exif_internal.h

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/*
 * EXIF metadata parser - internal functions
 * Copyright (c) 2013 Thilo Borgmann <thilo.borgmann _at_ mail.de>
 * Copyright (c) 2024-2025 Leo Izen <leo.izen@gmail.com>
 *
 * 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
 * EXIF metadata parser - internal functions
 * @author Thilo Borgmann <thilo.borgmann _at_ mail.de>
 * @author Leo Izen <leo.izen@gmail.com>
 */
 
#ifndef AVCODEC_EXIF_INTERNAL_H
#define AVCODEC_EXIF_INTERNAL_H
 
#include "libavutil/buffer.h"
#include "libavutil/frame.h"
 
#include "exif.h"
 
/**
 * Compares values in the IFD with data in the provided AVFrame and sets the values
 * in that IFD to match the ones in that AVFrame. This is mostly useful for an
 * encoder that wishes to use ff_exif_get_buffer, but would prefer to modify the
 * IFD after it is sanitized and call av_exif_write afterward.
 */
int ff_exif_sanitize_ifd(void *logctx, const AVFrame *frame, AVExifMetadata *ifd);
 
/**
 * Gets all relevant side data, collects it into an IFD, and writes it into the
 * corresponding buffer pointer. This includes both AV_FRAME_DATA_EXIF and other
 * side data types that are included in the frame data, such as possibly an
 * instance of AV_FRAME_DATA_DISPLAYMATRIX. It also sets width and height tags
 * to match those of the AVFrame if they are different.
 * The *buffer argument must be NULL before calling.
 *
 * On success, a positive number is returned, and the buffer becomes owned by the caller.
 * A negative AVERROR return value means that an error occurred.
 * A zero return value means that there was no EXIF data to write.
 * In both the negative and zero cases, *buffer will be NULL.
 */
int ff_exif_get_buffer(void *logctx, const AVFrame *frame, AVBufferRef **buffer, enum AVExifHeaderMode header_mode);
 
struct AVCodecContext;
/**
 * Attach the data buffer to the frame. This is mostly a wrapper for
 * av_side_data_new_from_buffer, but it checks if the orientation tag is
 * present in the provided EXIF buffer. If it is, it zeroes it out and
 * attaches that information as an AV_FRAME_DATA_DISPLAYMATRIX instead
 * of including it in the AV_FRAME_DATA_EXIF side data buffer.
 *
 * *buf is ALWAYS consumed by this function and NULL written in its place, even
 * on failure.
 */
int ff_decode_exif_attach_buffer(struct AVCodecContext *avctx, AVFrame *frame, AVBufferRef **buf,
                                 enum AVExifHeaderMode header_mode);
 
/**
 * Attach an already-parsed EXIF metadata struct to the frame as a side data
 * buffer. It writes the EXIF IFD into the buffer and attaches the buffer to
 * the frame.
 *
 * If the metadata struct contains an orientation tag, it will be zeroed before
 * writing, and instead, an AV_FRAME_DATA_DISPLAYMATRIX will be attached in
 * addition to the AV_FRAME_DATA_EXIF side data.
 */
int ff_decode_exif_attach_ifd(struct AVCodecContext *avctx, AVFrame *frame,
                              const struct AVExifMetadata *ifd);
 
#endif /* AVCODEC_EXIF_INTERNAL_H */