camerabin

camerabin — Handle lot of features present in DSC

Synopsis

                    GstCameraBin;
enum                GstCameraBinMode;

Object Hierarchy

  GObject
   +----GstObject
         +----GstElement
               +----GstBin
                     +----GstPipeline
                           +----GstCameraBin

Implemented Interfaces

GstCameraBin implements GstChildProxy, GstImplementsInterface, GstColorBalance, GstTagSetter and GstPhotography.

Properties

  "audioenc"                 GstElement*           : Read / Write
  "audiosrc"                 GstElement*           : Read / Write
  "filename"                 gchar*                : Read / Write
  "filter-caps"              GstCaps*              : Read / Write
  "imageenc"                 GstElement*           : Read / Write
  "imagepp"                  GstElement*           : Read / Write
  "inputcaps"                GstCaps*              : Read
  "mode"                     GstCameraBinMode      : Read / Write
  "mute"                     gboolean              : Read / Write
  "vfsink"                   GstElement*           : Read / Write
  "videoenc"                 GstElement*           : Read / Write
  "videomux"                 GstElement*           : Read / Write
  "videopp"                  GstElement*           : Read / Write
  "videosrc"                 GstElement*           : Read / Write
  "zoom"                     gint                  : Read / Write
  "preview-caps"             GstCaps*              : Read / Write
  "audio-encoder"            GstElement*           : Read / Write
  "audio-source"             GstElement*           : Read / Write
  "image-encoder"            GstElement*           : Read / Write
  "image-post-processing"    GstElement*           : Read / Write
  "video-encoder"            GstElement*           : Read / Write
  "video-muxer"              GstElement*           : Read / Write
  "video-post-processing"    GstElement*           : Read / Write
  "video-source"             GstElement*           : Read / Write
  "video-source-caps"        GstCaps*              : Read
  "viewfinder-sink"          GstElement*           : Read / Write
  "flags"                    GstCameraBinFlags     : Read / Write

Signals

  "img-done"                                       : Run Last
  "user-image-res"                                 : Run Last / Action
  "user-pause"                                     : Run Last / Action
  "user-res-fps"                                   : Run Last / Action
  "user-start"                                     : Run Last / Action
  "user-stop"                                      : Run Last / Action
  "capture-pause"                                  : Run Last / Action
  "capture-start"                                  : Run Last / Action
  "capture-stop"                                   : Run Last / Action
  "image-done"                                     : Run Last
  "set-image-resolution"                           : Run Last / Action
  "set-video-resolution-fps"                       : Run Last / Action

Description

GstCameraBin is a high-level camera object that encapsulates the gstreamer internals and provides a task based API for the application. It consists of three main data paths: view-finder, image capture and video capture.

CameraBin structure

Structural decomposition of CameraBin object.

Example launch line

1
gst-launch -v -m camerabin

Image capture

Taking still images is initiated with the "capture-start" action signal. Once the image has been captured, "image-captured" gst message is posted to the bus and capturing another image is possible. If application has set "preview-caps" property, then a "preview-image" gst message is posted to bus containing preview image formatted according to specified caps. Eventually when image has been saved "image-done" signal is emitted.

Available resolutions can be taken from the "video-source-caps" property. Image capture resolution can be set with "set-image-resolution" action signal.


Video capture

Video capture is started with the "capture-start" action signal too. In addition to image capture one can use "capture-pause" to pause recording and "capture-stop" to end recording.

Available resolutions and fps can be taken from the "video-source-caps" property. "set-video-resolution-fps" action signal can be used to set frame rate and resolution for the video recording and view finder as well.


Photography interface

GstCameraBin implements GstPhotography interface, which can be used to set and get different settings related to digital imaging. Since currently many of these settings require low-level support the photography interface support is dependent on video src element. In practice photography interface settings cannot be used successfully until in PAUSED state when the video src has opened the video device. However it is possible to configure photography settings in NULL state and camerabin will try applying them later.


States

Elements within GstCameraBin are created and destroyed when switching between NULL and READY states. Therefore element properties should be set in NULL state. User set elements are not unreffed until GstCameraBin is unreffed or replaced by a new user set element. Initially only elements needed for view finder mode are created to speed up startup. Image bin and video bin elements are created when setting the mode or starting capture.


Video and image previews

GstCameraBin contains "preview-caps" property, which is used to determine whether the application wants a preview image of the captured picture or video. When set, a GstMessage named "preview-image" will be sent. This message will contain a GstBuffer holding the preview image, converted to a format defined by those preview caps. The ownership of the preview image is kept in GstCameraBin, so application should ref the preview buffer object if it needs to use it elsewhere than in message handler.

Defining preview caps is done by selecting the capturing mode first and then setting the property. Camerabin remembers caps separately for both modes, so it is not necessary to set the caps again after changing the mode.


Note

Since the muxers tested so far have problems with discontinous buffers, QoS has been disabled, and then in order to record video, you MUST ensure that there is enough CPU to encode the video. Thus choose smart resolution and frames per second values. It is also highly recommended to avoid color conversions; make sure all the elements involved work with the same colorspace (i.e. rgb or yuv i420 or whatelse).

Details

GstCameraBin

typedef struct _GstCameraBin GstCameraBin;

The opaque GstCameraBin structure.


enum GstCameraBinMode

typedef enum
{
  MODE_IMAGE = 0,
  MODE_VIDEO
} GstCameraBinMode;

Capture mode to use.

MODE_IMAGE

image capture

MODE_VIDEO

video capture

Property Details

The "audioenc" property

  "audioenc"                 GstElement*           : Read / Write

Audio encoder GStreamer element (default is vorbisenc).


The "audiosrc" property

  "audiosrc"                 GstElement*           : Read / Write

Audio source GStreamer element (default is pulsesrc).


The "filename" property

  "filename"                 gchar*                : Read / Write

Set filename for the still image capturing or video capturing.

Default value: ""


The "filter-caps" property

  "filter-caps"              GstCaps*              : Read / Write

Caps applied to capsfilter element after videosrc [ ! ffmpegcsp ]. You can use this e.g. to make sure video color format matches with encoders and other elements configured to camerabin and/or change resolution and frame rate.


The "imageenc" property

  "imageenc"                 GstElement*           : Read / Write

Image encoder GStreamer element (default is jpegenc).


The "imagepp" property

  "imagepp"                  GstElement*           : Read / Write

Image Post-Processing GStreamer element (default is NULL).


The "inputcaps" property

  "inputcaps"                GstCaps*              : Read

The allowed modes of the video source operation.


The "mode" property

  "mode"                     GstCameraBinMode      : Read / Write

Set the mode of operation: still image capturing or video recording. Setting the mode will create and destroy image bin or video bin elements according to the mode. You can set this property at any time, changing the mode will stop ongoing capture.

Default value: Still image capture (default)


The "mute" property

  "mute"                     gboolean              : Read / Write

Mute audio in video recording mode. Set this property only when GstCameraBin is in READY, PAUSED or PLAYING.

Default value: FALSE


The "vfsink" property

  "vfsink"                   GstElement*           : Read / Write

View finder sink GStreamer element (default is autovideosink).


The "videoenc" property

  "videoenc"                 GstElement*           : Read / Write

Video encoder GStreamer element (default is theoraenc).


The "videomux" property

  "videomux"                 GstElement*           : Read / Write

Video muxer GStreamer element (default is oggmux).


The "videopp" property

  "videopp"                  GstElement*           : Read / Write

Video post processing GStreamer element (default is NULL).


The "videosrc" property

  "videosrc"                 GstElement*           : Read / Write

Video source GStreamer element (default is v4l2src).


The "zoom" property

  "zoom"                     gint                  : Read / Write

Set up the zoom applied to the frames. Set this property only when GstCameraBin is in READY, PAUSED or PLAYING.

Allowed values: [100,1000]

Default value: 100


The "preview-caps" property

  "preview-caps"             GstCaps*              : Read / Write

If application wants to receive a preview image, it needs to set this property to depict the desired image format caps. When this property is not set (NULL), message containing the preview image is not sent.


The "audio-encoder" property

  "audio-encoder"            GstElement*           : Read / Write

Set up an audio encoder element. This property can only be set while GstCameraBin is in NULL state. The ownership of the element will be taken by GstCameraBin.


The "audio-source" property

  "audio-source"             GstElement*           : Read / Write

Set up an audio source element. By default "autoaudiosrc" or DEFAULT_AUDIOSRC will be used. This property can only be set while GstCameraBin is in NULL state. The ownership of the element will be taken by GstCameraBin.


The "image-encoder" property

  "image-encoder"            GstElement*           : Read / Write

Set up an image encoder (for example, jpegenc or pngenc) element. This property can only be set while GstCameraBin is in NULL state. The ownership of the element will be taken by GstCameraBin.


The "image-post-processing" property

  "image-post-processing"    GstElement*           : Read / Write

Set up an element to do image post processing. This property can only be set while GstCameraBin is in NULL state. The ownership of the element will be taken by GstCameraBin.


The "video-encoder" property

  "video-encoder"            GstElement*           : Read / Write

Set up a video encoder element. This property can only be set while GstCameraBin is in NULL state. The ownership of the element will be taken by GstCameraBin.


The "video-muxer" property

  "video-muxer"              GstElement*           : Read / Write

Set up a video muxer element. This property can only be set while GstCameraBin is in NULL state. The ownership of the element will be taken by GstCameraBin.


The "video-post-processing" property

  "video-post-processing"    GstElement*           : Read / Write

Set up an element to do video post processing. This property can only be set while GstCameraBin is in NULL state. The ownership of the element will be taken by GstCameraBin.


The "video-source" property

  "video-source"             GstElement*           : Read / Write

Set up a video source element. By default "autovideosrc" or DEFAULT_VIDEOSRC will be used. This property can only be set while GstCameraBin is in NULL state. The ownership of the element will be taken by GstCameraBin.


The "video-source-caps" property

  "video-source-caps"        GstCaps*              : Read

The allowed modes of operation of the video source. Have in mind that it doesn't mean GstCameraBin can operate in all those modes, it depends also on the other elements in the pipeline. Remember to gst_caps_unref after using it.


The "viewfinder-sink" property

  "viewfinder-sink"          GstElement*           : Read / Write

Set up a sink element to render frames in view finder. By default "autovideosink" or DEFAULT_VIDEOSINK will be used. This property can only be set while GstCameraBin is in NULL state. The ownership of the element will be taken by GstCameraBin.


The "flags" property

  "flags"                    GstCameraBinFlags     : Read / Write

Control the behaviour of camerabin.

Default value: Enable source crop and scale|Enable scale for viewfinder|Enable colorspace conversion for still image

Signal Details

The "img-done" signal

gboolean            user_function                      (GstCameraBin *gstcamerabin,
                                                        gchar        *arg1,
                                                        gpointer      user_data)         : Run Last

gstcamerabin :

the object which received the signal.

arg1 :

user_data :

user data set when the signal handler was connected.

Returns :


The "user-image-res" signal

void                user_function                      (GstCameraBin *gstcamerabin,
                                                        gint          arg1,
                                                        gint          arg2,
                                                        gpointer      user_data)         : Run Last / Action

gstcamerabin :

the object which received the signal.

arg1 :

arg2 :

user_data :

user data set when the signal handler was connected.

The "user-pause" signal

void                user_function                      (GstCameraBin *gstcamerabin,
                                                        gpointer      user_data)         : Run Last / Action

gstcamerabin :

the object which received the signal.

user_data :

user data set when the signal handler was connected.

The "user-res-fps" signal

void                user_function                      (GstCameraBin *gstcamerabin,
                                                        gint          arg1,
                                                        gint          arg2,
                                                        gint          arg3,
                                                        gint          arg4,
                                                        gpointer      user_data)         : Run Last / Action

gstcamerabin :

the object which received the signal.

arg1 :

arg2 :

arg3 :

arg4 :

user_data :

user data set when the signal handler was connected.

The "user-start" signal

void                user_function                      (GstCameraBin *gstcamerabin,
                                                        gpointer      user_data)         : Run Last / Action

gstcamerabin :

the object which received the signal.

user_data :

user data set when the signal handler was connected.

The "user-stop" signal

void                user_function                      (GstCameraBin *gstcamerabin,
                                                        gpointer      user_data)         : Run Last / Action

gstcamerabin :

the object which received the signal.

user_data :

user data set when the signal handler was connected.

The "capture-pause" signal

void                user_function                      (GstCameraBin *camera,
                                                        gpointer      user_data)      : Run Last / Action

Pauses video recording or resumes paused video recording. If in image mode or not recording, does nothing.

camera :

the camera bin element

user_data :

user data set when the signal handler was connected.

The "capture-start" signal

void                user_function                      (GstCameraBin *camera,
                                                        gpointer      user_data)      : Run Last / Action

Starts image capture or video recording depending on the Mode. If there is a capture already going on, does nothing. Resumes video recording if it has been paused.

camera :

the camera bin element

user_data :

user data set when the signal handler was connected.

The "capture-stop" signal

void                user_function                      (GstCameraBin *camera,
                                                        gpointer      user_data)      : Run Last / Action

Stops still image preview, continuous image capture and video recording and returns to the view finder mode.

camera :

the camera bin element

user_data :

user data set when the signal handler was connected.

The "image-done" signal

gboolean            user_function                      (GstCameraBin *camera,
                                                        gchar        *filename,
                                                        gpointer      user_data)      : Run Last

Signal emitted when the file has just been saved.

Don't call any GstCameraBin method from this signal, if you do so there will be a deadlock.

camera :

the camera bin element

filename :

the name of the file just saved

user_data :

user data set when the signal handler was connected.

The "set-image-resolution" signal

void                user_function                      (GstCameraBin *camera,
                                                        gint          width,
                                                        gint          height,
                                                        gpointer      user_data)      : Run Last / Action

Changes the resolution used for still image capture. Does not affect view finder mode and video recording.

camera :

the camera bin element

width :

number of horizontal pixels

height :

number of vertical pixels

user_data :

user data set when the signal handler was connected.

The "set-video-resolution-fps" signal

void                user_function                      (GstCameraBin *camera,
                                                        gint          width,
                                                        gint          height,
                                                        gint          fps_n,
                                                        gint          fps_d,
                                                        gpointer      user_data)      : Run Last / Action

Changes the frame resolution and frames per second of the video source. The application must be aware of the resolutions supported by the camera. Supported resolutions and frame rates can be get using input-caps property.

Setting fps_n or fps_d to 0 configures maximum framerate for the given resolution, unless in night mode when minimum is configured.

camera :

the camera bin element

width :

number of horizontal pixels

height :

number of vertical pixels

fps_n :

frames per second numerator

fps_d :

frames per second denominator

user_data :

user data set when the signal handler was connected.