FFmpeg/libavfilter/internal.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 AVFILTER_INTERNAL_H
#define AVFILTER_INTERNAL_H

/**
 * @file
 * internal API functions
 */

#include "avfilter.h"

#if !FF_API_AVFILTERPAD_PUBLIC
/**
 * A filter pad used for either input or output.
 */
struct AVFilterPad {
    /**
     * Pad name. The name is unique among inputs and among outputs, but an
     * input may have the same name as an output. This may be NULL if this
     * pad has no need to ever be referenced by name.
     */
    const char *name;

    /**
     * AVFilterPad type.
     */
    enum AVMediaType type;

    /**
     * Minimum required permissions on incoming buffers. Any buffer with
     * insufficient permissions will be automatically copied by the filter
     * system to a new buffer which provides the needed access permissions.
     *
     * Input pads only.
     */
    int min_perms;

    /**
     * Permissions which are not accepted on incoming buffers. Any buffer
     * which has any of these permissions set will be automatically copied
     * by the filter system to a new buffer which does not have those
     * permissions. This can be used to easily disallow buffers with
     * AV_PERM_REUSE.
     *
     * Input pads only.
     */
    int rej_perms;

    /**
     * Callback called before passing the first slice of a new frame. If
     * NULL, the filter layer will default to storing a reference to the
     * picture inside the link structure.
     *
     * Input video pads only.
     *
     * @return >= 0 on success, a negative AVERROR on error. picref will be
     * unreferenced by the caller in case of error.
     */
    void (*start_frame)(AVFilterLink *link, AVFilterBufferRef *picref);

    /**
     * Callback function to get a video buffer. If NULL, the filter system will
     * use avfilter_default_get_video_buffer().
     *
     * Input video pads only.
     */
    AVFilterBufferRef *(*get_video_buffer)(AVFilterLink *link, int perms, int w, int h);

    /**
     * Callback function to get an audio buffer. If NULL, the filter system will
     * use avfilter_default_get_audio_buffer().
     *
     * Input audio pads only.
     */
    AVFilterBufferRef *(*get_audio_buffer)(AVFilterLink *link, int perms,
                                           int nb_samples);

    /**
     * Callback called after the slices of a frame are completely sent. If
     * NULL, the filter layer will default to releasing the reference stored
     * in the link structure during start_frame().
     *
     * Input video pads only.
     */
    void (*end_frame)(AVFilterLink *link);

    /**
     * Slice drawing callback. This is where a filter receives video data
     * and should do its processing.
     *
     * Input video pads only.
     *
     * @return >= 0 on success, a negative AVERROR on error.
     */
    int (*draw_slice)(AVFilterLink *link, int y, int height, int slice_dir);

    /**
     * Samples filtering callback. This is where a filter receives audio data
     * and should do its processing.
     *
     * Input audio pads only.
     *
     * @return >= 0 on success, a negative AVERROR on error. This function
     * must ensure that samplesref is properly unreferenced on error if it
     * hasn't been passed on to another filter.
     */
    int (*filter_samples)(AVFilterLink *link, AVFilterBufferRef *samplesref);

    /**
     * Frame poll callback. This returns the number of immediately available
     * samples. It should return a positive value if the next request_frame()
     * is guaranteed to return one frame (with no delay).
     *
     * Defaults to just calling the source poll_frame() method.
     *
     * Output pads only.
     */
    int (*poll_frame)(AVFilterLink *link);

    /**
     * Frame request callback. A call to this should result in at least one
     * frame being output over the given link. This should return zero on
     * success, and another value on error.
     *
     * Output pads only.
     */
    int (*request_frame)(AVFilterLink *link);

    /**
     * Link configuration callback.
     *
     * For output pads, this should set the link properties such as
     * width/height. This should NOT set the format property - that is
     * negotiated between filters by the filter system using the
     * query_formats() callback before this function is called.
     *
     * For input pads, this should check the properties of the link, and update
     * the filter's internal state as necessary.
     *
     * For both input and output filters, this should return zero on success,
     * and another value on error.
     */
    int (*config_props)(AVFilterLink *link);

    /**
     * The filter expects a fifo to be inserted on its input link,
     * typically because it has a delay.
     *
     * input pads only.
     */
    int needs_fifo;
};
#endif

/** default handler for freeing audio/video buffer when there are no references left */
void ff_avfilter_default_free_buffer(AVFilterBuffer *buf);

/** Tell is a format is contained in the provided list terminated by -1. */
int ff_fmt_is_in(int fmt, const int *fmts);

#define FF_DPRINTF_START(ctx, func) av_dlog(NULL, "%-16s: ", #func)

void ff_dlog_link(void *ctx, AVFilterLink *link, int end);

/**
 * Insert a new pad.
 *
 * @param idx Insertion point. Pad is inserted at the end if this point
 *            is beyond the end of the list of pads.
 * @param count Pointer to the number of pads in the list
 * @param padidx_off Offset within an AVFilterLink structure to the element
 *                   to increment when inserting a new pad causes link
 *                   numbering to change
 * @param pads Pointer to the pointer to the beginning of the list of pads
 * @param links Pointer to the pointer to the beginning of the list of links
 * @param newpad The new pad to add. A copy is made when adding.
 */
void ff_insert_pad(unsigned idx, unsigned *count, size_t padidx_off,
                   AVFilterPad **pads, AVFilterLink ***links,
                   AVFilterPad *newpad);

/** Insert a new input pad for the filter. */
static inline void ff_insert_inpad(AVFilterContext *f, unsigned index,
                                   AVFilterPad *p)
{
    ff_insert_pad(index, &f->nb_inputs, offsetof(AVFilterLink, dstpad),
                  &f->input_pads, &f->inputs, p);
#if FF_API_FOO_COUNT
    f->input_count = f->nb_inputs;
#endif
}

/** Insert a new output pad for the filter. */
static inline void ff_insert_outpad(AVFilterContext *f, unsigned index,
                                    AVFilterPad *p)
{
    ff_insert_pad(index, &f->nb_outputs, offsetof(AVFilterLink, srcpad),
                  &f->output_pads, &f->outputs, p);
#if FF_API_FOO_COUNT
    f->output_count = f->nb_outputs;
#endif
}

/**
 * Poll a frame from the filter chain.
 *
 * @param  link the input link
 * @return the number of immediately available frames, a negative
 * number in case of error
 */
int ff_poll_frame(AVFilterLink *link);

/**
 * Request an input frame from the filter at the other end of the link.
 *
 * @param link the input link
 * @return     zero on success
 */
int ff_request_frame(AVFilterLink *link);

#endif /* AVFILTER_INTERNAL_H */