gstreamer/gst/vaapi/gstvaapidecode.c
2012-09-12 13:41:47 +02:00

758 lines
22 KiB
C

/*
* gstvaapidecode.c - VA-API video decoder
*
* Copyright (C) 2010-2011 Splitted-Desktop Systems
* Copyright (C) 2011-2012 Intel Corporation
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1
* 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free
* Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301 USA
*/
/**
* SECTION:gstvaapidecode
* @short_description: A VA-API based video decoder
*
* vaapidecode decodes from raw bitstreams to surfaces suitable for
* the vaapisink element.
*/
#include "gst/vaapi/sysdeps.h"
#include <gst/vaapi/gstvaapidisplay.h>
#include <gst/vaapi/gstvaapivideobuffer.h>
#include <gst/video/videocontext.h>
#include "gstvaapidecode.h"
#include "gstvaapipluginutil.h"
#include "gstvaapipluginbuffer.h"
#include <gst/vaapi/gstvaapidecoder_h264.h>
#include <gst/vaapi/gstvaapidecoder_jpeg.h>
#include <gst/vaapi/gstvaapidecoder_mpeg2.h>
#include <gst/vaapi/gstvaapidecoder_mpeg4.h>
#include <gst/vaapi/gstvaapidecoder_vc1.h>
#define GST_PLUGIN_NAME "vaapidecode"
#define GST_PLUGIN_DESC "A VA-API based video decoder"
GST_DEBUG_CATEGORY_STATIC(gst_debug_vaapidecode);
#define GST_CAT_DEFAULT gst_debug_vaapidecode
/* ElementFactory information */
static const GstElementDetails gst_vaapidecode_details =
GST_ELEMENT_DETAILS(
"VA-API decoder",
"Codec/Decoder/Video",
GST_PLUGIN_DESC,
"Gwenole Beauchesne <gwenole.beauchesne@intel.com>");
/* Default templates */
#define GST_CAPS_CODEC(CODEC) CODEC "; "
static const char gst_vaapidecode_sink_caps_str[] =
GST_CAPS_CODEC("video/mpeg, mpegversion=2, systemstream=(boolean)false")
GST_CAPS_CODEC("video/mpeg, mpegversion=4")
GST_CAPS_CODEC("video/x-divx")
GST_CAPS_CODEC("video/x-xvid")
GST_CAPS_CODEC("video/x-h263")
GST_CAPS_CODEC("video/x-h264")
GST_CAPS_CODEC("video/x-wmv")
GST_CAPS_CODEC("image/jpeg")
;
static const char gst_vaapidecode_src_caps_str[] =
GST_VAAPI_SURFACE_CAPS;
static GstStaticPadTemplate gst_vaapidecode_sink_factory =
GST_STATIC_PAD_TEMPLATE(
"sink",
GST_PAD_SINK,
GST_PAD_ALWAYS,
GST_STATIC_CAPS(gst_vaapidecode_sink_caps_str));
static GstStaticPadTemplate gst_vaapidecode_src_factory =
GST_STATIC_PAD_TEMPLATE(
"src",
GST_PAD_SRC,
GST_PAD_ALWAYS,
GST_STATIC_CAPS(gst_vaapidecode_src_caps_str));
static void
gst_vaapidecode_implements_iface_init(GstImplementsInterfaceClass *iface);
static void
gst_video_context_interface_init(GstVideoContextInterface *iface);
#define GstVideoContextClass GstVideoContextInterface
G_DEFINE_TYPE_WITH_CODE(
GstVaapiDecode,
gst_vaapidecode,
GST_TYPE_ELEMENT,
G_IMPLEMENT_INTERFACE(GST_TYPE_IMPLEMENTS_INTERFACE,
gst_vaapidecode_implements_iface_init);
G_IMPLEMENT_INTERFACE(GST_TYPE_VIDEO_CONTEXT,
gst_video_context_interface_init))
static gboolean
gst_vaapidecode_update_src_caps(GstVaapiDecode *decode, GstCaps *caps);
static void
gst_vaapi_decoder_notify_caps(GObject *obj, GParamSpec *pspec, void *user_data)
{
GstVaapiDecode * const decode = GST_VAAPIDECODE(user_data);
GstCaps *caps;
g_assert(decode->decoder == GST_VAAPI_DECODER(obj));
caps = gst_vaapi_decoder_get_caps(decode->decoder);
gst_vaapidecode_update_src_caps(decode, caps);
}
static inline gboolean
gst_vaapidecode_update_sink_caps(GstVaapiDecode *decode, GstCaps *caps)
{
if (decode->sinkpad_caps)
gst_caps_unref(decode->sinkpad_caps);
decode->sinkpad_caps = gst_caps_ref(caps);
return TRUE;
}
static gboolean
gst_vaapidecode_update_src_caps(GstVaapiDecode *decode, GstCaps *caps)
{
GstCaps *other_caps;
GstStructure *structure;
const GValue *v_width, *v_height, *v_framerate, *v_par, *v_interlaced;
gboolean success;
if (!decode->srcpad_caps) {
decode->srcpad_caps = gst_caps_from_string(GST_VAAPI_SURFACE_CAPS_NAME);
if (!decode->srcpad_caps)
return FALSE;
}
structure = gst_caps_get_structure(caps, 0);
v_width = gst_structure_get_value(structure, "width");
v_height = gst_structure_get_value(structure, "height");
v_framerate = gst_structure_get_value(structure, "framerate");
v_par = gst_structure_get_value(structure, "pixel-aspect-ratio");
v_interlaced = gst_structure_get_value(structure, "interlaced");
structure = gst_caps_get_structure(decode->srcpad_caps, 0);
if (v_width && v_height) {
gst_structure_set_value(structure, "width", v_width);
gst_structure_set_value(structure, "height", v_height);
}
if (v_framerate)
gst_structure_set_value(structure, "framerate", v_framerate);
if (v_par)
gst_structure_set_value(structure, "pixel-aspect-ratio", v_par);
if (v_interlaced)
gst_structure_set_value(structure, "interlaced", v_interlaced);
gst_structure_set(structure, "type", G_TYPE_STRING, "vaapi", NULL);
gst_structure_set(structure, "opengl", G_TYPE_BOOLEAN, USE_GLX, NULL);
other_caps = gst_caps_copy(decode->srcpad_caps);
success = gst_pad_set_caps(decode->srcpad, other_caps);
gst_caps_unref(other_caps);
return success;
}
static void
gst_vaapidecode_release(GstVaapiDecode *decode, GObject *dead_object)
{
if (!decode->decoder_mutex || !decode->decoder_ready)
return;
g_mutex_lock(decode->decoder_mutex);
g_cond_signal(decode->decoder_ready);
g_mutex_unlock(decode->decoder_mutex);
}
static GstFlowReturn
gst_vaapidecode_step(GstVaapiDecode *decode)
{
GstVaapiSurfaceProxy *proxy;
GstVaapiDecoderStatus status;
GstBuffer *buffer;
GstFlowReturn ret;
GstClockTime timestamp;
gint64 end_time;
for (;;) {
end_time = decode->render_time_base;
if (!end_time)
end_time = g_get_monotonic_time();
end_time += GST_TIME_AS_USECONDS(decode->last_buffer_time);
end_time += G_TIME_SPAN_SECOND;
proxy = gst_vaapi_decoder_get_surface(decode->decoder, &status);
if (!proxy) {
if (status == GST_VAAPI_DECODER_STATUS_ERROR_NO_SURFACE) {
gboolean was_signalled;
g_mutex_lock(decode->decoder_mutex);
was_signalled = g_cond_wait_until(
decode->decoder_ready,
decode->decoder_mutex,
end_time
);
g_mutex_unlock(decode->decoder_mutex);
if (was_signalled)
continue;
goto error_decode_timeout;
}
if (status != GST_VAAPI_DECODER_STATUS_ERROR_NO_DATA)
goto error_decode;
/* More data is needed */
break;
}
g_object_weak_ref(
G_OBJECT(proxy),
(GWeakNotify)gst_vaapidecode_release,
decode
);
buffer = gst_vaapi_video_buffer_new(decode->display);
if (!buffer)
goto error_create_buffer;
timestamp = GST_VAAPI_SURFACE_PROXY_TIMESTAMP(proxy);
if (!decode->render_time_base)
decode->render_time_base = g_get_monotonic_time();
decode->last_buffer_time = timestamp;
GST_BUFFER_TIMESTAMP(buffer) = timestamp;
GST_BUFFER_DURATION(buffer) = GST_VAAPI_SURFACE_PROXY_DURATION(proxy);
gst_buffer_set_caps(buffer, GST_PAD_CAPS(decode->srcpad));
if (GST_VAAPI_SURFACE_PROXY_TFF(proxy))
GST_BUFFER_FLAG_SET(buffer, GST_VIDEO_BUFFER_TFF);
gst_vaapi_video_buffer_set_surface_proxy(
GST_VAAPI_VIDEO_BUFFER(buffer),
proxy
);
ret = gst_pad_push(decode->srcpad, buffer);
if (ret != GST_FLOW_OK)
goto error_commit_buffer;
g_object_unref(proxy);
}
return GST_FLOW_OK;
/* ERRORS */
error_decode_timeout:
{
GST_DEBUG("decode timeout. Decoder required a VA surface but none "
"got available within one second");
return GST_FLOW_UNEXPECTED;
}
error_decode:
{
GST_DEBUG("decode error %d", status);
switch (status) {
case GST_VAAPI_DECODER_STATUS_ERROR_UNSUPPORTED_CODEC:
case GST_VAAPI_DECODER_STATUS_ERROR_UNSUPPORTED_PROFILE:
case GST_VAAPI_DECODER_STATUS_ERROR_UNSUPPORTED_CHROMA_FORMAT:
ret = GST_FLOW_NOT_SUPPORTED;
break;
default:
ret = GST_FLOW_UNEXPECTED;
break;
}
return ret;
}
error_create_buffer:
{
const GstVaapiID surface_id =
gst_vaapi_surface_get_id(GST_VAAPI_SURFACE_PROXY_SURFACE(proxy));
GST_DEBUG("video sink failed to create video buffer for proxy'ed "
"surface %" GST_VAAPI_ID_FORMAT " (error %d)",
GST_VAAPI_ID_ARGS(surface_id), ret);
g_object_unref(proxy);
return GST_FLOW_UNEXPECTED;
}
error_commit_buffer:
{
GST_DEBUG("video sink rejected the video buffer (error %d)", ret);
g_object_unref(proxy);
return GST_FLOW_UNEXPECTED;
}
}
static inline gboolean
gst_vaapidecode_ensure_display(GstVaapiDecode *decode)
{
return gst_vaapi_ensure_display(decode, GST_VAAPI_DISPLAY_TYPE_ANY,
&decode->display);
}
static inline guint
gst_vaapi_codec_from_caps(GstCaps *caps)
{
return gst_vaapi_profile_get_codec(gst_vaapi_profile_from_caps(caps));
}
static gboolean
gst_vaapidecode_create(GstVaapiDecode *decode, GstCaps *caps)
{
GstVaapiDisplay *dpy;
if (!gst_vaapidecode_ensure_display(decode))
return FALSE;
dpy = decode->display;
decode->decoder_mutex = g_mutex_new();
if (!decode->decoder_mutex)
return FALSE;
decode->decoder_ready = g_cond_new();
if (!decode->decoder_ready)
return FALSE;
switch (gst_vaapi_codec_from_caps(caps)) {
case GST_VAAPI_CODEC_MPEG2:
decode->decoder = gst_vaapi_decoder_mpeg2_new(dpy, caps);
break;
case GST_VAAPI_CODEC_MPEG4:
case GST_VAAPI_CODEC_H263:
decode->decoder = gst_vaapi_decoder_mpeg4_new(dpy, caps);
break;
case GST_VAAPI_CODEC_H264:
decode->decoder = gst_vaapi_decoder_h264_new(dpy, caps);
break;
case GST_VAAPI_CODEC_WMV3:
case GST_VAAPI_CODEC_VC1:
decode->decoder = gst_vaapi_decoder_vc1_new(dpy, caps);
break;
#if USE_JPEG_DECODER
case GST_VAAPI_CODEC_JPEG:
decode->decoder = gst_vaapi_decoder_jpeg_new(dpy, caps);
break;
#endif
default:
decode->decoder = NULL;
break;
}
if (!decode->decoder)
return FALSE;
g_signal_connect(
G_OBJECT(decode->decoder),
"notify::caps",
G_CALLBACK(gst_vaapi_decoder_notify_caps),
decode
);
decode->decoder_caps = gst_caps_ref(caps);
return TRUE;
}
static void
gst_vaapidecode_destroy(GstVaapiDecode *decode)
{
if (decode->decoder) {
gst_vaapi_decoder_put_buffer(decode->decoder, NULL);
g_object_unref(decode->decoder);
decode->decoder = NULL;
}
if (decode->decoder_caps) {
gst_caps_unref(decode->decoder_caps);
decode->decoder_caps = NULL;
}
if (decode->decoder_ready) {
gst_vaapidecode_release(decode, NULL);
g_cond_free(decode->decoder_ready);
decode->decoder_ready = NULL;
}
if (decode->decoder_mutex) {
g_mutex_free(decode->decoder_mutex);
decode->decoder_mutex = NULL;
}
}
static gboolean
gst_vaapidecode_reset(GstVaapiDecode *decode, GstCaps *caps)
{
GstVaapiCodec codec;
/* Only reset decoder if codec type changed */
if (decode->decoder && decode->decoder_caps) {
if (gst_caps_is_always_compatible(caps, decode->decoder_caps))
return TRUE;
codec = gst_vaapi_codec_from_caps(caps);
if (codec == gst_vaapi_decoder_get_codec(decode->decoder))
return TRUE;
}
gst_vaapidecode_destroy(decode);
return gst_vaapidecode_create(decode, caps);
}
/* GstImplementsInterface interface */
static gboolean
gst_vaapidecode_implements_interface_supported(
GstImplementsInterface *iface,
GType type
)
{
return (type == GST_TYPE_VIDEO_CONTEXT);
}
static void
gst_vaapidecode_implements_iface_init(GstImplementsInterfaceClass *iface)
{
iface->supported = gst_vaapidecode_implements_interface_supported;
}
/* GstVideoContext interface */
static void
gst_vaapidecode_set_video_context(GstVideoContext *context, const gchar *type,
const GValue *value)
{
GstVaapiDecode *decode = GST_VAAPIDECODE (context);
gst_vaapi_set_display (type, value, &decode->display);
}
static void
gst_video_context_interface_init(GstVideoContextInterface *iface)
{
iface->set_context = gst_vaapidecode_set_video_context;
}
static void
gst_vaapidecode_finalize(GObject *object)
{
GstVaapiDecode * const decode = GST_VAAPIDECODE(object);
gst_vaapidecode_destroy(decode);
if (decode->sinkpad_caps) {
gst_caps_unref(decode->sinkpad_caps);
decode->sinkpad_caps = NULL;
}
if (decode->srcpad_caps) {
gst_caps_unref(decode->srcpad_caps);
decode->srcpad_caps = NULL;
}
g_clear_object(&decode->display);
if (decode->allowed_caps) {
gst_caps_unref(decode->allowed_caps);
decode->allowed_caps = NULL;
}
if (decode->delayed_new_seg) {
gst_event_unref(decode->delayed_new_seg);
decode->delayed_new_seg = NULL;
}
G_OBJECT_CLASS(gst_vaapidecode_parent_class)->finalize(object);
}
static GstStateChangeReturn
gst_vaapidecode_change_state(GstElement *element, GstStateChange transition)
{
GstVaapiDecode * const decode = GST_VAAPIDECODE(element);
GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
switch (transition) {
case GST_STATE_CHANGE_NULL_TO_READY:
decode->is_ready = TRUE;
break;
case GST_STATE_CHANGE_READY_TO_PAUSED:
break;
case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
break;
default:
break;
}
ret = GST_ELEMENT_CLASS(gst_vaapidecode_parent_class)->change_state(element, transition);
if (ret != GST_STATE_CHANGE_SUCCESS)
return ret;
switch (transition) {
case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
break;
case GST_STATE_CHANGE_PAUSED_TO_READY:
break;
case GST_STATE_CHANGE_READY_TO_NULL:
gst_vaapidecode_destroy(decode);
g_clear_object(&decode->display);
decode->is_ready = FALSE;
break;
default:
break;
}
return GST_STATE_CHANGE_SUCCESS;
}
static void
gst_vaapidecode_class_init(GstVaapiDecodeClass *klass)
{
GObjectClass * const object_class = G_OBJECT_CLASS(klass);
GstElementClass * const element_class = GST_ELEMENT_CLASS(klass);
GstPadTemplate *pad_template;
GST_DEBUG_CATEGORY_INIT(gst_debug_vaapidecode,
GST_PLUGIN_NAME, 0, GST_PLUGIN_DESC);
object_class->finalize = gst_vaapidecode_finalize;
element_class->change_state = gst_vaapidecode_change_state;
gst_element_class_set_details_simple(
element_class,
gst_vaapidecode_details.longname,
gst_vaapidecode_details.klass,
gst_vaapidecode_details.description,
gst_vaapidecode_details.author
);
/* sink pad */
pad_template = gst_static_pad_template_get(&gst_vaapidecode_sink_factory);
gst_element_class_add_pad_template(element_class, pad_template);
gst_object_unref(pad_template);
/* src pad */
pad_template = gst_static_pad_template_get(&gst_vaapidecode_src_factory);
gst_element_class_add_pad_template(element_class, pad_template);
gst_object_unref(pad_template);
}
static gboolean
gst_vaapidecode_ensure_allowed_caps(GstVaapiDecode *decode)
{
GstCaps *decode_caps;
guint i, n_decode_caps;
if (decode->allowed_caps)
return TRUE;
if (!gst_vaapidecode_ensure_display(decode))
goto error_no_display;
decode_caps = gst_vaapi_display_get_decode_caps(decode->display);
if (!decode_caps)
goto error_no_decode_caps;
n_decode_caps = gst_caps_get_size(decode_caps);
decode->allowed_caps = gst_caps_new_empty();
if (!decode->allowed_caps)
goto error_no_memory;
for (i = 0; i < n_decode_caps; i++) {
GstStructure *structure;
structure = gst_caps_get_structure(decode_caps, i);
if (!structure)
continue;
structure = gst_structure_copy(structure);
if (!structure)
continue;
gst_structure_remove_field(structure, "profile");
gst_structure_set(
structure,
"width", GST_TYPE_INT_RANGE, 1, G_MAXINT,
"height", GST_TYPE_INT_RANGE, 1, G_MAXINT,
NULL
);
gst_caps_merge_structure(decode->allowed_caps, structure);
}
gst_caps_unref(decode_caps);
return TRUE;
/* ERRORS */
error_no_display:
{
GST_DEBUG("failed to retrieve VA display");
return FALSE;
}
error_no_decode_caps:
{
GST_DEBUG("failed to retrieve VA decode caps");
return FALSE;
}
error_no_memory:
{
GST_DEBUG("failed to allocate allowed-caps set");
gst_caps_unref(decode_caps);
return FALSE;
}
}
static GstCaps *
gst_vaapidecode_get_caps(GstPad *pad)
{
GstVaapiDecode * const decode = GST_VAAPIDECODE(GST_OBJECT_PARENT(pad));
if (!decode->is_ready)
return gst_static_pad_template_get_caps(&gst_vaapidecode_sink_factory);
if (!gst_vaapidecode_ensure_allowed_caps(decode))
return gst_caps_new_empty();
return gst_caps_ref(decode->allowed_caps);
}
static gboolean
gst_vaapidecode_set_caps(GstPad *pad, GstCaps *caps)
{
GstVaapiDecode * const decode = GST_VAAPIDECODE(GST_OBJECT_PARENT(pad));
g_return_val_if_fail(pad == decode->sinkpad, FALSE);
if (!gst_vaapidecode_update_sink_caps(decode, caps))
return FALSE;
if (!gst_vaapidecode_update_src_caps(decode, caps))
return FALSE;
if (!gst_vaapidecode_reset(decode, decode->sinkpad_caps))
return FALSE;
/* Propagate NEWSEGMENT event downstream, now that pads are linked */
if (decode->delayed_new_seg) {
if (gst_pad_push_event(decode->srcpad, decode->delayed_new_seg))
gst_event_unref(decode->delayed_new_seg);
decode->delayed_new_seg = NULL;
}
return TRUE;
}
static GstFlowReturn
gst_vaapidecode_chain(GstPad *pad, GstBuffer *buf)
{
GstVaapiDecode * const decode = GST_VAAPIDECODE(GST_OBJECT_PARENT(pad));
if (!gst_vaapi_decoder_put_buffer(decode->decoder, buf))
goto error_push_buffer;
gst_buffer_unref(buf);
return gst_vaapidecode_step(decode);
/* ERRORS */
error_push_buffer:
{
GST_DEBUG("failed to push input buffer to decoder");
gst_buffer_unref(buf);
return GST_FLOW_UNEXPECTED;
}
}
static gboolean
gst_vaapidecode_sink_event(GstPad *pad, GstEvent *event)
{
GstVaapiDecode * const decode = GST_VAAPIDECODE(GST_OBJECT_PARENT(pad));
GST_DEBUG("handle sink event '%s'", GST_EVENT_TYPE_NAME(event));
/* Propagate event downstream */
switch (GST_EVENT_TYPE(event)) {
case GST_EVENT_NEWSEGMENT:
if (decode->delayed_new_seg) {
gst_event_unref(decode->delayed_new_seg);
decode->delayed_new_seg = NULL;
}
if (!GST_PAD_PEER(decode->srcpad)) {
decode->delayed_new_seg = gst_event_ref(event);
return TRUE;
}
break;
default:
break;
}
return gst_pad_push_event(decode->srcpad, event);
}
static gboolean
gst_vaapidecode_src_event(GstPad *pad, GstEvent *event)
{
GstVaapiDecode * const decode = GST_VAAPIDECODE(GST_OBJECT_PARENT(pad));
GST_DEBUG("handle src event '%s'", GST_EVENT_TYPE_NAME(event));
/* Propagate event upstream */
return gst_pad_push_event(decode->sinkpad, event);
}
static gboolean
gst_vaapidecode_query (GstPad *pad, GstQuery *query) {
GstVaapiDecode *decode = GST_VAAPIDECODE (gst_pad_get_parent_element (pad));
gboolean res;
GST_DEBUG ("sharing display %p", decode->display);
if (gst_vaapi_reply_to_query (query, decode->display))
res = TRUE;
else
res = gst_pad_query_default (pad, query);
g_object_unref (decode);
return res;
}
static void
gst_vaapidecode_init(GstVaapiDecode *decode)
{
GstVaapiDecodeClass *klass = GST_VAAPIDECODE_GET_CLASS(decode);
GstElementClass * const element_class = GST_ELEMENT_CLASS(klass);
decode->display = NULL;
decode->decoder = NULL;
decode->decoder_mutex = NULL;
decode->decoder_ready = NULL;
decode->decoder_caps = NULL;
decode->allowed_caps = NULL;
decode->delayed_new_seg = NULL;
decode->render_time_base = 0;
decode->last_buffer_time = 0;
decode->is_ready = FALSE;
/* Pad through which data comes in to the element */
decode->sinkpad = gst_pad_new_from_template(
gst_element_class_get_pad_template(element_class, "sink"),
"sink"
);
decode->sinkpad_caps = NULL;
gst_pad_set_getcaps_function(decode->sinkpad, gst_vaapidecode_get_caps);
gst_pad_set_setcaps_function(decode->sinkpad, gst_vaapidecode_set_caps);
gst_pad_set_chain_function(decode->sinkpad, gst_vaapidecode_chain);
gst_pad_set_event_function(decode->sinkpad, gst_vaapidecode_sink_event);
gst_pad_set_query_function(decode->sinkpad, gst_vaapidecode_query);
gst_element_add_pad(GST_ELEMENT(decode), decode->sinkpad);
/* Pad through which data goes out of the element */
decode->srcpad = gst_pad_new_from_template(
gst_element_class_get_pad_template(element_class, "src"),
"src"
);
decode->srcpad_caps = NULL;
gst_pad_use_fixed_caps(decode->srcpad);
gst_pad_set_event_function(decode->srcpad, gst_vaapidecode_src_event);
gst_pad_set_query_function(decode->srcpad, gst_vaapidecode_query);
gst_element_add_pad(GST_ELEMENT(decode), decode->srcpad);
}