FFmpeg/libavfilter/avfiltergraph.h

/*
 * Filter graphs
 * copyright (c) 2007 Bobby Bingham
 *
 * 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
 */

#ifndef AVFILTER_AVFILTERGRAPH_H
#define AVFILTER_AVFILTERGRAPH_H

#include "avfilter.h"
#include "libavutil/log.h"

typedef struct AVFilterGraph {
#if FF_API_GRAPH_AVCLASS
    const AVClass *av_class;
#endif
    unsigned filter_count;
    AVFilterContext **filters;

    char *scale_sws_opts; ///< sws options to use for the auto-inserted scale filters

    /**
     * Private fields
     *
     * The following fields are for internal use only.
     * Their type, offset, number and semantic can change without notice.
     */

    AVFilterLink **sink_links;
    int sink_links_count;
} AVFilterGraph;

/**
 * Allocate a filter graph.
 */
AVFilterGraph *avfilter_graph_alloc(void);

/**
 * Get a filter instance with name name from graph.
 *
 * @return the pointer to the found filter instance or NULL if it
 * cannot be found.
 */
AVFilterContext *avfilter_graph_get_filter(AVFilterGraph *graph, char *name);

/**
 * Add an existing filter instance to a filter graph.
 *
 * @param graphctx  the filter graph
 * @param filter the filter to be added
 */
int avfilter_graph_add_filter(AVFilterGraph *graphctx, AVFilterContext *filter);

/**
 * Create and add a filter instance into an existing graph.
 * The filter instance is created from the filter filt and inited
 * with the parameters args and opaque.
 *
 * In case of success put in *filt_ctx the pointer to the created
 * filter instance, otherwise set *filt_ctx to NULL.
 *
 * @param name the instance name to give to the created filter instance
 * @param graph_ctx the filter graph
 * @return a negative AVERROR error code in case of failure, a non
 * negative value otherwise
 */
int avfilter_graph_create_filter(AVFilterContext **filt_ctx, AVFilter *filt,
                                 const char *name, const char *args, void *opaque,
                                 AVFilterGraph *graph_ctx);

/**
 * Check validity and configure all the links and formats in the graph.
 *
 * @param graphctx the filter graph
 * @param log_ctx context used for logging
 * @return 0 in case of success, a negative AVERROR code otherwise
 */
int avfilter_graph_config(AVFilterGraph *graphctx, void *log_ctx);

/**
 * Free a graph, destroy its links, and set *graph to NULL.
 * If *graph is NULL, do nothing.
 */
void avfilter_graph_free(AVFilterGraph **graph);

/**
 * A linked-list of the inputs/outputs of the filter chain.
 *
 * This is mainly useful for avfilter_graph_parse() / avfilter_graph_parse2(),
 * where it is used to communicate open (unlinked) inputs and outputs from and
 * to the caller.
 * This struct specifies, per each not connected pad contained in the graph, the
 * filter context and the pad index required for establishing a link.
 */
typedef struct AVFilterInOut {
    /** unique name for this input/output in the list */
    char *name;

    /** filter context associated to this input/output */
    AVFilterContext *filter_ctx;

    /** index of the filt_ctx pad to use for linking */
    int pad_idx;

    /** next input/input in the list, NULL if this is the last */
    struct AVFilterInOut *next;
} AVFilterInOut;

/**
 * Allocate a single AVFilterInOut entry.
 * Must be freed with avfilter_inout_free().
 * @return allocated AVFilterInOut on success, NULL on failure.
 */
AVFilterInOut *avfilter_inout_alloc(void);

/**
 * Free the supplied list of AVFilterInOut and set *inout to NULL.
 * If *inout is NULL, do nothing.
 */
void avfilter_inout_free(AVFilterInOut **inout);

/**
 * Add a graph described by a string to a graph.
 *
 * @param graph   the filter graph where to link the parsed graph context
 * @param filters string to be parsed
 * @param inputs  pointer to a linked list to the inputs of the graph, may be NULL.
 *                If non-NULL, *inputs is updated to contain the list of open inputs
 *                after the parsing, should be freed with avfilter_inout_free().
 * @param outputs pointer to a linked list to the outputs of the graph, may be NULL.
 *                If non-NULL, *outputs is updated to contain the list of open outputs
 *                after the parsing, should be freed with avfilter_inout_free().
 * @return non negative on success, a negative AVERROR code on error
 */
int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,
                         AVFilterInOut **inputs, AVFilterInOut **outputs,
                         void *log_ctx);

/**
 * Add a graph described by a string to a graph.
 *
 * @param[in]  graph   the filter graph where to link the parsed graph context
 * @param[in]  filters string to be parsed
 * @param[out] inputs  a linked list of all free (unlinked) inputs of the
 *                     parsed graph will be returned here. It is to be freed
 *                     by the caller using avfilter_inout_free().
 * @param[out] outputs a linked list of all free (unlinked) outputs of the
 *                     parsed graph will be returned here. It is to be freed by the
 *                     caller using avfilter_inout_free().
 * @return zero on success, a negative AVERROR code on error
 *
 * @note the difference between avfilter_graph_parse2() and
 * avfilter_graph_parse() is that in avfilter_graph_parse(), the caller provides
 * the lists of inputs and outputs, which therefore must be known before calling
 * the function. On the other hand, avfilter_graph_parse2() \em returns the
 * inputs and outputs that are left unlinked after parsing the graph and the
 * caller then deals with them. Another difference is that in
 * avfilter_graph_parse(), the inputs parameter describes inputs of the
 * <em>already existing</em> part of the graph; i.e. from the point of view of
 * the newly created part, they are outputs. Similarly the outputs parameter
 * describes outputs of the already existing filters, which are provided as
 * inputs to the parsed filters.
 * avfilter_graph_parse2() takes the opposite approach -- it makes no reference
 * whatsoever to already existing parts of the graph and the inputs parameter
 * will on return contain inputs of the newly parsed part of the graph.
 * Analogously the outputs parameter will contain outputs of the newly created
 * filters.
 */
int avfilter_graph_parse2(AVFilterGraph *graph, const char *filters,
                          AVFilterInOut **inputs,
                          AVFilterInOut **outputs);


/**
 * Send a command to one or more filter instances.
 *
 * @param graph  the filter graph
 * @param target the filter(s) to which the command should be sent
 *               "all" sends to all filters
 *               otherwise it can be a filter or filter instance name
 *               which will send the command to all matching filters.
 * @param cmd    the command to sent, for handling simplicity all commands must be alphanumeric only
 * @param arg    the argument for the command
 * @param res    a buffer with size res_size where the filter(s) can return a response.
 *
 * @returns >=0 on success otherwise an error code.
 *              AVERROR(ENOSYS) on unsupported commands
 */
int avfilter_graph_send_command(AVFilterGraph *graph, const char *target, const char *cmd, const char *arg, char *res, int res_len, int flags);

/**
 * Queue a command for one or more filter instances.
 *
 * @param graph  the filter graph
 * @param target the filter(s) to which the command should be sent
 *               "all" sends to all filters
 *               otherwise it can be a filter or filter instance name
 *               which will send the command to all matching filters.
 * @param cmd    the command to sent, for handling simplicity all commands must be alphanummeric only
 * @param arg    the argument for the command
 * @param ts     time at which the command should be sent to the filter
 *
 * @note As this executes commands after this function returns, no return code
 *       from the filter is provided, also AVFILTER_CMD_FLAG_ONE is not supported.
 */
int avfilter_graph_queue_command(AVFilterGraph *graph, const char *target, const char *cmd, const char *arg, int flags, double ts);


/**
 * Dump a graph into a human-readable string representation.
 *
 * @param graph    the graph to dump
 * @param options  formatting options; currently ignored
 * @return  a string, or NULL in case of memory allocation failure;
 *          the string must be freed using av_free
 */
char *avfilter_graph_dump(AVFilterGraph *graph, const char *options);

/**
 * Request a frame on the oldest sink link.
 *
 * If the request returns AVERROR_EOF, try the next.
 *
 * Note that this function is not meant to be the sole scheduling mechanism
 * of a filtergraph, only a convenience function to help drain a filtergraph
 * in a balanced way under normal circumstances.
 *
 * @return  the return value of avfilter_request_frame,
 *          or AVERROR_EOF of all links returned AVERROR_EOF.
 */
int avfilter_graph_request_oldest(AVFilterGraph *graph);

#endif /* AVFILTER_AVFILTERGRAPH_H */