gistfile1.c

static gboolean
gst_aravis_set_caps (GstBaseSrc *src, GstCaps *caps)
{
        GstAravis* gst_aravis = GST_ARAVIS(src);
	GstStructure *structure;
	ArvPixelFormat pixel_format;
	int height, width;
	int bpp, depth;
	const GValue *frame_rate;
	const char *caps_string;
	unsigned int i;
	guint32 fourcc;

	GST_LOG_OBJECT (gst_aravis, "Requested caps = %" GST_PTR_FORMAT, caps);

	arv_camera_stop_acquisition (gst_aravis->camera);

	if (gst_aravis->stream != NULL)
		g_object_unref (gst_aravis->stream);

	structure = gst_caps_get_structure (caps, 0);

	gst_structure_get_int (structure, "width", &width);
	gst_structure_get_int (structure, "height", &height);
	frame_rate = gst_structure_get_value (structure, "framerate");
	gst_structure_get_int (structure, "bpp", &bpp);
	gst_structure_get_int (structure, "depth", &depth);

	if (gst_structure_get_field_type (structure, "format") == G_TYPE_STRING) {
		const char *string;

	       	string = gst_structure_get_string (structure, "format");
		fourcc = GST_STR_FOURCC (string);
	} else if (gst_structure_get_field_type (structure, "format") == GST_TYPE_FOURCC) {
		gst_structure_get_fourcc (structure, "format", &fourcc);
	} else
		fourcc = 0;

	pixel_format = arv_pixel_format_from_gst_caps (gst_structure_get_name (structure), bpp, depth, fourcc);

	arv_camera_set_region (gst_aravis->camera, gst_aravis->offset_x, gst_aravis->offset_y, width, height);
	arv_camera_set_binning (gst_aravis->camera, gst_aravis->h_binning, gst_aravis->v_binning);
	arv_camera_set_pixel_format (gst_aravis->camera, pixel_format);

	if (frame_rate != NULL) {
		double dbl_frame_rate;

		dbl_frame_rate = (double) gst_value_get_fraction_numerator (frame_rate) /
			(double) gst_value_get_fraction_denominator (frame_rate);

		GST_DEBUG_OBJECT (gst_aravis, "Frame rate = %g Hz", dbl_frame_rate);
		arv_camera_set_frame_rate (gst_aravis->camera, dbl_frame_rate);

		if (dbl_frame_rate > 0.0)
			gst_aravis->buffer_timeout_us = MAX (GST_ARAVIS_BUFFER_TIMEOUT_DEFAULT,
							     3e6 / dbl_frame_rate);
		else
			gst_aravis->buffer_timeout_us = GST_ARAVIS_BUFFER_TIMEOUT_DEFAULT;
	} else
		gst_aravis->buffer_timeout_us = GST_ARAVIS_BUFFER_TIMEOUT_DEFAULT;

	GST_DEBUG_OBJECT (gst_aravis, "Buffer timeout = %Ld µs", gst_aravis->buffer_timeout_us);

	GST_DEBUG_OBJECT (gst_aravis, "Actual frame rate = %g Hz", arv_camera_get_frame_rate (gst_aravis->camera));

	if(gst_aravis->gain_auto) {
		arv_camera_set_gain_auto (gst_aravis->camera, ARV_AUTO_CONTINUOUS);
		GST_DEBUG_OBJECT (gst_aravis, "Auto Gain = continuous", gst_aravis->gain_auto);
	} else {
		if (gst_aravis->gain >= 0) {
			GST_DEBUG_OBJECT (gst_aravis, "Gain = %d", gst_aravis->gain);
			arv_camera_set_gain_auto (gst_aravis->camera, ARV_AUTO_OFF);
			arv_camera_set_gain (gst_aravis->camera, gst_aravis->gain);
		}
		GST_DEBUG_OBJECT (gst_aravis, "Actual gain = %d", arv_camera_get_gain (gst_aravis->camera));
	}

	if(gst_aravis->exposure_auto) {
		arv_camera_set_exposure_time_auto (gst_aravis->camera, ARV_AUTO_CONTINUOUS);
		GST_DEBUG_OBJECT (gst_aravis, "Auto Exposure = contiuous", gst_aravis->exposure_auto);
	} else {
		if (gst_aravis->exposure_time_us > 0.0) {
			GST_DEBUG_OBJECT (gst_aravis, "Exposure = %g µs", gst_aravis->exposure_time_us);
			arv_camera_set_exposure_time_auto (gst_aravis->camera, ARV_AUTO_OFF);
			arv_camera_set_exposure_time (gst_aravis->camera, gst_aravis->exposure_time_us);
		}
		GST_DEBUG_OBJECT (gst_aravis, "Actual exposure = %g µs", arv_camera_get_exposure_time (gst_aravis->camera));
	}

	if (gst_aravis->fixed_caps != NULL)
		gst_caps_unref (gst_aravis->fixed_caps);

	caps_string = arv_pixel_format_to_gst_caps_string (pixel_format);
	if (caps_string != NULL) {
		GstStructure *structure;
		GstCaps *caps;

		caps = gst_caps_new_empty ();
		structure = gst_structure_from_string (caps_string, NULL);
		gst_structure_set (structure,
				   "width", G_TYPE_INT, width,
				   "height", G_TYPE_INT, height,
				   NULL);

		if (frame_rate != NULL)
			gst_structure_set_value (structure, "framerate", frame_rate);

		gst_caps_append_structure (caps, structure);

		gst_aravis->fixed_caps = caps;
	} else
		gst_aravis->fixed_caps = NULL;

	gst_aravis->payload = arv_camera_get_payload (gst_aravis->camera);
	gst_aravis->stream = arv_camera_create_stream (gst_aravis->camera, NULL, NULL);

	for (i = 0; i < GST_ARAVIS_N_BUFFERS; i++)
		arv_stream_push_buffer (gst_aravis->stream,
					arv_buffer_new (gst_aravis->payload, NULL));

	GST_LOG_OBJECT (gst_aravis, "Start acquisition");
	arv_camera_start_acquisition (gst_aravis->camera);

	gst_aravis->timestamp_offset = 0;
	gst_aravis->last_timestamp = 0;

	return TRUE;
}