impl(GstBaseTransform *trans,
     out_format = GST_VIDEO_FORMAT_ENCODED;
 #endif
     find_best_size(postproc, &vi, &width, &height);
-    gst_video_info_set_format(&vi, out_format, width, height);
+    gst_video_info_change_format(&vi, out_format, width, height);
 
 #if GST_CHECK_VERSION(1,1,0)
     out_caps = gst_video_info_to_caps(&vi);
@@ -1177,7 +1177,7 @@ gst_vaapipostproc_transform_caps_impl(GstBaseTransform *trans,
             if (feature == GST_VAAPI_CAPS_FEATURE_GL_TEXTURE_UPLOAD_META)
                 format = GST_VIDEO_FORMAT_RGBA;
 
-            gst_video_info_set_format(&vi, format, width, height);
+            gst_video_info_change_format(&vi, format, width, height);
             sink_caps = gst_video_info_to_caps(&vi);
             if (sink_caps) {
                 if (feature_str)
@@ -1318,7 +1318,7 @@ ensure_srcpad_buffer_pool(GstVaapiPostproc *postproc, GstCaps *caps)
 
     gst_video_info_init(&vi);
     gst_video_info_from_caps(&vi, caps);
-    gst_video_info_set_format(&vi, postproc->format,
+    gst_video_info_change_format(&vi, postproc->format,
         GST_VIDEO_INFO_WIDTH(&vi), GST_VIDEO_INFO_HEIGHT(&vi));
 
     if (postproc->filter_pool && !video_info_changed(&vi, &postproc->filter_pool_info))