> From: ffmpeg-devel <ffmpeg-devel-boun...@ffmpeg.org> On Behalf Of Fu, > Linjie > Sent: Thursday, May 21, 2020 14:38 > To: FFmpeg development discussions and patches <ffmpeg- > de...@ffmpeg.org> > Cc: Xu, Guangxin <guangxin...@intel.com> > Subject: Re: [FFmpeg-devel] [PATCH 2/2] lavc/hevc_refs: Fix the logic of > find_ref_idx() > > > From: ffmpeg-devel <ffmpeg-devel-boun...@ffmpeg.org> On Behalf Of > Fu, > > Linjie > > Sent: Monday, May 18, 2020 15:17 > > To: ffmpeg-devel@ffmpeg.org > > Cc: Xu, Guangxin <guangxin...@intel.com> > > Subject: Re: [FFmpeg-devel] [PATCH 2/2] lavc/hevc_refs: Fix the logic of > > find_ref_idx() > > > > > From: Fu, Linjie <linjie...@intel.com> > > > Sent: Tuesday, May 12, 2020 21:44 > > > To: ffmpeg-devel@ffmpeg.org > > > Cc: Xu, Guangxin <guangxin...@intel.com>; Fu, Linjie > <linjie...@intel.com> > > > Subject: [PATCH 2/2] lavc/hevc_refs: Fix the logic of find_ref_idx() > > > > > > From: Xu Guangxin <guangxin...@intel.com> > > > > > > Currently find_ref_idx() would trigger 2 scans in DPB to find the > > > requested POC: > > > 1. Firstly, ignore MSB of ref->poc and search for the requested POC; > > > 2. Secondly, compare the entire ref->poc with requested POC; > > > > > > For long term reference, we are able to only check LSB if MSB is not > > > presented(e.g. delta_poc_msb_present_flag == 0). However, for short > > > term reference, we should never ignore poc's MSB and it should be > > > kind of bit-exact. (Details in 8.3.2) > > > > > > Otherwise this leads to decoding failures like: > > > [hevc @ 0x5638f4328600] Error constructing the frame RPS. > > > [hevc @ 0x5638f4328600] Error parsing NAL unit #2. > > > [hevc @ 0x5638f4338a80] Could not find ref with POC 21 > > > Error while decoding stream #0:0: Invalid data found when processing > input > > > > > > Search the requested POC based on whether MSB is used, and avoid > > > the 2-times scan for DPB buffer. This benefits both native HEVC > > > decoder and integrated HW decoders. > > > > > > Signed-off-by: Linjie Fu <linjie...@intel.com> > > > --- > > > > > > Since it's kind of difficult to generate an identical bitstream for > > > fate or test, I'd like to elaborate more about one of the failures: > > > > > > requested POC = 5; > > > LtMask = (1 << 4) - 1 = 15; > > > ref[0]->poc = 21; // unexpected ref for poc = 5 (short term) > > > ref[1]->poc = 5; // expected ref for poc = 5 (short term) > > > > > > Hence find_ref_idx() would wrongly return a ref with poc = 21, which > > > leads to the decoding error. > > > > > > libavcodec/hevc_refs.c | 38 ++++++++++++++++++++------------------ > > > 1 file changed, 20 insertions(+), 18 deletions(-) > > > > > > diff --git a/libavcodec/hevc_refs.c b/libavcodec/hevc_refs.c > > > index 7870a72..73aa6d8 100644 > > > --- a/libavcodec/hevc_refs.c > > > +++ b/libavcodec/hevc_refs.c > > > @@ -358,24 +358,26 @@ int ff_hevc_slice_rpl(HEVCContext *s) > > > return 0; > > > } > > > > > > -static HEVCFrame *find_ref_idx(HEVCContext *s, int poc) > > > +static HEVCFrame *find_ref_idx(HEVCContext *s, int poc, uint8_t > > use_msb) > > > { > > > int i; > > > - int LtMask = (1 << s->ps.sps->log2_max_poc_lsb) - 1; > > > > > > - for (i = 0; i < FF_ARRAY_ELEMS(s->DPB); i++) { > > > - HEVCFrame *ref = &s->DPB[i]; > > > - if (ref->frame->buf[0] && (ref->sequence == s->seq_decode)) { > > > - if ((ref->poc & LtMask) == poc) > > > - return ref; > > > + if (use_msb) { > > > + for (i = 0; i < FF_ARRAY_ELEMS(s->DPB); i++) { > > > + HEVCFrame *ref = &s->DPB[i]; > > > + if (ref->frame->buf[0] && (ref->sequence == s->seq_decode)) { > > > + if (ref->poc == poc) > > > + return ref; > > > + } > > > } > > > - } > > > - > > > - for (i = 0; i < FF_ARRAY_ELEMS(s->DPB); i++) { > > > - HEVCFrame *ref = &s->DPB[i]; > > > - if (ref->frame->buf[0] && ref->sequence == s->seq_decode) { > > > - if (ref->poc == poc || (ref->poc & LtMask) == poc) > > > - return ref; > > > + } else { > > > + int LtMask = (1 << s->ps.sps->log2_max_poc_lsb) - 1; > > > + for (i = 0; i < FF_ARRAY_ELEMS(s->DPB); i++) { > > > + HEVCFrame *ref = &s->DPB[i]; > > > + if (ref->frame->buf[0] && ref->sequence == s->seq_decode) { > > > + if ((ref->poc & LtMask) == poc) > > > + return ref; > > > + } > > > } > > > } > > > > > > @@ -427,9 +429,9 @@ static HEVCFrame > > > *generate_missing_ref(HEVCContext *s, int poc) > > > > > > /* add a reference with the given poc to the list and mark it as used in > DPB > > > */ > > > static int add_candidate_ref(HEVCContext *s, RefPicList *list, > > > - int poc, int ref_flag) > > > + int poc, int ref_flag, uint8_t use_msb) > > > { > > > - HEVCFrame *ref = find_ref_idx(s, poc); > > > + HEVCFrame *ref = find_ref_idx(s, poc, use_msb); > > > > > > if (ref == s->ref || list->nb_refs >= HEVC_MAX_REFS) > > > return AVERROR_INVALIDDATA; > > > @@ -485,7 +487,7 @@ int ff_hevc_frame_rps(HEVCContext *s) > > > else > > > list = ST_CURR_AFT; > > > > > > - ret = add_candidate_ref(s, &rps[list], poc, > > > HEVC_FRAME_FLAG_SHORT_REF); > > > + ret = add_candidate_ref(s, &rps[list], poc, > > > HEVC_FRAME_FLAG_SHORT_REF, 1); > > > if (ret < 0) > > > goto fail; > > > } > > > @@ -495,7 +497,7 @@ int ff_hevc_frame_rps(HEVCContext *s) > > > int poc = long_rps->poc[i]; > > > int list = long_rps->used[i] ? LT_CURR : LT_FOLL; > > > > > > - ret = add_candidate_ref(s, &rps[list], poc, > > > HEVC_FRAME_FLAG_LONG_REF); > > > + ret = add_candidate_ref(s, &rps[list], poc, > > > HEVC_FRAME_FLAG_LONG_REF, long_rps->poc_msb_present[i]); > > > if (ret < 0) > > > goto fail; > > > } > > > -- > > > 2.7.4 > > > > Ping for this patch set. > > Verified with 1000 + decoding conformance cases including 8/10 bit, no > > regression observed. > > > > Also see descriptions in chapter 2.4.3 in <High Efficiency Video Coding>[1]: > > "Since it is possible to have more than one picture with the same POC LSB > value in the DPB, there is an optional > possibility to also signal POC MSB information for long-term pictures." > > This patch is to fix the potential " more than one picture with the same POC > LSB value in the DPB" issue. > > Ping for comments. (Would like to apply the set after this weekend, if no > objections) > > - Linjie > > [1] < http://what-when-how.com/Tutorial/topic-397pct9eq3/High-Efficiency- > Video-Coding-HEVC-51.html>
Applied, thx. - Linjie _______________________________________________ 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".