When the current subpicture has sps_subpic_treated_as_pic_flag equal to 1, motion vectors are cropped such that they cannot point to other subpictures. This was accounted for in the prediction logic, but not in pred_get_y, which is used by the scheduling logic to determine which parts of the reference pictures must have been reconstructed before inter prediction of a subsequent frame may begin. Consequently, where a motion vector pointed to a location significantly above the current subpicture, there was the possibility of a race condition. Patch fixes this by cropping the motion vector to the current subpicture in pred_get_y.
Signed-off-by: Frank Plowman <p...@frankplowman.com> --- You can reproduce this issue with the bitstream available here: https://chromium.googlesource.com/chromium/src/+/lkgr/media/test/data/vvc_frames_with_ltr.vvc?format=TEXT Note this link downloads the file in base 64 format rather than binary. You can use base64 -d <BASE 64 FILE> > <BINARY FILE> to convert it to binary. The issue does not reproduce very reliably with a normal number of threads. For better reproducibility, run ffmpeg with 100+ threads. --- libavcodec/vvc/ctu.c | 30 +++++++++++++++++++----------- 1 file changed, 19 insertions(+), 11 deletions(-) diff --git a/libavcodec/vvc/ctu.c b/libavcodec/vvc/ctu.c index f80bce637c..6857c79f2b 100644 --- a/libavcodec/vvc/ctu.c +++ b/libavcodec/vvc/ctu.c @@ -2393,23 +2393,30 @@ static int has_inter_luma(const CodingUnit *cu) return cu->pred_mode != MODE_INTRA && cu->pred_mode != MODE_PLT && cu->tree_type != DUAL_TREE_CHROMA; } -static int pred_get_y(const int y0, const Mv *mv, const int height) +static int pred_get_y(const VVCLocalContext *lc, const int y0, const Mv *mv, const int height, const VVCFrame *src_frame) { - return FFMAX(0, y0 + (mv->y >> 4) + height); + const VVCSPS *sps = src_frame->sps; + const VVCPPS *pps = src_frame->pps; + const int subpic_idx = lc->sc->sh.r->curr_subpic_idx; + const int subpic_t = pps->subpic_y[subpic_idx]; + const int subpic_treated_as_pic = sps->r->sps_subpic_treated_as_pic_flag[subpic_idx]; + return FFMAX(subpic_treated_as_pic ? subpic_t : 0, y0 + (mv->y >> 4) + height); } -static void cu_get_max_y(const CodingUnit *cu, int max_y[2][VVC_MAX_REF_ENTRIES], const VVCFrameContext *fc) +static void cu_get_max_y(const VVCLocalContext *lc, const CodingUnit *cu, int max_y[2][VVC_MAX_REF_ENTRIES]) { + const VVCFrameContext *fc = lc->fc; const PredictionUnit *pu = &cu->pu; if (pu->merge_gpm_flag) { for (int i = 0; i < FF_ARRAY_ELEMS(pu->gpm_mv); i++) { - const MvField *mvf = pu->gpm_mv + i; - const int lx = mvf->pred_flag - PF_L0; - const int idx = mvf->ref_idx[lx]; - const int y = pred_get_y(cu->y0, mvf->mv + lx, cu->cb_height); + const MvField *mvf = pu->gpm_mv + i; + const int lx = mvf->pred_flag - PF_L0; + const int idx = mvf->ref_idx[lx]; + const VVCRefPic *refp = lc->sc->rpl[lx].refs + idx; + const int y = pred_get_y(lc, cu->y0, mvf->mv + lx, cu->cb_height, refp->ref); - max_y[lx][idx] = FFMAX(max_y[lx][idx], y); + max_y[lx][idx] = FFMAX(max_y[lx][idx], y); } } else { const MotionInfo *mi = &pu->mi; @@ -2424,8 +2431,9 @@ static void cu_get_max_y(const CodingUnit *cu, int max_y[2][VVC_MAX_REF_ENTRIES] for (int lx = 0; lx < 2; lx++) { const PredFlag mask = 1 << lx; if (mvf->pred_flag & mask) { - const int idx = mvf->ref_idx[lx]; - const int y = pred_get_y(y0, mvf->mv + lx, sbh); + const int idx = mvf->ref_idx[lx]; + const VVCRefPic *refp = lc->sc->rpl[lx].refs + idx; + int y = pred_get_y(lc, y0, mvf->mv + lx, sbh, refp->ref); max_y[lx][idx] = FFMAX(max_y[lx][idx], y + max_dmvr_off); } @@ -2452,7 +2460,7 @@ static void ctu_get_pred(VVCLocalContext *lc, const int rs) while (cu) { if (has_inter_luma(cu)) { - cu_get_max_y(cu, ctu->max_y, fc); + cu_get_max_y(lc, cu, ctu->max_y); ctu->has_dmvr |= cu->pu.dmvr_flag; } cu = cu->next; -- 2.47.0 _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
