diff --git a/libavfilter/avfilter.h b/libavfilter/avfilter.h index ad2d067f86..114fd11959 100644 --- a/libavfilter/avfilter.h +++ b/libavfilter/avfilter.h @@ -101,6 +101,91 @@ AVFilterPicRef *avfilter_ref_pic(AVFilterPicRef *ref, int pmask); */ 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 outut 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 fairly comprehensive list of colorspaces which are supported by + * many of the included filters. This is not truly "all" the colorspaces, but + * it is most of them, and it is the most commonly supported large subset. + */ +AVFilterFormats *avfilter_all_colorspaces(void); + +/** + * If a and b share at least one common format, they are merged into a new + * format list which is returned. All the references to a and b are updated + * to point to this new list, and a and b are 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 f */ +void avfilter_formats_ref(AVFilterFormats *f, 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 + */ +void avfilter_formats_unref(AVFilterFormats **ref); + /** * A filter pad used for either input or output */ @@ -139,18 +224,6 @@ struct AVFilterPad */ int rej_perms; - /** - * Callback to get a list of supported formats. The returned list should - * be terminated by -1 (see avfilter_make_format_list for an easy way to - * create such a list). - * - * This is used for both input and output pads. If ommitted from an output - * pad, it is assumed that the only format supported is the same format - * that is being used for the filter's first input. If the filter has no - * inputs, then this may not be ommitted for its output pads. - */ - int *(*query_formats)(AVFilterLink *link); - /** * Callback called before passing the first slice of a new frame. If * NULL, the filter layer will default to storing a reference to the @@ -219,11 +292,17 @@ void avfilter_default_end_frame(AVFilterLink *link); 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 query_formats() for video outputs */ -int *avfilter_default_query_output_formats(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 @@ -251,6 +330,15 @@ typedef struct */ 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; @@ -294,6 +382,14 @@ struct AVFilterLink 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 @@ -415,14 +511,15 @@ int avfilter_init_filter(AVFilterContext *filter, const char *args, void *opaque void avfilter_destroy(AVFilterContext *filter); /** - * Helper function to create a list of supported formats. This is intended - * for use in AVFilterPad->query_formats(). - * @param len The number of formats supported - * @param ... A list of the supported formats - * @return The format list in a form suitable for returning from - * AVFilterPad->query_formats() + * 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_make_format_list(int len, ...); +int avfilter_insert_filter(AVFilterLink *link, AVFilterContext *filt, + unsigned in, unsigned out); /** * Insert a new pad