> -----Original Message----- > From: ffmpeg-devel [mailto:ffmpeg-devel-boun...@ffmpeg.org] On Behalf > Of Mark Thompson > Sent: Tuesday, April 2, 2019 06:24 > To: ffmpeg-devel@ffmpeg.org > Subject: Re: [FFmpeg-devel] [PATCH] lavc/hevc_ps: parse constraint flags for > HEVC REXT > > On 01/04/2019 22:38, James Almer wrote: > > On 4/1/2019 6:43 AM, Linjie Fu wrote: > >> Parse all the constraint flags. > >> > >> It can be passed to hw decoders to detemine the exact profile for Range > >> Extension HEVC. > >> > >> Signed-off-by: Linjie Fu <linjie...@intel.com> > >> --- > >> libavcodec/hevc_ps.c | 18 +++++++++++++++--- > >> libavcodec/hevc_ps.h | 10 ++++++++++ > >> 2 files changed, 25 insertions(+), 3 deletions(-) > >> > >> diff --git a/libavcodec/hevc_ps.c b/libavcodec/hevc_ps.c > >> index 80df417e4f..1365a9d640 100644 > >> --- a/libavcodec/hevc_ps.c > >> +++ b/libavcodec/hevc_ps.c > >> @@ -295,9 +295,21 @@ static int > decode_profile_tier_level(GetBitContext *gb, AVCodecContext *avctx, > >> ptl->non_packed_constraint_flag = get_bits1(gb); > >> ptl->frame_only_constraint_flag = get_bits1(gb); > >> > >> - skip_bits(gb, 16); // XXX_reserved_zero_44bits[0..15] > >> - skip_bits(gb, 16); // XXX_reserved_zero_44bits[16..31] > >> - skip_bits(gb, 12); // XXX_reserved_zero_44bits[32..43] > >> + ptl->max_12bit_constraint_flag = get_bits1(gb); > >> + ptl->max_10bit_constraint_flag = get_bits1(gb); > >> + ptl->max_8bit_constraint_flag = get_bits1(gb); > >> + ptl->max_422chroma_constraint_flag = get_bits1(gb); > >> + ptl->max_420chroma_constraint_flag = get_bits1(gb); > >> + ptl->max_monochrome_constraint_flag = get_bits1(gb); > >> + ptl->intra_constraint_flag = get_bits1(gb); > >> + ptl->one_picture_only_constraint_flag = get_bits1(gb); > >> + ptl->lower_bit_rate_constraint_flag = get_bits1(gb); > >> + > >> + skip_bits(gb, 16); // XXX_reserved_zero_34bits[0..15] > > > > The first of these bits can be general_max_14bit_constraint_flag. I > > suppose no hardware really supports it? > > I think it's worth getting these right anyway. > > From the set of flags you've ended up with here I'm guessing you're working > from a pre-2018 version of the standard? Try the 201802 version - > <https://www.itu.int/rec/T-REC-H.265-201802-I/en>. > > >> + skip_bits(gb, 16); // XXX_reserved_zero_34bits[16..31] > >> + skip_bits(gb, 2); // XXX_reserved_zero_34bits[32..33] > >> + > >> + ptl->inbld_flag = get_bits1(gb); > > > > Strictly speaking, you should be checking ptl->profile_idc and > > ptl->profile_compatibility_flag to parse these, as per section 7.3.3 in > > the spec. > > Despite the amount of bits being fixed and the default value being 0, it > > would be ideal to prevent misparsing damaged samples. > > +1. Future profiles which could assign completely different meanings to > these bits are also a possibility, though I would hope the standard people > would avoid doing that.
Thanks for the suggestions, refined patch has been sent. _______________________________________________ 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".
