FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
Files | Data Structures | Enumerations | Functions | Variables
libavdevice

Special devices muxing/demuxing library. More...

Files

file  avdevice.h
 Main libavdevice API header.
 
file  version.h
 Libavdevice version macros.
 

Data Structures

struct  AVDeviceRect
 
struct  AVDeviceCapabilitiesQuery
 Following API allows user to probe device capabilities (supported codecs, pixel formats, sample formats, resolutions, channel counts, etc). More...
 
struct  AVDeviceInfo
 Structure describes basic parameters of the device. More...
 
struct  AVDeviceInfoList
 List of devices. More...
 

Enumerations

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')
}
 Message types used by avdevice_app_to_dev_control_message(). More...
 
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')
}
 Message types used by avdevice_dev_to_app_control_message(). More...
 

Functions

unsigned avdevice_version (void)
 Return the LIBAVDEVICE_VERSION_INT constant. More...
 
const char * avdevice_configuration (void)
 Return the libavdevice build-time configuration. More...
 
const char * avdevice_license (void)
 Return the libavdevice license. More...
 
const AVOutputFormatav_outdev_iterate (void **opaque)
 Iterate over all registered output devices. More...
 
const AVInputFormatav_indev_iterate (void **opaque)
 Iterate over all registered input devices. More...
 
void avdevice_register_all (void)
 Initialize libavdevice and register all the input and output devices. More...
 
attribute_deprecated
AVInputFormat
av_input_audio_device_next (AVInputFormat *d)
 Audio input devices iterator. More...
 
attribute_deprecated
AVInputFormat
av_input_video_device_next (AVInputFormat *d)
 Video input devices iterator. More...
 
attribute_deprecated
AVOutputFormat
av_output_audio_device_next (AVOutputFormat *d)
 Audio output devices iterator. More...
 
attribute_deprecated
AVOutputFormat
av_output_video_device_next (AVOutputFormat *d)
 Video output devices iterator. More...
 
int avdevice_app_to_dev_control_message (struct AVFormatContext *s, enum AVAppToDevMessageType type, void *data, size_t data_size)
 Send control message from application to device. More...
 
int avdevice_dev_to_app_control_message (struct AVFormatContext *s, enum AVDevToAppMessageType type, void *data, size_t data_size)
 Send control message from device to application. More...
 
int avdevice_capabilities_create (AVDeviceCapabilitiesQuery **caps, AVFormatContext *s, AVDictionary **device_options)
 Initialize capabilities probing API based on AVOption API. More...
 
void avdevice_capabilities_free (AVDeviceCapabilitiesQuery **caps, AVFormatContext *s)
 Free resources created by avdevice_capabilities_create() More...
 
int avdevice_list_devices (struct AVFormatContext *s, AVDeviceInfoList **device_list)
 List devices. More...
 
void avdevice_free_list_devices (AVDeviceInfoList **device_list)
 Convenient function to free result of avdevice_list_devices(). More...
 
int avdevice_list_input_sources (struct AVInputFormat *device, const char *device_name, AVDictionary *device_options, AVDeviceInfoList **device_list)
 List devices. More...
 
int avdevice_list_output_sinks (struct AVOutputFormat *device, const char *device_name, AVDictionary *device_options, AVDeviceInfoList **device_list)
 

Variables

const AVOption av_device_capabilities []
 AVOption table used by devices to implement device capabilities API. More...
 

Detailed Description

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.

Enumeration Type Documentation

Message types used by avdevice_app_to_dev_control_message().

Enumerator
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 

Definition at line 147 of file avdevice.h.

Message types used by avdevice_dev_to_app_control_message().

Enumerator
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.

Note
: 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.

Warning
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.

Definition at line 226 of file avdevice.h.

Function Documentation

unsigned avdevice_version ( void  )

Return the LIBAVDEVICE_VERSION_INT constant.

Definition at line 64 of file avdevice.c.

const char* avdevice_configuration ( void  )

Return the libavdevice build-time configuration.

Definition at line 70 of file avdevice.c.

const char* avdevice_license ( void  )

Return the libavdevice license.

Definition at line 75 of file avdevice.c.

const AVOutputFormat* av_outdev_iterate ( void **  opaque)

Iterate over all registered output devices.

Parameters
opaquea pointer where libavdevice will store the iteration state. Must point to NULL to start the iteration.
Returns
the next registered output device or NULL when the iteration is finished

Definition at line 69 of file alldevices.c.

const AVInputFormat* av_indev_iterate ( void **  opaque)

Iterate over all registered input devices.

Parameters
opaquea pointer where libavdevice will store the iteration state. Must point to NULL to start the iteration.
Returns
the next registered input device or NULL when the iteration is finished

Definition at line 79 of file alldevices.c.

void avdevice_register_all ( void  )

Initialize libavdevice and register all the input and output devices.

Referenced by main().

attribute_deprecated AVInputFormat* av_input_audio_device_next ( AVInputFormat d)

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.

attribute_deprecated AVInputFormat* av_input_video_device_next ( AVInputFormat d)

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.

attribute_deprecated AVOutputFormat* av_output_audio_device_next ( AVOutputFormat d)

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.

attribute_deprecated AVOutputFormat* av_output_video_device_next ( AVOutputFormat d)

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.

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

Send control message from application to device.

Parameters
sdevice context.
typemessage type.
datamessage data. Exact type depends on message type.
data_sizesize of message data.
Returns
>= 0 on success, negative on error. AVERROR(ENOSYS) when device doesn't implement handler of the message.

Definition at line 81 of file avdevice.c.

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

Send control message from device to application.

Parameters
sdevice context.
typemessage type.
datamessage data. Can be NULL.
data_sizesize of message data.
Returns
>= 0 on success, negative on error. AVERROR(ENOSYS) when application doesn't implement handler of the message.

Definition at line 89 of file avdevice.c.

Referenced by opengl_create_window(), opengl_draw(), opengl_release_window(), opengl_resize(), opengl_write_header(), opengl_write_trailer(), pulse_audio_sink_input_cb(), pulse_overflow(), pulse_stream_writable(), pulse_underflow(), and pulse_write_packet().

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

Initialize capabilities probing API based on AVOption API.

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

Parameters
[out]capsDevice capabilities data. Pointer to a NULL pointer must be passed.
sContext of the device.
device_optionsAn 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.
Returns
>= 0 on success, negative otherwise.

Definition at line 97 of file avdevice.c.

void avdevice_capabilities_free ( AVDeviceCapabilitiesQuery **  caps,
AVFormatContext s 
)

Free resources created by avdevice_capabilities_create()

Parameters
capsDevice capabilities data to be freed.
sContext of the device.

Definition at line 126 of file avdevice.c.

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

List devices.

Returns available device names and their parameters.

Note
: 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.
Parameters
sdevice context.
[out]device_listlist of autodetected devices.
Returns
count of autodetected devices, negative on error.

Definition at line 141 of file avdevice.c.

Referenced by list_devices_for_context().

void avdevice_free_list_devices ( AVDeviceInfoList **  device_list)

Convenient function to free result of avdevice_list_devices().

Parameters
devicesdevice list to be freed.

Definition at line 204 of file avdevice.c.

Referenced by avdevice_list_devices(), and ff_decklink_list_devices_legacy().

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

List devices.

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

Parameters
devicedevice format. May be NULL if device name is set.
device_namedevice name. May be NULL if device format is set.
device_optionsAn 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_listlist of autodetected devices
Returns
count of autodetected devices, negative on error.
Note
device argument takes precedence over device_name when both are set.

Definition at line 182 of file avdevice.c.

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

Definition at line 193 of file avdevice.c.

Variable Documentation

const AVOption av_device_capabilities[]

AVOption table used by devices to implement device capabilities API.

Should not be used by a user.

Definition at line 36 of file avdevice.c.