/*

  * filter layer

  * Copyright (c) 2007 Bobby Bingham

  *

  * 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_AVFILTER_H
 #define AVFILTER_AVFILTER_H

 /**
  * @file
  * @ingroup lavfi
  * Main libavfilter public API header
  */
 
 /**
  * @defgroup lavfi Libavfilter - graph-based frame editing library
  * @{
  */
 

 #include "libavutil/attributes.h"

 #include "libavutil/avutil.h"

 #include "libavutil/buffer.h"

 #include "libavutil/frame.h"

 #include "libavutil/log.h"

 #include "libavutil/samplefmt.h"

 #include "libavutil/pixfmt.h"

 #include "libavutil/rational.h"

 #include <stddef.h>

 #include "libavfilter/version.h"
 

 /**

  * Return the LIBAVFILTER_VERSION_INT constant.

  */
 unsigned avfilter_version(void);
 

 /**

  * Return the libavfilter build-time configuration.

  */

 const char *avfilter_configuration(void);

 
 /**

  * Return the libavfilter license.

  */

 const char *avfilter_license(void);

 typedef struct AVFilterContext AVFilterContext;
 typedef struct AVFilterLink    AVFilterLink;
 typedef struct AVFilterPad     AVFilterPad;

 typedef struct AVFilterFormats AVFilterFormats;

 /**

  * Get the number of elements in a NULL-terminated array of AVFilterPads (e.g.
  * AVFilter.inputs/outputs).
  */
 int avfilter_pad_count(const AVFilterPad *pads);
 
 /**

  * Get the name of an AVFilterPad.
  *
  * @param pads an array of AVFilterPads
  * @param pad_idx index of the pad in the array it; is the caller's
  *                responsibility to ensure the index is valid
  *
  * @return name of the pad_idx'th pad in pads
  */

 const char *avfilter_pad_get_name(const AVFilterPad *pads, int pad_idx);

 
 /**
  * Get the type of an AVFilterPad.
  *
  * @param pads an array of AVFilterPads
  * @param pad_idx index of the pad in the array; it is the caller's
  *                responsibility to ensure the index is valid
  *
  * @return type of the pad_idx'th pad in pads
  */

 enum AVMediaType avfilter_pad_get_type(const AVFilterPad *pads, int pad_idx);

 /**

  * The number of the filter inputs is not determined just by AVFilter.inputs.
  * The filter might add additional inputs during initialization depending on the
  * options supplied to it.
  */
 #define AVFILTER_FLAG_DYNAMIC_INPUTS        (1 << 0)
 /**
  * The number of the filter outputs is not determined just by AVFilter.outputs.
  * The filter might add additional outputs during initialization depending on
  * the options supplied to it.
  */
 #define AVFILTER_FLAG_DYNAMIC_OUTPUTS       (1 << 1)

 /**
  * The filter supports multithreading by splitting frames into multiple parts
  * and processing them concurrently.
  */
 #define AVFILTER_FLAG_SLICE_THREADS         (1 << 2)

 
 /**

  * Filter definition. This defines the pads a filter contains, and all the

  * callback functions used to interact with the filter.
  */

 typedef struct AVFilter {

     /**
      * Filter name. Must be non-NULL and unique among filters.
      */
     const char *name;

     /**

      * A description of the filter. May be NULL.
      *
      * You should use the NULL_IF_CONFIG_SMALL() macro to define it.

      */
     const char *description;
 

     /**
      * List of inputs, terminated by a zeroed element.
      *
      * NULL if there are no (static) inputs. Instances of filters with
      * AVFILTER_FLAG_DYNAMIC_INPUTS set may have more inputs than present in
      * this list.
      */
     const AVFilterPad *inputs;
     /**
      * List of outputs, terminated by a zeroed element.
      *
      * NULL if there are no (static) outputs. Instances of filters with
      * AVFILTER_FLAG_DYNAMIC_OUTPUTS set may have more outputs than present in
      * this list.
      */
     const AVFilterPad *outputs;

     /**

      * A class for the private data, used to declare filter private AVOptions.
      * This field is NULL for filters that do not declare any options.
      *
      * If this field is non-NULL, the first member of the filter private data
      * must be a pointer to AVClass, which will be set by libavfilter generic
      * code to this class.

      */
     const AVClass *priv_class;
 

     /**
      * A combination of AVFILTER_FLAG_*
      */
     int flags;
 

     /*****************************************************************
      * All fields below this line are not part of the public API. They
      * may not be used outside of libavfilter and can be changed and
      * removed at will.
      * New public fields should be added right above.
      *****************************************************************
      */

     /**

      * Filter initialization function.
      *
      * This callback will be called only once during the filter lifetime, after
      * all the options have been set, but before links between filters are
      * established and format negotiation is done.
      *
      * Basic filter initialization should be done here. Filters with dynamic
      * inputs and/or outputs should create those inputs/outputs here based on
      * provided options. No more changes to this filter's inputs/outputs can be
      * done after this callback.
      *
      * This callback must not assume that the filter links exist or frame
      * parameters are known.
      *
      * @ref AVFilter.uninit "uninit" is guaranteed to be called even if
      * initialization fails, so this callback does not have to clean up on
      * failure.
      *
      * @return 0 on success, a negative AVERROR on failure

      */

     int (*init)(AVFilterContext *ctx);

 
     /**

      * Should be set instead of @ref AVFilter.init "init" by the filters that
      * want to pass a dictionary of AVOptions to nested contexts that are
      * allocated during init.
      *
      * On return, the options dict should be freed and replaced with one that
      * contains all the options which could not be processed by this filter (or
      * with NULL if all the options were processed).
      *
      * Otherwise the semantics is the same as for @ref AVFilter.init "init".

      */
     int (*init_dict)(AVFilterContext *ctx, AVDictionary **options);
 
     /**

      * Filter uninitialization function.
      *
      * Called only once right before the filter is freed. Should deallocate any
      * memory held by the filter, release any buffer references, etc. It does
      * not need to deallocate the AVFilterContext.priv memory itself.
      *
      * This callback may be called even if @ref AVFilter.init "init" was not
      * called or failed, so it must be prepared to handle such a situation.

      */

     void (*uninit)(AVFilterContext *ctx);
 

     /**

      * Query formats supported by the filter on its inputs and outputs.
      *
      * This callback is called after the filter is initialized (so the inputs
      * and outputs are fixed), shortly before the format negotiation. This
      * callback may be called more than once.
      *
      * This callback must set AVFilterLink.out_formats on every input link and
      * AVFilterLink.in_formats on every output link to a list of pixel/sample
      * formats that the filter supports on that link. For audio links, this
      * filter must also set @ref AVFilterLink.in_samplerates "in_samplerates" /
      * @ref AVFilterLink.out_samplerates "out_samplerates" and
      * @ref AVFilterLink.in_channel_layouts "in_channel_layouts" /
      * @ref AVFilterLink.out_channel_layouts "out_channel_layouts" analogously.
      *
      * This callback may be NULL for filters with one input, in which case
      * libavfilter assumes that it supports all input formats and preserves
      * them on output.

      *

      * @return zero on success, a negative value corresponding to an
      * AVERROR code otherwise

      */
     int (*query_formats)(AVFilterContext *);
 

     int priv_size;      ///< size of private data to allocate for the filter

     /**
      * Used by the filter registration system. Must not be touched by any other
      * code.
      */

     struct AVFilter *next;

 } AVFilter;
 

 /**
  * Process multiple parts of the frame concurrently.
  */
 #define AVFILTER_THREAD_SLICE (1 << 0)
 
 typedef struct AVFilterInternal AVFilterInternal;
 

 /** An instance of a filter */

 struct AVFilterContext {

     const AVClass *av_class;              ///< needed for av_log()

     const AVFilter *filter;         ///< the AVFilter of which this is an instance

     char *name;                     ///< name of this filter instance

     AVFilterPad   *input_pads;      ///< array of input pads
     AVFilterLink **inputs;          ///< array of pointers to input links
     unsigned    nb_inputs;          ///< number of input pads

     AVFilterPad   *output_pads;     ///< array of output pads
     AVFilterLink **outputs;         ///< array of pointers to output links
     unsigned    nb_outputs;         ///< number of output pads

     void *priv;                     ///< private data for use by the filter

 
     struct AVFilterGraph *graph;    ///< filtergraph this filter belongs to

 
     /**
      * Type of multithreading being allowed/used. A combination of
      * AVFILTER_THREAD_* flags.
      *
      * May be set by the caller before initializing the filter to forbid some
      * or all kinds of multithreading for this filter. The default is allowing
      * everything.
      *
      * When the filter is initialized, this field is combined using bit AND with
      * AVFilterGraph.thread_type to get the final mask used for determining
      * allowed threading types. I.e. a threading type needs to be set in both
      * to be allowed.
      *
      * After the filter is initialzed, libavfilter sets this field to the
      * threading type that is actually used (0 for no multithreading).
      */
     int thread_type;
 
     /**
      * An opaque struct for libavfilter internal use.
      */
     AVFilterInternal *internal;

 
     /**
      * For filters which will create hardware frames, sets the device the
      * filter should create them in.  All other filters will ignore this field:
      * in particular, a filter which consumes or processes hardware frames will
      * instead use the hw_frames_ctx field in AVFilterLink to carry the
      * hardware context information.
      */
     AVBufferRef *hw_device_ctx;

 };
 

 /**

  * A link between two filters. This contains pointers to the source and

  * destination filters between which this link exists, and the indexes of

  * the pads involved. In addition, this link also contains the parameters

  * which have been negotiated and agreed upon between the filter, such as

  * image dimensions, format, etc.

  */

 struct AVFilterLink {

     AVFilterContext *src;       ///< source filter

     AVFilterPad *srcpad;        ///< output pad on the source filter

     AVFilterContext *dst;       ///< dest filter

     AVFilterPad *dstpad;        ///< input pad on the dest filter

     enum AVMediaType type;      ///< filter media type
 

     /* These parameters apply only to video */

     int w;                      ///< agreed upon image width
     int h;                      ///< agreed upon image height

     AVRational sample_aspect_ratio; ///< agreed upon sample aspect ratio

     /* These two parameters apply only to audio */

     uint64_t channel_layout;    ///< channel layout of current buffer (see libavutil/channel_layout.h)

     int sample_rate;            ///< samples per second

     int format;                 ///< agreed upon media format

     /**

      * Define the time base used by the PTS of the frames/samples
      * which will pass through this link.
      * During the configuration stage, each filter is supposed to
      * change only the output timebase, while the timebase of the
      * input link is assumed to be an unchangeable property.
      */
     AVRational time_base;

 
     /*****************************************************************
      * All fields below this line are not part of the public API. They
      * may not be used outside of libavfilter and can be changed and
      * removed at will.
      * New public fields should be added right above.
      *****************************************************************
      */
     /**

      * Lists of formats supported by the input and output filters respectively.
      * These lists are used for negotiating the format to actually be used,
      * which will be loaded into the format member, above, when chosen.
      */
     AVFilterFormats *in_formats;
     AVFilterFormats *out_formats;
 
     /**

      * Lists of channel layouts and sample rates used for automatic
      * negotiation.
      */
     AVFilterFormats  *in_samplerates;
     AVFilterFormats *out_samplerates;
     struct AVFilterChannelLayouts  *in_channel_layouts;
     struct AVFilterChannelLayouts *out_channel_layouts;

 
     /**
      * Audio only, the destination filter sets this to a non-zero value to
      * request that buffers with the given number of samples should be sent to
      * it. AVFilterPad.needs_fifo must also be set on the corresponding input
      * pad.
      * Last buffer before EOF will be padded with silence.
      */
     int request_samples;

 
     /** stage of the initialization of the link properties (dimensions, etc) */
     enum {
         AVLINK_UNINIT = 0,      ///< not started
         AVLINK_STARTINIT,       ///< started, but incomplete
         AVLINK_INIT             ///< complete
     } init_state;

 
     /**
      * Frame rate of the stream on the link, or 1/0 if unknown or variable;
      * if left to 0/0, will be automatically copied from the first input
      * of the source filter if it exists.
      *
      * Sources should set it to the real constant frame rate.
      * If the source frame rate is unknown or variable, set this to 1/0.
      * Filters should update it if necessary depending on their function.
      * Sinks can use it to set a default output frame rate.
      */
     AVRational frame_rate;

 
     /**
      * For hwaccel pixel formats, this should be a reference to the
      * AVHWFramesContext describing the frames.
      */
     AVBufferRef *hw_frames_ctx;

 };
 

 /**

  * Link two filters together.

  *

  * @param src    the source filter
  * @param srcpad index of the output pad on the source filter
  * @param dst    the destination filter
  * @param dstpad index of the input pad on the destination filter
  * @return       zero on success

  */

 int avfilter_link(AVFilterContext *src, unsigned srcpad,
                   AVFilterContext *dst, unsigned dstpad);
 

 /**

  * Negotiate the media format, dimensions, etc of all inputs to a filter.

  *

  * @param filter the filter to negotiate the properties for its inputs
  * @return       zero on successful negotiation

  */

 int avfilter_config_links(AVFilterContext *filter);

 /** Initialize the filter system. Register all builtin filters. */

 void avfilter_register_all(void);

 #if FF_API_OLD_FILTER_REGISTER

 /** Uninitialize the filter system. Unregister all filters. */

 attribute_deprecated

 void avfilter_uninit(void);

 #endif

 
 /**

  * Register a filter. This is only needed if you plan to use

  * avfilter_get_by_name later to lookup the AVFilter structure by name. A

  * filter can still by instantiated with avfilter_graph_alloc_filter even if it
  * is not registered.

  *

  * @param filter the filter to register

  * @return 0 if the registration was successful, a negative value

  * otherwise

  */

 int avfilter_register(AVFilter *filter);

 
 /**

  * Get a filter definition matching the given name.

  *

  * @param name the filter name to find
  * @return     the filter definition, if any matching one is registered.

  *             NULL if none found.
  */

 #if !FF_API_NOCONST_GET_NAME
 const
 #endif

 AVFilter *avfilter_get_by_name(const char *name);

 /**

  * Iterate over all registered filters.
  * @return If prev is non-NULL, next registered filter after prev or NULL if
  * prev is the last filter. If prev is NULL, return the first registered filter.
  */
 const AVFilter *avfilter_next(const AVFilter *prev);
 
 #if FF_API_OLD_FILTER_REGISTER
 /**

  * If filter is NULL, returns a pointer to the first registered filter pointer,
  * if filter is non-NULL, returns the next pointer after filter.
  * If the returned pointer points to NULL, the last registered filter
  * was already reached.

  * @deprecated use avfilter_next()

  */

 attribute_deprecated

 AVFilter **av_filter_next(AVFilter **filter);

 #endif

 #if FF_API_AVFILTER_OPEN

 /**

  * Create a filter instance.

  *
  * @param filter_ctx put here a pointer to the created filter context
  * on success, NULL on failure

  * @param filter    the filter to create an instance of

  * @param inst_name Name to give to the new instance. Can be NULL for none.

  * @return >= 0 in case of success, a negative error code otherwise

  * @deprecated use avfilter_graph_alloc_filter() instead

  */

 attribute_deprecated

 int avfilter_open(AVFilterContext **filter_ctx, AVFilter *filter, const char *inst_name);

 #endif

 
 #if FF_API_AVFILTER_INIT_FILTER

 /**

  * Initialize a filter.

  *

  * @param filter the filter to initialize

  * @param args   A string of parameters to use when initializing the filter.
  *               The format and meaning of this string varies by filter.

  * @param opaque Any extra non-string data needed by the filter. The meaning

  *               of this parameter varies by filter.

  * @return       zero on success

  */

 attribute_deprecated

 int avfilter_init_filter(AVFilterContext *filter, const char *args, void *opaque);

 #endif
 
 /**
  * Initialize a filter with the supplied parameters.
  *
  * @param ctx  uninitialized filter context to initialize
  * @param args Options to initialize the filter with. This must be a
  *             ':'-separated list of options in the 'key=value' form.
  *             May be NULL if the options have been set directly using the
  *             AVOptions API or there are no options that need to be set.
  * @return 0 on success, a negative AVERROR on failure
  */
 int avfilter_init_str(AVFilterContext *ctx, const char *args);

 
 /**

  * Initialize a filter with the supplied dictionary of options.
  *
  * @param ctx     uninitialized filter context to initialize
  * @param options An AVDictionary filled with options for this filter. On
  *                return this parameter will be destroyed and replaced with
  *                a dict containing options that were not found. This dictionary
  *                must be freed by the caller.
  *                May be NULL, then this function is equivalent to
  *                avfilter_init_str() with the second parameter set to NULL.
  * @return 0 on success, a negative AVERROR on failure
  *
  * @note This function and avfilter_init_str() do essentially the same thing,
  * the difference is in manner in which the options are passed. It is up to the
  * calling code to choose whichever is more preferable. The two functions also
  * behave differently when some of the provided options are not declared as
  * supported by the filter. In such a case, avfilter_init_str() will fail, but
  * this function will leave those extra options in the options AVDictionary and
  * continue as usual.
  */
 int avfilter_init_dict(AVFilterContext *ctx, AVDictionary **options);
 
 /**

  * Free a filter context. This will also remove the filter from its
  * filtergraph's list of filters.

  *

  * @param filter the filter to free

  */

 void avfilter_free(AVFilterContext *filter);

 /**

  * Insert a filter in the middle of an existing link.

  *

  * @param link the link into which the filter should be inserted
  * @param filt the filter to be inserted

  * @param filt_srcpad_idx the input pad on the filter to connect
  * @param filt_dstpad_idx the output pad on the filter to connect

  * @return     zero on success

  */

 int avfilter_insert_filter(AVFilterLink *link, AVFilterContext *filt,

                            unsigned filt_srcpad_idx, unsigned filt_dstpad_idx);

 /**
  * @return AVClass for AVFilterContext.
  *
  * @see av_opt_find().
  */
 const AVClass *avfilter_get_class(void);
 

 typedef struct AVFilterGraphInternal AVFilterGraphInternal;
 

 /**
  * A function pointer passed to the @ref AVFilterGraph.execute callback to be
  * executed multiple times, possibly in parallel.
  *
  * @param ctx the filter context the job belongs to
  * @param arg an opaque parameter passed through from @ref
  *            AVFilterGraph.execute
  * @param jobnr the index of the job being executed
  * @param nb_jobs the total number of jobs
  *
  * @return 0 on success, a negative AVERROR on error
  */
 typedef int (avfilter_action_func)(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs);
 
 /**
  * A function executing multiple jobs, possibly in parallel.
  *
  * @param ctx the filter context to which the jobs belong
  * @param func the function to be called multiple times
  * @param arg the argument to be passed to func
  * @param ret a nb_jobs-sized array to be filled with return values from each
  *            invocation of func
  * @param nb_jobs the number of jobs to execute
  *
  * @return 0 on success, a negative AVERROR on error
  */
 typedef int (avfilter_execute_func)(AVFilterContext *ctx, avfilter_action_func *func,
                                     void *arg, int *ret, int nb_jobs);
 

 typedef struct AVFilterGraph {
     const AVClass *av_class;
     AVFilterContext **filters;
     unsigned nb_filters;
 
     char *scale_sws_opts; ///< sws options to use for the auto-inserted scale filters
     char *resample_lavr_opts;   ///< libavresample options to use for the auto-inserted resample filters

 
     /**
      * Type of multithreading allowed for filters in this graph. A combination
      * of AVFILTER_THREAD_* flags.
      *
      * May be set by the caller at any point, the setting will apply to all
      * filters initialized after that. The default is allowing everything.
      *
      * When a filter in this graph is initialized, this field is combined using
      * bit AND with AVFilterContext.thread_type to get the final mask used for
      * determining allowed threading types. I.e. a threading type needs to be
      * set in both to be allowed.
      */
     int thread_type;
 
     /**
      * Maximum number of threads used by filters in this graph. May be set by
      * the caller before adding any filters to the filtergraph. Zero (the
      * default) means that the number of threads is determined automatically.
      */
     int nb_threads;
 
     /**
      * Opaque object for libavfilter internal use.
      */
     AVFilterGraphInternal *internal;

 
     /**
      * Opaque user data. May be set by the caller to an arbitrary value, e.g. to
      * be used from callbacks like @ref AVFilterGraph.execute.
      * Libavfilter will not touch this field in any way.
      */
     void *opaque;
 
     /**
      * This callback may be set by the caller immediately after allocating the
      * graph and before adding any filters to it, to provide a custom
      * multithreading implementation.
      *
      * If set, filters with slice threading capability will call this callback
      * to execute multiple jobs in parallel.
      *
      * If this field is left unset, libavfilter will use its internal
      * implementation, which may or may not be multithreaded depending on the
      * platform and build options.
      */
     avfilter_execute_func *execute;

 } AVFilterGraph;
 
 /**
  * Allocate a filter graph.

  *
  * @return the allocated filter graph on success or NULL.

  */
 AVFilterGraph *avfilter_graph_alloc(void);
 
 /**

  * Create a new filter instance in a filter graph.
  *
  * @param graph graph in which the new filter will be used
  * @param filter the filter to create an instance of
  * @param name Name to give to the new instance (will be copied to
  *             AVFilterContext.name). This may be used by the caller to identify
  *             different filters, libavfilter itself assigns no semantics to
  *             this parameter. May be NULL.
  *
  * @return the context of the newly created filter instance (note that it is
  *         also retrievable directly through AVFilterGraph.filters or with
  *         avfilter_graph_get_filter()) on success or NULL or failure.
  */
 AVFilterContext *avfilter_graph_alloc_filter(AVFilterGraph *graph,
                                              const AVFilter *filter,
                                              const char *name);
 
 /**

  * 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);
 

 #if FF_API_AVFILTER_OPEN

 /**
  * Add an existing filter instance to a filter graph.
  *
  * @param graphctx  the filter graph
  * @param filter the filter to be added

  *
  * @deprecated use avfilter_graph_alloc_filter() to allocate a filter in a
  * filter graph

  */

 attribute_deprecated

 int avfilter_graph_add_filter(AVFilterGraph *graphctx, AVFilterContext *filter);

 #endif

 
 /**
  * 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, const 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  linked list to the inputs of the graph
  * @param outputs linked list to the outputs of the graph
  * @return zero 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);
 

 /**
  * @}
  */
 

 #endif /* AVFILTER_AVFILTER_H */