/*
 * 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
 */

module ffmpeg.libavfilter.avfilter;

import ffmpeg.libavutil;

extern (C) @nogc nothrow:

/**
 * @file
 * @ingroup lavfi
 * Main libavfilter public API header
 */

/**
 * @defgroup lavfi libavfilter
 * Graph-based frame editing library.
 *
 * @{
 */

/**
 * Return the LIBAVFILTER_VERSION_INT constant.
 */
uint avfilter_version ();

/**
 * Return the libavfilter build-time configuration.
 */
const(char)* avfilter_configuration ();

/**
 * Return the libavfilter license.
 */
const(char)* avfilter_license ();

struct AVFilterPad;
struct AVFilterFormats;
struct AVFilterChannelLayouts;

/**
 * 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
 */
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.
 */
enum 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.
 */
enum AVFILTER_FLAG_DYNAMIC_OUTPUTS = 1 << 1;
/**
 * The filter supports multithreading by splitting frames into multiple parts
 * and processing them concurrently.
 */
enum 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.
 */
enum 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.
 */
enum AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL = 1 << 17;
/**
 * Handy mask to test whether the filter supports or no the timeline feature
 * (internally or generically).
 */
enum 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.
 */
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 pre-initialization function
     *
     * This callback will be called immediately after the filter context is
     * allocated, to allow allocating and initing sub-objects.
     *
     * If this callback is not NULL, the uninit callback will be called on
     * allocation failure.
     *
     * @return 0 on success,
     *         AVERROR code on failure (but the code will be
     *           dropped and treated as ENOMEM by the calling code)
     */
    int function (AVFilterContext* ctx) preinit;

    /**
     * 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 function (AVFilterContext* ctx) init;

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

    /**
     * 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 function (AVFilterContext* ctx) uninit;

    /**
     * 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.outcfg.formats on every input link and
     * AVFilterLink.incfg.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.incfg.samplerates "in_samplerates" /
     * @ref AVFilterLink.outcfg.samplerates "out_samplerates" and
     * @ref AVFilterLink.incfg.channel_layouts "in_channel_layouts" /
     * @ref AVFilterLink.outcfg.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 function (AVFilterContext*) query_formats;

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

    int flags_internal; ///< Additional flags for avfilter internal use only.

    /**
     * Used by the filter registration system. Must not be touched by any other
     * code.
     */
    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 function (AVFilterContext*, const(char)* cmd, const(char)* arg, char* res, int res_len, int flags) process_command;

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

    /**
     * Filter activation function.
     *
     * Called when any processing is needed from the filter, instead of any
     * filter_frame and request_frame on pads.
     *
     * The function must examine inlinks and outlinks and perform a single
     * step of processing. If there is nothing to do, the function must do
     * nothing and not return an error. If more steps are or may be
     * possible, it must use ff_filter_set_ready() to schedule another
     * activation.
     */
    int function (AVFilterContext* ctx) activate;
}

/**
 * Process multiple parts of the frame concurrently.
 */
enum AVFILTER_THREAD_SLICE = 1 << 0;

struct 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
    uint nb_inputs; ///< number of input pads

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

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

    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;
    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

    /**
     * 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;

    /**
     * Max number of threads allowed in this filter instance.
     * If <= 0, its value is ignored.
     * Overrides global number of threads set per filter graph.
     */
    int nb_threads;

    /**
     * Ready status of the filter.
     * A non-0 value means that the filter needs activating;
     * a higher value suggests a more urgent activation.
     */
    uint ready;

    /**
     * Sets the number of extra hardware frames which the filter will
     * allocate on its output links for use in following filters or by
     * the caller.
     *
     * Some hardware filters require all frames that they will use for
     * output to be defined in advance before filtering starts.  For such
     * filters, any hardware frame pools used for output must therefore be
     * of fixed size.  The extra frames set here are on top of any number
     * that the filter needs internally in order to operate normally.
     *
     * This field must be set before the graph containing this filter is
     * configured.
     */
    int extra_hw_frames;
}

/**
 * Lists of formats / etc. supported by an end of a link.
 *
 * This structure is directly part of AVFilterLink, in two copies:
 * one for the source filter, one for the destination filter.

 * These lists are used for negotiating the format to actually be used,
 * which will be loaded into the format and channel_layout members of
 * AVFilterLink, when chosen.
 */
struct AVFilterFormatsConfig
{
    /**
     * List of supported formats (pixel or sample).
     */
    AVFilterFormats* formats;

    /**
     * Lists of supported sample rates, only for audio.
     */
    AVFilterFormats* samplerates;

    /**
     * Lists of supported channel layouts, only for audio.
     */
    AVFilterChannelLayouts* channel_layouts;
}

/**
 * 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.
 *
 * Applications must not normally access the link structure directly.
 * Use the buffersrc and buffersink API instead.
 * In the future, access to the header may be reserved for filters
 * implementation.
 */
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

    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 */
    ulong 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 supported formats / etc. supported by the input filter.
     */
    AVFilterFormatsConfig incfg;

    /**
     * Lists of supported formats / etc. supported by the output filter.
     */
    AVFilterFormatsConfig outcfg;

    /** stage of the initialization of the link properties (dimensions, etc) */
    enum _Anonymous_0
    {
        AVLINK_UNINIT = 0, ///< not started
        AVLINK_STARTINIT = 1, ///< started, but incomplete
        AVLINK_INIT = 2 ///< complete
    }

    _Anonymous_0 init_state;

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

    /**
     * Current timestamp of the link, as defined by the most recent
     * frame(s), in link time_base units.
     */
    long current_pts;

    /**
     * Current timestamp of the link, as defined by the most recent
     * frame(s), in AV_TIME_BASE units.
     */
    long current_pts_us;

    /**
     * Index in the age array.
     */
    int age_index;

    /**
     * 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 best estimation of the real 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.
     * 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;

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

    /**
     * Number of past frames sent through the link.
     */
    long frame_count_in;
    long frame_count_out;

    /**
     * A pointer to a FFFramePool struct.
     */
    void* frame_pool;

    /**
     * True if a frame is currently wanted on the output of this filter.
     * Set when ff_request_frame() is called by the output,
     * cleared when a frame is filtered.
     */
    int frame_wanted_out;

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

    /**
     * Internal structure members.
     * The fields below this limit are internal for libavfilter's use
     * and must in no way be accessed by applications.
     */
    char[0xF000] reserved;

    /* FF_INTERNAL_FIELDS */

    /**
     * Queue of frames waiting to be filtered.
     */

    /**
     * If set, the source filter can not generate a frame as is.
     * The goal is to avoid repeatedly calling the request_frame() method on
     * the same link.
     */

    /**
     * Link input status.
     * If not zero, all attempts of filter_frame will fail with the
     * corresponding code.
     */

    /**
     * Timestamp of the input status change.
     */

    /**
     * Link output status.
     * If not zero, all attempts of request_frame will fail with the
     * corresponding code.
     */

    /* FF_INTERNAL_FIELDS */
}

alias AVLINK_UNINIT = AVFilterLink._Anonymous_0.AVLINK_UNINIT;
alias AVLINK_STARTINIT = AVFilterLink._Anonymous_0.AVLINK_STARTINIT;
alias AVLINK_INIT = AVFilterLink._Anonymous_0.AVLINK_INIT;

/**
 * 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,
    uint srcpad,
    AVFilterContext* dst,
    uint 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.
 * @deprecated Use av_buffersink_get_channels()
 */
int avfilter_link_get_channels (AVFilterLink* link);

/**
 * Set the closed field of a link.
 * @deprecated applications are not supposed to mess with links, they should
 * close the sinks.
 */
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);

enum AVFILTER_CMD_FLAG_ONE = 1; ///< Stop once a filter understood the command (for target=all for example), fast filters are favored automatically
enum 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);

/**
 * Iterate over all registered filters.
 *
 * @param opaque a pointer where libavfilter will store the iteration state. Must
 *               point to NULL to start the iteration.
 *
 * @return the next registered filter or NULL when the iteration is
 *         finished
 */
const(AVFilter)* av_filter_iterate (void** opaque);

/** Initialize the filter system. Register all builtin filters. */
void avfilter_register_all ();

/**
 * 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);

/**
 * 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);

/**
 * 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.
 */
const(AVFilter)* avfilter_get_by_name (const(char)* name);

/**
 * 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,
    uint filt_srcpad_idx,
    uint filt_dstpad_idx);

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

struct 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
 */
alias avfilter_action_func = int function (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
 */
alias avfilter_execute_func = int function (
    AVFilterContext* ctx,
    int function () func,
    void* arg,
    int* ret,
    int nb_jobs);

struct AVFilterGraph
{
    const(AVClass)* av_class;
    AVFilterContext** filters;
    uint 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.
     */
    int function () 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;

    uint disable_auto_convert;
}

/**
 * Allocate a filter graph.
 *
 * @return the allocated filter graph on success or NULL.
 */
AVFilterGraph* avfilter_graph_alloc ();

/**
 * 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);

/**
 * Create and add a filter instance into an existing graph.
 * The filter instance is created from the filter filt and inited
 * with the parameter args. opaque is currently ignored.
 *
 * 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, uint 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.
 */
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 */
    AVFilterInOut* next;
}

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

/**
 * 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.
 *
 * @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);

/**
 * 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);

/**
 * @}
 */

/* AVFILTER_AVFILTER_H */