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lavc/hevc/hevcdec: implement MV-HEVC inter-layer prediction

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The per-frame reference picture set contains two more lists -
INTER_LAYER[01]. Assuming at most two layers, INTER_LAYER1 is always
empty, but is added anyway for completeness.

When inter-layer prediction is enabled, INTER_LAYER0 for the
second-layer frame will contain the base-layer frame from the same
access unit, if it exists.

The new lists are then used in per-slice reference picture set
construction as per F.8.3.4 "Decoding process for reference picture
lists construction".
This commit is contained in:
Anton Khirnov 2024-06-12 11:26:13 +02:00
parent 02a9435cb0
commit 75914b5822
5 changed files with 59 additions and 18 deletions
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7
libavcodec/hevc/hevcdec.c
View File

@ -784,7 +784,7 @@ static int hls_slice_header(SliceHeader *sh, const HEVCContext *s, GetBitContext
sh->rpl_modification_flag[0] = 0;
sh->rpl_modification_flag[1] = 0;
nb_refs = ff_hevc_frame_nb_refs(sh, pps);
nb_refs = ff_hevc_frame_nb_refs(sh, pps, layer_idx);
if (!nb_refs) {
av_log(s->avctx, AV_LOG_ERROR, "Zero refs for a frame with P or B slices.\n");
return AVERROR_INVALIDDATA;
@ -3356,6 +3356,11 @@ static int decode_nal_units(HEVCContext *s, const uint8_t *buf, int length)
s->eos = 0;
s->slice_initialized = 0;
for (int i = 0; i < FF_ARRAY_ELEMS(s->layers); i++) {
HEVCLayerContext *l = &s->layers[i];
l->cur_frame = NULL;
}
/* split the input packet into NAL units, so we know the upper bound on the
* number of slices in the frame */
ret = ff_h2645_packet_split(&s->pkt, buf, length, s->avctx,

8
libavcodec/hevc/hevcdec.h
View File

@ -84,6 +84,8 @@ enum RPSType {
ST_FOLL,
LT_CURR,
LT_FOLL,
INTER_LAYER0,
INTER_LAYER1,
NB_RPS_TYPE,
};
@ -442,6 +444,7 @@ typedef struct HEVCLocalContext {
typedef struct HEVCLayerContext {
HEVCFrame DPB[32];
HEVCFrame *cur_frame;
const HEVCSPS *sps; // RefStruct reference
@ -498,7 +501,7 @@ typedef struct HEVCContext {
struct AVMD5 *md5_ctx;
///< candidate references for the current frame
RefPicList rps[5];
RefPicList rps[NB_RPS_TYPE];
const HEVCVPS *vps; ///< RefStruct reference
const HEVCPPS *pps; ///< RefStruct reference
@ -615,7 +618,8 @@ int ff_hevc_res_scale_sign_flag(HEVCLocalContext *lc, int idx);
/**
* Get the number of candidate references for the current frame.
*/
int ff_hevc_frame_nb_refs(const SliceHeader *sh, const HEVCPPS *pps);
int ff_hevc_frame_nb_refs(const SliceHeader *sh, const HEVCPPS *pps,
unsigned layer_idx);
int ff_hevc_set_new_ref(HEVCContext *s, HEVCLayerContext *l, int poc);

58
libavcodec/hevc/refs.c
View File

@ -162,6 +162,7 @@ int ff_hevc_set_new_ref(HEVCContext *s, HEVCLayerContext *l, int poc)
return AVERROR(ENOMEM);
s->cur_frame = ref;
l->cur_frame = ref;
s->collocated_ref = NULL;
if (s->sh.pic_output_flag)
@ -261,7 +262,9 @@ int ff_hevc_slice_rpl(HEVCContext *s)
return ret;
if (!(s->rps[ST_CURR_BEF].nb_refs + s->rps[ST_CURR_AFT].nb_refs +
s->rps[LT_CURR].nb_refs) && !s->pps->pps_curr_pic_ref_enabled_flag) {
s->rps[LT_CURR].nb_refs +
s->rps[INTER_LAYER0].nb_refs + s->rps[INTER_LAYER1].nb_refs) &&
!s->pps->pps_curr_pic_ref_enabled_flag) {
av_log(s->avctx, AV_LOG_ERROR, "Zero refs in the frame RPS.\n");
return AVERROR_INVALIDDATA;
}
@ -271,11 +274,14 @@ int ff_hevc_slice_rpl(HEVCContext *s)
RefPicList *rpl = &s->cur_frame->refPicList[list_idx];
/* The order of the elements is
* ST_CURR_BEF - ST_CURR_AFT - LT_CURR for the L0 and
* ST_CURR_AFT - ST_CURR_BEF - LT_CURR for the L1 */
int cand_lists[3] = { list_idx ? ST_CURR_AFT : ST_CURR_BEF,
list_idx ? ST_CURR_BEF : ST_CURR_AFT,
LT_CURR };
* ST_CURR_BEF - INTER_LAYER0 - ST_CURR_AFT - LT_CURR - INTER_LAYER1 for the L0 and
* ST_CURR_AFT - INTER_LAYER1 - ST_CURR_BEF - LT_CURR - INTER_LAYER0 for the L1 */
int cand_lists[] = { list_idx ? ST_CURR_AFT : ST_CURR_BEF,
list_idx ? INTER_LAYER1 : INTER_LAYER0,
list_idx ? ST_CURR_BEF : ST_CURR_AFT,
LT_CURR,
list_idx ? INTER_LAYER0 : INTER_LAYER1
};
/* concatenate the candidate lists for the current frame */
while (rpl_tmp.nb_refs < sh->nb_refs[list_idx]) {
@ -284,7 +290,11 @@ int ff_hevc_slice_rpl(HEVCContext *s)
for (j = 0; j < rps->nb_refs && rpl_tmp.nb_refs < HEVC_MAX_REFS; j++) {
rpl_tmp.list[rpl_tmp.nb_refs] = rps->list[j];
rpl_tmp.ref[rpl_tmp.nb_refs] = rps->ref[j];
rpl_tmp.isLongTerm[rpl_tmp.nb_refs] = i == 2;
// multiview inter-layer refs are treated as long-term here,
// cf. G.8.1.3
rpl_tmp.isLongTerm[rpl_tmp.nb_refs] = cand_lists[i] == LT_CURR ||
cand_lists[i] == INTER_LAYER0 ||
cand_lists[i] == INTER_LAYER1;
rpl_tmp.nb_refs++;
}
}
@ -423,11 +433,6 @@ int ff_hevc_frame_rps(HEVCContext *s, HEVCLayerContext *l)
RefPicList *rps = s->rps;
int i, ret = 0;
if (!short_rps) {
rps[0].nb_refs = rps[1].nb_refs = 0;
return 0;
}
unref_missing_refs(l);
/* clear the reference flags on all frames except the current one */
@ -443,6 +448,9 @@ int ff_hevc_frame_rps(HEVCContext *s, HEVCLayerContext *l)
for (i = 0; i < NB_RPS_TYPE; i++)
rps[i].nb_refs = 0;
if (!short_rps)
goto inter_layer;
/* add the short refs */
for (i = 0; i < short_rps->num_delta_pocs; i++) {
int poc = s->poc + short_rps->delta_poc[i];
@ -472,6 +480,24 @@ int ff_hevc_frame_rps(HEVCContext *s, HEVCLayerContext *l)
goto fail;
}
inter_layer:
/* add inter-layer refs */
if (s->sh.inter_layer_pred) {
HEVCLayerContext *l0 = &s->layers[0];
av_assert0(l != l0);
/* Given the assumption of at most two layers, refPicSet0Flag is
* always 1, so only RefPicSetInterLayer0 can ever contain a frame. */
if (l0->cur_frame) {
// inter-layer refs are treated as short-term here, cf. F.8.1.6
ret = add_candidate_ref(s, l0, &rps[INTER_LAYER0], l0->cur_frame->poc,
HEVC_FRAME_FLAG_SHORT_REF, 1);
if (ret < 0)
goto fail;
}
}
fail:
/* release any frames that are now unused */
for (i = 0; i < FF_ARRAY_ELEMS(l->DPB); i++)
@ -480,7 +506,8 @@ fail:
return ret;
}
int ff_hevc_frame_nb_refs(const SliceHeader *sh, const HEVCPPS *pps)
int ff_hevc_frame_nb_refs(const SliceHeader *sh, const HEVCPPS *pps,
unsigned layer_idx)
{
int ret = 0;
int i;
@ -499,6 +526,11 @@ int ff_hevc_frame_nb_refs(const SliceHeader *sh, const HEVCPPS *pps)
ret += !!long_rps->used[i];
}
if (sh->inter_layer_pred) {
av_assert0(pps->sps->vps->num_direct_ref_layers[layer_idx] < 2);
ret++;
}
if (pps->pps_curr_pic_ref_enabled_flag)
ret++;

2
libavcodec/nvdec_hevc.c
View File

@ -188,7 +188,7 @@ static int nvdec_hevc_start_frame(AVCodecContext *avctx,
.NumBitsForShortTermRPSInSlice = s->sh.short_term_rps ? s->sh.short_term_ref_pic_set_size : 0,
.NumDeltaPocsOfRefRpsIdx = s->sh.short_term_rps ? s->sh.short_term_rps->rps_idx_num_delta_pocs : 0,
.NumPocTotalCurr = ff_hevc_frame_nb_refs(&s->sh, pps),
.NumPocTotalCurr = ff_hevc_frame_nb_refs(&s->sh, pps, s->cur_layer),
.NumPocStCurrBefore = s->rps[ST_CURR_BEF].nb_refs,
.NumPocStCurrAfter = s->rps[ST_CURR_AFT].nb_refs,
.NumPocLtCurr = s->rps[LT_CURR].nb_refs,

2
libavcodec/vdpau_hevc.c
View File

@ -206,7 +206,7 @@ static int vdpau_hevc_start_frame(AVCodecContext *avctx,
}
}
/* See section 7.4.7.2 of the specification. */
info->NumPocTotalCurr = ff_hevc_frame_nb_refs(&h->sh, pps);
info->NumPocTotalCurr = ff_hevc_frame_nb_refs(&h->sh, pps, h->cur_layer);
if (sh->short_term_ref_pic_set_sps_flag == 0 && sh->short_term_rps) {
/* Corresponds to specification field, NumDeltaPocs[RefRpsIdx].
Only applicable when short_term_ref_pic_set_sps_flag == 0.