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ffmpeg/libavfilter/formats.h

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/*
* 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);
/**
* Construct an AVFilterFormats representing all possible color spaces.
*
* Note: This list does not include AVCOL_SPC_RESERVED.
*/
av_warn_unused_result
AVFilterFormats *ff_all_color_spaces(void);
/**
* Construct an AVFilterFormats representing all possible color ranges.
*/
av_warn_unused_result
AVFilterFormats *ff_all_color_ranges(void);
/**
* 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);
av_warn_unused_result
int ff_set_common_color_spaces(AVFilterContext *ctx,
AVFilterFormats *color_spaces);
/**
* Equivalent to ff_set_common_color_spaces(ctx, ff_make_format_list(color_spaces))
*/
av_warn_unused_result
int ff_set_common_color_spaces_from_list(AVFilterContext *ctx,
const int *color_spaces);
/**
* Equivalent to ff_set_common_color_spaces(ctx, ff_all_color_spaces())
*/
av_warn_unused_result
int ff_set_common_all_color_spaces(AVFilterContext *ctx);
av_warn_unused_result
int ff_set_common_color_ranges(AVFilterContext *ctx,
AVFilterFormats *color_ranges);
/**
* Equivalent to ff_set_common_color_ranges(ctx, ff_make_format_list(color_ranges))
*/
av_warn_unused_result
int ff_set_common_color_ranges_from_list(AVFilterContext *ctx,
const int *color_ranges);
/**
* Equivalent to ff_set_common_color_ranges(ctx, ff_all_color_ranges())
*/
av_warn_unused_result
int ff_set_common_all_color_ranges(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);
/**
* Sets all remaining unset filter lists for all inputs/outputs to their
* corresponding `ff_all_*()` lists.
*/
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);
/**
* Check that fmts is a valid formats list for YUV colorspace metadata.
*
* In particular, check for duplicates.
*/
int ff_formats_check_color_spaces(void *log, const AVFilterFormats *fmts);
int ff_formats_check_color_ranges(void *log, const AVFilterFormats *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 */
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