AV1_COMMON: Comments for scale factors, show*frame
BUG=aomedia:2610
Change-Id: Ie24ade0acfce8b73f4bb310e3d4ea344fe990709
diff --git a/av1/common/onyxc_int.h b/av1/common/onyxc_int.h
index 8ca9327..5252e3b 100644
--- a/av1/common/onyxc_int.h
+++ b/av1/common/onyxc_int.h
@@ -367,9 +367,6 @@
int context_update_tile_id;
- // Scale of the current frame with respect to itself.
- struct scale_factors sf_identity;
-
// Buffer where previous frame is stored.
RefCntBuffer *prev_frame;
@@ -397,6 +394,15 @@
// have a remapped index for the same.
int remapped_ref_idx[REF_FRAMES];
+ // Scale of the current frame with respect to itself.
+ // This is currently used for intra block copy, which behaves like an inter
+ // prediction mode, where the reference frame is the current frame itself.
+ struct scale_factors sf_identity;
+
+ // Scale factors of the reference frame with respect to the current frame.
+ // This is required for generating inter prediction and will be non-identity
+ // for a reference frame, if it has different dimensions than the coded
+ // dimensions of the current frame.
struct scale_factors ref_scale_factors[REF_FRAMES];
// For decoder, ref_frame_map[i] maps reference type 'i' to a pointer to
@@ -406,10 +412,26 @@
// a pointer to the buffer in the buffer pool 'cm->buffer_pool.frame_bufs'.
RefCntBuffer *ref_frame_map[REF_FRAMES];
- FRAME_TYPE last_frame_type; /* last frame's frame type for motion search.*/
+ // Frame type of the last frame. May be used in some heuristics for speeding
+ // up the encoding.
+ // TODO(urvang): Used only by encoder (this variable and a few others in this
+ // struct). Ideally we should separate them out and move outside this struct.
+ FRAME_TYPE last_frame_type;
+ // If true, this frame is actually shown after decoding.
+ // If false, this frame is coded in the bitstream, but not shown. It is only
+ // used as a reference for other frames coded later.
int show_frame;
- int showable_frame; // frame can be used as show existing frame in future
+
+ // If true, this frame can be used as a show-existing frame for other frames
+ // coded later.
+ // When 'show_frame' is true, this is always true for all non-keyframes.
+ // When 'show_frame' is false, this value is transmitted in the bitstream.
+ int showable_frame;
+
+ // If true, show an existing frame coded before, instead of actually coding a
+ // frame. The existing frame comes from one of the existing reference buffers,
+ // as signaled in the bitstream.
int show_existing_frame;
uint8_t disable_cdf_update;
