Commit 2ac7367f2f for ffmpeg
commit 2ac7367f2ff82dc6f43d4577c89d59f7831d70ed
Author: James Almer <jamrial@gmail.com>
Date: Mon Oct 5 17:05:57 2026 -0300
avutil/gain_map: move ISO 21496-1 gain map payload parsing from libavcodec
And export both functions. This is needed for a following change that will make
use of these functions from lavf.
Signed-off-by: James Almer <jamrial@gmail.com>
diff --git a/doc/APIchanges b/doc/APIchanges
index 7d7956eac3..f7f9f5d9e1 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -2,6 +2,10 @@ The last version increases of all libraries were on 2026-06-23.
API changes, most recent first:
+2026-10-xx - xxxxxxxxxx - lavu 61.14.100 - gain_map.h
+ Add av_gain_map_params_from_iso21496() and av_gain_map_params_to_iso21496().
+ Add AV_GAIN_MAP_MAX_PAYLOAD_SIZE.
+
2026-10-12 - xxxxxxxxxx - lavc 63.19.100 - packet.h
Add AV_PKT_DATA_GAIN_MAP_PARAMS.
diff --git a/libavcodec/gain_map.c b/libavcodec/gain_map.c
index 172adc218b..e85e120634 100644
--- a/libavcodec/gain_map.c
+++ b/libavcodec/gain_map.c
@@ -28,148 +28,6 @@
#include "bytestream.h"
#include "gain_map.h"
-#define ISO21496_HEADER_SIZE 5
-
-#define ISO21496_FLAG_MULTICHANNEL (1 << 7)
-#define ISO21496_FLAG_USE_BASE_CG (1 << 6)
-#define ISO21496_FLAG_RESERVED 0x3f
-
-static size_t iso21496_payload_size(int nb_channels)
-{
- return 4 * 4 + (size_t) nb_channels * 10 * 4;
-}
-
-static int make_q(int64_t num, uint32_t den, AVRational *out)
-{
- if (!den)
- return AVERROR_INVALIDDATA;
-
- /* Ensure the result fits in AVRational */
- av_reduce(&out->num, &out->den, num, den, INT32_MAX);
- return 0;
-}
-
-static int get_sq(GetByteContext *gb, AVRational *out)
-{
- int32_t num = (int32_t) bytestream2_get_be32(gb);
- uint32_t den = bytestream2_get_be32u(gb);
- return make_q(num, den, out);
-}
-
-static int get_uq(GetByteContext *gb, AVRational *out)
-{
- uint32_t num = bytestream2_get_be32u(gb);
- uint32_t den = bytestream2_get_be32u(gb);
- return make_q(num, den, out);
-}
-
-int ff_gain_map_params_from_iso21496(AVGainMapParams *restrict p,
- const uint8_t *data, size_t size)
-{
- int ret;
- if (!p || !data)
- return AVERROR(EINVAL);
-
- if (size < ISO21496_HEADER_SIZE || size > INT_MAX)
- return AVERROR_INVALIDDATA;
-
- GetByteContext gb;
- bytestream2_init(&gb, data, size);
-
- /* Parse header */
- const uint16_t minimum_version = bytestream2_get_be16(&gb);
- const uint16_t writer_version = bytestream2_get_be16(&gb);
- if (minimum_version > FF_GAIN_MAP_VERSION || writer_version < minimum_version)
- return AVERROR_PATCHWELCOME;
- const uint8_t flags = bytestream2_get_byte(&gb);
-
- /**
- * While the spec does not require reserved bits to be 0, older versions
- * of the ISO 21496-1 draft specification had extra flags that got removed
- * from the final publication, so conservatively error out just in case;
- * unless the writer version is >0 in which case these may be genuine
- * additions to later revisions of the published spec, the validity of
- * ignoring which is already guarded by the `minimum_version` check.
- */
- if (writer_version == 0 && (flags & ISO21496_FLAG_RESERVED))
- return AVERROR_INVALIDDATA;
-
- p->version = FF_GAIN_MAP_VERSION;
- p->nb_channels = (flags & ISO21496_FLAG_MULTICHANNEL) ? 3 : 1;
- p->use_base_color_space = !!(flags & ISO21496_FLAG_USE_BASE_CG);
-
- /* Parse payload */
- if (bytestream2_get_bytes_left(&gb) < iso21496_payload_size(p->nb_channels))
- return AVERROR_INVALIDDATA;
-
- if ((ret = get_uq(&gb, &p->base_hdr_headroom)) < 0 ||
- (ret = get_uq(&gb, &p->alternate_hdr_headroom)) < 0)
- return ret;
-
- for (int c = 0; c < p->nb_channels; c++) {
- struct AVGainMapChannel *const ch = &p->channels[c];
- if ((ret = get_sq(&gb, &ch->gain_map_min)) < 0 ||
- (ret = get_sq(&gb, &ch->gain_map_max)) < 0 ||
- (ret = get_uq(&gb, &ch->gamma)) < 0 ||
- (ret = get_sq(&gb, &ch->base_offset)) < 0 ||
- (ret = get_sq(&gb, &ch->alternate_offset)) < 0)
- return ret;
- }
-
- /* nb_channels == 1 means every channel shares the same parameters */
- for (int c = p->nb_channels; c < 3; c++)
- p->channels[c] = p->channels[0];
-
- return av_gain_map_params_validate(p);
-}
-
-static void put_q(PutByteContext *pb, AVRational q)
-{
- bytestream2_put_be32(pb, (unsigned) q.num);
- bytestream2_put_be32(pb, (unsigned) q.den);
-}
-
-int ff_gain_map_params_to_iso21496(const AVGainMapParams *p, uint8_t *buf)
-{
- if (!p || !buf)
- return AVERROR(EINVAL);
-
- /* Ensures representability in the bitstream */
- int ret = av_gain_map_params_validate(p);
- if (ret < 0)
- return ret;
-
- if (p->version > FF_GAIN_MAP_VERSION)
- return AVERROR_PATCHWELCOME; /* e.g. libraries out of sync */
-
- PutByteContext pb;
- bytestream2_init_writer(&pb, buf, FF_GAIN_MAP_MAX_PAYLOAD_SIZE);
-
- int channels = av_gain_map_channels_identical(p) ? 1 : p->nb_channels;
- uint8_t flags = 0;
- if (channels == 3)
- flags |= ISO21496_FLAG_MULTICHANNEL;
- if (p->use_base_color_space)
- flags |= ISO21496_FLAG_USE_BASE_CG;
-
- bytestream2_put_be16(&pb, p->version); /* minimum_version */
- bytestream2_put_be16(&pb, p->version); /* writer_version */
- bytestream2_put_byte(&pb, flags);
- put_q(&pb, p->base_hdr_headroom);
- put_q(&pb, p->alternate_hdr_headroom);
-
- for (int c = 0; c < channels; c++) {
- const struct AVGainMapChannel *const ch = &p->channels[c];
- put_q(&pb, ch->gain_map_min);
- put_q(&pb, ch->gain_map_max);
- put_q(&pb, ch->gamma);
- put_q(&pb, ch->base_offset);
- put_q(&pb, ch->alternate_offset);
- }
-
- return bytestream2_tell_p(&pb);
-}
-
int ff_gain_map_params_check_xmp(const AVGainMapParams *p)
{
if (av_gain_map_params_validate(p) < 0)
diff --git a/libavcodec/gain_map.h b/libavcodec/gain_map.h
index 53207e448b..7d98723ef5 100644
--- a/libavcodec/gain_map.h
+++ b/libavcodec/gain_map.h
@@ -31,42 +31,12 @@
/* May differ from AV_ISO21496_VERSION if libraries are not in sync */
#define FF_GAIN_MAP_VERSION 0
-#define FF_GAIN_MAP_MAX_PAYLOAD_SIZE 141 /* = 5 + 2*8 + 3*5*8 */
/* For XMP-based encoding */
#define FF_GAIN_MAP_XMP_IDENT "http://ns.adobe.com/xap/1.0/"
#define FF_GAIN_MAP_XMP_NAMESPACE "http://ns.adobe.com/hdr-gain-map/1.0/"
#define FF_GAIN_MAP_XMP_MAX_LEN 1024
-/**
- * Parse the payload of an ISO 21496-1 gain map metadata blob.
- *
- * @param p struct to fill; overwritten on success, untouched on failure
- * @param data payload, excluding container-specific identifiers
- * @param size size of `data` in bytes
- *
- * @return >= 0 on success, or a negative AVERROR on failure
- */
-int ff_gain_map_params_from_iso21496(AVGainMapParams *p, const uint8_t *data,
- size_t size);
-
-/**
- * Serialize an AVGainMapParams as an ISO 21496-1 gain map metadata blob.
- *
- * The output starts at the minimum_version field; the caller should prepend
- * whatever identifier its container requires.
- *
- * @param p parameters to serialize
- * @param buf Byte buffer to fill with the serialized data. Must contain at
- * least FF_GAIN_MAP_MAX_PAYLOAD_SIZE bytes.
- *
- * @return Number of bytes written on success, or a negative AVERROR on failure
- *
- * @note Always succeeds if av_gain_map_params_validate() returns >= 0, and
- * p->version <= AV_ISO21496_VERSION.
- */
-int ff_gain_map_params_to_iso21496(const AVGainMapParams *p, uint8_t *buf);
-
/**
* Returns 1 if the gain map parameters are compatible with the XMP-based
* encoding, or 0 otherwise.
diff --git a/libavcodec/mjpegenc_common.c b/libavcodec/mjpegenc_common.c
index 235a46799a..bc58ca9903 100644
--- a/libavcodec/mjpegenc_common.c
+++ b/libavcodec/mjpegenc_common.c
@@ -182,7 +182,7 @@ int ff_mjpeg_add_gain_map_size(AVCodecContext *avctx, struct MJpegContext *m,
if (ret < 0)
return ret;
- size_t extra_size = 4 + sizeof(AV_ISO21496_IDENTIFIER) + FF_GAIN_MAP_MAX_PAYLOAD_SIZE;
+ size_t extra_size = 4 + sizeof(AV_ISO21496_IDENTIFIER) + AV_GAIN_MAP_MAX_PAYLOAD_SIZE;
if (m && m->xmp_gain_map) {
if (!ff_gain_map_params_check_xmp(params)) {
const int level = m->xmp_gain_map > 0 ? AV_LOG_ERROR : AV_LOG_WARNING;
@@ -294,7 +294,7 @@ static void jpeg_put_comments(AVCodecContext *avctx, PutBitContext *p,
flush_put_bits(p);
/* pre-validated by ff_mjpeg_add_gain_map_size() */
- size = ff_gain_map_params_to_iso21496(gmp, put_bits_ptr(p));
+ size = av_gain_map_params_to_iso21496(gmp, put_bits_ptr(p));
av_assert0(size >= 0);
skip_put_bytes(p, size);
AV_WB16(ptr, 2 + sizeof(AV_ISO21496_IDENTIFIER) + size);
diff --git a/libavutil/gain_map.c b/libavutil/gain_map.c
index 83c5bd31cf..03cb4ca578 100644
--- a/libavutil/gain_map.c
+++ b/libavutil/gain_map.c
@@ -18,6 +18,7 @@
#include "gain_map.h"
#include "mem.h"
+#include "libavcodec/bytestream.h"
static void gain_map_params_default(AVGainMapParams *p)
{
@@ -72,6 +73,145 @@ int av_gain_map_params_validate(const AVGainMapParams *p)
return 0;
}
+#define ISO21496_HEADER_SIZE 5
+
+#define ISO21496_FLAG_MULTICHANNEL (1 << 7)
+#define ISO21496_FLAG_USE_BASE_CG (1 << 6)
+#define ISO21496_FLAG_RESERVED 0x3f
+
+static size_t iso21496_payload_size(int nb_channels)
+{
+ return 4 * 4 + (size_t) nb_channels * 10 * 4;
+}
+
+static int make_q(int64_t num, uint32_t den, AVRational *out)
+{
+ if (!den)
+ return AVERROR_INVALIDDATA;
+
+ /* Ensure the result fits in AVRational */
+ av_reduce(&out->num, &out->den, num, den, INT32_MAX);
+ return 0;
+}
+
+static int get_sq(GetByteContext *gb, AVRational *out)
+{
+ int32_t num = (int32_t) bytestream2_get_be32(gb);
+ uint32_t den = bytestream2_get_be32u(gb);
+ return make_q(num, den, out);
+}
+
+static int get_uq(GetByteContext *gb, AVRational *out)
+{
+ uint32_t num = bytestream2_get_be32u(gb);
+ uint32_t den = bytestream2_get_be32u(gb);
+ return make_q(num, den, out);
+}
+
+int av_gain_map_params_from_iso21496(AVGainMapParams *restrict p,
+ const uint8_t *data, size_t size)
+{
+ int ret;
+ if (!p || !data)
+ return AVERROR(EINVAL);
+
+ if (size < ISO21496_HEADER_SIZE || size > INT_MAX)
+ return AVERROR_INVALIDDATA;
+
+ GetByteContext gb;
+ bytestream2_init(&gb, data, size);
+
+ /* Parse header */
+ const uint16_t minimum_version = bytestream2_get_be16(&gb);
+ const uint16_t writer_version = bytestream2_get_be16(&gb);
+ if (minimum_version > AV_ISO21496_VERSION || writer_version < minimum_version)
+ return AVERROR_PATCHWELCOME;
+ const uint8_t flags = bytestream2_get_byte(&gb);
+
+ /**
+ * While the spec does not require reserved bits to be 0, older versions
+ * of the ISO 21496-1 draft specification had extra flags that got removed
+ * from the final publication, so conservatively error out just in case;
+ * unless the writer version is >0 in which case these may be genuine
+ * additions to later revisions of the published spec, the validity of
+ * ignoring which is already guarded by the `minimum_version` check.
+ */
+ if (writer_version == 0 && (flags & ISO21496_FLAG_RESERVED))
+ return AVERROR_INVALIDDATA;
+
+ p->version = AV_ISO21496_VERSION;
+ p->nb_channels = (flags & ISO21496_FLAG_MULTICHANNEL) ? 3 : 1;
+ p->use_base_color_space = !!(flags & ISO21496_FLAG_USE_BASE_CG);
+
+ /* Parse payload */
+ if (bytestream2_get_bytes_left(&gb) < iso21496_payload_size(p->nb_channels))
+ return AVERROR_INVALIDDATA;
+
+ if ((ret = get_uq(&gb, &p->base_hdr_headroom)) < 0 ||
+ (ret = get_uq(&gb, &p->alternate_hdr_headroom)) < 0)
+ return ret;
+
+ for (int c = 0; c < p->nb_channels; c++) {
+ struct AVGainMapChannel *const ch = &p->channels[c];
+ if ((ret = get_sq(&gb, &ch->gain_map_min)) < 0 ||
+ (ret = get_sq(&gb, &ch->gain_map_max)) < 0 ||
+ (ret = get_uq(&gb, &ch->gamma)) < 0 ||
+ (ret = get_sq(&gb, &ch->base_offset)) < 0 ||
+ (ret = get_sq(&gb, &ch->alternate_offset)) < 0)
+ return ret;
+ }
+
+ /* nb_channels == 1 means every channel shares the same parameters */
+ for (int c = p->nb_channels; c < 3; c++)
+ p->channels[c] = p->channels[0];
+
+ return av_gain_map_params_validate(p);
+}
+
+static void put_q(PutByteContext *pb, AVRational q)
+{
+ bytestream2_put_be32(pb, (unsigned) q.num);
+ bytestream2_put_be32(pb, (unsigned) q.den);
+}
+
+int av_gain_map_params_to_iso21496(const AVGainMapParams *p, uint8_t *buf)
+{
+ if (!p || !buf)
+ return AVERROR(EINVAL);
+
+ /* Ensures representability in the bitstream */
+ int ret = av_gain_map_params_validate(p);
+ if (ret < 0)
+ return ret;
+
+ PutByteContext pb;
+ bytestream2_init_writer(&pb, buf, AV_GAIN_MAP_MAX_PAYLOAD_SIZE);
+
+ int channels = av_gain_map_channels_identical(p) ? 1 : p->nb_channels;
+ uint8_t flags = 0;
+ if (channels == 3)
+ flags |= ISO21496_FLAG_MULTICHANNEL;
+ if (p->use_base_color_space)
+ flags |= ISO21496_FLAG_USE_BASE_CG;
+
+ bytestream2_put_be16(&pb, p->version); /* minimum_version */
+ bytestream2_put_be16(&pb, p->version); /* writer_version */
+ bytestream2_put_byte(&pb, flags);
+ put_q(&pb, p->base_hdr_headroom);
+ put_q(&pb, p->alternate_hdr_headroom);
+
+ for (int c = 0; c < channels; c++) {
+ const struct AVGainMapChannel *const ch = &p->channels[c];
+ put_q(&pb, ch->gain_map_min);
+ put_q(&pb, ch->gain_map_max);
+ put_q(&pb, ch->gamma);
+ put_q(&pb, ch->base_offset);
+ put_q(&pb, ch->alternate_offset);
+ }
+
+ return bytestream2_tell_p(&pb);
+}
+
int av_gain_map_channels_identical(const AVGainMapParams *p)
{
static_assert(sizeof(p->channels[0]) == sizeof(int[2]) * 5,
diff --git a/libavutil/gain_map.h b/libavutil/gain_map.h
index 7d922d7b40..12499cdd52 100644
--- a/libavutil/gain_map.h
+++ b/libavutil/gain_map.h
@@ -83,6 +83,36 @@ typedef struct AVGainMapParams {
int nb_channels;
} AVGainMapParams;
+/**
+ * Parse the payload of an ISO 21496-1 gain map metadata blob.
+ *
+ * @param p struct to fill; overwritten on success, untouched on failure
+ * @param data payload, excluding container-specific identifiers
+ * @param size size of `data` in bytes
+ *
+ * @return >= 0 on success, or a negative AVERROR on failure
+ */
+int av_gain_map_params_from_iso21496(AVGainMapParams *p, const uint8_t *data,
+ size_t size);
+
+#define AV_GAIN_MAP_MAX_PAYLOAD_SIZE 141 /* = 5 + 2*8 + 3*5*8 */
+
+/**
+ * Serialize an AVGainMapParams as an ISO 21496-1 gain map metadata blob.
+ *
+ * The output starts at the minimum_version field; the caller should prepend
+ * whatever identifier its container requires.
+ *
+ * @param p parameters to serialize
+ * @param buf Byte buffer to fill with the serialized data. Must contain at
+ * least AV_GAIN_MAP_MAX_PAYLOAD_SIZE bytes.
+ *
+ * @return Number of bytes written on success, or a negative AVERROR on failure
+ *
+ * @note Always succeeds if av_gain_map_params_validate() returns >= 0.
+ */
+int av_gain_map_params_to_iso21496(const AVGainMapParams *p, uint8_t *buf);
+
/**
* Returns >= 0 if the given AVGainMapParams struct contains valid data;
* or a negative AVERROR otherwise.
diff --git a/libavutil/version.h b/libavutil/version.h
index de614c9866..ed6abeab78 100644
--- a/libavutil/version.h
+++ b/libavutil/version.h
@@ -79,7 +79,7 @@
*/
#define LIBAVUTIL_VERSION_MAJOR 61
-#define LIBAVUTIL_VERSION_MINOR 13
+#define LIBAVUTIL_VERSION_MINOR 14
#define LIBAVUTIL_VERSION_MICRO 100
#define LIBAVUTIL_VERSION_INT AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \