From b74a1da49db5ebed51aceae6cacc2329288a92c1 Mon Sep 17 00:00:00 2001 From: Anton Khirnov Date: Wed, 30 May 2012 10:12:55 +0200 Subject: lavfi: make formats API private on next bump. It is only useful inside filters and we don't allow user filters for now. --- libavfilter/formats.h | 138 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 138 insertions(+) (limited to 'libavfilter/formats.h') diff --git a/libavfilter/formats.h b/libavfilter/formats.h index 9acd31f38a..8961cb1a65 100644 --- a/libavfilter/formats.h +++ b/libavfilter/formats.h @@ -21,6 +21,56 @@ #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. + */ +#if !FF_API_FILTERS_PUBLIC +struct AVFilterFormats { + unsigned format_count; ///< number of formats + int *formats; ///< list of media formats + + unsigned refcount; ///< number of references to this list + struct AVFilterFormats ***refs; ///< references to this list +}; +#endif + typedef struct AVFilterChannelLayouts { uint64_t *channel_layouts; ///< list of channel layouts int nb_channel_layouts; ///< number of channel layouts @@ -59,6 +109,13 @@ void ff_set_common_channel_layouts(AVFilterContext *ctx, 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); /** @@ -77,4 +134,85 @@ void ff_channel_layouts_changeref(AVFilterChannelLayouts **oldref, 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); + +/** + * 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 -- cgit v1.2.3