Logging Facility

Modules
	Logging Constants

Macros
#define	AV_LOG_C(x)   ((x) << 8)
	Sets additional colors for extended debugging sessions. More...
#define	AV_LOG_SKIP_REPEATED   1
	Skip repeated messages, this requires the user app to use av_log() instead of (f)printf as the 2 would otherwise interfere and lead to "Last message repeated x times" messages below (f)printf messages with some bad luck. More...
#define	AV_LOG_PRINT_LEVEL   2
	Include the log severity in messages originating from codecs. More...

Functions
void	av_log (void *avcl, int level, const char *fmt,...) av_printf_format(3
	Send the specified message to the log if the level is less than or equal to the current av_log_level. More...
void void	av_log_once (void *avcl, int initial_level, int subsequent_level, int *state, const char *fmt,...) av_printf_format(5
	Send the specified message to the log once with the initial_level and then with the subsequent_level. More...
void void void	av_vlog (void *avcl, int level, const char *fmt, va_list vl)
	Send the specified message to the log if the level is less than or equal to the current av_log_level. More...
int	av_log_get_level (void)
	Get the current log level. More...
void	av_log_set_level (int level)
	Set the log level. More...
void	av_log_set_callback (void(*callback)(void *, int, const char *, va_list))
	Set the logging callback. More...
void	av_log_default_callback (void *avcl, int level, const char *fmt, va_list vl)
	Default logging callback. More...
const char *	av_default_item_name (void *ctx)
	Return the context name. More...
AVClassCategory	av_default_get_category (void *ptr)
void	av_log_format_line (void *ptr, int level, const char *fmt, va_list vl, char *line, int line_size, int *print_prefix)
	Format a line of log the same way as the default callback. More...
int	av_log_format_line2 (void *ptr, int level, const char *fmt, va_list vl, char *line, int line_size, int *print_prefix)
	Format a line of log the same way as the default callback. More...
void	av_log_set_flags (int arg)
int	av_log_get_flags (void)

Detailed Description

Macro Definition Documentation

AV_LOG_C

#define AV_LOG_C

(

x

)

((x) << 8)

Sets additional colors for extended debugging sessions.

av_log(ctx, AV_LOG_DEBUG|AV_LOG_C(134), "Message in purple\n");

Requires 256color terminal support. Uses outside debugging is not recommended.

Definition at line 222 of file log.h.

AV_LOG_SKIP_REPEATED

#define AV_LOG_SKIP_REPEATED   1

Skip repeated messages, this requires the user app to use av_log() instead of (f)printf as the 2 would otherwise interfere and lead to "Last message repeated x times" messages below (f)printf messages with some bad luck.

Also to receive the last, "last repeated" line if any, the user app must call av_log(NULL, AV_LOG_QUIET, "%s", ""); at the end

Definition at line 370 of file log.h.

AV_LOG_PRINT_LEVEL

#define AV_LOG_PRINT_LEVEL   2

Include the log severity in messages originating from codecs.

Results in messages such as: [rawvideo @ 0xDEADBEEF] [error] encode did not produce valid pts

Definition at line 378 of file log.h.

Function Documentation

av_log()

void av_log	(	void *	avcl,
		int	level,
		const char *	fmt,
			...
	)

Send the specified message to the log if the level is less than or equal to the current av_log_level.

By default, all logging messages are sent to stderr. This behavior can be altered by setting a different logging callback function.

See also

av_log_set_callback

Parameters

avcl	A pointer to an arbitrary struct of which the first field is a pointer to an AVClass struct or NULL if general log.
level	The importance level of the message expressed using a Logging Constant.
fmt	The format string (printf-compatible) that specifies how subsequent arguments are converted to output.

Examples

filter_audio.c, filtering_audio.c, filtering_video.c, http_multiclient.c, metadata.c, and transcoding.c.

Referenced by encode_write_frame(), filter_encode_write_frame(), flush_encoder(), init_filter(), init_filter_graph(), init_filters(), list_op(), main(), open_input_file(), open_output_file(), and process_client().

av_log_once()

void void av_log_once	(	void *	avcl,
		int	initial_level,
		int	subsequent_level,
		int *	state,
		const char *	fmt,
			...
	)

Send the specified message to the log once with the initial_level and then with the subsequent_level.

By default, all logging messages are sent to stderr. This behavior can be altered by setting a different logging callback function.

See also

av_log

Parameters

avcl	A pointer to an arbitrary struct of which the first field is a pointer to an AVClass struct or NULL if general log.
initial_level	importance level of the message expressed using a Logging Constant for the first occurance.
subsequent_level	importance level of the message expressed using a Logging Constant after the first occurance.
fmt	The format string (printf-compatible) that specifies how subsequent arguments are converted to output.
state	a variable to keep trak of if a message has already been printed this must be initialized to 0 before the first use. The same state must not be accessed by 2 Threads simultaneously.

av_vlog()

void void void av_vlog	(	void *	avcl,
		int	level,
		const char *	fmt,
		va_list	vl
	)

Send the specified message to the log if the level is less than or equal to the current av_log_level.

By default, all logging messages are sent to stderr. This behavior can be altered by setting a different logging callback function.

See also

av_log_set_callback

Parameters

avcl	A pointer to an arbitrary struct of which the first field is a pointer to an AVClass struct.
level	The importance level of the message expressed using a Logging Constant.
fmt	The format string (printf-compatible) that specifies how subsequent arguments are converted to output.
vl	The arguments referenced by the format string.

av_log_get_level()

int av_log_get_level

(

void

)

Get the current log level.

See also

Logging Constants

Returns

Current log level

av_log_set_level()

void av_log_set_level

(

int

level

)

Set the log level.

See also

Logging Constants

Parameters

level

Logging level

Examples

http_multiclient.c.

Referenced by main().

av_log_set_callback()

void av_log_set_callback

(

void(*)(void *, int, const char *, va_list)

callback

)

Set the logging callback.

Note

The callback must be thread safe, even if the application does not use threads itself as some codecs are multithreaded.

See also

av_log_default_callback

Parameters

callback

A logging function with a compatible signature.

av_log_default_callback()

void av_log_default_callback	(	void *	avcl,
		int	level,
		const char *	fmt,
		va_list	vl
	)

Default logging callback.

It prints the message to stderr, optionally colorizing it.

Parameters

avcl	A pointer to an arbitrary struct of which the first field is a pointer to an AVClass struct.
level	The importance level of the message expressed using a Logging Constant.
fmt	The format string (printf-compatible) that specifies how subsequent arguments are converted to output.
vl	The arguments referenced by the format string.

av_default_item_name()

const char * av_default_item_name

(

void *

ctx

)

Return the context name.

Parameters

ctx	The AVClass context

Returns

The AVClass class_name

av_default_get_category()

AVClassCategory av_default_get_category

(

void *

ptr

)

av_log_format_line()

void av_log_format_line	(	void *	ptr,
		int	level,
		const char *	fmt,
		va_list	vl,
		char *	line,
		int	line_size,
		int *	print_prefix
	)

Format a line of log the same way as the default callback.

Parameters

line	buffer to receive the formatted line
line_size	size of the buffer
print_prefix	used to store whether the prefix must be printed; must point to a persistent integer initially set to 1

av_log_format_line2()

int av_log_format_line2	(	void *	ptr,
		int	level,
		const char *	fmt,
		va_list	vl,
		char *	line,
		int	line_size,
		int *	print_prefix
	)

Format a line of log the same way as the default callback.

Parameters

line	buffer to receive the formatted line; may be NULL if line_size is 0
line_size	size of the buffer; at most line_size-1 characters will be written to the buffer, plus one null terminator
print_prefix	used to store whether the prefix must be printed; must point to a persistent integer initially set to 1

Returns

Returns a negative value if an error occurred, otherwise returns the number of characters that would have been written for a sufficiently large buffer, not including the terminating null character. If the return value is not less than line_size, it means that the log message was truncated to fit the buffer.

av_log_set_flags()

void av_log_set_flags

(

int

arg

)

av_log_get_flags()

int av_log_get_flags

(

void

)