On Mon, Feb 01, 2016 at 12:11:10PM -0800, Neil Birkbeck wrote: > Please see updated patch. > > On Mon, Jan 25, 2016 at 11:39 PM, Neil Birkbeck <neil.birkb...@gmail.com> > wrote: > > I guess png is another example; 100000 is the denominator for the 32-bit > > integer: > > https://github.com/FFmpeg/FFmpeg/blob/b58cfa616c169c90166938608e7135cdab5820e0/libavcodec/pngenc.c#L290 > > > > In the standards, the primaries and white point coords are usually only > > referenced in 2-4 significant figures (ISO/IEC 23001-8:2013(E) has them all > > in one doc). The display primaries can be different from these, but I don't > > think you'd see them measured with any more precision (more precision is > > unlikely to matter for this metadata anyway). > > > > It seems that most are in favor of AVRational, so I'll change the avutil > > struct float internal fields to rational. > > > > > > > > > > > > On Mon, Jan 25, 2016 at 1:43 PM, Hendrik Leppkes <h.lepp...@gmail.com> > > wrote: > >> > >> On Mon, Jan 25, 2016 at 10:37 PM, Michael Niedermayer > >> <mich...@niedermayer.cc> wrote: > >> > On Fri, Jan 22, 2016 at 02:54:21PM -0800, Neil Birkbeck wrote: > >> >> Hmm. I don't have a good idea of how likely it is for this conversion > >> >> to > >> >> float (by dividing a constant) to not be bit-exact on different > >> >> architectures (compilers?) when there should not be any other math > >> >> transforming the metadata (other than the conversion back to the > >> >> integer > >> >> coding for cases like hevc, which for a given architecture is possible > >> >> without loss). The fact that this could happen at all does make it > >> >> annoying > >> >> in terms of bit-exact test expectations across arch, and this is the > >> >> main > >> >> concern, right? (for this type of metadata, it is really a hint to > >> >> TVs/algorithms, and some will ignore it altogether) > >> > > >> > bitexactness is one concern, also theres the issue with what is ideally > >> > correct. > >> > that is what are the ideal values dictated by various standards > >> > that hardware (cammeras, ...) aim at ? > >> > are these rational or float or what can represent them better ? > >> > > >> > >> Both HEVC and the HDMI Info Frames use fixed-point integers (the same > >> scales too, apparently), I do not know of the formats anything else > >> uses. > >> Maybe we should be using AVRationals? > >> > >> I would argue that MKV storing floats is a terrible idea, and someone > >> should bonk them over the head and store fixed point as well. > >> > >> - Hendrik > >> _______________________________________________ > >> ffmpeg-devel mailing list > >> ffmpeg-devel@ffmpeg.org > >> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > > >
> hevc.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ > hevc.h | 7 +++++++ > hevc_sei.c | 22 ++++++++++++++++++++++ > version.h | 2 +- > 4 files changed, 76 insertions(+), 1 deletion(-) > a1660d647add89f41e8ed85f8bc26eb4fb36379b > 0001-lavc-hevc-Parse-SEI_TYPE_MASTERING_DISPLAY_INFO-and-.patch > From 345db2caf7cac5c0acfb74501b6db9bd57e66f7d Mon Sep 17 00:00:00 2001 > From: Neil Birkbeck <neil.birkb...@gmail.com> > Date: Thu, 21 Jan 2016 10:56:50 -0800 > Subject: [PATCH] lavc/hevc Parse SEI_TYPE_MASTERING_DISPLAY_INFO and propagate > content into the AVMasteringDisplayMetadata side data. > > Add support for parsing SEI_TYPE_MASTERING_DISPLAY_INFO and propagate > contents into > the AVMasteringDisplayMetadata side data. Primaries are ordered in RGB order > and > the values are converted to rationals ([0,1] for CEI 1931 Chroma coords, > and cd/m^2 for luma). > > Signed-off-by: Neil Birkbeck <neil.birkb...@gmail.com> > --- > libavcodec/hevc.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ > libavcodec/hevc.h | 7 +++++++ > libavcodec/hevc_sei.c | 22 ++++++++++++++++++++++ > libavcodec/version.h | 2 +- > 4 files changed, 76 insertions(+), 1 deletion(-) > > diff --git a/libavcodec/hevc.c b/libavcodec/hevc.c > index c245d3b..e475f94 100644 > --- a/libavcodec/hevc.c > +++ b/libavcodec/hevc.c > @@ -28,6 +28,7 @@ > #include "libavutil/common.h" > #include "libavutil/display.h" > #include "libavutil/internal.h" > +#include "libavutil/mastering_display_metadata.h" > #include "libavutil/md5.h" > #include "libavutil/opt.h" > #include "libavutil/pixdesc.h" > @@ -2580,6 +2581,51 @@ static int set_side_data(HEVCContext *s) > s->sei_hflip, s->sei_vflip); > } > > + if (s->sei_mastering_display_info_present) { > + // HEVC uses a g,b,r ordering, which we convert to a more natural > r,g,b > + const int mapping[3] = {2, 0, 1}; > + const int chroma_den = 50000; > + const int luma_den = 10000; > + int i; > + AVMasteringDisplayMetadata *metadata = > + av_mastering_display_metadata_create_side_data(out); > + if (!metadata) > + return AVERROR(ENOMEM); > + > + for (i = 0; i < 3; i++) { > + const int j = mapping[i]; > + metadata->display_primaries[i][0].num = > s->display_primaries[j][0]; > + metadata->display_primaries[i][0].den = chroma_den; > + metadata->display_primaries[i][1].num = > s->display_primaries[j][1]; > + metadata->display_primaries[i][1].den = chroma_den; > + } > + metadata->white_point[0].num = s->white_point[0]; > + metadata->white_point[0].den = chroma_den; > + metadata->white_point[1].num = s->white_point[1]; > + metadata->white_point[1].den = chroma_den; > + > + metadata->max_luminance.num = s->max_mastering_luminance; > + metadata->max_luminance.den = luma_den; > + metadata->min_luminance.num = s->min_mastering_luminance; > + metadata->min_luminance.den = luma_den; > + metadata->has_luminance = 1; > + metadata->has_primaries = 1; > + > + av_log(s->avctx, AV_LOG_DEBUG, "Mastering Display Metadata:\n"); > + av_log(s->avctx, AV_LOG_DEBUG, > + "r(%5.4f,%5.4f) g(%5.4f,%5.4f) b(%5.4f %5.4f) wp(%5.4f, > %5.4f)\n", > + av_q2d(metadata->display_primaries[0][0]), > + av_q2d(metadata->display_primaries[0][1]), > + av_q2d(metadata->display_primaries[1][0]), > + av_q2d(metadata->display_primaries[1][1]), > + av_q2d(metadata->display_primaries[2][0]), > + av_q2d(metadata->display_primaries[2][1]), > + av_q2d(metadata->white_point[0]), > av_q2d(metadata->white_point[1])); > + av_log(s->avctx, AV_LOG_DEBUG, > + "min_luminance=%f, max_luminance=%f\n", > + av_q2d(metadata->min_luminance), > av_q2d(metadata->max_luminance)); > + } > + should sei_mastering_display_info_present be reset to 0 somewhere ? [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB I am the wisest man alive, for I know one thing, and that is that I know nothing. -- Socrates
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