/* * 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_FORMATS_H #define AVFILTER_FORMATS_H #include "avfilter.h" /** * 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. */ struct AVFilterFormats { unsigned nb_formats; ///< number of formats int *formats; ///< list of media formats unsigned refcount; ///< number of references to this list struct AVFilterFormats ***refs; ///< references to this list }; typedef struct AVFilterChannelLayouts { uint64_t *channel_layouts; ///< list of channel layouts int nb_channel_layouts; ///< number of channel layouts unsigned refcount; ///< number of references to this list struct AVFilterChannelLayouts ***refs; ///< references to this list } AVFilterChannelLayouts; /** * Return a channel layouts/samplerates list which contains the intersection of * the layouts/samplerates 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 elements, neither is modified, and NULL * is returned. */ AVFilterChannelLayouts *ff_merge_channel_layouts(AVFilterChannelLayouts *a, AVFilterChannelLayouts *b); AVFilterFormats *ff_merge_samplerates(AVFilterFormats *a, AVFilterFormats *b); /** * Construct an empty AVFilterChannelLayouts/AVFilterFormats struct -- * representing any channel layout/sample rate. */ AVFilterChannelLayouts *ff_all_channel_layouts(void); AVFilterFormats *ff_all_samplerates(void); /** * A helper for query_formats() which sets all links to the same list of channel * layouts/sample rates. If there are no links hooked to this filter, the list * is freed. */ void ff_set_common_channel_layouts(AVFilterContext *ctx, AVFilterChannelLayouts *layouts); void ff_set_common_samplerates(AVFilterContext *ctx, AVFilterFormats *samplerates); /** * 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 ff_set_common_formats(AVFilterContext *ctx, AVFilterFormats *formats); int ff_add_channel_layout(AVFilterChannelLayouts **l, uint64_t channel_layout); /** * Add *ref as a new reference to f. */ void ff_channel_layouts_ref(AVFilterChannelLayouts *f, AVFilterChannelLayouts **ref); /** * Remove a reference to a channel layouts list. */ void ff_channel_layouts_unref(AVFilterChannelLayouts **ref); void ff_channel_layouts_changeref(AVFilterChannelLayouts **oldref, AVFilterChannelLayouts **newref); int ff_default_query_formats(AVFilterContext *ctx); /** * 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 *ff_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 ff_add_format(AVFilterFormats **avff, int fmt); /** * Return a list of all formats supported by Libav for the given media type. */ AVFilterFormats *ff_all_formats(enum AVMediaType type); /** * Construct a formats list containing all planar sample formats. */ AVFilterFormats *ff_planar_sample_fmts(void); /** * 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 *ff_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 ff_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 ff_formats_unref(AVFilterFormats **ref); /** * Before After * ________ ________ * |formats |<---------. |formats |<---------. * | ____ | ___|___ | ____ | ___|___ * | |refs| | | | | | |refs| | | | | NULL * | |* *--------->|*oldref| | |* *--------->|*newref| ^ * | |* * | | |_______| | |* * | | |_______| ___|___ * | |____| | | |____| | | | | * |________| |________| |*oldref| * |_______| */ void ff_formats_changeref(AVFilterFormats **oldref, AVFilterFormats **newref); #endif /* AVFILTER_FORMATS_H */