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AVOptions

Data Structures

AVOptions provide a generic system to declare options on arbitrary structs ("objects"). More...

Modules

Evaluating option strings

This group of functions can be used to evaluate option strings and get numbers out of them.

Option setting functions

Those functions set the field of obj with the given name to value.

Option getting functions

Those functions get a value of the option with the given name from an object.

Data Structures

struct AVOption

AVOption. More...

struct AVOptionRange

A single allowed range of values, or a single allowed value. More...

struct AVOptionRanges

List of AVOptionRange structs. More...

Macros

#define AV_OPT_SEARCH_CHILDREN (1 << 0)

Search in possible children of the given object first. More...

#define AV_OPT_SEARCH_FAKE_OBJ (1 << 1)

The obj passed to av_opt_find() is fake – only a double pointer to AVClass instead of a required pointer to a struct containing AVClass. More...

#define AV_OPT_ALLOW_NULL (1 << 2)

In av_opt_get, return NULL if the option has a pointer type and is set to NULL, rather than returning an empty string. More...

#define AV_OPT_MULTI_COMPONENT_RANGE (1 << 12)

Allows av_opt_query_ranges and av_opt_query_ranges_default to return more than one component for certain option types. More...

#define AV_OPT_SERIALIZE_SKIP_DEFAULTS 0x00000001

Serialize options that are not set to default values only. More...

#define AV_OPT_SERIALIZE_OPT_FLAGS_EXACT 0x00000002

Serialize options that exactly match opt_flags only. More...

Enumerations

enum { AV_OPT_FLAG_IMPLICIT_KEY = 1 }

Functions

int av_opt_show2 (void *obj, void *av_log_obj, int req_flags, int rej_flags)

Show the obj options. More...

void av_opt_set_defaults (void *s)

Set the values of all AVOption fields to their default values. More...

void av_opt_set_defaults2 (void *s, int mask, int flags)

Set the values of all AVOption fields to their default values. More...

int av_set_options_string (void *ctx, const char *opts, const char *key_val_sep, const char *pairs_sep)

Parse the key/value pairs list in opts. More...

int av_opt_set_from_string (void *ctx, const char *opts, const char *const *shorthand, const char *key_val_sep, const char *pairs_sep)

Parse the key-value pairs list in opts. More...

void av_opt_free (void *obj)

Free all allocated objects in obj. More...

int av_opt_flag_is_set (void *obj, const char *field_name, const char *flag_name)

Check whether a particular flag is set in a flags field. More...

int av_opt_set_dict (void *obj, struct AVDictionary **options)

Set all the options from a given dictionary on an object. More...

int av_opt_set_dict2 (void *obj, struct AVDictionary **options, int search_flags)

Set all the options from a given dictionary on an object. More...

int av_opt_get_key_value (const char **ropts, const char *key_val_sep, const char *pairs_sep, unsigned flags, char **rkey, char **rval)

Extract a key-value pair from the beginning of a string. More...

const AVOption * av_opt_find (void *obj, const char *name, const char *unit, int opt_flags, int search_flags)

Look for an option in an object. More...

const AVOption * av_opt_find2 (void *obj, const char *name, const char *unit, int opt_flags, int search_flags, void **target_obj)

Look for an option in an object. More...

const AVOption * av_opt_next (const void *obj, const AVOption *prev)

Iterate over all AVOptions belonging to obj. More...

void * av_opt_child_next (void *obj, void *prev)

Iterate over AVOptions-enabled children of obj. More...

const AVClass * av_opt_child_class_next (const AVClass *parent, const AVClass *prev)

Iterate over potential AVOptions-enabled children of parent. More...

void * av_opt_ptr (const AVClass *avclass, void *obj, const char *name)

Gets a pointer to the requested field in a struct. More...

void av_opt_freep_ranges (AVOptionRanges **ranges)

Free an AVOptionRanges struct and set it to NULL. More...

int av_opt_query_ranges (AVOptionRanges **, void *obj, const char *key, int flags)

Get a list of allowed ranges for the given option. More...

int av_opt_copy (void *dest, const void *src)

Copy options from src object into dest object. More...

int av_opt_query_ranges_default (AVOptionRanges **, void *obj, const char *key, int flags)

Get a default list of allowed ranges for the given option. More...

int av_opt_is_set_to_default (void *obj, const AVOption *o)

Check if given option is set to its default value. More...

int av_opt_is_set_to_default_by_name (void *obj, const char *name, int search_flags)

Check if given option is set to its default value. More...

int av_opt_serialize (void *obj, int opt_flags, int flags, char **buffer, const char key_val_sep, const char pairs_sep)

Serialize object's options. More...

Detailed Description

AVOptions provide a generic system to declare options on arbitrary structs ("objects").

An option can have a help text, a type and a range of possible values. Options may then be enumerated, read and written to.

Implementing AVOptions

This section describes how to add AVOptions capabilities to a struct.

All AVOptions-related information is stored in an AVClass. Therefore the first member of the struct should be a pointer to an AVClass describing it. The option field of the AVClass must be set to a NULL-terminated static array of AVOptions. Each AVOption must have a non-empty name, a type, a default value and for number-type AVOptions also a range of allowed values. It must also declare an offset in bytes from the start of the struct, where the field associated with this AVOption is located. Other fields in the AVOption struct should also be set when applicable, but are not required.

The following example illustrates an AVOptions-enabled struct:

typedef struct test_struct {

const AVClass *class;

int int_opt;

char *str_opt;

uint8_t *bin_opt;

int bin_len;

} test_struct;

static const AVOption test_options[] = {

{ "test_int", "This is a test option of int type.", offsetof(test_struct, int_opt),

AV_OPT_TYPE_INT, { .i64 = -1 }, INT_MIN, INT_MAX },

{ "test_str", "This is a test option of string type.", offsetof(test_struct, str_opt),

AV_OPT_TYPE_STRING },

{ "test_bin", "This is a test option of binary type.", offsetof(test_struct, bin_opt),

AV_OPT_TYPE_BINARY },

{ NULL },

};

static const AVClass test_class = {

.class_name = "test class",

.item_name = av_default_item_name,

.option = test_options,

.version = LIBAVUTIL_VERSION_INT,

};

Next, when allocating your struct, you must ensure that the AVClass pointer is set to the correct value. Then, av_opt_set_defaults() can be called to initialize defaults. After that the struct is ready to be used with the AVOptions API.

When cleaning up, you may use the av_opt_free() function to automatically free all the allocated string and binary options.

Continuing with the above example:

test_struct *alloc_test_struct(void)

{

test_struct *ret = av_mallocz(sizeof(*ret));

ret->class = &test_class;

av_opt_set_defaults(ret);

return ret;

}

void free_test_struct(test_struct **foo)

{

av_opt_free(*foo);

av_freep(foo);

}

Nesting

It may happen that an AVOptions-enabled struct contains another AVOptions-enabled struct as a member (e.g. AVCodecContext in libavcodec exports generic options, while its priv_data field exports codec-specific options). In such a case, it is possible to set up the parent struct to export a child's options. To do that, simply implement AVClass.child_next() and AVClass.child_class_next() in the parent struct's AVClass. Assuming that the test_struct from above now also contains a child_struct field:

typedef struct child_struct {

AVClass *class;

int flags_opt;

} child_struct;

static const AVOption child_opts[] = {

{ "test_flags", "This is a test option of flags type.",

offsetof(child_struct, flags_opt), AV_OPT_TYPE_FLAGS, { .i64 = 0 }, INT_MIN, INT_MAX },

{ NULL },

};

static const AVClass child_class = {

.class_name = "child class",

.item_name = av_default_item_name,

.option = child_opts,

.version = LIBAVUTIL_VERSION_INT,

};

void *child_next(void *obj, void *prev)

{

test_struct *t = obj;

if (!prev && t->child_struct)

return t->child_struct;

return NULL

}

const AVClass child_class_next(const AVClass *prev)

{

return prev ? NULL : &child_class;

}

Putting child_next() and child_class_next() as defined above into test_class will now make child_struct's options accessible through test_struct (again, proper setup as described above needs to be done on child_struct right after it is created).

From the above example it might not be clear why both child_next() and child_class_next() are needed. The distinction is that child_next() iterates over actually existing objects, while child_class_next() iterates over all possible child classes. E.g. if an AVCodecContext was initialized to use a codec which has private options, then its child_next() will return AVCodecContext.priv_data and finish iterating. OTOH child_class_next() on AVCodecContext.av_class will iterate over all available codecs with private options.

Named constants

It is possible to create named constants for options. Simply set the unit field of the option the constants should apply to a string and create the constants themselves as options of type AV_OPT_TYPE_CONST with their unit field set to the same string. Their default_val field should contain the value of the named constant. For example, to add some named constants for the test_flags option above, put the following into the child_opts array:

{ "test_flags", "This is a test option of flags type.",

offsetof(child_struct, flags_opt), AV_OPT_TYPE_FLAGS, { .i64 = 0 }, INT_MIN, INT_MAX, "test_unit" },

{ "flag1", "This is a flag with value 16", 0, AV_OPT_TYPE_CONST, { .i64 = 16 }, 0, 0, "test_unit" },

Using AVOptions

This section deals with accessing options in an AVOptions-enabled struct. Such structs in FFmpeg are e.g. AVCodecContext in libavcodec or AVFormatContext in libavformat.

Examining AVOptions

The basic functions for examining options are av_opt_next(), which iterates over all options defined for one object, and av_opt_find(), which searches for an option with the given name.

The situation is more complicated with nesting. An AVOptions-enabled struct may have AVOptions-enabled children. Passing the AV_OPT_SEARCH_CHILDREN flag to av_opt_find() will make the function search children recursively.

For enumerating there are basically two cases. The first is when you want to get all options that may potentially exist on the struct and its children (e.g. when constructing documentation). In that case you should call av_opt_child_class_next() recursively on the parent struct's AVClass. The second case is when you have an already initialized struct with all its children and you want to get all options that can be actually written or read from it. In that case you should call av_opt_child_next() recursively (and av_opt_next() on each result).

Reading and writing AVOptions

When setting options, you often have a string read directly from the user. In such a case, simply passing it to av_opt_set() is enough. For non-string type options, av_opt_set() will parse the string according to the option type.

Similarly av_opt_get() will read any option type and convert it to a string which will be returned. Do not forget that the string is allocated, so you have to free it with av_free().

In some cases it may be more convenient to put all options into an AVDictionary and call av_opt_set_dict() on it. A specific case of this are the format/codec open functions in lavf/lavc which take a dictionary filled with option as a parameter. This makes it possible to set some options that cannot be set otherwise, since e.g. the input file format is not known before the file is actually opened.

Macro Definition Documentation

#define AV_OPT_SEARCH_CHILDREN (1 << 0)

Search in possible children of the given object first.

Examples:: filter_audio.c, filtering_audio.c, filtering_video.c, http_multiclient.c, and transcoding.c.

Definition at line 555 of file opt.h.

Referenced by av_bsf_list_append2(), av_opt_find2(), av_probe_input_buffer2(), avfilter_init_dict(), avformat_find_stream_info(), configure_output_audio_filter(), estimate_timings_from_pts(), ff_rtp_chain_mux_open(), init(), init_filter(), init_filter_graph(), init_filters(), init_muxer(), insert_trim(), lavfi_read_header(), list_devices_for_context(), mpjpeg_get_boundary(), open_input_file(), open_output_file(), open_url(), opt_default(), parse_key_value_pair(), parse_manifest(), parse_playlist(), pcm_read_header(), process_client(), process_options(), read_data(), read_frame_internal(), save_avio_options(), update_options(), and writer_open().

#define AV_OPT_SEARCH_FAKE_OBJ (1 << 1)

The obj passed to av_opt_find() is fake – only a double pointer to AVClass instead of a required pointer to a struct containing AVClass.

This is useful for searching for options without needing to allocate the corresponding object.

Definition at line 564 of file opt.h.

Referenced by av_opt_find2(), av_opt_ptr(), filter_codec_opts(), init(), init_dict(), open_input_file(), open_output_file(), opt_default(), opt_list(), and process_options().

#define AV_OPT_ALLOW_NULL (1 << 2)

In av_opt_get, return NULL if the option has a pointer type and is set to NULL, rather than returning an empty string.

Definition at line 570 of file opt.h.

Referenced by av_opt_get(), and save_avio_options().

#define AV_OPT_MULTI_COMPONENT_RANGE (1 << 12)

Allows av_opt_query_ranges and av_opt_query_ranges_default to return more than one component for certain option types.

See Also: AVOptionRanges for details.

Definition at line 577 of file opt.h.

Referenced by av_opt_query_ranges().

#define AV_OPT_SERIALIZE_SKIP_DEFAULTS 0x00000001

Serialize options that are not set to default values only.

Definition at line 838 of file opt.h.

Referenced by av_opt_serialize().

#define AV_OPT_SERIALIZE_OPT_FLAGS_EXACT 0x00000002

Serialize options that exactly match opt_flags only.

Definition at line 839 of file opt.h.

Referenced by av_opt_serialize().

Enumeration Type Documentation

enum AVOptionType

Enumerator
AV_OPT_TYPE_FLAGS
AV_OPT_TYPE_INT
AV_OPT_TYPE_INT64
AV_OPT_TYPE_DOUBLE
AV_OPT_TYPE_FLOAT
AV_OPT_TYPE_STRING
AV_OPT_TYPE_RATIONAL
AV_OPT_TYPE_BINARY	offset must point to a pointer immediately followed by an int for the length
AV_OPT_TYPE_DICT
AV_OPT_TYPE_UINT64
AV_OPT_TYPE_CONST
AV_OPT_TYPE_IMAGE_SIZE	offset must point to two consecutive integers
AV_OPT_TYPE_PIXEL_FMT
AV_OPT_TYPE_SAMPLE_FMT
AV_OPT_TYPE_VIDEO_RATE	offset must point to AVRational
AV_OPT_TYPE_DURATION
AV_OPT_TYPE_COLOR
AV_OPT_TYPE_CHANNEL_LAYOUT
AV_OPT_TYPE_BOOL

Definition at line 221 of file opt.h.

anonymous enum

Enumerator
AV_OPT_FLAG_IMPLICIT_KEY	Accept to parse a value without a key; the key will then be returned as NULL.

Definition at line 522 of file opt.h.

Function Documentation

int av_opt_show2 ( void * obj,

void * av_log_obj,

int req_flags,

int rej_flags

)

Show the obj options.

Parameters: req_flags requested flags for the options to show. Show only the options for which it is opt->flags & req_flags.

rej_flags rejected flags for the options to show. Show only the options for which it is !(opt->flags & req_flags).

av_log_obj log context to use for showing the options

Definition at line 1280 of file opt.c.

Referenced by main(), and show_help_children().

void av_opt_set_defaults ( void * s )

Set the values of all AVOption fields to their default values.

Parameters: s an AVOption-enabled struct (its first member must be a pointer to AVClass)

Definition at line 1292 of file opt.c.

Referenced by av_bsf_alloc(), avcodec_dct_alloc(), avcodec_open2(), avdevice_capabilities_create(), avfilter_graph_alloc(), avformat_alloc_output_context2(), avformat_get_context_defaults(), avformat_open_input(), avresample_alloc_context(), chunk_mux_init(), ff_alloc_input_device_context(), ff_filter_alloc(), ff_framesync_preinit(), init_context_defaults(), init_muxer(), main(), swr_alloc(), sws_alloc_context(), url_alloc_for_protocol(), and writer_open().

void av_opt_set_defaults2 ( void * s,

int mask,

int flags

)

Set the values of all AVOption fields to their default values.

Only these AVOption fields for which (opt->flags & mask) == flags will have their default applied to s.

Parameters: s an AVOption-enabled struct (its first member must be a pointer to AVClass)

mask combination of AV_OPT_FLAG_*

flags combination of AV_OPT_FLAG_*

Definition at line 1297 of file opt.c.

Referenced by av_opt_set_defaults(), and init_context_defaults().

int av_set_options_string ( void * ctx,

const char * opts,

const char * key_val_sep,

const char * pairs_sep

)

Parse the key/value pairs list in opts.

For each key/value pair found, stores the value in the field in ctx that is named like the key. ctx must be an AVClass context, storing is done using AVOptions.

Parameters: opts options string to parse, may be NULL

key_val_sep a 0-terminated list of characters used to separate key from value

pairs_sep a 0-terminated list of characters used to separate two pairs from each other

Returns: the number of successfully set key/value pairs, or a negative value corresponding to an AVERROR code in case of error: AVERROR(EINVAL) if opts cannot be parsed, the error code issued by av_opt_set() if a key/value pair cannot be set

Definition at line 1413 of file opt.c.

Referenced by command(), and main().

int av_opt_set_from_string ( void * ctx,

const char * opts,

const char *const * shorthand,

const char * key_val_sep,

const char * pairs_sep

)

Parse the key-value pairs list in opts.

For each key=value pair found, set the value of the corresponding option in ctx.

Parameters: ctx the AVClass object to set options on

opts the options string, key-value pairs separated by a delimiter

shorthand a NULL-terminated array of options names for shorthand notation: if the first field in opts has no key part, the key is taken from the first element of shorthand; then again for the second, etc., until either opts is finished, shorthand is finished or a named option is found; after that, all options must be named

key_val_sep a 0-terminated list of characters used to separate key from value, for example '='

pairs_sep a 0-terminated list of characters used to separate two pairs from each other, for example ':' or ','

Returns: the number of successfully set key=value pairs, or a negative value corresponding to an AVERROR code in case of error: AVERROR(EINVAL) if opts cannot be parsed, the error code issued by av_set_string3() if a key/value pair cannot be set

Options names must use only the following characters: a-z A-Z 0-9 - . / _ Separators must use characters distinct from option names and from each other.

Definition at line 1493 of file opt.c.

Referenced by av_bitstream_filter_filter(), ff_stream_add_bitstream_filter(), main(), and new_output_stream().

void av_opt_free ( void * obj )

Free all allocated objects in obj.

Definition at line 1545 of file opt.c.

Referenced by av_bsf_free(), av_write_trailer(), avcodec_close(), avfilter_free(), avformat_free_context(), avio_close(), avresample_free(), copy_context_reset(), ff_frame_thread_free(), ffurl_closep(), main(), seg_write_trailer(), uninit(), and writer_close().

int av_opt_flag_is_set ( void * obj,

const char * field_name,

const char * flag_name

)

Check whether a particular flag is set in a flags field.

Parameters: field_name the name of the flag field option

flag_name the name of the flag to check

Returns: non-zero if the flag is set, zero if the flag isn't set, isn't of the right type, or the flags field doesn't exist.

Definition at line 1011 of file opt.c.

Referenced by ff_rtp_get_payload_type().

int av_opt_set_dict ( void * obj,

struct AVDictionary ** options

)

Set all the options from a given dictionary on an object.

Parameters: obj a struct whose first element is a pointer to AVClass

options options to process. This dictionary will be freed and replaced by a new one containing all options not found in obj. Of course this new dictionary needs to be freed by caller with av_dict_free().

Returns: 0 on success, a negative AVERROR if some option was found in obj, but could not be set.

See Also: av_dict_copy()

Definition at line 1590 of file opt.c.

Referenced by avcodec_open2(), avdevice_capabilities_create(), avfilter_init_dict(), avformat_open_input(), avio_open_dir(), config_output(), ffurl_open_whitelist(), init_muxer(), and init_output_stream_streamcopy().

int av_opt_set_dict2 ( void * obj,

struct AVDictionary ** options,

int search_flags

)

Set all the options from a given dictionary on an object.

Parameters: obj a struct whose first element is a pointer to AVClass

options options to process. This dictionary will be freed and replaced by a new one containing all options not found in obj. Of course this new dictionary needs to be freed by caller with av_dict_free().

search_flags A combination of AV_OPT_SEARCH_*.

Returns: 0 on success, a negative AVERROR if some option was found in obj, but could not be set.

See Also: av_dict_copy()

Definition at line 1565 of file opt.c.

Referenced by av_bsf_list_append2(), av_opt_set_dict(), avfilter_init_dict(), init_muxer(), and list_devices_for_context().

int av_opt_get_key_value ( const char ** ropts,

const char * key_val_sep,

const char * pairs_sep,

unsigned flags,

char ** rkey,

char ** rval

)

Extract a key-value pair from the beginning of a string.

Parameters: ropts pointer to the options string, will be updated to point to the rest of the string (one of the pairs_sep or the final NUL)

key_val_sep a 0-terminated list of characters used to separate key from value, for example '='

pairs_sep a 0-terminated list of characters used to separate two pairs from each other, for example ':' or ','

flags flags; see the AV_OPT_FLAG_* values below

rkey parsed key; must be freed using av_free()

rval parsed value; must be freed using av_free()

Returns: >=0 for success, or a negative value corresponding to an AVERROR code in case of error; in particular: AVERROR(EINVAL) if no key is present

Definition at line 1471 of file opt.c.

Referenced by av_opt_set_from_string(), ff_tee_parse_slave_options(), init_report(), and process_options().

const AVOption* av_opt_find ( void * obj,

const char * name,

const char * unit,

int opt_flags,

int search_flags

)

Look for an option in an object.

Consider only options which have all the specified flags set.

Parameters: [in] obj A pointer to a struct whose first element is a pointer to an AVClass. Alternatively a double pointer to an AVClass, if AV_OPT_SEARCH_FAKE_OBJ search flag is set.

[in] name The name of the option to look for.

[in] unit When searching for named constants, name of the unit it belongs to.

opt_flags Find only options with all the specified flags set (AV_OPT_FLAG).

search_flags A combination of AV_OPT_SEARCH_*.

Returns: A pointer to the option found, or NULL if no option was found.

Note: Options found with AV_OPT_SEARCH_CHILDREN flag may not be settable directly with av_opt_set(). Use special calls which take an options AVDictionary (e.g. avformat_open_input()) to set options found with this flag.

Definition at line 1595 of file opt.c.

Referenced by add_input_streams(), av_opt_flag_is_set(), av_opt_query_ranges_default(), filter_codec_opts(), init(), init_dict(), open_input_file(), open_output_file(), opt_find(), process_options(), set_encoder_id(), and set_string_number().

const AVOption* av_opt_find2 ( void * obj,

const char * name,

const char * unit,

int opt_flags,

int search_flags,

void ** target_obj

)

Look for an option in an object.

Consider only options which have all the specified flags set.

Parameters: [in] obj A pointer to a struct whose first element is a pointer to an AVClass. Alternatively a double pointer to an AVClass, if AV_OPT_SEARCH_FAKE_OBJ search flag is set.

[in] name The name of the option to look for.

[in] unit When searching for named constants, name of the unit it belongs to.

opt_flags Find only options with all the specified flags set (AV_OPT_FLAG).

search_flags A combination of AV_OPT_SEARCH_*.

[out] target_obj if non-NULL, an object to which the option belongs will be written here. It may be different from obj if AV_OPT_SEARCH_CHILDREN is present in search_flags. This parameter is ignored if search_flags contain AV_OPT_SEARCH_FAKE_OBJ.

Returns: A pointer to the option found, or NULL if no option was found.

Definition at line 1601 of file opt.c.

Referenced by av_opt_find(), av_opt_find2(), av_opt_get(), av_opt_get_channel_layout(), av_opt_get_dict_val(), av_opt_get_image_size(), av_opt_is_set_to_default_by_name(), av_opt_ptr(), av_opt_set(), av_opt_set_bin(), av_opt_set_channel_layout(), av_opt_set_dict_val(), av_opt_set_image_size(), av_opt_set_video_rate(), get_format(), get_number(), set_format(), and set_number().

const AVOption* av_opt_next ( const void * obj,

const AVOption * prev

)

Iterate over all AVOptions belonging to obj.

Parameters: obj an AVOptions-enabled struct or a double pointer to an AVClass describing it.

prev result of the previous call to av_opt_next() on this object or NULL

Returns: next AVOption or NULL

Definition at line 45 of file opt.c.

Referenced by av_bitstream_filter_filter(), av_opt_copy(), av_opt_find2(), av_opt_free(), av_opt_serialize(), av_opt_set_defaults2(), check_video_streams(), dump_video_streams(), ff_stream_add_bitstream_filter(), get_opt_const_name(), get_opt_flags_string(), main(), new_output_stream(), opt_list(), process_options(), set_string_number(), and show_stream().

void* av_opt_child_next ( void * obj,

void * prev

)

Iterate over AVOptions-enabled children of obj.

Parameters: prev result of a previous call to this function or NULL

Returns: next AVOptions-enabled child or NULL

Definition at line 1645 of file opt.c.

Referenced by av_opt_find2().

const AVClass* av_opt_child_class_next ( const AVClass * parent,

const AVClass * prev

)

Iterate over potential AVOptions-enabled children of parent.

Parameters: prev result of a previous call to this function or NULL

Returns: AVClass corresponding to next potential child or NULL

Definition at line 1653 of file opt.c.

Referenced by av_opt_find2(), and show_help_children().

void* av_opt_ptr ( const AVClass * avclass,

void * obj,

const char * name

)

Gets a pointer to the requested field in a struct.

This function allows accessing a struct even when its fields are moved or renamed since the application making the access has been compiled,

Returns: a pointer to the field, it can be cast to the correct type and read or written to.

Definition at line 1660 of file opt.c.

Referenced by avformat_find_stream_info().

void av_opt_freep_ranges ( AVOptionRanges ** ranges )

Free an AVOptionRanges struct and set it to NULL.

Definition at line 1853 of file opt.c.

Referenced by opt_list().

int av_opt_query_ranges ( AVOptionRanges ** ,

void * obj,

const char * key,

int flags

)

Get a list of allowed ranges for the given option.

The returned list may depend on other fields in obj like for example profile.

Parameters: flags is a bitmask of flags, undefined flags should not be set and should be ignored AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component,

See Also: AVOptionRanges

The result must be freed with av_opt_freep_ranges.

Returns: number of compontents returned on success, a negative errro code otherwise

Definition at line 1760 of file opt.c.

Referenced by opt_list().

int av_opt_copy ( void * dest,

const void * src

)

Copy options from src object into dest object.

Options that require memory allocation (e.g. string or binary) are malloc'ed in dest object. Original memory allocated for such options is freed unless both src and dest options points to the same memory.

Parameters: dest Object to copy from

src Object to copy into

Returns: 0 on success, negative on error

Definition at line 1703 of file opt.c.

Referenced by avcodec_copy_context(), ff_frame_thread_encoder_init(), and ffurl_open_whitelist().

int av_opt_query_ranges_default ( AVOptionRanges ** ,

void * obj,

const char * key,

int flags

)

Get a default list of allowed ranges for the given option.

This list is constructed without using the AVClass.query_ranges() callback and can be used as fallback from within the callback.

Parameters: flags is a bitmask of flags, undefined flags should not be set and should be ignored AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component,

See Also: AVOptionRanges

The result must be freed with av_opt_free_ranges.

Returns: number of compontents returned on success, a negative errro code otherwise

Definition at line 1781 of file opt.c.

Referenced by av_opt_query_ranges().

int av_opt_is_set_to_default ( void * obj,

const AVOption * o

)

Check if given option is set to its default value.

Options o must belong to the obj. This function must not be called to check child's options state.

See Also: av_opt_is_set_to_default_by_name().

Parameters: obj AVClass object to check option on

o option to be checked

Returns: >0 when option is set to its default, 0 when option is not set its default, <0 on error

Definition at line 1872 of file opt.c.

Referenced by av_opt_is_set_to_default_by_name(), and av_opt_serialize().

int av_opt_is_set_to_default_by_name ( void * obj,

const char * name,

int search_flags

)

Check if given option is set to its default value.

Parameters: obj AVClass object to check option on

name option name

search_flags combination of AV_OPT_SEARCH_*

Returns: >0 when option is set to its default, 0 when option is not set its default, <0 on error

Definition at line 1969 of file opt.c.

Referenced by main().

int av_opt_serialize ( void * obj,

int opt_flags,

int flags,

char ** buffer,

const char key_val_sep,

const char pairs_sep

)

Serialize object's options.

Create a string containing object's serialized options. Such string may be passed back to av_opt_set_from_string() in order to restore option values. A key/value or pairs separator occurring in the serialized value or name string are escaped through the av_escape() function.

Parameters: [in] obj AVClass object to serialize

[in] opt_flags serialize options with all the specified flags set (AV_OPT_FLAG)

[in] flags combination of AV_OPT_SERIALIZE_* flags

[out] buffer Pointer to buffer that will be allocated with string containg serialized options. Buffer must be freed by the caller when is no longer needed.

[in] key_val_sep character used to separate key from value

[in] pairs_sep character used to separate two pairs from each other

Returns: >= 0 on success, negative on error

Warning: Separators cannot be neither '\' nor '0円'. They also cannot be the same.

Definition at line 1981 of file opt.c.

Referenced by main().

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