On 10/2/2019 8:04 PM, Mark Thompson wrote:
> ---
> With intent to add some sort of support for this in H.265 metadata, though
> it's not in this set.
>
> Is there any thought on what a human-usable text serialisation of
> AVMasteringDisplayMetadata should look like? Ideally it wants to be
> something which would require no escaping when using it on the command-line.
> (This is relevant to video filters as well.)
>
>
> libavcodec/Makefile | 2 +-
> libavcodec/cbs_h265.c | 94 +++++++++++++++++++++++++++++++++++++++++++
> libavcodec/cbs_h265.h | 18 +++++++++
> 3 files changed, 113 insertions(+), 1 deletion(-)
> create mode 100644 libavcodec/cbs_h265.c
>
> diff --git a/libavcodec/Makefile b/libavcodec/Makefile
> index 86e512b605..d383d4a539 100644
> --- a/libavcodec/Makefile
> +++ b/libavcodec/Makefile
> @@ -65,7 +65,7 @@ OBJS-$(CONFIG_CABAC) += cabac.o
> OBJS-$(CONFIG_CBS) += cbs.o
> OBJS-$(CONFIG_CBS_AV1) += cbs_av1.o
> OBJS-$(CONFIG_CBS_H264) += cbs_h2645.o cbs_h264.o
> h2645_parse.o
> -OBJS-$(CONFIG_CBS_H265) += cbs_h2645.o h2645_parse.o
> +OBJS-$(CONFIG_CBS_H265) += cbs_h2645.o cbs_h265.o
> h2645_parse.o
> OBJS-$(CONFIG_CBS_JPEG) += cbs_jpeg.o
> OBJS-$(CONFIG_CBS_MPEG2) += cbs_mpeg2.o
> OBJS-$(CONFIG_CBS_VP9) += cbs_vp9.o
> diff --git a/libavcodec/cbs_h265.c b/libavcodec/cbs_h265.c
> new file mode 100644
> index 0000000000..b4850bd565
> --- /dev/null
> +++ b/libavcodec/cbs_h265.c
> @@ -0,0 +1,94 @@
> +/*
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * FFmpeg is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with FFmpeg; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
> USA
> + */
> +
> +#include "libavutil/mathematics.h"
> +#include "libavutil/mastering_display_metadata.h"
> +
> +#include "cbs_h265.h"
> +
> +
> +static unsigned int rescale(AVRational value, unsigned int max)
> +{
> + int64_t scaled = av_rescale(max, value.num, value.den);
> + return av_clip(scaled, 0, max);
> +}
> +
> +void
> ff_cbs_h265_fill_sei_mastering_display(H265RawSEIMasteringDisplayColourVolume
> *mdcv,
> + const AVMasteringDisplayMetadata
> *mdm)
> +{
> + memset(mdcv, 0, sizeof(*mdcv));
> +
> + if (mdm->has_primaries) {
> + // The values in the metadata are rationals in the range [0, 1],
> + // while the SEI structure contains fixed-point values with an
> + // increment of 0.00002. So, scale up by 50000 to convert between
> + // them.
> +
> + for (int a = 0; a < 3; a++) {
> + // The metadata stores this in RGB order, but the SEI wants it
> + // in GBR order.
> + int b = (a + 1) % 3;
> + mdcv->display_primaries_x[a] =
> + rescale(mdm->display_primaries[b][0], 50000);
> + mdcv->display_primaries_y[a] =
> + rescale(mdm->display_primaries[b][1], 50000);
> + }
> +
> + mdcv->white_point_x = rescale(mdm->white_point[0], 50000);
> + mdcv->white_point_y = rescale(mdm->white_point[1], 50000);
> + }
> +
> + if (mdm->has_luminance) {
> + // Metadata are rational values in candelas per square metre, SEI
> + // contains fixed point in units of 0.0001 candelas per square
> + // metre. So, scale up by 10000 to convert between them.
> +
> + mdcv->max_display_mastering_luminance =
> + rescale(mdm->max_luminance, 10000);
> + mdcv->min_display_mastering_luminance =
> + rescale(mdm->min_luminance, 10000);
I don't think 1.0 is the max value for these two. The spec doesn't state
a range. I for example have a sample using WebM's Mastering Metadata
elements (also based on the CIE 1931 definition), and max_luminance is
1000.0
If i were to re-encode it to h265 using vaapi after patch 18/18 from
this set, that value would get clipped.
> +
> + // The spec has a hard requirement that min is less than the max,
> + // and the SEI-writing code enforces that.
> + if (!(mdcv->min_display_mastering_luminance <
> + mdcv->max_display_mastering_luminance)) {
> + if (mdcv->max_display_mastering_luminance == 10000)
> + mdcv->min_display_mastering_luminance =
> + mdcv->max_display_mastering_luminance - 1;
> + else
> + mdcv->max_display_mastering_luminance =
> + mdcv->min_display_mastering_luminance + 1;
> + }
> + } else {
> + mdcv->max_display_mastering_luminance = 1;
> + mdcv->min_display_mastering_luminance = 0;
> + }
> +}
> +
> +void
> ff_cbs_h265_fill_sei_content_light_level(H265RawSEIContentLightLevelInfo *cll,
> + const AVContentLightMetadata
> *clm)
> +{
> + memset(cll, 0, sizeof(*cll));
> +
> + // Both the metadata and the SEI are in units of candelas per square
> + // metre, so we only need to clip to ensure that they are in the valid
> + // range.
> +
> + cll->max_content_light_level = av_clip_uintp2(clm->MaxCLL, 16);
> + cll->max_pic_average_light_level = av_clip_uintp2(clm->MaxCLL, 16);
> +}
> diff --git a/libavcodec/cbs_h265.h b/libavcodec/cbs_h265.h
> index f5eb5af5b2..793675ad41 100644
> --- a/libavcodec/cbs_h265.h
> +++ b/libavcodec/cbs_h265.h
> @@ -746,4 +746,22 @@ typedef struct CodedBitstreamH265Context {
> } CodedBitstreamH265Context;
>
>
> +struct AVMasteringDisplayMetadata;
> +struct AVContentLightMetadata;
> +
> +/**
> + * Fill an SEI Mastering Display Colour Volume structure with values derived
> + * from the AVMasteringDisplayMetadata side-data structure.
> + */
> +void
> ff_cbs_h265_fill_sei_mastering_display(H265RawSEIMasteringDisplayColourVolume
> *mdcv,
> + const struct
> AVMasteringDisplayMetadata *mdm);
> +
> +/**
> + * Fill an SEI Content Light Level Info structure with values derived from
> + * the AVContentLightMetadata side-data structure.
> + */
> +void
> ff_cbs_h265_fill_sei_content_light_level(H265RawSEIContentLightLevelInfo *cll,
> + const struct
> AVContentLightMetadata *clm);
> +
> +
> #endif /* AVCODEC_CBS_H265_H */
>
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