/* * 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 * 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 FFmpeg; 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 }; /** * A list of supported channel layouts. * * The list works the same as AVFilterFormats, except for the following * differences: * - A list with all_layouts = 1 means all channel layouts with a known * disposition; nb_channel_layouts must then be 0. * - A list with all_counts = 1 means all channel counts, with a known or * unknown disposition; nb_channel_layouts must then be 0 and all_layouts 1. * - The list must not contain a layout with a known disposition and a * channel count with unknown disposition with the same number of channels * (e.g. AV_CH_LAYOUT_STEREO and FF_COUNT2LAYOUT(2). */ struct AVFilterChannelLayouts { AVChannelLayout *channel_layouts; ///< list of channel layouts int nb_channel_layouts; ///< number of channel layouts char all_layouts; ///< accept any known channel layout char all_counts; ///< accept any channel layout or count unsigned refcount; ///< number of references to this list struct AVFilterChannelLayouts ***refs; ///< references to this list }; /** * Encode a channel count as a channel layout. * FF_COUNT2LAYOUT(c) means any channel layout with c channels, with a known * or unknown disposition. * The result is only valid inside AVFilterChannelLayouts and immediately * related functions. */ #define FF_COUNT2LAYOUT(c) ((AVChannelLayout) { .order = AV_CHANNEL_ORDER_UNSPEC, .nb_channels = c }) /** * Decode a channel count encoded as a channel layout. * Return 0 if the channel layout was a real one. */ #define FF_LAYOUT2COUNT(l) (((l)->order == AV_CHANNEL_ORDER_UNSPEC) ? \ (l)->nb_channels : 0) #define KNOWN(l) (!FF_LAYOUT2COUNT(l)) /* for readability */ /** * Construct an empty AVFilterChannelLayouts/AVFilterFormats struct -- * representing any channel layout (with known disposition)/sample rate. */ av_warn_unused_result AVFilterChannelLayouts *ff_all_channel_layouts(void); av_warn_unused_result AVFilterFormats *ff_all_samplerates(void); /** * Construct an AVFilterChannelLayouts coding for any channel layout, with * known or unknown disposition. */ av_warn_unused_result AVFilterChannelLayouts *ff_all_channel_counts(void); av_warn_unused_result AVFilterChannelLayouts *ff_make_channel_layout_list(const AVChannelLayout *fmts); /** * Helpers for query_formats() which set all free audio links to the same list * of channel layouts/sample rates. If there are no links hooked to this list, * the list is freed. */ av_warn_unused_result int ff_set_common_channel_layouts(AVFilterContext *ctx, AVFilterChannelLayouts *layouts); /** * Equivalent to ff_set_common_channel_layouts(ctx, ff_make_channel_layout_list(fmts)) */ av_warn_unused_result int ff_set_common_channel_layouts_from_list(AVFilterContext *ctx, const AVChannelLayout *fmts); /** * Equivalent to ff_set_common_channel_layouts(ctx, ff_all_channel_counts()) */ av_warn_unused_result int ff_set_common_all_channel_counts(AVFilterContext *ctx); av_warn_unused_result int ff_set_common_samplerates(AVFilterContext *ctx, AVFilterFormats *samplerates); /** * Equivalent to ff_set_common_samplerates(ctx, ff_make_format_list(samplerates)) */ av_warn_unused_result int ff_set_common_samplerates_from_list(AVFilterContext *ctx, const int *samplerates); /** * Equivalent to ff_set_common_samplerates(ctx, ff_all_samplerates()) */ av_warn_unused_result int ff_set_common_all_samplerates(AVFilterContext *ctx); /** * 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. */ av_warn_unused_result int ff_set_common_formats(AVFilterContext *ctx, AVFilterFormats *formats); /** * Equivalent to ff_set_common_formats(ctx, ff_make_format_list(fmts)) */ av_warn_unused_result int ff_set_common_formats_from_list(AVFilterContext *ctx, const int *fmts); av_warn_unused_result int ff_add_channel_layout(AVFilterChannelLayouts **l, const AVChannelLayout *channel_layout); /** * Add *ref as a new reference to f. */ av_warn_unused_result int 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); av_warn_unused_result 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 */ av_warn_unused_result AVFilterFormats *ff_make_format_list(const int *fmts); /** * Equivalent to ff_make_format_list({const int[]}{ fmt, -1 }) */ av_warn_unused_result AVFilterFormats *ff_make_formats_list_singleton(int fmt); /** * 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 */ av_warn_unused_result int ff_add_format(AVFilterFormats **avff, int64_t fmt); /** * Return a list of all formats supported by FFmpeg for the given media type. */ av_warn_unused_result AVFilterFormats *ff_all_formats(enum AVMediaType type); /** * Construct a formats list containing all pixel formats with certain * properties */ av_warn_unused_result AVFilterFormats *ff_formats_pixdesc_filter(unsigned want, unsigned rej); //* format is software, non-planar with sub-sampling #define FF_PIX_FMT_FLAG_SW_FLAT_SUB (1 << 24) /** * Construct a formats list containing all planar sample formats. */ av_warn_unused_result AVFilterFormats *ff_planar_sample_fmts(void); /** * Add *ref as a new reference to formats. * That is the pointers will point like in the ascii art below: * ________ * |formats |<--------. * | ____ | ____|___________________ * | |refs| | | __|_ * | |* * | | | | | | AVFilterLink * | |* *--------->|*ref| * | |____| | | |____| * |________| |________________________ */ av_warn_unused_result int 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); /** * Check that fmts is a valid pixel formats list. * * In particular, check for duplicates. */ int ff_formats_check_pixel_formats(void *log, const AVFilterFormats *fmts); /** * Check that fmts is a valid sample formats list. * * In particular, check for duplicates. */ int ff_formats_check_sample_formats(void *log, const AVFilterFormats *fmts); /** * Check that fmts is a valid sample rates list. * * In particular, check for duplicates. */ int ff_formats_check_sample_rates(void *log, const AVFilterFormats *fmts); /** * Check that fmts is a valid channel layouts list. * * In particular, check for duplicates. */ int ff_formats_check_channel_layouts(void *log, const AVFilterChannelLayouts *fmts); typedef struct AVFilterFormatMerger { unsigned offset; int (*merge)(void *a, void *b); int (*can_merge)(const void *a, const void *b); } AVFilterFormatsMerger; /** * Callbacks and properties to describe the steps of a format negotiation. * * The steps are: * * 1. query_formats(): call the callbacks on all filter to set lists of * supported formats. * When links on a filter must eventually have the same * format, the lists of supported formats are the same * object in memory. * See: * http://www.normalesup.org/~george/articles/format_negotiation_in_libavfilter/#12 * * * 2. query_formats(): merge lists of supported formats or insert automatic * conversion filters. * Compute the intersection of the lists of supported * formats on the ends of links. If it succeeds, replace * both objects with the intersection everywhere they * are referenced. * If the intersection is empty, insert an automatic * conversion filter. * If several formats are negotiated at once (format, * rate, layout), only merge if all three can be, since * the conversion filter can convert all three at once. * This process goes on as long as progress is made. * See: * http://www.normalesup.org/~george/articles/format_negotiation_in_libavfilter/#14 * http://www.normalesup.org/~george/articles/format_negotiation_in_libavfilter/#29 * * 3. reduce_formats(): try to reduce format conversion within filters. * For each link where there is only one supported * formats on output, for each output of the connected * filter, if the media type is the same and said * format is supported, keep only this one. * This process goes on as long as progress is made. * Rationale: conversion filters will set a large list * of supported formats on outputs but users will * expect the output to be as close as possible as the * input (examples: scale without changing the pixel * format, resample without changint the layout). * FIXME: this can probably be done by merging the * input and output lists instead of re-implementing * the logic. * * 4. swap_sample_fmts(): * swap_samplerates(): * swap_channel_layouts(): For each filter with an input with only one * supported format, when outputs have several * supported formats, put the best one with * reference to the input at the beginning of the * list, to prepare it for being picked up by * pick_formats(). * The best format is the one that is most * similar to the input while not losing too much * information. * This process need to run only once. * FIXME: reduce_formats() operates on all inputs * with a single format, swap_*() operates on the * first one only: check if the difference makes * sense. * TODO: the swapping done for one filter can * override the swapping done for another filter * connected to the same list of formats, maybe * it would be better to compute a total score * for all connected filters and use the score to * pick the format instead of just swapping. * TODO: make the similarity logic available as * public functions in libavutil. * * 5. pick_formats(): Choose one format from the lists of supported formats, * use it for the link and reduce the list to a single * element to force other filters connected to the same * list to use it. * First process all links where there is a single format * and the output links of all filters with an input, * trying to preserve similarity between input and * outputs. * Repeat as long as process is made. * Then do a final run for the remaining filters. * FIXME: the similarity logic (the ref argument to * pick_format()) added in FFmpeg duplicates and * overrides the swapping logic added in libav. Better * merge them into a score system. */ typedef struct AVFilterNegotiation { unsigned nb_mergers; const AVFilterFormatsMerger *mergers; const char *conversion_filter; unsigned conversion_opts_offset; } AVFilterNegotiation; const AVFilterNegotiation *ff_filter_get_negotiation(AVFilterLink *link); #endif /* AVFILTER_FORMATS_H */