PeerStreamer

/*

 * filter layer

 * Copyright (c) 2007 Bobby Bingham

 *

 * This file is part of Libav.

 *

 * Libav is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * Libav is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with Libav; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

#ifndef AVFILTER_AVFILTER_H

#define AVFILTER_AVFILTER_H

#include "libavutil/avutil.h"

#include "libavutil/samplefmt.h"

#define LIBAVFILTER_VERSION_MAJOR  2

#define LIBAVFILTER_VERSION_MINOR  4

#define LIBAVFILTER_VERSION_MICRO  0

#define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \

                                               LIBAVFILTER_VERSION_MINOR, \

                                               LIBAVFILTER_VERSION_MICRO)

#define LIBAVFILTER_VERSION     AV_VERSION(LIBAVFILTER_VERSION_MAJOR,   \

                                           LIBAVFILTER_VERSION_MINOR,   \

                                           LIBAVFILTER_VERSION_MICRO)

#define LIBAVFILTER_BUILD       LIBAVFILTER_VERSION_INT

#include <stddef.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;

/**

 * 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

    int linesize[8];            ///< number of bytes per line

    unsigned refcount;          ///< number of references to this buffer

    /** 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

} 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

/**

 * 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 {

    int64_t channel_layout;     ///< channel layout of audio buffer

    int nb_samples;             ///< number of audio samples

    int size;                   ///< audio buffer size

    uint32_t sample_rate;       ///< audio buffer sample rate

    int planar;                 ///< audio buffer - planar or packed

} 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 pixel_aspect;    ///< pixel 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

} 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

    int linesize[8];            ///< number of bytes per line

    int format;                 ///< media format

    /**

     * 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 perms;                  ///< permissions, see the AV_PERM_* flags

    enum AVMediaType type;      ///< media type of buffer data

    AVFilterBufferRefVideoProps *video; ///< video buffer specific properties

    AVFilterBufferRefAudioProps *audio; ///< audio buffer specific properties

} AVFilterBufferRef;

/**

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

 */

static inline void avfilter_copy_buffer_ref_props(AVFilterBufferRef *dst, AVFilterBufferRef *src)

{

    // copy common properties

    dst->pts             = src->pts;

    dst->pos             = src->pos;

    switch (src->type) {

    case AVMEDIA_TYPE_VIDEO: *dst->video = *src->video; break;

    case AVMEDIA_TYPE_AUDIO: *dst->audio = *src->audio; break;

    }

}

/**

 * 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

 */

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

 */

void avfilter_unref_buffer(AVFilterBufferRef *ref);

/**

 * A list of supported formats for one end of a filter link. This is used

 * during the format negotiation process to try to pick the best format to

 * use to minimize the number of necessary conversions. Each filter gives a

 * list of the formats supported by each input and output pad. The list

 * given for each pad need not be distinct - they may be references to the

 * same list of formats, as is often the case when a filter supports multiple

 * formats, but will always output the same format as it is given in input.

 *

 * In this way, a list of possible input formats and a list of possible

 * output formats are associated with each link. When a set of formats is

 * negotiated over a link, the input and output lists are merged to form a

 * new list containing only the common elements of each list. In the case

 * that there were no common elements, a format conversion is necessary.

 * Otherwise, the lists are merged, and all other links which reference

 * either of the format lists involved in the merge are also affected.

 *

 * For example, consider the filter chain:

 * filter (a) --> (b) filter (b) --> (c) filter

 *

 * where the letters in parenthesis indicate a list of formats supported on

 * the input or output of the link. Suppose the lists are as follows:

 * (a) = {A, B}

 * (b) = {A, B, C}

 * (c) = {B, C}

 *

 * First, the first link's lists are merged, yielding:

 * filter (a) --> (a) filter (a) --> (c) filter

 *

 * Notice that format list (b) now refers to the same list as filter list (a).

 * Next, the lists for the second link are merged, yielding:

 * filter (a) --> (a) filter (a) --> (a) filter

 *

 * where (a) = {B}.

 *

 * Unfortunately, when the format lists at the two ends of a link are merged,

 * we must ensure that all links which reference either pre-merge format list

 * get updated as well. Therefore, we have the format list structure store a

 * pointer to each of the pointers to itself.

 */

typedef struct AVFilterFormats {

    unsigned format_count;      ///< number of formats

    int *formats;               ///< list of media formats

    unsigned refcount;          ///< number of references to this list

    struct AVFilterFormats ***refs; ///< references to this list

}  AVFilterFormats;

/**

 * Create a list of supported formats. This is intended for use in

 * AVFilter->query_formats().

 *

 * @param fmts list of media formats, terminated by -1

 * @return the format list, with no existing references

 */

AVFilterFormats *avfilter_make_format_list(const int *fmts);

/**

 * Add fmt to the list of media formats contained in *avff.

 * If *avff is NULL the function allocates the filter formats struct

 * and puts its pointer in *avff.

 *

 * @return a non negative value in case of success, or a negative

 * value corresponding to an AVERROR code in case of error

 */

int avfilter_add_format(AVFilterFormats **avff, int fmt);

/**

 * Return a list of all formats supported by Libav for the given media type.

 */

AVFilterFormats *avfilter_all_formats(enum AVMediaType type);

/**

 * Return a format list which contains the intersection of the formats of

 * a and b. Also, all the references of a, all the references of b, and

 * a and b themselves will be deallocated.

 *

 * If a and b do not share any common formats, neither is modified, and NULL

 * is returned.

 */

AVFilterFormats *avfilter_merge_formats(AVFilterFormats *a, AVFilterFormats *b);

/**

 * Add *ref as a new reference to formats.

 * That is the pointers will point like in the ascii art below:

 *   ________

 *  |formats |<--------.

 *  |  ____  |     ____|___________________

 *  | |refs| |    |  __|_

 *  | |* * | |    | |  | |  AVFilterLink

 *  | |* *--------->|*ref|

 *  | |____| |    | |____|

 *  |________|    |________________________

 */

void avfilter_formats_ref(AVFilterFormats *formats, AVFilterFormats **ref);

/**

 * If *ref is non-NULL, remove *ref as a reference to the format list

 * it currently points to, deallocates that list if this was the last

 * reference, and sets *ref to NULL.

 *

 *         Before                                 After

 *   ________                               ________         NULL

 *  |formats |<--------.                   |formats |         ^

 *  |  ____  |     ____|________________   |  ____  |     ____|________________

 *  | |refs| |    |  __|_                  | |refs| |    |  __|_

 *  | |* * | |    | |  | |  AVFilterLink   | |* * | |    | |  | |  AVFilterLink

 *  | |* *--------->|*ref|                 | |*   | |    | |*ref|

 *  | |____| |    | |____|                 | |____| |    | |____|

 *  |________|    |_____________________   |________|    |_____________________

 */

void avfilter_formats_unref(AVFilterFormats **ref);

/**

 *

 *         Before                                 After

 *   ________                         ________

 *  |formats |<---------.            |formats |<---------.

 *  |  ____  |       ___|___         |  ____  |       ___|___

 *  | |refs| |      |   |   |        | |refs| |      |   |   |   NULL

 *  | |* *--------->|*oldref|        | |* *--------->|*newref|     ^

 *  | |* * | |      |_______|        | |* * | |      |_______|  ___|___

 *  | |____| |                       | |____| |                |   |   |

 *  |________|                       |________|                |*oldref|

 *                                                             |_______|

 */

void avfilter_formats_changeref(AVFilterFormats **oldref,

                                AVFilterFormats **newref);

/**

 * A filter pad used for either input or output.

 */

struct AVFilterPad {

    /**

     * Pad name. The name is unique among inputs and among outputs, but an

     * input may have the same name as an output. This may be NULL if this

     * pad has no need to ever be referenced by name.

     */

    const char *name;

    /**

     * AVFilterPad type. Only video supported now, hopefully someone will

     * add audio in the future.

     */

    enum AVMediaType type;

    /**

     * Minimum required permissions on incoming buffers. Any buffer with

     * insufficient permissions will be automatically copied by the filter

     * system to a new buffer which provides the needed access permissions.

     *

     * Input pads only.

     */

    int min_perms;

    /**

     * Permissions which are not accepted on incoming buffers. Any buffer

     * which has any of these permissions set will be automatically copied

     * by the filter system to a new buffer which does not have those

     * permissions. This can be used to easily disallow buffers with

     * AV_PERM_REUSE.

     *

     * Input pads only.

     */

    int rej_perms;

    /**

     * Callback called before passing the first slice of a new frame. If

     * NULL, the filter layer will default to storing a reference to the

     * picture inside the link structure.

     *

     * Input video pads only.

     */

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

    /**

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

     * use avfilter_default_get_video_buffer().

     *

     * Input video pads only.

     */

    AVFilterBufferRef *(*get_video_buffer)(AVFilterLink *link, int perms, int w, int h);

    /**

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

     * use avfilter_default_get_audio_buffer().

     *

     * Input audio pads only.

     */

    AVFilterBufferRef *(*get_audio_buffer)(AVFilterLink *link, int perms,

                                           enum AVSampleFormat sample_fmt, int size,

                                           int64_t channel_layout, int planar);

    /**

     * Callback called after the slices of a frame are completely sent. If

     * NULL, the filter layer will default to releasing the reference stored

     * in the link structure during start_frame().

     *

     * Input video pads only.

     */

    void (*end_frame)(AVFilterLink *link);

    /**

     * Slice drawing callback. This is where a filter receives video data

     * and should do its processing.

     *

     * Input video pads only.

     */

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

    /**

     * Samples filtering callback. This is where a filter receives audio data

     * and should do its processing.

     *

     * Input audio pads only.

     */

    void (*filter_samples)(AVFilterLink *link, AVFilterBufferRef *samplesref);

    /**

     * Frame poll callback. This returns the number of immediately available

     * samples. It should return a positive value if the next request_frame()

     * is guaranteed to return one frame (with no delay).

     *

     * Defaults to just calling the source poll_frame() method.

     *

     * Output video pads only.

     */

    int (*poll_frame)(AVFilterLink *link);

    /**

     * Frame request callback. A call to this should result in at least one

     * frame being output over the given link. This should return zero on

     * success, and another value on error.

     *

     * Output video pads only.

     */

    int (*request_frame)(AVFilterLink *link);

    /**

     * Link configuration callback.

     *

     * For output pads, this should set the link properties such as

     * width/height. This should NOT set the format property - that is

     * negotiated between filters by the filter system using the

     * query_formats() callback before this function is called.

     *

     * For input pads, this should check the properties of the link, and update

     * the filter's internal state as necessary.

     *

     * For both input and output filters, this should return zero on success,

     * and another value on error.

     */

    int (*config_props)(AVFilterLink *link);

};

/** default handler for start_frame() for video inputs */

void avfilter_default_start_frame(AVFilterLink *link, AVFilterBufferRef *picref);

/** default handler for draw_slice() for video inputs */

void avfilter_default_draw_slice(AVFilterLink *link, int y, int h, int slice_dir);

/** default handler for end_frame() for video inputs */

void avfilter_default_end_frame(AVFilterLink *link);

/** default handler for filter_samples() for audio inputs */

void avfilter_default_filter_samples(AVFilterLink *link, AVFilterBufferRef *samplesref);

/** default handler for config_props() for audio/video outputs */

int avfilter_default_config_output_link(AVFilterLink *link);

/** default handler for config_props() for audio/video inputs */

int avfilter_default_config_input_link (AVFilterLink *link);

/** default handler for get_video_buffer() for video inputs */

AVFilterBufferRef *avfilter_default_get_video_buffer(AVFilterLink *link,

                                                     int perms, int w, int h);

/** default handler for get_audio_buffer() for audio inputs */

AVFilterBufferRef *avfilter_default_get_audio_buffer(AVFilterLink *link, int perms,

                                                     enum AVSampleFormat sample_fmt, int size,

                                                     int64_t channel_layout, int planar);

/**

 * A helper for query_formats() which sets all links to the same list of

 * formats. If there are no links hooked to this filter, the list of formats is

 * freed.

 */

void avfilter_set_common_formats(AVFilterContext *ctx, AVFilterFormats *formats);

/** Default handler for query_formats() */

int avfilter_default_query_formats(AVFilterContext *ctx);

/** start_frame() handler for filters which simply pass video along */

void avfilter_null_start_frame(AVFilterLink *link, AVFilterBufferRef *picref);

/** draw_slice() handler for filters which simply pass video along */

void avfilter_null_draw_slice(AVFilterLink *link, int y, int h, int slice_dir);

/** end_frame() handler for filters which simply pass video along */

void avfilter_null_end_frame(AVFilterLink *link);

/** filter_samples() handler for filters which simply pass audio along */

void avfilter_null_filter_samples(AVFilterLink *link, AVFilterBufferRef *samplesref);

/** get_video_buffer() handler for filters which simply pass video along */

AVFilterBufferRef *avfilter_null_get_video_buffer(AVFilterLink *link,

                                                  int perms, int w, int h);

/** get_audio_buffer() handler for filters which simply pass audio along */

AVFilterBufferRef *avfilter_null_get_audio_buffer(AVFilterLink *link, int perms,

                                                  enum AVSampleFormat sample_fmt, int size,

                                                  int64_t channel_layout, int planar);

/**

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

 * callback functions used to interact with the filter.

 */

typedef struct AVFilter {

    const char *name;         ///< filter name

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

    /**

     * Filter initialization function. Args contains the user-supplied

     * parameters. FIXME: maybe an AVOption-based system would be better?

     * opaque is data provided by the code requesting creation of the filter,

     * and is used to pass data to the filter.

     */

    int (*init)(AVFilterContext *ctx, const char *args, void *opaque);

    /**

     * Filter uninitialization function. Should deallocate any memory held

     * by the filter, release any buffer references, etc. This does not need

     * to deallocate the AVFilterContext->priv memory itself.

     */

    void (*uninit)(AVFilterContext *ctx);

    /**

     * Queries formats supported by the filter and its pads, and sets the

     * in_formats for links connected to its output pads, and out_formats

     * for links connected to its input pads.

     *

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

     * AVERROR code otherwise

     */

    int (*query_formats)(AVFilterContext *);

    const AVFilterPad *inputs;  ///< NULL terminated list of inputs. NULL if none

    const AVFilterPad *outputs; ///< NULL terminated list of outputs. NULL if none

    /**

     * A description for the filter. You should use the

     * NULL_IF_CONFIG_SMALL() macro to define it.

     */

    const char *description;

} AVFilter;

/** An instance of a filter */

struct AVFilterContext {

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

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

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

    unsigned input_count;           ///< number of input pads

    AVFilterPad   *input_pads;      ///< array of input pads

    AVFilterLink **inputs;          ///< array of pointers to input links

    unsigned output_count;          ///< number of output pads

    AVFilterPad   *output_pads;     ///< array of output pads

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

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

};

/**

 * 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

    /** 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;

    enum AVMediaType type;      ///< filter media type

    /* These parameters apply only to video */

    int w;                      ///< agreed upon image width

    int h;                      ///< agreed upon image height

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

    /* These two parameters apply only to audio */

    int64_t channel_layout;     ///< channel layout of current buffer (see libavutil/audioconvert.h)

    int64_t sample_rate;        ///< samples per second

    int format;                 ///< agreed upon media format

    /**

     * Lists of formats supported by the input and output filters respectively.

     * These lists are used for negotiating the format to actually be used,

     * which will be loaded into the format member, above, when chosen.

     */

    AVFilterFormats *in_formats;

    AVFilterFormats *out_formats;

    /**

     * The buffer reference currently being sent across the link by the source

     * 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 *src_buf;

    AVFilterBufferRef *cur_buf;

    AVFilterBufferRef *out_buf;

    /**

     * 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;

};

/**

 * Link two filters together.

 *

 * @param src    the source filter

 * @param srcpad index of the output pad on the source filter

 * @param dst    the destination filter

 * @param dstpad index of the input pad on the destination filter

 * @return       zero on success

 */

int avfilter_link(AVFilterContext *src, unsigned srcpad,

                  AVFilterContext *dst, unsigned dstpad);

/**

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

 *

 * @param filter the filter to negotiate the properties for its inputs

 * @return       zero on successful negotiation

 */

int avfilter_config_links(AVFilterContext *filter);

/**

 * Request a picture buffer with a specific set of permissions.

 *

 * @param link  the output link to the filter from which the buffer will

 *              be requested

 * @param perms the required access permissions

 * @param w     the minimum width of the buffer to allocate

 * @param h     the minimum height of the buffer to allocate

 * @return      A reference to the buffer. This must be unreferenced with

 *              avfilter_unref_buffer when you are finished with it.

 */

AVFilterBufferRef *avfilter_get_video_buffer(AVFilterLink *link, int perms,

                                          int w, int h);

/**

 * 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

 */

AVFilterBufferRef *

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

                                          int w, int h, enum PixelFormat format);

/**

 * Request an audio samples buffer with a specific set of permissions.

 *

 * @param link           the output link to the filter from which the buffer will

 *                       be requested

 * @param perms          the required access permissions

 * @param sample_fmt     the format of each sample in the buffer to allocate

 * @param size           the buffer size in bytes

 * @param channel_layout the number and type of channels per sample in the buffer to allocate

 * @param planar         audio data layout - planar or packed

 * @return               A reference to the samples. This must be unreferenced with

 *                       avfilter_unref_buffer when you are finished with it.

 */

AVFilterBufferRef *avfilter_get_audio_buffer(AVFilterLink *link, int perms,

                                             enum AVSampleFormat sample_fmt, int size,

                                             int64_t channel_layout, int planar);

/**

 * Request an input frame from the filter at the other end of the link.

 *

 * @param link the input link

 * @return     zero on success

 */

int avfilter_request_frame(AVFilterLink *link);

/**

 * Poll a frame from the filter chain.

 *

 * @param  link the input link

 * @return the number of immediately available frames, a negative

 * number in case of error

 */

int avfilter_poll_frame(AVFilterLink *link);

/**

 * Notifie the next filter of the start of a frame.

 *

 * @param link   the output link the frame will be sent over

 * @param picref A reference to the frame about to be sent. The data for this

 *               frame need only be valid once draw_slice() is called for that

 *               portion. The receiving filter will free this reference when

 *               it no longer needs it.

 */

void avfilter_start_frame(AVFilterLink *link, AVFilterBufferRef *picref);

/**

 * Notifie the next filter that the current frame has finished.

 *

 * @param link the output link the frame was sent over

 */

void avfilter_end_frame(AVFilterLink *link);

/**

 * Send a slice to the next filter.

 *

 * Slices have to be provided in sequential order, either in

 * top-bottom or bottom-top order. If slices are provided in

 * non-sequential order the behavior of the function is undefined.

 *

 * @param link the output link over which the frame is being sent

 * @param y    offset in pixels from the top of the image for this slice

 * @param h    height of this slice in pixels

 * @param slice_dir the assumed direction for sending slices,

 *             from the top slice to the bottom slice if the value is 1,

 *             from the bottom slice to the top slice if the value is -1,

 *             for other values the behavior of the function is undefined.

 */

void avfilter_draw_slice(AVFilterLink *link, int y, int h, int slice_dir);

/**

 * Send a buffer of audio samples to the next filter.

 *

 * @param link       the output link over which the audio samples are being sent

 * @param samplesref a reference to the buffer of audio samples being sent. The

 *                   receiving filter will free this reference when it no longer

 *                   needs it or pass it on to the next filter.

 */

void avfilter_filter_samples(AVFilterLink *link, AVFilterBufferRef *samplesref);

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

void avfilter_register_all(void);

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

void avfilter_uninit(void);

/**

 * 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_open even if it is not

 * registered.

 *

 * @param filter the filter to register

 * @return 0 if the registration was succesfull, 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.

 */

AVFilter *avfilter_get_by_name(const char *name);

/**

 * 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.

 */

AVFilter **av_filter_next(AVFilter **filter);

/**

 * 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

 */

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

/**

 * 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

 */

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

/**

 * Free a filter context.

 *

 * @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);

/**

 * Insert a new pad.

 *

 * @param idx Insertion point. Pad is inserted at the end if this point

 *            is beyond the end of the list of pads.

 * @param count Pointer to the number of pads in the list

 * @param padidx_off Offset within an AVFilterLink structure to the element

 *                   to increment when inserting a new pad causes link

 *                   numbering to change

 * @param pads Pointer to the pointer to the beginning of the list of pads

 * @param links Pointer to the pointer to the beginning of the list of links

 * @param newpad The new pad to add. A copy is made when adding.

 */

void avfilter_insert_pad(unsigned idx, unsigned *count, size_t padidx_off,

                         AVFilterPad **pads, AVFilterLink ***links,

                         AVFilterPad *newpad);

/** Insert a new input pad for the filter. */

static inline void avfilter_insert_inpad(AVFilterContext *f, unsigned index,

                                         AVFilterPad *p)

{

    avfilter_insert_pad(index, &f->input_count, offsetof(AVFilterLink, dstpad),

                        &f->input_pads, &f->inputs, p);

}

/** Insert a new output pad for the filter. */

static inline void avfilter_insert_outpad(AVFilterContext *f, unsigned index,

                                          AVFilterPad *p)

{

    avfilter_insert_pad(index, &f->output_count, offsetof(AVFilterLink, srcpad),

                        &f->output_pads, &f->outputs, p);

}

#endif  /* AVFILTER_AVFILTER_H */