[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
Fri Feb 5 04:36:04 CET 2016
On Thu, Feb 04, 2016 at 06:05:08PM -0800, Neil Birkbeck wrote:
> According to the ITU-T H.265 v3, in Table D - 1, the persistence scope
> of the mastering display metadata is "The Coded Video Sequence (CVS)
> containing the SEI message". So I guess we want to clear when we start
> the next CVS, so I guess when we see the next IDR frame.
>
> Given that the SEI comes before the IDR, I don't see a great way to do
> this aside from initializing the flag to 2 and decrementing (when > 0)
> when we see an IDR.
hmm, yes, i dont see a nicer way atm either
>
> On Tue, Feb 2, 2016 at 7:13 AM, Michael Niedermayer
> <michael at niedermayer.cc> wrote:
> > 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
> >
> > _______________________________________________
> > ffmpeg-devel mailing list
> > ffmpeg-devel at ffmpeg.org
> > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> >
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
I have often repented speaking, but never of holding my tongue.
-- Xenocrates
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