[FFmpeg-devel] [PATCH 1/7] avutil: add an API to handle 3D Reference Displays Information

[Timo Rothenpieler <timo@rothenpieler.org>]

From: James Almer <jamrial@gmail.com>

As defined in section G.14.3.2.3 of ITU-T H.265, it's required for proper
signaling of MV-HEVC.

Signed-off-by: James Almer <jamrial@gmail.com>
---
 libavutil/Makefile |   2 +
 libavutil/tdrdi.c  |  51 ++++++++++++++
 libavutil/tdrdi.h  | 164 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 217 insertions(+)
 create mode 100644 libavutil/tdrdi.c
 create mode 100644 libavutil/tdrdi.h

diff --git a/libavutil/Makefile b/libavutil/Makefile
index 9ef118016b..94a56bb72f 100644
--- a/libavutil/Makefile
+++ b/libavutil/Makefile
@@ -85,6 +85,7 @@ HEADERS = adler32.h                                                     \
           sha512.h                                                      \
           spherical.h                                                   \
           stereo3d.h                                                    \
+          tdrdi.h                                                       \
           threadmessage.h                                               \
           time.h                                                        \
           timecode.h                                                    \
@@ -179,6 +180,7 @@ OBJS = adler32.o                                                        \
        slicethread.o                                                    \
        spherical.o                                                      \
        stereo3d.o                                                       \
+       tdrdi.o                                                          \
        threadmessage.o                                                  \
        time.o                                                           \
        timecode.o                                                       \
diff --git a/libavutil/tdrdi.c b/libavutil/tdrdi.c
new file mode 100644
index 0000000000..26192a1d2f
--- /dev/null
+++ b/libavutil/tdrdi.c
@@ -0,0 +1,51 @@
+/*
+ * 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 <stddef.h>
+#include <stdint.h>
+
+#include "mem.h"
+#include "tdrdi.h"
+
+AV3DReferenceDisplaysInfo *av_tdrdi_alloc(unsigned int nb_displays, size_t *out_size)
+{
+    struct TestStruct {
+        AV3DReferenceDisplaysInfo p;
+        AV3DReferenceDisplay      b;
+    };
+    const size_t entries_offset = offsetof(struct TestStruct, b);
+    size_t size = entries_offset;
+    AV3DReferenceDisplaysInfo *tdrdi;
+
+    if (nb_displays > (SIZE_MAX - size) / sizeof(AV3DReferenceDisplay))
+        return NULL;
+    size += sizeof(AV3DReferenceDisplay) * nb_displays;
+
+    tdrdi = av_mallocz(size);
+    if (!tdrdi)
+        return NULL;
+
+    tdrdi->num_ref_displays = nb_displays;
+    tdrdi->entry_size       = sizeof(AV3DReferenceDisplay);
+    tdrdi->entries_offset   = entries_offset;
+
+    if (out_size)
+        *out_size = size;
+
+    return tdrdi;
+}
diff --git a/libavutil/tdrdi.h b/libavutil/tdrdi.h
new file mode 100644
index 0000000000..8dcca42c7b
--- /dev/null
+++ b/libavutil/tdrdi.h
@@ -0,0 +1,164 @@
+/*
+ * 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
+ */
+
+/**
+ * @file
+ * @ingroup lavu_video_3d_reference_displays_info
+ * Spherical video
+ */
+
+#ifndef AVUTIL_TDRDI_H
+#define AVUTIL_TDRDI_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "libavutil/avassert.h"
+
+/**
+ * @defgroup lavu_video_3d_reference_displays_info 3D Reference Displays Information
+ * @ingroup lavu_video
+ *
+ * The 3D Reference Displays Information describes information about the reference display
+ * width(s) and reference viewing distance(s) as well as information about the corresponding
+ * reference stereo pair(s).
+ * @{
+ */
+
+#define AV_TDRDI_MAX_NUM_REF_DISPLAY 32
+
+/**
+ * This structure describes information about the reference display width(s) and reference
+ * viewing distance(s) as well as information about the corresponding reference stereo pair(s).
+ * See section G.14.3.2.3 of ITU-T H.265 for more information.
+ *
+ * @note The struct must be allocated with av_tdrdi_alloc() and
+ *       its size is not a part of the public ABI.
+ */
+typedef struct AV3DReferenceDisplaysInfo {
+    /**
+     * The exponent of the maximum allowable truncation error for
+     * {exponent,mantissa}_ref_display_width as given by 2<sup>(-prec_ref_display_width)</sup>.
+     */
+    uint8_t prec_ref_display_width;
+
+    /**
+     * A flag to indicate the presence of reference viewing distance.
+     * If false, the values of prec_ref_viewing_dist, exponent_ref_viewing_distance,
+     * and mantissa_ref_viewing_distance are undefined.
+     */
+    uint8_t ref_viewing_distance_flag;
+
+    /**
+     * The exponent of the maximum allowable truncation error for
+     * {exponent,mantissa}_ref_viewing_distance as given by 2<sup>^(-prec_ref_viewing_dist)</sup>.
+     * The value of prec_ref_viewing_dist shall be in the range of 0 to 31, inclusive.
+     */
+    uint8_t prec_ref_viewing_dist;
+
+    /**
+     * The number of reference displays that are signalled in this struct.
+     * Allowed range is 1 to 32, inclusive.
+     */
+    uint8_t num_ref_displays;
+
+    /**
+     * Offset in bytes from the beginning of this structure at which the array
+     * of reference displays starts.
+     */
+    size_t entries_offset;
+
+    /**
+     * Size of each entry in bytes. May not match sizeof(AV3DReferenceDisplay).
+     */
+    size_t entry_size;
+} AV3DReferenceDisplaysInfo;
+
+/**
+ * Data structure for single deference display information.
+ * It is allocated as a part of AV3DReferenceDisplaysInfo and should be retrieved with
+ * av_tdrdi_get_display().
+ *
+ * sizeof(AV3DReferenceDisplay) is not a part of the ABI and new fields may be
+ * added to it.
+*/
+typedef struct AV3DReferenceDisplay {
+    /**
+     * The ViewId of the left view of a stereo pair corresponding to the n-th reference display.
+     */
+    uint16_t left_view_id;
+
+    /**
+     * The ViewId of the left view of a stereo pair corresponding to the n-th reference display.
+     */
+    uint16_t right_view_id;
+
+    /**
+     * The exponent part of the reference display width of the n-th reference display.
+     */
+    uint8_t exponent_ref_display_width;
+
+    /**
+     * The mantissa part of the reference display width of the n-th reference display.
+     */
+    uint8_t mantissa_ref_display_width;
+
+    /**
+     * Tthe exponent part of the reference viewing distance of the n-th reference display.
+     */
+    uint8_t exponent_ref_viewing_distance;
+
+    /**
+     * The mantissa part of the reference viewing distance of the n-th reference display.
+     */
+    uint8_t mantissa_ref_viewing_distance;
+
+    /**
+     * An array of flags to indicates that the information about additional horizontal shift of
+     * the left and right views for the n-th reference display is present.
+     */
+    uint8_t additional_shift_present_flag;
+
+    /**
+     * The recommended additional horizontal shift for a stereo pair corresponding to the n-th
+     * reference baseline and the n-th reference display.
+     */
+    int16_t num_sample_shift;
+} AV3DReferenceDisplay;
+
+static av_always_inline AV3DReferenceDisplay*
+av_tdrdi_get_display(AV3DReferenceDisplaysInfo *tdrdi, unsigned int idx)
+{
+    av_assert0(idx < tdrdi->num_ref_displays);
+    return (AV3DReferenceDisplay *)((uint8_t *)tdrdi + tdrdi->entries_offset +
+                                    idx * tdrdi->entry_size);
+}
+
+/**
+ * Allocate a AV3DReferenceDisplaysInfo structure and initialize its fields to default
+ * values.
+ *
+ * @return the newly allocated struct or NULL on failure
+ */
+AV3DReferenceDisplaysInfo *av_tdrdi_alloc(unsigned int nb_displays, size_t *size);
+
+/**
+ * @}
+ */
+
+#endif /* AVUTIL_TDRDI_H */
-- 
2.49.0

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