gstreamer基于appsink实现截图

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gstreamer基于appsink实现截图

对gstreamer官方教程中的基于appsink的视频帧采样代码进行了重新封装，以达到通过GTK的button事件直接调用封装进行视频截图。注意设置好主pipeline中的节点tee与封装中的tee_main进行同步。参考代码如下：appdata.mediaData.tee_main = data.tee_main;

.html?gi-language=c#appsink-example

typedef struct _MediaData
{GstElement *pipeline;GstElement *tee_main ;GstElement *capsfilter_cap, *videoconvert_cap, *capture_queue,*file_sink_capture;GstCaps *filter_caps_cap;GstPad *queue_capture_pad, *tee_capture_pad;
} MediaData;typedef struct _AppData
{GstElement *pipeline_app;GstElement *video_sink;MediaData  mediaData;
} AppData;static int image_cap_cb (GtkEventBox *e, CustomData * data)
{static int screenshot_time = 1;GstSample *sample;MediaData*  imageData = &appdata.mediaData;GstPadTemplate *templ;templ = gst_element_class_get_pad_template (GST_ELEMENT_GET_CLASS (imageData->tee_main), "src_%u");imageData->tee_capture_pad   = gst_element_request_pad  (imageData->tee_main, templ, NULL, NULL);if ( 1 ){imageData->capture_queue     = gst_element_factory_make ("queue", "record_queue");imageData->videoconvert_cap  = gst_element_factory_make ("videoconvert", "videoconvert_cap");imageData->capsfilter_cap = gst_element_factory_make ("capsfilter", "capsfilter_cap");imageData->file_sink_capture = gst_element_factory_make ("appsink", "file_sink_capture");g_object_set (imageData->file_sink_capture, "emit-signals", TRUE, NULL);/* set the resolution */char resolution_cap[200];sprintf(resolution_cap, "video/x-raw,format=RGBA, pixel-aspect-ratio=1/1");g_printerr("%s\n",resolution_cap);imageData->filter_caps_cap   = gst_caps_from_string (resolution_cap);g_object_set(GST_OBJECT( imageData->capsfilter_cap), "caps",  imageData->filter_caps_cap, NULL);gst_caps_unref ( imageData->filter_caps_cap);char  filename_png[1000];sprintf(filename_png, "/home/123/screeshot%d.jpg", screenshot_time);screenshot_time++;gst_bin_add_many (GST_BIN (imageData->pipeline), imageData->capture_queue,imageData->videoconvert_cap, imageData->capsfilter_cap, imageData->file_sink_capture,NULL);if (gst_element_link_many (imageData->capture_queue,  imageData->videoconvert_cap,   imageData->capsfilter_cap, imageData->file_sink_capture, NULL) != TRUE){g_printerr ("Elements could not be linked in record branch\n");}gst_element_sync_state_with_parent (imageData->capture_queue);gst_element_sync_state_with_parent (imageData->videoconvert_cap);gst_element_sync_state_with_parent (imageData->capsfilter_cap);gst_element_sync_state_with_parent (imageData->file_sink_capture);imageData->queue_capture_pad = gst_element_get_static_pad (imageData->capture_queue, "sink");if(gst_pad_link (imageData->tee_capture_pad,  imageData->queue_capture_pad) != GST_PAD_LINK_OK){g_printerr ("Elements could not be linked in record branch\n");}if (sample){GstBuffer *buffer;GstPad *pad;GstStructure *s;gint width, height;GstPadTemplate *template;g_signal_emit_by_name (imageData->file_sink_capture, "pull-preroll", &sample, NULL);GstCaps *videosink_caps = gst_sample_get_caps (sample);s = gst_caps_get_structure (videosink_caps, 0);gboolean res;res = gst_structure_get_int (s, "width", &width);res |= gst_structure_get_int (s, "height", &height);GstMapInfo map;GError *error = NULL;buffer = gst_sample_get_buffer (sample);gst_buffer_map (buffer, &map, GST_MAP_READ);g_printerr("width :%d, height :%d \n", width, height);pixbuf = gdk_pixbuf_new_from_data (map.data, GDK_COLORSPACE_RGB, TRUE, 8, width, height, GST_ROUND_UP_4 (width*4), NULL, NULL);gdk_pixbuf_save (pixbuf, filename_png, "jpeg", &error,NULL);gst_buffer_unmap (buffer, &map);}usleep(100*1000);gst_element_set_state (imageData->file_sink_capture, GST_STATE_NULL);gst_element_set_state (imageData->videoconvert_cap, GST_STATE_NULL);gst_element_set_state (imageData->capture_queue, GST_STATE_NULL);gst_element_set_state (imageData->capsfilter_cap, GST_STATE_NULL);imageData->queue_capture_pad = gst_element_get_static_pad (imageData->capture_queue, "sink");if(gst_pad_unlink(imageData->tee_capture_pad, imageData->queue_capture_pad) != TRUE){g_printerr ("Tee record queue could not be unlinked.\n");}gst_bin_remove(GST_BIN (imageData->pipeline), imageData->capture_queue);gst_bin_remove(GST_BIN (imageData->pipeline), imageData->videoconvert_cap);gst_bin_remove(GST_BIN (imageData->pipeline), imageData->file_sink_capture);gst_bin_remove(GST_BIN (imageData->pipeline), imageData->capsfilter_cap);gst_element_release_request_pad (imageData->tee_main, imageData->tee_capture_pad);gst_object_unref (imageData->queue_capture_pad);gst_object_unref (imageData->tee_capture_pad);g_printerr("TRUE \n");}return 1;
}