libavdevice

Special devices muxing/demuxing library. Подробнее...

Файлы
файл	avdevice.h
файл	version.h

Классы
struct	AVDeviceRect
struct	AVDeviceCapabilitiesQuery
struct	AVDeviceInfo
struct	AVDeviceInfoList

Определения типов
typedef struct AVDeviceRect	AVDeviceRect
typedef struct AVDeviceCapabilitiesQuery	AVDeviceCapabilitiesQuery
typedef struct AVDeviceInfo	AVDeviceInfo
typedef struct AVDeviceInfoList	AVDeviceInfoList

Перечисления
enum	AVAppToDevMessageType {   AV_APP_TO_DEV_NONE = MKBETAG('N','O','N','E'), AV_APP_TO_DEV_WINDOW_SIZE = MKBETAG('G','E','O','M'), AV_APP_TO_DEV_WINDOW_REPAINT = MKBETAG('R','E','P','A'), AV_APP_TO_DEV_PAUSE = MKBETAG('P', 'A', 'U', ' '),   AV_APP_TO_DEV_PLAY = MKBETAG('P', 'L', 'A', 'Y'), AV_APP_TO_DEV_TOGGLE_PAUSE = MKBETAG('P', 'A', 'U', 'T'), AV_APP_TO_DEV_SET_VOLUME = MKBETAG('S', 'V', 'O', 'L'), AV_APP_TO_DEV_MUTE = MKBETAG(' ', 'M', 'U', 'T'),   AV_APP_TO_DEV_UNMUTE = MKBETAG('U', 'M', 'U', 'T'), AV_APP_TO_DEV_TOGGLE_MUTE = MKBETAG('T', 'M', 'U', 'T'), AV_APP_TO_DEV_GET_VOLUME = MKBETAG('G', 'V', 'O', 'L'), AV_APP_TO_DEV_GET_MUTE = MKBETAG('G', 'M', 'U', 'T') }
enum	AVDevToAppMessageType {   AV_DEV_TO_APP_NONE = MKBETAG('N','O','N','E'), AV_DEV_TO_APP_CREATE_WINDOW_BUFFER = MKBETAG('B','C','R','E'), AV_DEV_TO_APP_PREPARE_WINDOW_BUFFER = MKBETAG('B','P','R','E'), AV_DEV_TO_APP_DISPLAY_WINDOW_BUFFER = MKBETAG('B','D','I','S'),   AV_DEV_TO_APP_DESTROY_WINDOW_BUFFER = MKBETAG('B','D','E','S'), AV_DEV_TO_APP_BUFFER_OVERFLOW = MKBETAG('B','O','F','L'), AV_DEV_TO_APP_BUFFER_UNDERFLOW = MKBETAG('B','U','F','L'), AV_DEV_TO_APP_BUFFER_READABLE = MKBETAG('B','R','D',' '),   AV_DEV_TO_APP_BUFFER_WRITABLE = MKBETAG('B','W','R',' '), AV_DEV_TO_APP_MUTE_STATE_CHANGED = MKBETAG('C','M','U','T'), AV_DEV_TO_APP_VOLUME_LEVEL_CHANGED = MKBETAG('C','V','O','L') }

Функции
unsigned	avdevice_version (void)
const char *	avdevice_configuration (void)
const char *	avdevice_license (void)
void	avdevice_register_all (void)
AVInputFormat *	av_input_audio_device_next (AVInputFormat *d)
AVInputFormat *	av_input_video_device_next (AVInputFormat *d)
AVOutputFormat *	av_output_audio_device_next (AVOutputFormat *d)
AVOutputFormat *	av_output_video_device_next (AVOutputFormat *d)
int	avdevice_app_to_dev_control_message (struct AVFormatContext *s, enum AVAppToDevMessageType type, void *data, size_t data_size)
int	avdevice_dev_to_app_control_message (struct AVFormatContext *s, enum AVDevToAppMessageType type, void *data, size_t data_size)
int	avdevice_capabilities_create (AVDeviceCapabilitiesQuery **caps, AVFormatContext *s, AVDictionary **device_options)
void	avdevice_capabilities_free (AVDeviceCapabilitiesQuery **caps, AVFormatContext *s)
int	avdevice_list_devices (struct AVFormatContext *s, AVDeviceInfoList **device_list)
void	avdevice_free_list_devices (AVDeviceInfoList **device_list)
int	avdevice_list_input_sources (struct AVInputFormat *device, const char *device_name, AVDictionary *device_options, AVDeviceInfoList **device_list)
int	avdevice_list_output_sinks (struct AVOutputFormat *device, const char *device_name, AVDictionary *device_options, AVDeviceInfoList **device_list)

Переменные
const AVOption	av_device_capabilities []

Подробное описание

Special devices muxing/demuxing library.

Libavdevice is a complementary library to libavformat. It provides various "special" platform-specific muxers and demuxers, e.g. for grabbing devices, audio capture and playback etc. As a consequence, the (de)muxers in libavdevice are of the AVFMT_NOFILE type (they use their own I/O functions). The filename passed to avformat_open_input() often does not refer to an actually existing file, but has some special device-specific meaning - e.g. for xcbgrab it is the display name.

To use libavdevice, simply call avdevice_register_all() to register all compiled muxers and demuxers. They all use standard libavformat API.

Типы

AVDeviceRect

typedef struct AVDeviceRect AVDeviceRect

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

AVDeviceCapabilitiesQuery

typedef struct AVDeviceCapabilitiesQuery AVDeviceCapabilitiesQuery

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

Following API allows user to probe device capabilities (supported codecs, pixel formats, sample formats, resolutions, channel counts, etc). It is build on top op AVOption API. Queried capabilities make it possible to set up converters of video or audio parameters that fit to the device.

List of capabilities that can be queried:

• Capabilities valid for both audio and video devices:
  • codec: supported audio/video codecs. type: AV_OPT_TYPE_INT (AVCodecID value)
• Capabilities valid for audio devices:
  • sample_format: supported sample formats. type: AV_OPT_TYPE_INT (AVSampleFormat value)
  • sample_rate: supported sample rates. type: AV_OPT_TYPE_INT
  • channels: supported number of channels. type: AV_OPT_TYPE_INT
  • channel_layout: supported channel layouts. type: AV_OPT_TYPE_INT64
• Capabilities valid for video devices:
  • pixel_format: supported pixel formats. type: AV_OPT_TYPE_INT (AVPixelFormat value)
  • window_size: supported window sizes (describes size of the window size presented to the user). type: AV_OPT_TYPE_IMAGE_SIZE
  • frame_size: supported frame sizes (describes size of provided video frames). type: AV_OPT_TYPE_IMAGE_SIZE
  • fps: supported fps values type: AV_OPT_TYPE_RATIONAL

Value of the capability may be set by user using av_opt_set() function and AVDeviceCapabilitiesQuery object. Following queries will limit results to the values matching already set capabilities. For example, setting a codec may impact number of formats or fps values returned during next query. Setting invalid value may limit results to zero.

Example of the usage basing on opengl output device:

 AVFormatContext *oc = NULL;
 AVDeviceCapabilitiesQuery *caps = NULL;
 AVOptionRanges *ranges;
 int ret;
 
 if ((ret = avformat_alloc_output_context2(&oc, NULL, "opengl", NULL)) < 0)
     goto fail;
 if (avdevice_capabilities_create(&caps, oc, NULL) < 0)
     goto fail;
 
 //query codecs
 if (av_opt_query_ranges(&ranges, caps, "codec", AV_OPT_MULTI_COMPONENT_RANGE)) < 0)
     goto fail;
 //pick codec here and set it
 av_opt_set(caps, "codec", AV_CODEC_ID_RAWVIDEO, 0);
 
 //query format
 if (av_opt_query_ranges(&ranges, caps, "pixel_format", AV_OPT_MULTI_COMPONENT_RANGE)) < 0)
     goto fail;
 //pick format here and set it
 av_opt_set(caps, "pixel_format", AV_PIX_FMT_YUV420P, 0);
 
 //query and set more capabilities
 
fail:
 //clean up code
 avdevice_capabilities_free(&query, oc);
 avformat_free_context(oc);

Structure describes device capabilities.

It is used by devices in conjunction with av_device_capabilities AVOption table to implement capabilities probing API based on AVOption API. Should not be used directly.

AVDeviceInfo

typedef struct AVDeviceInfo AVDeviceInfo

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

Structure describes basic parameters of the device.

AVDeviceInfoList

typedef struct AVDeviceInfoList AVDeviceInfoList

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

List of devices.

Перечисления

AVAppToDevMessageType

enum AVAppToDevMessageType

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

Message types used by avdevice_app_to_dev_control_message().

Элементы перечислений
AV_APP_TO_DEV_NONE	Dummy message.
AV_APP_TO_DEV_WINDOW_SIZE	Window size change message. Message is sent to the device every time the application changes the size of the window device renders to. Message should also be sent right after window is created. data: AVDeviceRect: new window size.
AV_APP_TO_DEV_WINDOW_REPAINT	Repaint request message. Message is sent to the device when window has to be repainted. data: AVDeviceRect: area required to be repainted. NULL: whole area is required to be repainted.
AV_APP_TO_DEV_PAUSE	Request pause/play. Application requests pause/unpause playback. Mostly usable with devices that have internal buffer. By default devices are not paused. data: NULL
AV_APP_TO_DEV_PLAY
AV_APP_TO_DEV_TOGGLE_PAUSE
AV_APP_TO_DEV_SET_VOLUME	Volume control message. Set volume level. It may be device-dependent if volume is changed per stream or system wide. Per stream volume change is expected when possible. data: double: new volume with range of 0.0 - 1.0.
AV_APP_TO_DEV_MUTE	Mute control messages. Change mute state. It may be device-dependent if mute status is changed per stream or system wide. Per stream mute status change is expected when possible. data: NULL.
AV_APP_TO_DEV_UNMUTE
AV_APP_TO_DEV_TOGGLE_MUTE
AV_APP_TO_DEV_GET_VOLUME	Get volume/mute messages. Force the device to send AV_DEV_TO_APP_VOLUME_LEVEL_CHANGED or AV_DEV_TO_APP_MUTE_STATE_CHANGED command respectively. data: NULL.
AV_APP_TO_DEV_GET_MUTE

См. определение в файле avdevice.h строка 119

                           {
    AV_APP_TO_DEV_NONE = MKBETAG('N','O','N','E'),
 
    AV_APP_TO_DEV_WINDOW_SIZE = MKBETAG('G','E','O','M'),
 
    AV_APP_TO_DEV_WINDOW_REPAINT = MKBETAG('R','E','P','A'),
 
    AV_APP_TO_DEV_PAUSE        = MKBETAG('P', 'A', 'U', ' '),
    AV_APP_TO_DEV_PLAY         = MKBETAG('P', 'L', 'A', 'Y'),
    AV_APP_TO_DEV_TOGGLE_PAUSE = MKBETAG('P', 'A', 'U', 'T'),
 
    AV_APP_TO_DEV_SET_VOLUME = MKBETAG('S', 'V', 'O', 'L'),
 
    AV_APP_TO_DEV_MUTE        = MKBETAG(' ', 'M', 'U', 'T'),
    AV_APP_TO_DEV_UNMUTE      = MKBETAG('U', 'M', 'U', 'T'),
    AV_APP_TO_DEV_TOGGLE_MUTE = MKBETAG('T', 'M', 'U', 'T'),
 
    AV_APP_TO_DEV_GET_VOLUME = MKBETAG('G', 'V', 'O', 'L'),
    AV_APP_TO_DEV_GET_MUTE   = MKBETAG('G', 'M', 'U', 'T'),
};

AVDevToAppMessageType

enum AVDevToAppMessageType

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

Message types used by avdevice_dev_to_app_control_message().

Элементы перечислений
AV_DEV_TO_APP_NONE	Dummy message.
AV_DEV_TO_APP_CREATE_WINDOW_BUFFER	Create window buffer message. Device requests to create a window buffer. Exact meaning is device- and application-dependent. Message is sent before rendering first frame and all one-shot initializations should be done here. Application is allowed to ignore preferred window buffer size. Заметки : Application is obligated to inform about window buffer size with AV_APP_TO_DEV_WINDOW_SIZE message. data: AVDeviceRect: preferred size of the window buffer. NULL: no preferred size of the window buffer.
AV_DEV_TO_APP_PREPARE_WINDOW_BUFFER	Prepare window buffer message. Device requests to prepare a window buffer for rendering. Exact meaning is device- and application-dependent. Message is sent before rendering of each frame. data: NULL.
AV_DEV_TO_APP_DISPLAY_WINDOW_BUFFER	Display window buffer message. Device requests to display a window buffer. Message is sent when new frame is ready to be displayed. Usually buffers need to be swapped in handler of this message. data: NULL.
AV_DEV_TO_APP_DESTROY_WINDOW_BUFFER	Destroy window buffer message. Device requests to destroy a window buffer. Message is sent when device is about to be destroyed and window buffer is not required anymore. data: NULL.
AV_DEV_TO_APP_BUFFER_OVERFLOW	Buffer fullness status messages. Device signals buffer overflow/underflow. data: NULL.
AV_DEV_TO_APP_BUFFER_UNDERFLOW
AV_DEV_TO_APP_BUFFER_READABLE	Buffer readable/writable. Device informs that buffer is readable/writable. When possible, device informs how many bytes can be read/write. Предупреждения Device may not inform when number of bytes than can be read/write changes. data: int64_t: amount of bytes available to read/write. NULL: amount of bytes available to read/write is not known.
AV_DEV_TO_APP_BUFFER_WRITABLE
AV_DEV_TO_APP_MUTE_STATE_CHANGED	Mute state change message. Device informs that mute state has changed. data: int: 0 for not muted state, non-zero for muted state.
AV_DEV_TO_APP_VOLUME_LEVEL_CHANGED	Volume level change message. Device informs that volume level has changed. data: double: new volume with range of 0.0 - 1.0.

См. определение в файле avdevice.h строка 198

                           {
    AV_DEV_TO_APP_NONE = MKBETAG('N','O','N','E'),
 
    AV_DEV_TO_APP_CREATE_WINDOW_BUFFER = MKBETAG('B','C','R','E'),
 
    AV_DEV_TO_APP_PREPARE_WINDOW_BUFFER = MKBETAG('B','P','R','E'),
 
    AV_DEV_TO_APP_DISPLAY_WINDOW_BUFFER = MKBETAG('B','D','I','S'),
 
    AV_DEV_TO_APP_DESTROY_WINDOW_BUFFER = MKBETAG('B','D','E','S'),
 
    AV_DEV_TO_APP_BUFFER_OVERFLOW = MKBETAG('B','O','F','L'),
    AV_DEV_TO_APP_BUFFER_UNDERFLOW = MKBETAG('B','U','F','L'),
 
    AV_DEV_TO_APP_BUFFER_READABLE = MKBETAG('B','R','D',' '),
    AV_DEV_TO_APP_BUFFER_WRITABLE = MKBETAG('B','W','R',' '),
 
    AV_DEV_TO_APP_MUTE_STATE_CHANGED = MKBETAG('C','M','U','T'),
 
    AV_DEV_TO_APP_VOLUME_LEVEL_CHANGED = MKBETAG('C','V','O','L'),
};

Функции

avdevice_version()

unsigned avdevice_version

(

void

)

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

Return the LIBAVDEVICE_VERSION_INT constant.

avdevice_configuration()

const char* avdevice_configuration

(

void

)

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

Return the libavdevice build-time configuration.

avdevice_license()

const char* avdevice_license

(

void

)

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

Return the libavdevice license.

avdevice_register_all()

void avdevice_register_all

(

void

)

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

Initialize libavdevice and register all the input and output devices.

av_input_audio_device_next()

AVInputFormat* av_input_audio_device_next

(

AVInputFormat *

d

)

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

Audio input devices iterator.

If d is NULL, returns the first registered input audio/video device, if d is non-NULL, returns the next registered input audio/video device after d or NULL if d is the last one.

av_input_video_device_next()

AVInputFormat* av_input_video_device_next

(

AVInputFormat *

d

)

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

Video input devices iterator.

If d is NULL, returns the first registered input audio/video device, if d is non-NULL, returns the next registered input audio/video device after d or NULL if d is the last one.

av_output_audio_device_next()

AVOutputFormat* av_output_audio_device_next

(

AVOutputFormat *

d

)

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

Audio output devices iterator.

If d is NULL, returns the first registered output audio/video device, if d is non-NULL, returns the next registered output audio/video device after d or NULL if d is the last one.

av_output_video_device_next()

AVOutputFormat* av_output_video_device_next

(

AVOutputFormat *

d

)

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

Video output devices iterator.

If d is NULL, returns the first registered output audio/video device, if d is non-NULL, returns the next registered output audio/video device after d or NULL if d is the last one.

avdevice_app_to_dev_control_message()

int avdevice_app_to_dev_control_message	(	struct AVFormatContext *	s,
		enum AVAppToDevMessageType	type,
		void *	data,
		size_t	data_size
	)

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

Send control message from application to device.

Аргументы

s	device context.
type	message type.
data	message data. Exact type depends on message type.
data_size	size of message data.

Возвращает

>= 0 on success, negative on error. AVERROR(ENOSYS) when device doesn't implement handler of the message.

avdevice_dev_to_app_control_message()

int avdevice_dev_to_app_control_message	(	struct AVFormatContext *	s,
		enum AVDevToAppMessageType	type,
		void *	data,
		size_t	data_size
	)

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

Send control message from device to application.

Аргументы

s	device context.
type	message type.
data	message data. Can be NULL.
data_size	size of message data.

Возвращает

>= 0 on success, negative on error. AVERROR(ENOSYS) when application doesn't implement handler of the message.

avdevice_capabilities_create()

int avdevice_capabilities_create	(	AVDeviceCapabilitiesQuery **	caps,
		AVFormatContext *	s,
		AVDictionary **	device_options
	)

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

Initialize capabilities probing API based on AVOption API.

avdevice_capabilities_free() must be called when query capabilities API is not used anymore.

Аргументы

[out]	caps	Device capabilities data. Pointer to a NULL pointer must be passed.
	s	Context of the device.
	device_options	An AVDictionary filled with device-private options. On return this parameter will be destroyed and replaced with a dict containing options that were not found. May be NULL. The same options must be passed later to avformat_write_header() for output devices or avformat_open_input() for input devices, or at any other place that affects device-private options.

Возвращает

>= 0 on success, negative otherwise.

avdevice_capabilities_free()

void avdevice_capabilities_free	(	AVDeviceCapabilitiesQuery **	caps,
		AVFormatContext *	s
	)

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

Free resources created by avdevice_capabilities_create()

Аргументы

caps	Device capabilities data to be freed.
s	Context of the device.

avdevice_list_devices()

int avdevice_list_devices	(	struct AVFormatContext *	s,
		AVDeviceInfoList **	device_list
	)

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

List devices.

Returns available device names and their parameters.

Заметки

: Some devices may accept system-dependent device names that cannot be autodetected. The list returned by this function cannot be assumed to be always completed.

Аргументы

	s	device context.
[out]	device_list	list of autodetected devices.

Возвращает

count of autodetected devices, negative on error.

avdevice_free_list_devices()

void avdevice_free_list_devices

(

AVDeviceInfoList **

device_list

)

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

Convenient function to free result of avdevice_list_devices().

Аргументы

devices

device list to be freed.

avdevice_list_input_sources()

int avdevice_list_input_sources	(	struct AVInputFormat *	device,
		const char *	device_name,
		AVDictionary *	device_options,
		AVDeviceInfoList **	device_list
	)

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

List devices.

Returns available device names and their parameters. These are convinient wrappers for avdevice_list_devices(). Device context is allocated and deallocated internally.

Аргументы

	device	device format. May be NULL if device name is set.
	device_name	device name. May be NULL if device format is set.
	device_options	An AVDictionary filled with device-private options. May be NULL. The same options must be passed later to avformat_write_header() for output devices or avformat_open_input() for input devices, or at any other place that affects device-private options.
[out]	device_list	list of autodetected devices

Возвращает

count of autodetected devices, negative on error.

Заметки

device argument takes precedence over device_name when both are set.

avdevice_list_output_sinks()

int avdevice_list_output_sinks	(	struct AVOutputFormat *	device,
		const char *	device_name,
		AVDictionary *	device_options,
		AVDeviceInfoList **	device_list
	)

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

Переменные

av_device_capabilities

const AVOption av_device_capabilities[]

#include <C:/git/world-of-might-and-magic/lib/win32/x86/ffmpeg-4.2.2/include/libavdevice/avdevice.h>

AVOption table used by devices to implement device capabilities API. Should not be used by a user.