FFmpeg/libavutil/frame.h

/*
 *
 * This file is part of Libav.
 *
 * Libav 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.
 *
 * Libav 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 Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#ifndef AVUTIL_FRAME_H
#define AVUTIL_FRAME_H

#include <stdint.h>

#include "libavcodec/version.h"

#include "avutil.h"
#include "buffer.h"
#include "dict.h"
#include "rational.h"
#include "samplefmt.h"

enum AVFrameSideDataType {
    /**
     * The data is the AVPanScan struct defined in libavcodec.
     */
    AV_FRAME_DATA_PANSCAN,
};

typedef struct AVFrameSideData {
    enum AVFrameSideDataType type;
    uint8_t *data;
    int      size;
    AVDictionary *metadata;
} AVFrameSideData;

/**
 * This structure describes decoded (raw) audio or video data.
 *
 * AVFrame must be allocated using av_frame_alloc(). Not that this only
 * allocates the AVFrame itself, the buffers for the data must be managed
 * through other means (see below).
 * AVFrame must be freed with av_frame_free().
 *
 * AVFrame is typically allocated once and then reused multiple times to hold
 * different data (e.g. a single AVFrame to hold frames received from a
 * decoder). In such a case, av_frame_unref() will free any references held by
 * the frame and reset it to its original clean state before it
 * is reused again.
 *
 * The data described by an AVFrame is usually reference counted through the
 * AVBuffer API. The underlying buffer references are stored in AVFrame.buf /
 * AVFrame.extended_buf. An AVFrame is considered to be reference counted if at
 * least one reference is set, i.e. if AVFrame.buf[0] != NULL. In such a case,
 * every single data plane must be contained in one of the buffers in
 * AVFrame.buf or AVFrame.extended_buf.
 * There may be a single buffer for all the data, or one separate buffer for
 * each plane, or anything in between.
 *
 * sizeof(AVFrame) is not a part of the public ABI, so new fields may be added
 * to the end with a minor bump.
 */
typedef struct AVFrame {
#define AV_NUM_DATA_POINTERS 8
    /**
     * pointer to the picture/channel planes.
     * This might be different from the first allocated byte
     */
    uint8_t *data[AV_NUM_DATA_POINTERS];

    /**
     * For video, size in bytes of each picture line.
     * For audio, size in bytes of each plane.
     *
     * For audio, only linesize[0] may be set. For planar audio, each channel
     * plane must be the same size.
     */
    int linesize[AV_NUM_DATA_POINTERS];

    /**
     * pointers to the data planes/channels.
     *
     * For video, this should simply point to data[].
     *
     * For planar audio, each channel has a separate data pointer, and
     * linesize[0] contains the size of each channel buffer.
     * For packed audio, there is just one data pointer, and linesize[0]
     * contains the total size of the buffer for all channels.
     *
     * Note: Both data and extended_data should always be set in a valid frame,
     * but for planar audio with more channels that can fit in data,
     * extended_data must be used in order to access all channels.
     */
    uint8_t **extended_data;

    /**
     * width and height of the video frame
     */
    int width, height;

    /**
     * number of audio samples (per channel) described by this frame
     */
    int nb_samples;

    /**
     * format of the frame, -1 if unknown or unset
     * Values correspond to enum AVPixelFormat for video frames,
     * enum AVSampleFormat for audio)
     */
    int format;

    /**
     * 1 -> keyframe, 0-> not
     */
    int key_frame;

    /**
     * Picture type of the frame.
     */
    enum AVPictureType pict_type;

    uint8_t *base[AV_NUM_DATA_POINTERS];

    /**
     * Sample aspect ratio for the video frame, 0/1 if unknown/unspecified.
     */
    AVRational sample_aspect_ratio;

    /**
     * Presentation timestamp in time_base units (time when frame should be shown to user).
     */
    int64_t pts;

    /**
     * PTS copied from the AVPacket that was decoded to produce this frame.
     */
    int64_t pkt_pts;

    /**
     * DTS copied from the AVPacket that triggered returning this frame.
     */
    int64_t pkt_dts;

    /**
     * picture number in bitstream order
     */
    int coded_picture_number;
    /**
     * picture number in display order
     */
    int display_picture_number;

    /**
     * quality (between 1 (good) and FF_LAMBDA_MAX (bad))
     */
    int quality;

    int reference;

    /**
     * QP table
     */
    int8_t *qscale_table;
    /**
     * QP store stride
     */
    int qstride;

    int qscale_type;

    /**
     * mbskip_table[mb]>=1 if MB didn't change
     * stride= mb_width = (width+15)>>4
     */
    uint8_t *mbskip_table;

    /**
     * motion vector table
     * @code
     * example:
     * int mv_sample_log2= 4 - motion_subsample_log2;
     * int mb_width= (width+15)>>4;
     * int mv_stride= (mb_width << mv_sample_log2) + 1;
     * motion_val[direction][x + y*mv_stride][0->mv_x, 1->mv_y];
     * @endcode
     */
    int16_t (*motion_val[2])[2];

    /**
     * macroblock type table
     * mb_type_base + mb_width + 2
     */
    uint32_t *mb_type;

    /**
     * DCT coefficients
     */
    short *dct_coeff;

    /**
     * motion reference frame index
     * the order in which these are stored can depend on the codec.
     */
    int8_t *ref_index[2];

    /**
     * for some private data of the user
     */
    void *opaque;

    /**
     * error
     */
    uint64_t error[AV_NUM_DATA_POINTERS];

    int type;

    /**
     * When decoding, this signals how much the picture must be delayed.
     * extra_delay = repeat_pict / (2*fps)
     */
    int repeat_pict;

    /**
     * The content of the picture is interlaced.
     */
    int interlaced_frame;

    /**
     * If the content is interlaced, is top field displayed first.
     */
    int top_field_first;

    /**
     * Tell user application that palette has changed from previous frame.
     */
    int palette_has_changed;

    int buffer_hints;

    /**
     * Pan scan.
     */
    struct AVPanScan *pan_scan;

    /**
     * reordered opaque 64bit (generally an integer or a double precision float
     * PTS but can be anything).
     * The user sets AVCodecContext.reordered_opaque to represent the input at
     * that time,
     * the decoder reorders values as needed and sets AVFrame.reordered_opaque
     * to exactly one of the values provided by the user through AVCodecContext.reordered_opaque
     * @deprecated in favor of pkt_pts
     */
    int64_t reordered_opaque;

#if FF_API_AVFRAME_LAVC
    /**
     * @deprecated this field is unused
     */
    attribute_deprecated void *hwaccel_picture_private;
#endif

    struct AVCodecContext *owner;
    void *thread_opaque;

    /**
     * log2 of the size of the block which a single vector in motion_val represents:
     * (4->16x16, 3->8x8, 2-> 4x4, 1-> 2x2)
     */
    uint8_t motion_subsample_log2;

    /**
     * Sample rate of the audio data.
     */
    int sample_rate;

    /**
     * Channel layout of the audio data.
     */
    uint64_t channel_layout;

    /**
     * AVBuffer references backing the data for this frame. If all elements of
     * this array are NULL, then this frame is not reference counted.
     *
     * There may be at most one AVBuffer per data plane, so for video this array
     * always contains all the references. For planar audio with more than
     * AV_NUM_DATA_POINTERS channels, there may be more buffers than can fit in
     * this array. Then the extra AVBufferRef pointers are stored in the
     * extended_buf array.
     */
    AVBufferRef *buf[AV_NUM_DATA_POINTERS];

    /**
     * For planar audio which requires more than AV_NUM_DATA_POINTERS
     * AVBufferRef pointers, this array will hold all the references which
     * cannot fit into AVFrame.buf.
     *
     * Note that this is different from AVFrame.extended_data, which always
     * contains all the pointers. This array only contains the extra pointers,
     * which cannot fit into AVFrame.buf.
     *
     * This array is always allocated using av_malloc() by whoever constructs
     * the frame. It is freed in av_frame_unref().
     */
    AVBufferRef **extended_buf;
    /**
     * Number of elements in extended_buf.
     */
    int        nb_extended_buf;

    AVFrameSideData **side_data;
    int            nb_side_data;
} AVFrame;

/**
 * Allocate an AVFrame and set its fields to default values.  The resulting
 * struct must be freed using av_frame_free().
 *
 * @return An AVFrame filled with default values or NULL on failure.
 *
 * @note this only allocates the AVFrame itself, not the data buffers. Those
 * must be allocated through other means, e.g. with av_frame_get_buffer() or
 * manually.
 */
AVFrame *av_frame_alloc(void);

/**
 * Free the frame and any dynamically allocated objects in it,
 * e.g. extended_data. If the frame is reference counted, it will be
 * unreferenced first.
 *
 * @param frame frame to be freed. The pointer will be set to NULL.
 */
void av_frame_free(AVFrame **frame);

/**
 * Setup a new reference to the data described by an given frame.
 *
 * Copy frame properties from src to dst and create a new reference for each
 * AVBufferRef from src.
 *
 * If src is not reference counted, new buffers are allocated and the data is
 * copied.
 *
 * @return 0 on success, a negative AVERROR on error
 */
int av_frame_ref(AVFrame *dst, AVFrame *src);

/**
 * Create a new frame that references the same data as src.
 *
 * This is a shortcut for av_frame_alloc()+av_frame_ref().
 *
 * @return newly created AVFrame on success, NULL on error.
 */
AVFrame *av_frame_clone(AVFrame *src);

/**
 * Unreference all the buffers referenced by frame and reset the frame fields.
 */
void av_frame_unref(AVFrame *frame);

/**
 * Move everythnig contained in src to dst and reset src.
 */
void av_frame_move_ref(AVFrame *dst, AVFrame *src);

/**
 * Allocate new buffer(s) for audio or video data.
 *
 * The following fields must be set on frame before calling this function:
 * - format (pixel format for video, sample format for audio)
 * - width and height for video
 * - nb_samples and channel_layout for audio
 *
 * This function will fill AVFrame.data and AVFrame.buf arrays and, if
 * necessary, allocate and fill AVFrame.extended_data and AVFrame.extended_buf.
 * For planar formats, one buffer will be allocated for each plane.
 *
 * @param frame frame in which to store the new buffers.
 * @param align required buffer size alignment
 *
 * @return 0 on success, a negative AVERROR on error.
 */
int av_frame_get_buffer(AVFrame *frame, int align);

/**
 * Check if the frame data is writable.
 *
 * @return A positive value if the frame data is writable (which is true if and
 * only if each of the underlying buffers has only one reference, namely the one
 * stored in this frame). Return 0 otherwise.
 *
 * If 1 is returned the answer is valid until av_buffer_ref() is called on any
 * of the underlying AVBufferRefs (e.g. through av_frame_ref() or directly).
 *
 * @see av_frame_make_writable(), av_buffer_is_writable()
 */
int av_frame_is_writable(AVFrame *frame);

/**
 * Ensure that the frame data is writable, avoiding data copy if possible.
 *
 * Do nothing if the frame is writable, allocate new buffers and copy the data
 * if it is not.
 *
 * @return 0 on success, a negative AVERROR on error.
 *
 * @see av_frame_is_writable(), av_buffer_is_writable(),
 * av_buffer_make_writable()
 */
int av_frame_make_writable(AVFrame *frame);

/**
 * Copy only "metadata" fields from src to dst.
 *
 * Metadata for the purpose of this function are those fields that do not affect
 * the data layout in the buffers.  E.g. pts, sample rate (for audio) or sample
 * aspect ratio (for video), but not width/height or channel layout.
 * Side data is also copied.
 */
int av_frame_copy_props(AVFrame *dst, const AVFrame *src);

/**
 * Get the buffer reference a given data plane is stored in.
 *
 * @param plane index of the data plane of interest in frame->extended_data.
 *
 * @return the buffer reference that contains the plane or NULL if the input
 * frame is not valid.
 */
AVBufferRef *av_frame_get_plane_buffer(AVFrame *frame, int plane);

/**
 * Add a new side data to a frame.
 *
 * @param frame a frame to which the side data should be added
 * @param type type of the added side data
 * @param size size of the side data
 *
 * @return newly added side data on success, NULL on error
 */
AVFrameSideData *av_frame_new_side_data(AVFrame *frame,
                                        enum AVFrameSideDataType type,
                                        int size);

/**
 * @return a pointer to the side data of a given type on success, NULL if there
 * is no side data with such type in this frame.
 */
AVFrameSideData *av_frame_get_side_data(AVFrame *frame,
                                        enum AVFrameSideDataType type);

#endif /* AVUTIL_FRAME_H */