blob: 9f455bb4474e3a644697b9c7df12e701e23b694a [file] [log] [blame]
* 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
* 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
#include <stddef.h>
#include "libavcodec/avcodec.h"
* Returns the LIBAVFILTER_VERSION_INT constant.
unsigned avfilter_version(void);
typedef struct AVFilterContext AVFilterContext;
typedef struct AVFilterLink AVFilterLink;
typedef struct AVFilterPad AVFilterPad;
/* TODO: look for other flags which may be useful in this structure (interlace
* flags, etc)
* A reference-counted picture data type used by the filter system. Filters
* should not store pointers to this structure directly, but instead use the
* AVFilterPicRef structure below.
typedef struct AVFilterPic
uint8_t *data[4]; ///< picture data for each plane
int linesize[4]; ///< number of bytes per line
enum PixelFormat format; ///< colorspace
unsigned refcount; ///< number of references to this image
/** private data to be used by a custom free function */
void *priv;
* A pointer to the function to deallocate this image 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 AVFilterPic *pic);
} AVFilterPic;
* A reference to an AVFilterPic. Since filters can manipulate the origin of
* a picture to, for example, crop image without any memcpy, the picture 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 AVFilterPicRef
AVFilterPic *pic; ///< the picture that this is a reference to
uint8_t *data[4]; ///< picture data for each plane
int linesize[4]; ///< number of bytes per line
int w; ///< image width
int h; ///< image height
int64_t pts; ///< presentation timestamp in units of 1/AV_TIME_BASE
AVRational pixel_aspect; ///< pixel aspect ratio
int perms; ///< permissions
#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
} AVFilterPicRef;
* Add a new reference to a picture.
* @param ref an existing reference to the picture
* @param pmask a bitmask containing the allowable permissions in the new
* reference
* @return a new reference to the picture with the same properties as the
* old, excluding any permissions denied by pmask
AVFilterPicRef *avfilter_ref_pic(AVFilterPicRef *ref, int pmask);
* Remove a reference to a picture. If this is the last reference to the
* picture, the picture itself is also automatically freed.
* @param ref reference to the picture
void avfilter_unref_pic(AVFilterPicRef *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 AVFilterFormats;
struct AVFilterFormats
unsigned format_count; ///< number of formats
int *formats; ///< list of formats
unsigned refcount; ///< number of references to this list
AVFilterFormats ***refs; ///< references to this list
* Helper function to create a list of supported formats. This is intended
* for use in AVFilter->query_formats().
* @param len the number of formats supported
* @param ... a list of the supported formats
* @return the format list, with no existing references
AVFilterFormats *avfilter_make_format_list(int len, ...);
* Returns a list of all colorspaces supported by FFmpeg.
AVFilterFormats *avfilter_all_colorspaces(void);
* Returns 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);
* Adds *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);
* Remove *ref as a reference to the format list it currently points to,
* deallocate that list if this was the last reference, and set *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 CodecType 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
* 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, AVFilterPicRef *picref);
* Callback function to get a buffer. If NULL, the filter system will
* handle buffer requests.
* Input video pads only.
AVFilterPicRef *(*get_video_buffer)(AVFilterLink *link, int perms);
* 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);
* Frame poll callback. This returns the number of immediately available
* frames. 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, AVFilterPicRef *picref);
/** default handler for draw_slice() for video inputs */
void avfilter_default_draw_slice(AVFilterLink *link, int y, int h);
/** 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 immediately available frames, a negative
* number in case of error
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);