gstreamer/sys/v4l2/gstv4l2transform.c
2014-05-08 15:56:37 -04:00

766 lines
22 KiB
C

/*
* Copyright (C) 2014 Collabora Ltd.
* Author: Nicolas Dufresne <nicolas.dufresne@collabora.co.uk>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include "gstv4l2transform.h"
#include "v4l2_calls.h"
#include <string.h>
#include <gst/gst-i18n-plugin.h>
#define DEFAULT_PROP_DEVICE "/dev/video10"
#define V4L2_TRANSFORM_QUARK \
g_quark_from_static_string("gst-v4l2-transform-info")
GST_DEBUG_CATEGORY_STATIC (gst_v4l2_transform_debug);
#define GST_CAT_DEFAULT gst_v4l2_transform_debug
enum
{
PROP_0,
V4L2_STD_OBJECT_PROPS,
PROP_CAPTURE_IO_MODE,
};
typedef struct
{
gchar *device;
GstCaps *sink_caps;
GstCaps *src_caps;
} GstV4l2TransformCData;
#define gst_v4l2_transform_parent_class parent_class
G_DEFINE_ABSTRACT_TYPE (GstV4l2Transform, gst_v4l2_transform,
GST_TYPE_BASE_TRANSFORM);
static void
gst_v4l2_transform_set_property (GObject * object,
guint prop_id, const GValue * value, GParamSpec * pspec)
{
GstV4l2Transform *self = GST_V4L2_TRANSFORM (object);
switch (prop_id) {
/* Split IO mode so output is configure through 'io-mode' and capture
* through 'capture-io-mode' */
case PROP_IO_MODE:
gst_v4l2_object_set_property_helper (self->v4l2output, prop_id, value,
pspec);
break;
case PROP_CAPTURE_IO_MODE:
gst_v4l2_object_set_property_helper (self->v4l2capture, PROP_IO_MODE,
value, pspec);
break;
case PROP_DEVICE:
gst_v4l2_object_set_property_helper (self->v4l2output, prop_id, value,
pspec);
gst_v4l2_object_set_property_helper (self->v4l2capture, prop_id, value,
pspec);
break;
/* By default, only set on output */
default:
if (!gst_v4l2_object_set_property_helper (self->v4l2output,
prop_id, value, pspec)) {
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
}
break;
}
}
static void
gst_v4l2_transform_get_property (GObject * object,
guint prop_id, GValue * value, GParamSpec * pspec)
{
GstV4l2Transform *self = GST_V4L2_TRANSFORM (object);
switch (prop_id) {
case PROP_IO_MODE:
gst_v4l2_object_get_property_helper (self->v4l2output, prop_id, value,
pspec);
break;
case PROP_CAPTURE_IO_MODE:
gst_v4l2_object_get_property_helper (self->v4l2output, PROP_IO_MODE,
value, pspec);
break;
/* By default read from output */
default:
if (!gst_v4l2_object_get_property_helper (self->v4l2output,
prop_id, value, pspec)) {
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
}
break;
}
}
static gboolean
gst_v4l2_transform_open (GstV4l2Transform * self)
{
GST_DEBUG_OBJECT (self, "Opening");
if (!gst_v4l2_object_open (self->v4l2output))
goto failure;
if (!gst_v4l2_object_open_shared (self->v4l2capture, self->v4l2output))
goto failure;
self->probed_sinkcaps = gst_v4l2_object_get_caps (self->v4l2output,
gst_v4l2_object_get_raw_caps ());
if (gst_caps_is_empty (self->probed_sinkcaps))
goto no_input_format;
self->probed_srccaps = gst_v4l2_object_get_caps (self->v4l2capture,
gst_v4l2_object_get_raw_caps ());
if (gst_caps_is_empty (self->probed_srccaps))
goto no_output_format;
return TRUE;
no_input_format:
GST_ELEMENT_ERROR (self, RESOURCE, SETTINGS,
(_("Converter on device %s has no supported input format"),
self->v4l2output->videodev), (NULL));
goto failure;
no_output_format:
GST_ELEMENT_ERROR (self, RESOURCE, SETTINGS,
(_("Converter on device %s has no supported output format"),
self->v4l2output->videodev), (NULL));
goto failure;
failure:
if (GST_V4L2_IS_OPEN (self->v4l2output))
gst_v4l2_object_close (self->v4l2output);
if (GST_V4L2_IS_OPEN (self->v4l2capture))
gst_v4l2_object_close (self->v4l2capture);
gst_caps_replace (&self->probed_srccaps, NULL);
gst_caps_replace (&self->probed_sinkcaps, NULL);
return FALSE;
}
static void
gst_v4l2_transform_close (GstV4l2Transform * self)
{
GST_DEBUG_OBJECT (self, "Closing");
gst_v4l2_object_close (self->v4l2output);
gst_v4l2_object_close (self->v4l2capture);
gst_caps_replace (&self->probed_srccaps, NULL);
gst_caps_replace (&self->probed_srccaps, NULL);
}
static gboolean
gst_v4l2_transform_stop (GstBaseTransform * trans)
{
GstV4l2Transform *self = GST_V4L2_TRANSFORM (trans);
GST_DEBUG_OBJECT (self, "Stop");
gst_v4l2_object_stop (self->v4l2output);
gst_v4l2_object_stop (self->v4l2capture);
gst_caps_replace (&self->incaps, NULL);
gst_caps_replace (&self->outcaps, NULL);
return TRUE;
}
static gboolean
gst_v4l2_transform_set_caps (GstBaseTransform * trans, GstCaps * incaps,
GstCaps * outcaps)
{
GstV4l2Transform *self = GST_V4L2_TRANSFORM (trans);
if (self->incaps && self->outcaps) {
if (gst_caps_is_equal (incaps, self->incaps) &&
gst_caps_is_equal (outcaps, self->outcaps)) {
GST_DEBUG_OBJECT (trans, "Caps did not changed");
return TRUE;
}
}
/* TODO Add renegotiation support */
g_return_val_if_fail (!GST_V4L2_IS_ACTIVE (self->v4l2output), FALSE);
g_return_val_if_fail (!GST_V4L2_IS_ACTIVE (self->v4l2capture), FALSE);
gst_caps_replace (&self->incaps, incaps);
gst_caps_replace (&self->outcaps, outcaps);
if (!gst_v4l2_object_set_format (self->v4l2output, incaps))
goto incaps_failed;
if (!gst_v4l2_object_set_format (self->v4l2capture, outcaps))
goto outcaps_failed;
/* FIXME implement fallback if crop not supported */
if (!gst_v4l2_object_set_crop (self->v4l2output))
goto failed;
if (!gst_v4l2_object_set_crop (self->v4l2capture))
goto failed;
return TRUE;
incaps_failed:
{
GST_ERROR_OBJECT (self, "failed to set input caps: %" GST_PTR_FORMAT,
incaps);
goto failed;
}
outcaps_failed:
{
gst_v4l2_object_stop (self->v4l2output);
GST_ERROR_OBJECT (self, "failed to set output caps: %" GST_PTR_FORMAT,
outcaps);
goto failed;
}
failed:
return FALSE;
}
static gboolean
gst_v4l2_transform_query (GstBaseTransform * trans, GstPadDirection direction,
GstQuery * query)
{
GstV4l2Transform *self = GST_V4L2_TRANSFORM (trans);
gboolean ret = TRUE;
switch (GST_QUERY_TYPE (query)) {
case GST_QUERY_CAPS:{
GstCaps *filter, *caps = NULL, *result = NULL;
GstPad *pad, *otherpad;
gst_query_parse_caps (query, &filter);
if (direction == GST_PAD_SRC) {
pad = GST_BASE_TRANSFORM_SRC_PAD (trans);
otherpad = GST_BASE_TRANSFORM_SINK_PAD (trans);
if (self->probed_srccaps)
caps = gst_caps_ref (self->probed_srccaps);
} else {
pad = GST_BASE_TRANSFORM_SINK_PAD (trans);
otherpad = GST_BASE_TRANSFORM_SRC_PAD (trans);
if (self->probed_srccaps)
caps = gst_caps_ref (self->probed_sinkcaps);
}
if (!caps)
caps = gst_pad_get_pad_template_caps (pad);
if (filter) {
GstCaps *tmp = caps;
caps = gst_caps_intersect_full (filter, tmp, GST_CAPS_INTERSECT_FIRST);
gst_caps_unref (tmp);
}
result = gst_pad_peer_query_caps (otherpad, caps);
result = gst_caps_make_writable (result);
gst_caps_append (result, caps);
GST_DEBUG_OBJECT (self, "Returning %s caps %" GST_PTR_FORMAT,
GST_PAD_NAME (pad), result);
gst_query_set_caps_result (query, result);
gst_caps_unref (result);
break;
}
default:
ret = GST_BASE_TRANSFORM_CLASS (parent_class)->query (trans, direction,
query);
break;
}
return ret;
}
static gboolean
gst_v4l2_transform_decide_allocation (GstBaseTransform * trans,
GstQuery * query)
{
GstV4l2Transform *self = GST_V4L2_TRANSFORM (trans);
gboolean ret = FALSE;
GST_DEBUG_OBJECT (self, "called");
if (gst_v4l2_object_decide_allocation (self->v4l2capture, query)) {
GstBufferPool *pool = GST_BUFFER_POOL (self->v4l2capture->pool);
ret = GST_BASE_TRANSFORM_CLASS (parent_class)->decide_allocation (trans,
query);
if (!gst_buffer_pool_set_active (pool, TRUE))
goto activate_failed;
}
return ret;
activate_failed:
GST_ELEMENT_ERROR (self, RESOURCE, SETTINGS,
("failed to activate bufferpool"), ("failed to activate bufferpool"));
return TRUE;
}
static gboolean
gst_v4l2_transform_propose_allocation (GstBaseTransform * trans,
GstQuery * decide_query, GstQuery * query)
{
GstV4l2Transform *self = GST_V4L2_TRANSFORM (trans);
gboolean ret = FALSE;
GST_DEBUG_OBJECT (self, "called");
if (decide_query == NULL)
ret = TRUE;
else
ret = gst_v4l2_object_propose_allocation (self->v4l2output, query);
if (ret)
ret = GST_BASE_TRANSFORM_CLASS (parent_class)->propose_allocation (trans,
decide_query, query);
return ret;
}
/* copies the given caps */
static GstCaps *
gst_v4l2_transform_caps_remove_format_info (GstCaps * caps)
{
GstStructure *st;
GstCapsFeatures *f;
gint i, n;
GstCaps *res;
res = gst_caps_new_empty ();
n = gst_caps_get_size (caps);
for (i = 0; i < n; i++) {
st = gst_caps_get_structure (caps, i);
f = gst_caps_get_features (caps, i);
/* If this is already expressed by the existing caps
* skip this structure */
if (i > 0 && gst_caps_is_subset_structure_full (res, st, f))
continue;
st = gst_structure_copy (st);
/* Only remove format info for the cases when we can actually convert */
if (!gst_caps_features_is_any (f)
&& gst_caps_features_is_equal (f,
GST_CAPS_FEATURES_MEMORY_SYSTEM_MEMORY))
gst_structure_remove_fields (st, "format", "colorimetry", "chroma-site",
NULL);
gst_caps_append_structure_full (res, st, gst_caps_features_copy (f));
}
return res;
}
/* The caps can be transformed into any other caps with format info removed.
* However, we should prefer passthrough, so if passthrough is possible,
* put it first in the list. */
static GstCaps *
gst_v4l2_transform_transform_caps (GstBaseTransform * btrans,
GstPadDirection direction, GstCaps * caps, GstCaps * filter)
{
GstCaps *tmp, *tmp2;
GstCaps *result;
/* Get all possible caps that we can transform to */
tmp = gst_v4l2_transform_caps_remove_format_info (caps);
if (filter) {
tmp2 = gst_caps_intersect_full (filter, tmp, GST_CAPS_INTERSECT_FIRST);
gst_caps_unref (tmp);
tmp = tmp2;
}
result = tmp;
GST_DEBUG_OBJECT (btrans, "transformed %" GST_PTR_FORMAT " into %"
GST_PTR_FORMAT, caps, result);
return result;
}
static GstCaps *
gst_v4l2_transform_fixate_caps (GstBaseTransform * trans,
GstPadDirection direction, GstCaps * caps, GstCaps * othercaps)
{
GstCaps *result;
GST_DEBUG_OBJECT (trans, "trying to fixate othercaps %" GST_PTR_FORMAT
" based on caps %" GST_PTR_FORMAT, othercaps, caps);
result = gst_caps_intersect (othercaps, caps);
if (gst_caps_is_empty (result)) {
gst_caps_unref (result);
result = othercaps;
} else {
gst_caps_unref (othercaps);
}
GST_DEBUG_OBJECT (trans, "now fixating %" GST_PTR_FORMAT, result);
result = gst_caps_fixate (result);
return result;
}
static GstFlowReturn
gst_v4l2_transform_prepare_output_buffer (GstBaseTransform * trans,
GstBuffer * inbuf, GstBuffer ** outbuf)
{
GstV4l2Transform *self = GST_V4L2_TRANSFORM (trans);
GstBufferPool *pool = GST_BUFFER_POOL (self->v4l2output->pool);
GstFlowReturn ret = GST_FLOW_OK;
GstBaseTransformClass *bclass = GST_BASE_TRANSFORM_CLASS (parent_class);
if (gst_base_transform_is_passthrough (trans)) {
GST_DEBUG_OBJECT (self, "Passthrough, no need to do anything");
*outbuf = inbuf;
goto beach;
}
/* Ensure input internal pool is active */
if (!gst_buffer_pool_is_active (pool)) {
GstStructure *config = gst_buffer_pool_get_config (pool);
gst_buffer_pool_config_set_params (config, self->incaps,
self->v4l2output->sizeimage, 2, 2);
/* There is no reason to refuse this config */
if (!gst_buffer_pool_set_config (pool, config))
goto activate_failed;
if (!gst_buffer_pool_set_active (pool, TRUE))
goto activate_failed;
}
GST_DEBUG_OBJECT (self, "Queue input buffer");
ret = gst_v4l2_buffer_pool_process (GST_V4L2_BUFFER_POOL (pool), &inbuf);
if (G_UNLIKELY (ret != GST_FLOW_OK))
goto beach;
pool = gst_base_transform_get_buffer_pool (trans);
if (!gst_buffer_pool_set_active (pool, TRUE))
goto activate_failed;
GST_DEBUG_OBJECT (self, "Dequeue output buffer");
ret = gst_buffer_pool_acquire_buffer (pool, outbuf, NULL);
g_object_unref (pool);
if (ret != GST_FLOW_OK)
goto alloc_failed;
pool = self->v4l2capture->pool;
ret = gst_v4l2_buffer_pool_process (GST_V4L2_BUFFER_POOL (pool), outbuf);
if (ret != GST_FLOW_OK) {
gst_buffer_unref (*outbuf);
*outbuf = NULL;
}
if (bclass->copy_metadata)
if (!bclass->copy_metadata (trans, inbuf, *outbuf)) {
/* something failed, post a warning */
GST_ELEMENT_WARNING (self, STREAM, NOT_IMPLEMENTED,
("could not copy metadata"), (NULL));
}
beach:
return ret;
activate_failed:
GST_ELEMENT_ERROR (self, RESOURCE, SETTINGS,
("failed to activate bufferpool"), ("failed to activate bufferpool"));
return GST_FLOW_ERROR;
alloc_failed:
GST_DEBUG_OBJECT (self, "could not allocate buffer from pool");
return ret;
}
static GstFlowReturn
gst_v4l2_transform_transform (GstBaseTransform * trans, GstBuffer * inbuf,
GstBuffer * outbuf)
{
/* Nothing to do */
return GST_FLOW_OK;
}
static gboolean
gst_v4l2_transform_sink_event (GstBaseTransform * trans, GstEvent * event)
{
GstV4l2Transform *self = GST_V4L2_TRANSFORM (trans);
switch (GST_EVENT_TYPE (event)) {
case GST_EVENT_FLUSH_START:
GST_DEBUG_OBJECT (self, "flush start");
gst_v4l2_object_unlock (self->v4l2output);
gst_v4l2_object_unlock (self->v4l2capture);
case GST_EVENT_FLUSH_STOP:
GST_DEBUG_OBJECT (self, "flush stop");
gst_v4l2_object_unlock_stop (self->v4l2output);
gst_v4l2_object_unlock_stop (self->v4l2capture);
default:
break;
}
return GST_BASE_TRANSFORM_CLASS (parent_class)->sink_event (trans, event);
}
static GstStateChangeReturn
gst_v4l2_transform_change_state (GstElement * element,
GstStateChange transition)
{
GstV4l2Transform *self = GST_V4L2_TRANSFORM (element);
GstStateChangeReturn ret;
switch (transition) {
case GST_STATE_CHANGE_NULL_TO_READY:
if (!gst_v4l2_transform_open (self))
return GST_STATE_CHANGE_FAILURE;
break;
case GST_STATE_CHANGE_PAUSED_TO_READY:
gst_v4l2_object_unlock (self->v4l2output);
gst_v4l2_object_unlock (self->v4l2capture);
break;
default:
break;
}
ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
switch (transition) {
case GST_STATE_CHANGE_READY_TO_NULL:
gst_v4l2_transform_close (self);
break;
default:
break;
}
return ret;
}
static void
gst_v4l2_transform_dispose (GObject * object)
{
GstV4l2Transform *self = GST_V4L2_TRANSFORM (object);
gst_caps_replace (&self->probed_sinkcaps, NULL);
gst_caps_replace (&self->probed_srccaps, NULL);
G_OBJECT_CLASS (parent_class)->dispose (object);
}
static void
gst_v4l2_transform_finalize (GObject * object)
{
GstV4l2Transform *self = GST_V4L2_TRANSFORM (object);
gst_v4l2_object_destroy (self->v4l2capture);
gst_v4l2_object_destroy (self->v4l2output);
G_OBJECT_CLASS (parent_class)->finalize (object);
}
static void
gst_v4l2_transform_init (GstV4l2Transform * self)
{
/* V4L2 object are created in subinstance_init */
/* enable QoS */
gst_base_transform_set_qos_enabled (GST_BASE_TRANSFORM (self), TRUE);
}
static void
gst_v4l2_transform_subinstance_init (GTypeInstance * instance, gpointer g_class)
{
GstV4l2TransformClass *klass = GST_V4L2_TRANSFORM_CLASS (g_class);
GstV4l2Transform *self = GST_V4L2_TRANSFORM (instance);
self->v4l2output = gst_v4l2_object_new (GST_ELEMENT (self),
V4L2_BUF_TYPE_VIDEO_OUTPUT, klass->default_device,
gst_v4l2_get_output, gst_v4l2_set_output, NULL);
self->v4l2output->no_initial_format = TRUE;
self->v4l2output->keep_aspect = FALSE;
self->v4l2capture = gst_v4l2_object_new (GST_ELEMENT (self),
V4L2_BUF_TYPE_VIDEO_CAPTURE, klass->default_device,
gst_v4l2_get_input, gst_v4l2_set_input, NULL);
self->v4l2capture->no_initial_format = TRUE;
self->v4l2output->keep_aspect = FALSE;
g_object_set (self, "device", klass->default_device, NULL);
}
static void
gst_v4l2_transform_class_init (GstV4l2TransformClass * klass)
{
GstElementClass *element_class;
GObjectClass *gobject_class;
GstBaseTransformClass *base_transform_class;
element_class = (GstElementClass *) klass;
gobject_class = (GObjectClass *) klass;
base_transform_class = (GstBaseTransformClass *) klass;
GST_DEBUG_CATEGORY_INIT (gst_v4l2_transform_debug, "v4l2transform", 0,
"V4L2 Converter");
gst_element_class_set_static_metadata (element_class,
"V4L2 Video Converter",
"Filter/Converter/Video",
"Transform streams via V4L2 API",
"Nicolas Dufresne <nicolas.dufresne@collabora.com>");
gobject_class->dispose = GST_DEBUG_FUNCPTR (gst_v4l2_transform_dispose);
gobject_class->finalize = GST_DEBUG_FUNCPTR (gst_v4l2_transform_finalize);
gobject_class->set_property =
GST_DEBUG_FUNCPTR (gst_v4l2_transform_set_property);
gobject_class->get_property =
GST_DEBUG_FUNCPTR (gst_v4l2_transform_get_property);
base_transform_class->stop = GST_DEBUG_FUNCPTR (gst_v4l2_transform_stop);
base_transform_class->set_caps =
GST_DEBUG_FUNCPTR (gst_v4l2_transform_set_caps);
base_transform_class->query = GST_DEBUG_FUNCPTR (gst_v4l2_transform_query);
base_transform_class->sink_event =
GST_DEBUG_FUNCPTR (gst_v4l2_transform_sink_event);
base_transform_class->decide_allocation =
GST_DEBUG_FUNCPTR (gst_v4l2_transform_decide_allocation);
base_transform_class->propose_allocation =
GST_DEBUG_FUNCPTR (gst_v4l2_transform_propose_allocation);
base_transform_class->transform_caps =
GST_DEBUG_FUNCPTR (gst_v4l2_transform_transform_caps);
base_transform_class->fixate_caps =
GST_DEBUG_FUNCPTR (gst_v4l2_transform_fixate_caps);
base_transform_class->prepare_output_buffer =
GST_DEBUG_FUNCPTR (gst_v4l2_transform_prepare_output_buffer);
base_transform_class->transform =
GST_DEBUG_FUNCPTR (gst_v4l2_transform_transform);
base_transform_class->passthrough_on_same_caps = TRUE;
/* FIXME need this ? */
element_class->change_state =
GST_DEBUG_FUNCPTR (gst_v4l2_transform_change_state);
gst_v4l2_object_install_properties_helper (gobject_class,
DEFAULT_PROP_DEVICE);
/**
* GstV4l2Transform:capture-io-mode
*
* Capture IO Mode
*/
g_object_class_install_property (gobject_class, PROP_CAPTURE_IO_MODE,
g_param_spec_enum ("capture-io-mode", "Capture IO mode",
"Capture I/O mode",
GST_TYPE_V4L2_IO_MODE, GST_V4L2_IO_AUTO,
G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
}
static void
gst_v4l2_transform_subclass_init (gpointer g_class, gpointer data)
{
GstV4l2TransformClass *klass = GST_V4L2_TRANSFORM_CLASS (g_class);
GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
GstV4l2TransformCData *cdata = data;
klass->default_device = cdata->device;
/* Note: gst_pad_template_new() take the floating ref from the caps */
gst_element_class_add_pad_template (element_class,
gst_pad_template_new ("sink", GST_PAD_SINK, GST_PAD_ALWAYS,
cdata->sink_caps));
gst_element_class_add_pad_template (element_class,
gst_pad_template_new ("src", GST_PAD_SRC, GST_PAD_ALWAYS,
cdata->src_caps));
g_free (cdata);
}
/* Probing functions */
gboolean
gst_v4l2_is_transform (GstCaps * sink_caps, GstCaps * src_caps)
{
gboolean ret = FALSE;
if (gst_caps_is_subset (sink_caps, gst_v4l2_object_get_raw_caps ())
&& gst_caps_is_subset (src_caps, gst_v4l2_object_get_raw_caps ()))
ret = TRUE;
return ret;
}
gboolean
gst_v4l2_transform_register (GstPlugin * plugin, const gchar * basename,
const gchar * device_path, GstCaps * sink_caps, GstCaps * src_caps)
{
GTypeQuery type_query;
GTypeInfo type_info = { 0, };
GType type, subtype;
gchar *type_name;
GstV4l2TransformCData *cdata;
cdata = g_new0 (GstV4l2TransformCData, 1);
cdata->device = g_strdup (device_path);
cdata->sink_caps = gst_caps_ref (sink_caps);
cdata->src_caps = gst_caps_ref (src_caps);
type = gst_v4l2_transform_get_type ();
g_type_query (type, &type_query);
memset (&type_info, 0, sizeof (type_info));
type_info.class_size = type_query.class_size;
type_info.instance_size = type_query.instance_size;
type_info.class_init = gst_v4l2_transform_subclass_init;
type_info.class_data = cdata;
type_info.instance_init = gst_v4l2_transform_subinstance_init;
type_name = g_strdup_printf ("v4l2%sconvert", basename);
subtype = g_type_register_static (type, type_name, &type_info, 0);
gst_element_register (plugin, type_name, GST_RANK_PRIMARY + 1, subtype);
g_free (type_name);
return TRUE;
}