avfilter.h.svn-base

ffmpeg最新源码

     */
    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, AVFilterPicRef *picref);
/** Default handler for end_frame() for video inputs */
void avfilter_default_end_frame(AVFilterLink *link);
/** Default handler for config_props() for video outputs */
int avfilter_default_config_output_link(AVFilterLink *link);
/** Default handler for config_props() for video inputs */
int avfilter_default_config_input_link (AVFilterLink *link);
/** Default handler for get_video_buffer() for video inputs */
AVFilterPicRef *avfilter_default_get_video_buffer(AVFilterLink *link,
                                                  int perms);
/**
 * 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);

/**
 * Filter definition.  This defines the pads a filter contains, and all the
 * callback functions used to interact with the filter.
 */
typedef struct
{
    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 picture references, etc.  This does not need
     * to deallocate the AVFilterContext->priv memory itself.
     */
    void (*uninit)(AVFilterContext *ctx);

    /**
     * Query formats supported by the filter and its pads. Should set the
     * in_formats for links connected to its output pads, and out_formats
     * for links connected to its input pads.
     *
     * Should return zero on success.
     */
    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
} 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
    unsigned int srcpad;        ///< index of the output pad on the source filter

    AVFilterContext *dst;       ///< dest filter
    unsigned int dstpad;        ///< index of the 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;

    int w;                      ///< agreed upon image width
    int h;                      ///< agreed upon image height
    enum PixelFormat format;    ///< agreed upon image colorspace

    /**
     * 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 picture reference currently being sent across the link by the source
     * filter.  This is used internally by the filter system to allow
     * automatic copying of pictures which do not have sufficient permissions
     * for the destination.  This should not be accessed directly by the
     * filters.
     */
    AVFilterPicRef *srcpic;

    AVFilterPicRef *cur_pic;
    AVFilterPicRef *outpic;
};

/**
 * 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 colorspace, 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 picture will
 *              be requested
 * @param perms the required access permissions
 * @return      A reference to the picture.  This must be unreferenced with
 *              avfilter_unref_pic when you are finished with it.
 */
AVFilterPicRef *avfilter_get_video_buffer(AVFilterLink *link, int perms);

/**
 * 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 imediately available frames
 */
int avfilter_poll_frame(AVFilterLink *link);

/**
 * Notify 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, AVFilterPicRef *picref);

/**
 * Notify 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.
 * @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
 */
void avfilter_draw_slice(AVFilterLink *link, int y, int h);

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

/** Uninitialize the filter system.  Unregisters 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
 */
void avfilter_register(AVFilter *filter);

/**
 * Gets 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);

/**
 * Create a filter instance.
 * @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          Pointer to the new instance on success.  NULL on failure.
 */
AVFilterContext *avfilter_open(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);

/**
 * Destroy a filter.
 * @param filter the filter to destroy
 */
void avfilter_destroy(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 in   the input pad on the filter to connect
 * @param out  the output pad on the filter to connect
 * @return     zero on success
 */
int avfilter_insert_filter(AVFilterLink *link, AVFilterContext *filt,
                           unsigned in, unsigned out);

/**
 * 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  /* FFMPEG_AVFILTER_H */