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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   0x0001
 Search in possible children of the given object first.
 
#define AV_OPT_SEARCH_FAKE_OBJ   0x0002
 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.
 
#define AV_OPT_MULTI_COMPONENT_RANGE   0x1000
 Allows av_opt_query_ranges and av_opt_query_ranges_default to return more than one component for certain option types.
 

Enumerations

enum  AVOptionType {
  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,
  AV_OPT_TYPE_DICT, AV_OPT_TYPE_CONST = 128, AV_OPT_TYPE_IMAGE_SIZE = MKBETAG('S','I','Z','E'), AV_OPT_TYPE_PIXEL_FMT = MKBETAG('P','F','M','T'),
  AV_OPT_TYPE_SAMPLE_FMT = MKBETAG('S','F','M','T'), AV_OPT_TYPE_VIDEO_RATE = MKBETAG('V','R','A','T'), AV_OPT_TYPE_DURATION = MKBETAG('D','U','R',' '), AV_OPT_TYPE_COLOR = MKBETAG('C','O','L','R'),
  AV_OPT_TYPE_CHANNEL_LAYOUT = MKBETAG('C','H','L','A'), FF_OPT_TYPE_FLAGS = 0, FF_OPT_TYPE_INT, FF_OPT_TYPE_INT64,
  FF_OPT_TYPE_DOUBLE, FF_OPT_TYPE_FLOAT, FF_OPT_TYPE_STRING, FF_OPT_TYPE_RATIONAL,
  FF_OPT_TYPE_BINARY, FF_OPT_TYPE_CONST =128
}
 
enum  { AV_OPT_FLAG_IMPLICIT_KEY = 1 }
 

Functions

attribute_deprecated int av_set_string3 (void *obj, const char *name, const char *val, int alloc, const AVOption **o_out)
 Set the field of obj with the given name to value.
 
attribute_deprecated const
AVOption
av_set_double (void *obj, const char *name, double n)
 
attribute_deprecated const
AVOption
av_set_q (void *obj, const char *name, AVRational n)
 
attribute_deprecated const
AVOption
av_set_int (void *obj, const char *name, int64_t n)
 
double av_get_double (void *obj, const char *name, const AVOption **o_out)
 
AVRational av_get_q (void *obj, const char *name, const AVOption **o_out)
 
int64_t av_get_int (void *obj, const char *name, const AVOption **o_out)
 
attribute_deprecated const char * av_get_string (void *obj, const char *name, const AVOption **o_out, char *buf, int buf_len)
 
attribute_deprecated const
AVOption
av_next_option (void *obj, const AVOption *last)
 
int av_opt_show2 (void *obj, void *av_log_obj, int req_flags, int rej_flags)
 Show the obj options.
 
void av_opt_set_defaults (void *s)
 Set the values of all AVOption fields to their default values.
 
attribute_deprecated void av_opt_set_defaults2 (void *s, int mask, int flags)
 
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.
 
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.
 
void av_opt_free (void *obj)
 Free all allocated objects in obj.
 
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.
 
int av_opt_set_dict (void *obj, struct AVDictionary **options)
 Set all the options from a given dictionary on an object.
 
int av_opt_set_dict2 (void *obj, struct AVDictionary **options, int search_flags)
 Set all the options from a given dictionary on an object.
 
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.
 
const AVOptionav_opt_find (void *obj, const char *name, const char *unit, int opt_flags, int search_flags)
 Look for an option in an object.
 
const AVOptionav_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.
 
const AVOptionav_opt_next (void *obj, const AVOption *prev)
 Iterate over all AVOptions belonging to obj.
 
voidav_opt_child_next (void *obj, void *prev)
 Iterate over AVOptions-enabled children of obj.
 
const AVClassav_opt_child_class_next (const AVClass *parent, const AVClass *prev)
 Iterate over potential AVOptions-enabled children of parent.
 
voidav_opt_ptr (const AVClass *avclass, void *obj, const char *name)
 Gets a pointer to the requested field in a struct.
 
void av_opt_freep_ranges (AVOptionRanges **ranges)
 Free an AVOptionRanges struct and set it to NULL.
 
int av_opt_query_ranges (AVOptionRanges **, void *obj, const char *key, int flags)
 Get a list of allowed ranges for the given option.
 
int av_opt_copy (void *dest, void *src)
 
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.
 

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 {
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),
{ "test_bin", "This is a test option of binary type.", offsetof(test_struct, bin_opt),
{ NULL },
};
static const AVClass test_class = {
.class_name = "test class",
.item_name = av_default_item_name,
.option = test_options,
};

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_malloc(sizeof(*ret));
ret->class = &test_class;
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,
};
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 allows 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   0x0001
#define AV_OPT_SEARCH_FAKE_OBJ   0x0002

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 609 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_MULTI_COMPONENT_RANGE   0x1000

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 616 of file opt.h.

Referenced by av_opt_query_ranges().

Enumeration Type Documentation

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_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 
FF_OPT_TYPE_FLAGS 
FF_OPT_TYPE_INT 
FF_OPT_TYPE_INT64 
FF_OPT_TYPE_DOUBLE 
FF_OPT_TYPE_FLOAT 
FF_OPT_TYPE_STRING 
FF_OPT_TYPE_RATIONAL 
FF_OPT_TYPE_BINARY 

offset must point to a pointer immediately followed by an int for the length

FF_OPT_TYPE_CONST 

Definition at line 220 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 568 of file opt.h.

Function Documentation

attribute_deprecated int av_set_string3 ( void obj,
const char *  name,
const char *  val,
int  alloc,
const AVOption **  o_out 
)

Set the field of obj with the given name to value.

Parameters
[in]objA struct whose first element is a pointer to an AVClass.
[in]namethe name of the field to set
[in]valThe value to set. If the field is not of a string type, then the given string is parsed. SI postfixes and some named scalars are supported. If the field is of a numeric type, it has to be a numeric or named scalar. Behavior with more than one scalar and +- infix operators is undefined. If the field is of a flags type, it has to be a sequence of numeric scalars or named flags separated by '+' or '-'. Prefixing a flag with '+' causes it to be set without affecting the other flags; similarly, '-' unsets a flag.
[out]o_outif non-NULL put here a pointer to the AVOption found
allocthis parameter is currently ignored
Returns
0 if the value has been set, or an AVERROR code in case of error: AVERROR_OPTION_NOT_FOUND if no matching option exists AVERROR(ERANGE) if the value is out of range AVERROR(EINVAL) if the value is not valid
Deprecated:
use av_opt_set()

Definition at line 350 of file opt.c.

attribute_deprecated const AVOption* av_set_double ( void obj,
const char *  name,
double  n 
)

Definition at line 456 of file opt.c.

attribute_deprecated const AVOption* av_set_q ( void obj,
const char *  name,
AVRational  n 
)

Definition at line 464 of file opt.c.

attribute_deprecated const AVOption* av_set_int ( void obj,
const char *  name,
int64_t  n 
)

Definition at line 472 of file opt.c.

double av_get_double ( void obj,
const char *  name,
const AVOption **  o_out 
)

Definition at line 770 of file opt.c.

AVRational av_get_q ( void obj,
const char *  name,
const AVOption **  o_out 
)

Definition at line 781 of file opt.c.

int64_t av_get_int ( void obj,
const char *  name,
const AVOption **  o_out 
)

Definition at line 795 of file opt.c.

Referenced by config_output(), and query_formats().

attribute_deprecated const char* av_get_string ( void obj,
const char *  name,
const AVOption **  o_out,
char *  buf,
int  buf_len 
)
Parameters
bufa buffer which is used for returning non string values as strings, can be NULL
buf_lenallocated length in bytes of buf

Definition at line 626 of file opt.c.

attribute_deprecated const AVOption* av_next_option ( void obj,
const AVOption last 
)

Definition at line 44 of file opt.c.

Referenced by print_option(), and show_opts().

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

Show the obj options.

Parameters
req_flagsrequested flags for the options to show. Show only the options for which it is opt->flags & req_flags.
rej_flagsrejected flags for the options to show. Show only the options for which it is !(opt->flags & req_flags).
av_log_objlog context to use for showing the options

Definition at line 1150 of file opt.c.

Referenced by show_help_children().

void av_opt_set_defaults ( void s)
attribute_deprecated void av_opt_set_defaults2 ( void s,
int  mask,
int  flags 
)

Definition at line 1168 of file opt.c.

Referenced by av_opt_set_defaults(), and avcodec_get_context_defaults3().

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
optsoptions string to parse, may be NULL
key_val_sepa 0-terminated list of characters used to separate key from value
pairs_sepa 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_set_string3() if a key/value pair cannot be set

Definition at line 1285 of file opt.c.

Referenced by command().

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
ctxthe AVClass object to set options on
optsthe options string, key-value pairs separated by a delimiter
shorthanda 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_sepa 0-terminated list of characters used to separate key from value, for example '='
pairs_sepa 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 1365 of file opt.c.

void av_opt_free ( void obj)
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_namethe name of the flag field option
flag_namethe 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 943 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
obja struct whose first element is a pointer to AVClass
optionsoptions 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 1461 of file opt.c.

Referenced by avcodec_open2(), avdevice_capabilities_create(), avfilter_init_dict(), avformat_open_input(), config_output(), ffurl_open(), and init_muxer().

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
obja struct whose first element is a pointer to AVClass
optionsoptions 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_flagsA 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 1437 of file opt.c.

Referenced by av_opt_set_dict(), and init_muxer().

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
roptspointer 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_sepa 0-terminated list of characters used to separate key from value, for example '='
pairs_sepa 0-terminated list of characters used to separate two pairs from each other, for example ':' or ','
flagsflags; see the AV_OPT_FLAG_* values below
rkeyparsed key; must be freed using av_free()
rvalparsed 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 1343 of file opt.c.

Referenced by av_opt_set_from_string(), init_report(), opt_opencl(), parse_slave_options(), 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]objA 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]nameThe name of the option to look for.
[in]unitWhen searching for named constants, name of the unit it belongs to.
opt_flagsFind only options with all the specified flags set (AV_OPT_FLAG).
search_flagsA 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_set_string3(). Use special calls which take an options AVDictionary (e.g. avformat_open_input()) to set options found with this flag.

Definition at line 1466 of file opt.c.

Referenced by add_input_streams(), av_get_string(), av_opt_flag_is_set(), av_opt_query_ranges_default(), av_set_double(), av_set_int(), av_set_q(), av_set_string3(), ffserver_opt_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]objA 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]nameThe name of the option to look for.
[in]unitWhen searching for named constants, name of the unit it belongs to.
opt_flagsFind only options with all the specified flags set (AV_OPT_FLAG).
search_flagsA combination of AV_OPT_SEARCH_*.
[out]target_objif 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 1472 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_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 ( void obj,
const AVOption prev 
)

Iterate over all AVOptions belonging to obj.

Parameters
objan AVOptions-enabled struct or a double pointer to an AVClass describing it.
prevresult of the previous call to av_opt_next() on this object or NULL
Returns
next AVOption or NULL

Definition at line 50 of file opt.c.

Referenced by av_next_option(), av_opt_copy(), av_opt_find2(), av_opt_free(), av_opt_set_defaults2(), 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
prevresult of a previous call to this function or NULL
Returns
next AVOptions-enabled child or NULL

Definition at line 1516 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
prevresult of a previous call to this function or NULL
Returns
AVClass corresponding to next potential child or NULL

Definition at line 1524 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 1531 of file opt.c.

Referenced by decode_video(), and dump_stream_format().

void av_opt_freep_ranges ( AVOptionRanges **  ranges)

Free an AVOptionRanges struct and set it to NULL.

Definition at line 1696 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
flagsis 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 1605 of file opt.c.

Referenced by opt_list().

int av_opt_copy ( void dest,
void src 
)

Definition at line 1561 of file opt.c.

Referenced by avcodec_copy_context().

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
flagsis 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 1626 of file opt.c.

Referenced by av_opt_query_ranges().