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[av1d_parser]: add some comments

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Signed-off-by: Yandong Lin <yandong.lin@rock-chips.com>
Change-Id: I3be8086aa126dc34631f1b2e14db93d5f2d484ad
This commit is contained in:
Yandong Lin
2023-02-28 16:07:00 +08:00
parent 835d8b3e96
commit eaef6f5871
1 changed files with 38 additions and 0 deletions
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38
mpp/codec/dec/av1/av1d_cbs.c
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@@ -730,6 +730,8 @@ static RK_S32 mpp_av1_temporal_delimiter_obu(AV1Context *ctx, BitReadCtx_t *gb)
return 0;
}
/* spec 7.8 */
static RK_S32 mpp_av1_set_frame_refs(AV1Context *ctx, BitReadCtx_t *gb,
AV1RawFrameHeader *current)
{
@@ -749,11 +751,19 @@ static RK_S32 mpp_av1_set_frame_refs(AV1Context *ctx, BitReadCtx_t *gb,
ref_frame_idx[AV1_REF_FRAME_LAST - AV1_REF_FRAME_LAST] = current->last_frame_idx;
ref_frame_idx[AV1_REF_FRAME_GOLDEN - AV1_REF_FRAME_LAST] = current->golden_frame_idx;
/*
* An array usedFrame marking which reference frames
* have been used is prepared as follows:
*/
for (i = 0; i < AV1_NUM_REF_FRAMES; i++)
used_frame[i] = 0;
used_frame[current->last_frame_idx] = 1;
used_frame[current->golden_frame_idx] = 1;
/*
* An array shiftedOrderHints (containing the expected output order shifted
* such that the current frame has hint equal to curFrameHint) is prepared as follows:
*/
cur_frame_hint = 1 << (seq->order_hint_bits_minus_1);
for (i = 0; i < AV1_NUM_REF_FRAMES; i++)
shifted_order_hints[i] = cur_frame_hint +
@@ -763,6 +773,7 @@ static RK_S32 mpp_av1_set_frame_refs(AV1Context *ctx, BitReadCtx_t *gb,
latest_order_hint = shifted_order_hints[current->last_frame_idx];
earliest_order_hint = shifted_order_hints[current->golden_frame_idx];
/* find_latest_backward */
ref = -1;
for (i = 0; i < AV1_NUM_REF_FRAMES; i++) {
RK_S32 hint = shifted_order_hints[i];
@@ -772,11 +783,16 @@ static RK_S32 mpp_av1_set_frame_refs(AV1Context *ctx, BitReadCtx_t *gb,
latest_order_hint = hint;
}
}
/*
* The ALTREF_FRAME reference is set to be a backward reference to the frame
* with highest output order as follows:
*/
if (ref >= 0) {
ref_frame_idx[AV1_REF_FRAME_ALTREF - AV1_REF_FRAME_LAST] = ref;
used_frame[ref] = 1;
}
/* find_earliest_backward */
ref = -1;
for (i = 0; i < AV1_NUM_REF_FRAMES; i++) {
RK_S32 hint = shifted_order_hints[i];
@@ -786,6 +802,10 @@ static RK_S32 mpp_av1_set_frame_refs(AV1Context *ctx, BitReadCtx_t *gb,
earliest_order_hint = hint;
}
}
/*
* The BWDREF_FRAME reference is set to be a backward reference to
* the closest frame as follows:
*/
if (ref >= 0) {
ref_frame_idx[AV1_REF_FRAME_BWDREF - AV1_REF_FRAME_LAST] = ref;
used_frame[ref] = 1;
@@ -800,14 +820,24 @@ static RK_S32 mpp_av1_set_frame_refs(AV1Context *ctx, BitReadCtx_t *gb,
earliest_order_hint = hint;
}
}
/*
* The ALTREF2_FRAME reference is set to the next closest
* backward reference as follows:
*/
if (ref >= 0) {
ref_frame_idx[AV1_REF_FRAME_ALTREF2 - AV1_REF_FRAME_LAST] = ref;
used_frame[ref] = 1;
}
/*
* The remaining references are set to be forward references
* in anti-chronological order as follows:
*/
for (i = 0; i < AV1_REFS_PER_FRAME - 2; i++) {
RK_S32 ref_frame = ref_frame_list[i];
if (ref_frame_idx[ref_frame - AV1_REF_FRAME_LAST] < 0 ) {
/* find_latest_forward */
ref = -1;
for (j = 0; j < AV1_NUM_REF_FRAMES; j++) {
RK_S32 hint = shifted_order_hints[j];
@@ -824,6 +854,10 @@ static RK_S32 mpp_av1_set_frame_refs(AV1Context *ctx, BitReadCtx_t *gb,
}
}
/*
* Finally, any remaining references are set to the reference
* frame with smallest output order as follows:
*/
ref = -1;
for (i = 0; i < AV1_NUM_REF_FRAMES; i++) {
RK_S32 hint = shifted_order_hints[i];
@@ -1537,6 +1571,10 @@ static RK_S32 mpp_av1_global_motion_param(AV1Context *ctx, BitReadCtx_t *gb,
return 0;
}
/*
* Actual gm_params value is not reconstructed here.
* Real gm_params update in av1d_parser.c->global_motion_params()
*/
static RK_S32 mpp_av1_global_motion_params(AV1Context *ctx, BitReadCtx_t *gb,
AV1RawFrameHeader *current)
{