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222 lines
8.6 KiB
C
222 lines
8.6 KiB
C
/*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef AVFILTER_FORMATS_H
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#define AVFILTER_FORMATS_H
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#include "avfilter.h"
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/**
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* A list of supported formats for one end of a filter link. This is used
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* during the format negotiation process to try to pick the best format to
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* use to minimize the number of necessary conversions. Each filter gives a
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* list of the formats supported by each input and output pad. The list
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* given for each pad need not be distinct - they may be references to the
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* same list of formats, as is often the case when a filter supports multiple
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* formats, but will always output the same format as it is given in input.
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*
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* In this way, a list of possible input formats and a list of possible
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* output formats are associated with each link. When a set of formats is
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* negotiated over a link, the input and output lists are merged to form a
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* new list containing only the common elements of each list. In the case
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* that there were no common elements, a format conversion is necessary.
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* Otherwise, the lists are merged, and all other links which reference
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* either of the format lists involved in the merge are also affected.
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*
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* For example, consider the filter chain:
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* filter (a) --> (b) filter (b) --> (c) filter
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*
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* where the letters in parenthesis indicate a list of formats supported on
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* the input or output of the link. Suppose the lists are as follows:
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* (a) = {A, B}
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* (b) = {A, B, C}
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* (c) = {B, C}
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*
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* First, the first link's lists are merged, yielding:
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* filter (a) --> (a) filter (a) --> (c) filter
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*
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* Notice that format list (b) now refers to the same list as filter list (a).
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* Next, the lists for the second link are merged, yielding:
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* filter (a) --> (a) filter (a) --> (a) filter
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*
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* where (a) = {B}.
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*
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* Unfortunately, when the format lists at the two ends of a link are merged,
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* we must ensure that all links which reference either pre-merge format list
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* get updated as well. Therefore, we have the format list structure store a
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* pointer to each of the pointers to itself.
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*/
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struct AVFilterFormats {
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unsigned format_count; ///< number of formats
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int *formats; ///< list of media formats
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unsigned refcount; ///< number of references to this list
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struct AVFilterFormats ***refs; ///< references to this list
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};
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typedef struct AVFilterChannelLayouts {
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uint64_t *channel_layouts; ///< list of channel layouts
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int nb_channel_layouts; ///< number of channel layouts
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unsigned refcount; ///< number of references to this list
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struct AVFilterChannelLayouts ***refs; ///< references to this list
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} AVFilterChannelLayouts;
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/**
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* Return a channel layouts/samplerates list which contains the intersection of
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* the layouts/samplerates of a and b. Also, all the references of a, all the
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* references of b, and a and b themselves will be deallocated.
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*
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* If a and b do not share any common elements, neither is modified, and NULL
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* is returned.
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*/
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AVFilterChannelLayouts *ff_merge_channel_layouts(AVFilterChannelLayouts *a,
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AVFilterChannelLayouts *b);
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AVFilterFormats *ff_merge_samplerates(AVFilterFormats *a,
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AVFilterFormats *b);
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/**
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* Construct an empty AVFilterChannelLayouts/AVFilterFormats struct --
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* representing any channel layout/sample rate.
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*/
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AVFilterChannelLayouts *ff_all_channel_layouts(void);
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AVFilterFormats *ff_all_samplerates(void);
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/**
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* A helper for query_formats() which sets all links to the same list of channel
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* layouts/sample rates. If there are no links hooked to this filter, the list
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* is freed.
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*/
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void ff_set_common_channel_layouts(AVFilterContext *ctx,
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AVFilterChannelLayouts *layouts);
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void ff_set_common_samplerates(AVFilterContext *ctx,
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AVFilterFormats *samplerates);
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/**
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* A helper for query_formats() which sets all links to the same list of
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* formats. If there are no links hooked to this filter, the list of formats is
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* freed.
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*/
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void ff_set_common_formats(AVFilterContext *ctx, AVFilterFormats *formats);
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int ff_add_channel_layout(AVFilterChannelLayouts **l, uint64_t channel_layout);
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/**
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* Add *ref as a new reference to f.
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*/
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void ff_channel_layouts_ref(AVFilterChannelLayouts *f,
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AVFilterChannelLayouts **ref);
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/**
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* Remove a reference to a channel layouts list.
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*/
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void ff_channel_layouts_unref(AVFilterChannelLayouts **ref);
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void ff_channel_layouts_changeref(AVFilterChannelLayouts **oldref,
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AVFilterChannelLayouts **newref);
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int ff_default_query_formats(AVFilterContext *ctx);
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/**
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* Create a list of supported formats. This is intended for use in
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* AVFilter->query_formats().
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*
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* @param fmts list of media formats, terminated by -1
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* @return the format list, with no existing references
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*/
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AVFilterFormats *ff_make_format_list(const int *fmts);
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/**
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* Add fmt to the list of media formats contained in *avff.
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* If *avff is NULL the function allocates the filter formats struct
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* and puts its pointer in *avff.
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*
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* @return a non negative value in case of success, or a negative
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* value corresponding to an AVERROR code in case of error
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*/
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int ff_add_format(AVFilterFormats **avff, int fmt);
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/**
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* Return a list of all formats supported by Libav for the given media type.
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*/
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AVFilterFormats *ff_all_formats(enum AVMediaType type);
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/**
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* Construct a formats list containing all planar sample formats.
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*/
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AVFilterFormats *ff_planar_sample_fmts(void);
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/**
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* Return a format list which contains the intersection of the formats of
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* a and b. Also, all the references of a, all the references of b, and
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* a and b themselves will be deallocated.
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*
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* If a and b do not share any common formats, neither is modified, and NULL
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* is returned.
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*/
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AVFilterFormats *ff_merge_formats(AVFilterFormats *a, AVFilterFormats *b);
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/**
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* Add *ref as a new reference to formats.
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* That is the pointers will point like in the ascii art below:
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* ________
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* |formats |<--------.
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* | ____ | ____|___________________
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* | |refs| | | __|_
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* | |* * | | | | | | AVFilterLink
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* | |* *--------->|*ref|
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* | |____| | | |____|
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* |________| |________________________
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*/
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void ff_formats_ref(AVFilterFormats *formats, AVFilterFormats **ref);
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/**
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* If *ref is non-NULL, remove *ref as a reference to the format list
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* it currently points to, deallocates that list if this was the last
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* reference, and sets *ref to NULL.
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*
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* Before After
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* ________ ________ NULL
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* |formats |<--------. |formats | ^
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* | ____ | ____|________________ | ____ | ____|________________
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* | |refs| | | __|_ | |refs| | | __|_
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* | |* * | | | | | | AVFilterLink | |* * | | | | | | AVFilterLink
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* | |* *--------->|*ref| | |* | | | |*ref|
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* | |____| | | |____| | |____| | | |____|
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* |________| |_____________________ |________| |_____________________
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*/
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void ff_formats_unref(AVFilterFormats **ref);
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/**
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*
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* Before After
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* ________ ________
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* |formats |<---------. |formats |<---------.
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* | ____ | ___|___ | ____ | ___|___
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* | |refs| | | | | | |refs| | | | | NULL
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* | |* *--------->|*oldref| | |* *--------->|*newref| ^
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* | |* * | | |_______| | |* * | | |_______| ___|___
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* | |____| | | |____| | | | |
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* |________| |________| |*oldref|
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* |_______|
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*/
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void ff_formats_changeref(AVFilterFormats **oldref, AVFilterFormats **newref);
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#endif /* AVFILTER_FORMATS_H */
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