[FFmpeg-devel] [PATCH v2 1/2] lavc/av1: Record reference ordering information for each frame

[Mark Thompson]

This is needed by Vulkan.  Constructing this can't be delegated to CBS
because packets might contain multiple frames (when non-shown frames are
present) but we need separate snapshots immediately before each frame
for the decoder.
---
Changes over v1: rename the order hint field and document exactly what the new fields contain.

  libavcodec/av1dec.c | 26 ++++++++++++++++++++++++++
  libavcodec/av1dec.h |  8 ++++++++
  2 files changed, 34 insertions(+)

diff --git a/libavcodec/av1dec.c b/libavcodec/av1dec.c
index 824725c031..b4b741054a 100644
--- a/libavcodec/av1dec.c
+++ b/libavcodec/av1dec.c
@@ -359,6 +359,25 @@ static void coded_lossless_param(AV1DecContext *s)
      }
  }

+static void order_hint_info(AV1DecContext *s)
+{
+    const AV1RawFrameHeader *header = s->raw_frame_header;
+    const AV1RawSequenceHeader *seq = s->raw_seq;
+    AV1Frame *frame = &s->cur_frame;
+
+    frame->order_hint = header->order_hint;
+
+    for (int i = 0; i < AV1_REFS_PER_FRAME; i++) {
+        int ref_name = i + AV1_REF_FRAME_LAST;
+        int ref_slot = header->ref_frame_idx[i];
+        int ref_order_hint = s->ref[ref_slot].order_hint;
+
+        frame->order_hints[ref_name] = ref_order_hint;
+        frame->ref_frame_sign_bias[ref_name] =
+            get_relative_dist(seq, ref_order_hint, frame->order_hint);
+    }
+}
+
  static void load_grain_params(AV1DecContext *s)
  {
      const AV1RawFrameHeader *header = s->raw_frame_header;
@@ -701,6 +720,12 @@ static int av1_frame_ref(AVCodecContext *avctx, AV1Frame *dst, const AV1Frame *s
             sizeof(dst->film_grain));
      dst->coded_lossless = src->coded_lossless;

+    dst->order_hint = src->order_hint;
+    memcpy(dst->ref_frame_sign_bias, src->ref_frame_sign_bias,
+           sizeof(dst->ref_frame_sign_bias));
+    memcpy(dst->order_hints, src->order_hints,
+           sizeof(dst->order_hints));
+
      return 0;

  fail:
@@ -1257,6 +1282,7 @@ static int get_current_frame(AVCodecContext *avctx)
      global_motion_params(s);
      skip_mode_params(s);
      coded_lossless_param(s);
+    order_hint_info(s);
      load_grain_params(s);

      return ret;
diff --git a/libavcodec/av1dec.h b/libavcodec/av1dec.h
index 336eb61359..79a0be510b 100644
--- a/libavcodec/av1dec.h
+++ b/libavcodec/av1dec.h
@@ -53,6 +53,14 @@ typedef struct AV1Frame {
      AV1RawFilmGrainParams film_grain;

      uint8_t coded_lossless;
+
+    // OrderHint for this frame.
+    uint8_t order_hint;
+    // RefFrameSignBias[] used when decoding this frame.
+    uint8_t ref_frame_sign_bias[AV1_TOTAL_REFS_PER_FRAME];
+    // OrderHints[] when this is the current frame, otherwise
+    // SavedOrderHints[s][] when is the reference frame in slot s.
+    uint8_t order_hints[AV1_TOTAL_REFS_PER_FRAME];
  } AV1Frame;

  typedef struct TileGroupInfo {
-- 
2.43.0