[FFmpeg-devel] [PATCH] lavc/hevc Parse SEI_TYPE_MASTERING_DISPLAY_INFO and propagate contents into the AVMasteringDisplayMetadata side data.
Michael Niedermayer
michael at niedermayer.cc
Tue Feb 2 16:13:30 CET 2016
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.birkbeck at 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.leppkes at gmail.com>
> > wrote:
> >>
> >> On Mon, Jan 25, 2016 at 10:37 PM, Michael Niedermayer
> >> <michael at 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 at 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.birkbeck at 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.birkbeck at 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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