/*

  * filter layer

  * 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_AVFILTER_H
 #define AVFILTER_AVFILTER_H

 /**
  * @file
  * @ingroup lavfi

  * Main libavfilter public API header

  */
 
 /**

  * @defgroup lavfi Libavfilter - graph-based frame editing library

  * @{
  */
 

 #include <stddef.h>
 

 #include "libavutil/attributes.h"

 #include "libavutil/avutil.h"

 #include "libavutil/dict.h"

 #include "libavutil/frame.h"

 #include "libavutil/log.h"

 #include "libavutil/samplefmt.h"

 #include "libavutil/pixfmt.h"

 #include "libavutil/rational.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;

 #if FF_API_AVFILTERBUFFER

 /**

  * A reference-counted buffer data type used by the filter system. Filters

  * should not store pointers to this structure directly, but instead use the

  * AVFilterBufferRef structure below.

  */

 typedef struct AVFilterBuffer {

     uint8_t *data[8];           ///< buffer data for each plane/channel

 
     /**
      * 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 will always be set, 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;

     int linesize[8];            ///< number of bytes per line
 
     /** private data to be used by a custom free function */
     void *priv;
     /**
      * A pointer to the function to deallocate this buffer if the default
      * function is not sufficient. This could, for example, add the memory
      * back into a memory pool to be reused later without the overhead of
      * reallocating it from scratch.
      */
     void (*free)(struct AVFilterBuffer *buf);
 
     int format;                 ///< media format
     int w, h;                   ///< width and height of the allocated buffer
     unsigned refcount;          ///< number of references to this buffer

 } AVFilterBuffer;

 #define AV_PERM_READ     0x01   ///< can read from the buffer
 #define AV_PERM_WRITE    0x02   ///< can write to the buffer
 #define AV_PERM_PRESERVE 0x04   ///< nobody else can overwrite the buffer
 #define AV_PERM_REUSE    0x08   ///< can output the buffer multiple times, with the same contents each time
 #define AV_PERM_REUSE2   0x10   ///< can output the buffer multiple times, modified each time

 #define AV_PERM_NEG_LINESIZES 0x20  ///< the buffer requested can have negative linesizes

 #define AV_PERM_ALIGN    0x40   ///< the buffer must be aligned

 #define AVFILTER_ALIGN 16 //not part of ABI
 

 /**

  * Audio specific properties in a reference to an AVFilterBuffer. Since
  * AVFilterBufferRef is common to different media formats, audio specific
  * per reference properties must be separated out.
  */
 typedef struct AVFilterBufferRefAudioProps {

     uint64_t channel_layout;    ///< channel layout of audio buffer

     int nb_samples;             ///< number of audio samples per channel

     int sample_rate;            ///< audio buffer sample rate

     int channels;               ///< number of channels (do not access directly)

 } AVFilterBufferRefAudioProps;
 
 /**

  * Video specific properties in a reference to an AVFilterBuffer. Since
  * AVFilterBufferRef is common to different media formats, video specific
  * per reference properties must be separated out.
  */

 typedef struct AVFilterBufferRefVideoProps {

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

     AVRational sample_aspect_ratio; ///< sample aspect ratio

     int interlaced;             ///< is frame interlaced
     int top_field_first;        ///< field order

     enum AVPictureType pict_type; ///< picture type of the frame

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

     int qp_table_linesize;                ///< qp_table stride

     int qp_table_size;            ///< qp_table size

     int8_t *qp_table;             ///< array of Quantization Parameters

 } AVFilterBufferRefVideoProps;
 
 /**

  * A reference to an AVFilterBuffer. Since filters can manipulate the origin of

  * a buffer to, for example, crop image without any memcpy, the buffer origin

  * and dimensions are per-reference properties. Linesize is also useful for

  * image flipping, frame to field filters, etc, and so is also per-reference.

  *

  * TODO: add anything necessary for frame reordering

  */

 typedef struct AVFilterBufferRef {

     AVFilterBuffer *buf;        ///< the buffer that this is a reference to

     uint8_t *data[8];           ///< picture/audio data for each plane

     /**
      * 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 will always be set, 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;

     int linesize[8];            ///< number of bytes per line
 
     AVFilterBufferRefVideoProps *video; ///< video buffer specific properties
     AVFilterBufferRefAudioProps *audio; ///< audio buffer specific properties
 
     /**
      * presentation timestamp. The time unit may change during
      * filtering, as it is specified in the link and the filter code
      * may need to rescale the PTS accordingly.
      */
     int64_t pts;
     int64_t pos;                ///< byte position in stream, -1 if unknown
 
     int format;                 ///< media format
 
     int perms;                  ///< permissions, see the AV_PERM_* flags
 
     enum AVMediaType type;      ///< media type of buffer data

 
     AVDictionary *metadata;     ///< dictionary containing metadata key=value tags

 } AVFilterBufferRef;

 
 /**

  * Copy properties of src to dst, without copying the actual data

  */

 attribute_deprecated

 void avfilter_copy_buffer_ref_props(AVFilterBufferRef *dst, const AVFilterBufferRef *src);

 
 /**

  * Add a new reference to a buffer.

  *

  * @param ref   an existing reference to the buffer

  * @param pmask a bitmask containing the allowable permissions in the new

  *              reference

  * @return      a new reference to the buffer with the same properties as the

  *              old, excluding any permissions denied by pmask

  */

 attribute_deprecated

 AVFilterBufferRef *avfilter_ref_buffer(AVFilterBufferRef *ref, int pmask);

 
 /**

  * Remove a reference to a buffer. If this is the last reference to the
  * buffer, the buffer itself is also automatically freed.

  *

  * @param ref reference to the buffer, may be NULL

  *
  * @note it is recommended to use avfilter_unref_bufferp() instead of this
  * function

  */

 attribute_deprecated

 void avfilter_unref_buffer(AVFilterBufferRef *ref);

 /**

  * Remove a reference to a buffer and set the pointer to NULL.
  * If this is the last reference to the buffer, the buffer itself
  * is also automatically freed.
  *
  * @param ref pointer to the buffer reference
  */

 attribute_deprecated

 void avfilter_unref_bufferp(AVFilterBufferRef **ref);

 #endif

 /**
  * Get the number of channels of a buffer reference.
  */

 attribute_deprecated

 int avfilter_ref_get_channels(AVFilterBufferRef *ref);
 

 #if FF_API_AVFILTERPAD_PUBLIC

 /**

  * A filter pad used for either input or output.

  *
  * See doc/filter_design.txt for details on how to implement the methods.

  *
  * @warning this struct might be removed from public API.

  * users should call avfilter_pad_get_name() and avfilter_pad_get_type()
  * to access the name and type fields; there should be no need to access
  * any other fields from outside of libavfilter.

  */

 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;

 
     /**

      * Input pads:

      * 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.
      *

      * Output pads:
      * Guaranteed permissions on outgoing buffers. Any buffer pushed on the
      * link must have at least these permissions; this fact is checked by
      * asserts. It can be used to optimize buffer allocation.

      */

     attribute_deprecated int min_perms;

 
     /**

      * Input pads:

      * 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.

      *

      * Output pads:
      * Permissions which are automatically removed on outgoing buffers. It
      * can be used to optimize buffer allocation.

      */

     attribute_deprecated int rej_perms;

 
     /**

      * @deprecated unused

      */

     int (*start_frame)(AVFilterLink *link, AVFilterBufferRef *picref);

 
     /**

      * Callback function to get a video buffer. If NULL, the filter system will

      * use ff_default_get_video_buffer().

      *
      * Input video pads only.

      */

     AVFrame *(*get_video_buffer)(AVFilterLink *link, int w, int h);

 
     /**

      * Callback function to get an audio buffer. If NULL, the filter system will

      * use ff_default_get_audio_buffer().

      *
      * Input audio pads only.
      */

     AVFrame *(*get_audio_buffer)(AVFilterLink *link, int nb_samples);

 
     /**

      * @deprecated unused

      */

     int (*end_frame)(AVFilterLink *link);

 
     /**

      * @deprecated unused

      */

     int (*draw_slice)(AVFilterLink *link, int y, int height, int slice_dir);

 
     /**

      * Filtering callback. This is where a filter receives a frame with
      * audio/video data and should do its processing.

      *

      * Input pads only.

      *
      * @return >= 0 on success, a negative AVERROR on error. This function

      * must ensure that frame is properly unreferenced on error if it

      * hasn't been passed on to another filter.

      */

     int (*filter_frame)(AVFilterLink *link, AVFrame *frame);

 
     /**

      * 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.

      * See ff_request_frame() for the error codes with a specific

      * meaning.

      *

      * Output pads only.

      */

     int (*request_frame)(AVFilterLink *link);

 
     /**

      * Link configuration callback.
      *

      * For output pads, this should set the following link properties:
      * video: width, height, sample_aspect_ratio, time_base
      * audio: sample_rate.
      *
      * This should NOT set properties such as format, channel_layout, etc which
      * are 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 pads, 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;

     /**
      * The filter expects writable frames from its input link,
      * duplicating data buffers if needed.
      *
      * input pads only.
      */

     int needs_writable;

 };

 #endif

 /**

  * 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)

 /**

  * Some filters support a generic "enable" expression option that can be used
  * to enable or disable a filter in the timeline. Filters supporting this

  * option have this flag set. When the enable expression is false, the default
  * no-op filter_frame() function is called in place of the filter_frame()
  * callback defined on each input pad, thus the frame is passed unchanged to
  * the next filters.
  */
 #define AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC  (1 << 16)
 /**
  * Same as AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC, except that the filter will
  * have its filter_frame() callback(s) called as usual even when the enable
  * expression is false. The filter will disable filtering within the
  * filter_frame() callback(s) itself, for example executing code depending on
  * the AVFilterContext->is_disabled value.
  */
 #define AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL (1 << 17)
 /**
  * Handy mask to test whether the filter supports or no the timeline feature
  * (internally or generically).

  */

 #define AVFILTER_FLAG_SUPPORT_TIMELINE (AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL)

 
 /**

  * 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;

     /**
      * Make the filter instance process a command.
      *
      * @param cmd    the command to process, 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. This must not change when the command is not supported.
      * @param flags  if AVFILTER_CMD_FLAG_FAST is set and the command would be

      *               time consuming then a filter should treat it like an unsupported command

      *
      * @returns >=0 on success otherwise an error code.
      *          AVERROR(ENOSYS) on unsupported commands
      */
     int (*process_command)(AVFilterContext *, const char *cmd, const char *arg, char *res, int res_len, int flags);

 
     /**
      * Filter initialization function, alternative to the init()
      * callback. Args contains the user-supplied parameters, opaque is
      * used for providing binary data.
      */

     int (*init_opaque)(AVFilterContext *ctx, void *opaque);

 } 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() and filters common options

     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

 #if FF_API_FOO_COUNT

     attribute_deprecated unsigned input_count; ///< @deprecated use nb_inputs

 #endif

     unsigned    nb_inputs;          ///< number of input pads

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

 #if FF_API_FOO_COUNT

     attribute_deprecated unsigned output_count; ///< @deprecated use nb_outputs

 #endif

     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 initialized, 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;

     struct AVFilterCommand *command_queue;

 
     char *enable_str;               ///< enable expression string
     void *enable;                   ///< parsed expression (AVExpr*)
     double *var_values;             ///< variable values for the enable expression

     int is_disabled;                ///< the enabled state from the last expression evaluation

 };
 

 /**

  * 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 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 and channel layouts 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 and
      * channel_layout members, 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;
 

     struct AVFilterPool *pool;

 
     /**
      * Graph the filter belongs to.
      */
     struct AVFilterGraph *graph;
 

     /**
      * Current timestamp of the link, as defined by the most recent
      * frame(s), in AV_TIME_BASE units.
      */
     int64_t current_pts;
 
     /**
      * Index in the age array.
      */
     int age_index;

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

      * It is similar to the r_frame_rate field in AVStream.

      */
     AVRational frame_rate;

 
     /**
      * Buffer partially filled with samples to achieve a fixed/minimum size.
      */

     AVFrame *partial_buf;

 
     /**
      * Size of the partial buffer to allocate.
      * Must be between min_samples and max_samples.
      */
     int partial_buf_size;
 
     /**

      * Minimum number of samples to filter at once. If filter_frame() is

      * called with fewer samples, it will accumulate them in partial_buf.
      * This field and the related ones must not be changed after filtering
      * has started.
      * If 0, all related fields are ignored.
      */
     int min_samples;
 
     /**

      * Maximum number of samples to filter at once. If filter_frame() is

      * called with more samples, it will split them.
      */
     int max_samples;

 
     /**
      * The buffer reference currently being received across the link by the
      * destination filter. This is used internally by the filter system to
      * allow automatic copying of buffers which do not have sufficient
      * permissions for the destination. This should not be accessed directly
      * by the filters.
      */
     AVFilterBufferRef *cur_buf_copy;

 
     /**
      * True if the link is closed.

      * If set, all attempts of start_frame, filter_frame or request_frame

      * will fail with AVERROR_EOF, and if necessary the reference will be
      * destroyed.
      * If request_frame returns AVERROR_EOF, this flag is set on the
      * corresponding link.
      * It can be set also be set by either the source or the destination
      * filter.
      */
     int closed;

 
     /**
      * Number of channels.
      */
     int channels;

 
     /**
      * True if a frame is being requested on the link.
      * Used internally by the framework.
      */
     unsigned frame_requested;
 
     /**
      * Link processing flags.
      */
     unsigned flags;

 
     /**
      * Number of past frames sent through the link.
      */
     int64_t frame_count;

 };
 

 /**

  * 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);
 

 /**

  * Free the link in *link, and set its pointer to NULL.
  */
 void avfilter_link_free(AVFilterLink **link);
 
 /**

  * Get the number of channels of a link.
  */
 int avfilter_link_get_channels(AVFilterLink *link);
 
 /**

  * Set the closed field of a link.
  */
 void avfilter_link_set_closed(AVFilterLink *link, int closed);
 
 /**

  * 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);

 #if FF_API_AVFILTERBUFFER

 /**

  * Create a buffer reference wrapped around an already allocated image
  * buffer.
  *
  * @param data pointers to the planes of the image to reference
  * @param linesize linesizes for the planes of the image to reference
  * @param perms the required access permissions
  * @param w the width of the image specified by the data and linesize arrays
  * @param h the height of the image specified by the data and linesize arrays
  * @param format the pixel format of the image specified by the data and linesize arrays
  */

 attribute_deprecated

 AVFilterBufferRef *

 avfilter_get_video_buffer_ref_from_arrays(uint8_t * const data[4], const int linesize[4], int perms,

                                           int w, int h, enum AVPixelFormat format);

 
 /**

  * Create an audio buffer reference wrapped around an already
  * allocated samples buffer.
  *

  * See avfilter_get_audio_buffer_ref_from_arrays_channels() for a version
  * that can handle unknown channel layouts.
  *

  * @param data           pointers to the samples plane buffers
  * @param linesize       linesize for the samples plane buffers
  * @param perms          the required access permissions
  * @param nb_samples     number of samples per channel
  * @param sample_fmt     the format of each sample in the buffer to allocate
  * @param channel_layout the channel layout of the buffer
  */

 attribute_deprecated

 AVFilterBufferRef *avfilter_get_audio_buffer_ref_from_arrays(uint8_t **data,

                                                              int linesize,
                                                              int perms,
                                                              int nb_samples,
                                                              enum AVSampleFormat sample_fmt,
                                                              uint64_t channel_layout);

 /**
  * Create an audio buffer reference wrapped around an already
  * allocated samples buffer.
  *
  * @param data           pointers to the samples plane buffers
  * @param linesize       linesize for the samples plane buffers
  * @param perms          the required access permissions
  * @param nb_samples     number of samples per channel
  * @param sample_fmt     the format of each sample in the buffer to allocate
  * @param channels       the number of channels of the buffer
  * @param channel_layout the channel layout of the buffer,
  *                       must be either 0 or consistent with channels
  */

 attribute_deprecated

 AVFilterBufferRef *avfilter_get_audio_buffer_ref_from_arrays_channels(uint8_t **data,
                                                                       int linesize,
                                                                       int perms,
                                                                       int nb_samples,
                                                                       enum AVSampleFormat sample_fmt,
                                                                       int channels,
                                                                       uint64_t channel_layout);
 

 #endif

 #define AVFILTER_CMD_FLAG_ONE   1 ///< Stop once a filter understood the command (for target=all for example), fast filters are favored automatically
 #define AVFILTER_CMD_FLAG_FAST  2 ///< Only execute command when its fast (like a video out that supports contrast adjustment in hw)
 
 /**
  * Make the filter instance process a command.

  * It is recommended to use avfilter_graph_send_command().

  */
 int avfilter_process_command(AVFilterContext *filter, const char *cmd, const char *arg, char *res, int res_len, int flags);
 

 /** 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);

 #if FF_API_AVFILTERBUFFER

 /**
  * Copy the frame properties of src to dst, without copying the actual
  * image data.
  *
  * @return 0 on success, a negative number on error.
  */

 attribute_deprecated

 int avfilter_copy_frame_props(AVFilterBufferRef *dst, const AVFrame *src);
 

 /**
  * Copy the frame properties and data pointers of src to dst, without copying
  * the actual data.
  *
  * @return 0 on success, a negative number on error.
  */

 attribute_deprecated

 int avfilter_copy_buf_props(AVFrame *dst, const AVFilterBufferRef *src);

 #endif

 /**

  * @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;
 #if FF_API_FOO_COUNT
     attribute_deprecated

     unsigned filter_count_unused;

 #endif
     AVFilterContext **filters;
 #if !FF_API_FOO_COUNT
     unsigned nb_filters;
 #endif
 
     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
 #if FF_API_FOO_COUNT
     unsigned nb_filters;
 #endif

 
     /**
      * 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;

     char *aresample_swr_opts; ///< swr options to use for the auto-inserted aresample filters, Access ONLY through AVOptions
 
     /**
      * 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;
 
     unsigned disable_auto_convert;

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

  */
 AVFilterContext *avfilter_graph_alloc_filter(AVFilterGraph *graph,
                                              const AVFilter *filter,
                                              const char *name);
 
 /**

  * Get a filter instance identified by instance name from graph.

  *

  * @param graph filter graph to search through.
  * @param name filter instance name (should be unique in the graph).

  * @return the pointer to the found filter instance or NULL if it
  * cannot be found.
  */

 AVFilterContext *avfilter_graph_get_filter(AVFilterGraph *graph, const 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);
 
 /**

  * Enable or disable automatic format conversion inside the graph.
  *
  * Note that format conversion can still happen inside explicitly inserted
  * scale and aresample filters.
  *
  * @param flags  any of the AVFILTER_AUTO_CONVERT_* constants
  */
 void avfilter_graph_set_auto_convert(AVFilterGraph *graph, unsigned flags);
 
 enum {
     AVFILTER_AUTO_CONVERT_ALL  =  0, /**< all automatic conversions enabled */
     AVFILTER_AUTO_CONVERT_NONE = -1, /**< all automatic conversions disabled */
 };
 
 /**

  * 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);
 

 #if AV_HAVE_INCOMPATIBLE_LIBAV_ABI || !FF_API_OLD_GRAPH_PARSE

 /**
  * Add a graph described by a string to a graph.
  *
  * @note The caller must provide the lists of inputs and outputs,
  * which therefore must be known before calling the function.
  *
  * @note The inputs parameter describes inputs of the already existing
  * 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.
  *

  * @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);
 #else

 /**
  * 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

  * @deprecated Use avfilter_graph_parse_ptr() instead.

  */

 attribute_deprecated

 int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,

                          AVFilterInOut **inputs, AVFilterInOut **outputs,

                          void *log_ctx);

 #endif
 
 /**
  * Add a graph described by a string to a graph.
  *

  * In the graph filters description, if the input label of the first
  * filter is not specified, "in" is assumed; if the output label of
  * the last filter is not specified, "out" is assumed.
  *

  * @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_ptr(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 This function returns the inputs and outputs that are left
  * unlinked after parsing the graph and the caller then deals with
  * them.
  * @note This function 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 send, 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 alphanumeric 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.
  *
  * Also note that AVERROR_EOF does not mean that frames did not arrive on
  * some of the sinks during the process.
  * When there are multiple sink links, in case the requested link
  * returns an EOF, this may cause a filter to flush pending frames
  * which are sent to another sink link, although unrequested.
  *
  * @return  the return value of ff_request_frame(),
  *          or AVERROR_EOF if all links returned AVERROR_EOF
  */
 int avfilter_graph_request_oldest(AVFilterGraph *graph);
 

 /**
  * @}
  */

 #endif /* AVFILTER_AVFILTER_H */