Gstreamer 1.0 v4l2src到c应用程序的简单管道
我的管道是这样的Gstreamer 1.0 v4l2src到c应用程序的简单管道,gstreamer-1.0,Gstreamer 1.0,我的管道是这样的 gst-launch-1.0 v4l2src ! videoconvert ! xvimagesink #include <gst/gst.h> // easier to pass them as callbacks typedef struct _CustomData{ GstElement *pipeline; GstElement *source; GstElement *convert; GstElement *sink; }Cust
gst-launch-1.0 v4l2src ! videoconvert ! xvimagesink
#include <gst/gst.h>
// easier to pass them as callbacks
typedef struct _CustomData{
GstElement *pipeline;
GstElement *source;
GstElement *convert;
GstElement *sink;
}CustomData;
// callback function
// here src is the v4l2src, newpad is gstpad that has just been added to src element. This is usually the pad to which we want to lnk
// data is the pointer we provided when attaching to the signal.
static void pad_added_handler(GstElement *src, GstPad *new_pad,CustomData *data)
{
GstPad *sink_pad = gst_element_get_static_pad(data->convert, "sink");
GstPadLinkReturn ret;
GstCaps *new_pad_caps = NULL;
GstStructure *new_pad_struct = NULL;
const gchar *new_pad_type = NULL;
if(gst_pad_is_linked(sink_pad))
{
g_print("we are linked. igonring\n");
}
// check the new pad types
// we have previously created a piece of pipeline which deals with videoconvert linked with xvimagesink and we will nto be able to link it to a pad producing video.
//gst-pad_get_current_caps()- retrieves current capabilities of pad
new_pad_caps = gst_pad_get_current_caps(new_pad);
new_pad_struct = gst_caps_get_structure(new_pad_caps, 0);
new_pad_type = gst_structure_get_name(new_pad_struct);
if(!g_str_has_prefix(new_pad_type, "video/x-raw"))
{
g_print("It has new pad type");
}
// gst_pad_link tries to link two pads . the link must be specified from source to sink and both pads must be owned by elements residing in same pipeline
ret = gst_pad_link(new_pad, sink_pad);
if(GST_PAD_LINK_FAILED(ret))
{
g_print("type is new_pad_type");
}
if(new_pad_caps !=NULL)
{
gst_caps_unref(new_pad_caps);
}
gst_object_unref(sink_pad);
}
int main(int argc, char *argv[])
{
GMainLoop *loop;
CustomData data;
GstBus *bus;
GstMessage *msg;
gboolean terminate = FALSE;
gst_init(&argc, &argv);
// loop = g_main_loop_new(NULL, FALSE);
// create the elements
data.source = gst_element_factory_make("v4l2src", "source");
data.convert = gst_element_factory_make("videoconvert", "convert");
data.sink = gst_element_factory_make("xvimagesink", "sink");
data.pipeline = gst_pipeline_new("new-pipeline");
if(!data.pipeline || !data.source || !data.convert || !data.sink)
{
g_printerr("Not all elements could be created\n");
return -1;
}
//we did not link source at this point of time, we will do it later
gst_bin_add_many(GST_BIN(data.pipeline), data.source, data.convert, data.sink, NULL);
// we link convert element to sink, do not link them with source. we dont have source pads here. so we just have videoconvert->sink unlinked
// gst_element_link(data.source, data.convert);
if(!gst_element_link(data.convert,data.sink))
{
g_printerr("elements could not be linked\n");
gst_object_unref(data.pipeline);
return -1;
}
// we set the device source
//g_object_set(source, "device", "/dev/video0", NULL);
//connect to pad added signal.
// we want to attach pad added signal to source element. to do so, we are using g_signal_connect and provide callback function and datapointer.
// when source element has enough information to start producing data, it will create source pads and trigger the pad added signal. at this point, our callback is called
g_signal_connect(G_OBJECT(data.source), "pad-added", G_CALLBACK(pad_added_handler), &data );
//g_signal_connect(G_OBJECT(data.source), "pad-added", G_CALLBACK(handler), &data);
GstStateChangeReturn ret;
ret =gst_element_set_state (data.pipeline, GST_STATE_PLAYING);
if (ret == GST_STATE_CHANGE_FAILURE) {
g_printerr ("Unable to set the pipeline to the playing state.\n");
gst_object_unref (data.pipeline);
return -1;
}
// g_main_loop_run(loop);
/* Listen to the bus */
bus = gst_element_get_bus (data.pipeline);
do {
msg = gst_bus_timed_pop_filtered (bus, GST_CLOCK_TIME_NONE,
GST_MESSAGE_STATE_CHANGED | GST_MESSAGE_ERROR | GST_MESSAGE_EOS);
/* Parse message */
if (msg != NULL) {
GError *err;
gchar *debug_info;
switch (GST_MESSAGE_TYPE (msg)) {
case GST_MESSAGE_ERROR:
gst_message_parse_error (msg, &err, &debug_info);
g_printerr ("Error received from element %s: %s\n", GST_OBJECT_NAME (msg->src), err->message);
g_printerr ("Debugging information: %s\n", debug_info ? debug_info : "none");
g_clear_error (&err);
g_free (debug_info);
terminate = TRUE;
break;
case GST_MESSAGE_EOS:
g_print ("End-Of-Stream reached.\n");
terminate = TRUE;
break;
case GST_MESSAGE_STATE_CHANGED:
/* We are only interested in state-changed messages from the pipeline */
if (GST_MESSAGE_SRC (msg) == GST_OBJECT (data.pipeline)) {
GstState old_state, new_state, pending_state;
gst_message_parse_state_changed (msg, &old_state, &new_state, &pending_state);
g_print ("Pipeline state changed from %s to %s:\n",
gst_element_state_get_name (old_state), gst_element_state_get_name (new_state));
}
break;
default:
/* We should not reach here */
g_printerr ("Unexpected message received.\n");
break;
}
gst_message_unref (msg);
}
} while (!terminate);
/* Free resources */
gst_object_unref (bus);
gst_element_set_state(data.pipeline, GST_STATE_NULL);
gst_object_unref(data.pipeline);
return 0;
}
gst-launch-1.0 v4l2src ! videoconvert ! xvimagesink
#include <gst/gst.h>
// easier to pass them as callbacks
typedef struct _CustomData{
GstElement *pipeline;
GstElement *source;
GstElement *convert;
GstElement *sink;
}CustomData;
// callback function
// here src is the v4l2src, newpad is gstpad that has just been added to src element. This is usually the pad to which we want to lnk
// data is the pointer we provided when attaching to the signal.
static void pad_added_handler(GstElement *src, GstPad *new_pad,CustomData *data)
{
GstPad *sink_pad = gst_element_get_static_pad(data->convert, "sink");
GstPadLinkReturn ret;
GstCaps *new_pad_caps = NULL;
GstStructure *new_pad_struct = NULL;
const gchar *new_pad_type = NULL;
if(gst_pad_is_linked(sink_pad))
{
g_print("we are linked. igonring\n");
}
// check the new pad types
// we have previously created a piece of pipeline which deals with videoconvert linked with xvimagesink and we will nto be able to link it to a pad producing video.
//gst-pad_get_current_caps()- retrieves current capabilities of pad
new_pad_caps = gst_pad_get_current_caps(new_pad);
new_pad_struct = gst_caps_get_structure(new_pad_caps, 0);
new_pad_type = gst_structure_get_name(new_pad_struct);
if(!g_str_has_prefix(new_pad_type, "video/x-raw"))
{
g_print("It has new pad type");
}
// gst_pad_link tries to link two pads . the link must be specified from source to sink and both pads must be owned by elements residing in same pipeline
ret = gst_pad_link(new_pad, sink_pad);
if(GST_PAD_LINK_FAILED(ret))
{
g_print("type is new_pad_type");
}
if(new_pad_caps !=NULL)
{
gst_caps_unref(new_pad_caps);
}
gst_object_unref(sink_pad);
}
int main(int argc, char *argv[])
{
GMainLoop *loop;
CustomData data;
GstBus *bus;
GstMessage *msg;
gboolean terminate = FALSE;
gst_init(&argc, &argv);
// loop = g_main_loop_new(NULL, FALSE);
// create the elements
data.source = gst_element_factory_make("v4l2src", "source");
data.convert = gst_element_factory_make("videoconvert", "convert");
data.sink = gst_element_factory_make("xvimagesink", "sink");
data.pipeline = gst_pipeline_new("new-pipeline");
if(!data.pipeline || !data.source || !data.convert || !data.sink)
{
g_printerr("Not all elements could be created\n");
return -1;
}
//we did not link source at this point of time, we will do it later
gst_bin_add_many(GST_BIN(data.pipeline), data.source, data.convert, data.sink, NULL);
// we link convert element to sink, do not link them with source. we dont have source pads here. so we just have videoconvert->sink unlinked
// gst_element_link(data.source, data.convert);
if(!gst_element_link(data.convert,data.sink))
{
g_printerr("elements could not be linked\n");
gst_object_unref(data.pipeline);
return -1;
}
// we set the device source
//g_object_set(source, "device", "/dev/video0", NULL);
//connect to pad added signal.
// we want to attach pad added signal to source element. to do so, we are using g_signal_connect and provide callback function and datapointer.
// when source element has enough information to start producing data, it will create source pads and trigger the pad added signal. at this point, our callback is called
g_signal_connect(G_OBJECT(data.source), "pad-added", G_CALLBACK(pad_added_handler), &data );
//g_signal_connect(G_OBJECT(data.source), "pad-added", G_CALLBACK(handler), &data);
GstStateChangeReturn ret;
ret =gst_element_set_state (data.pipeline, GST_STATE_PLAYING);
if (ret == GST_STATE_CHANGE_FAILURE) {
g_printerr ("Unable to set the pipeline to the playing state.\n");
gst_object_unref (data.pipeline);
return -1;
}
// g_main_loop_run(loop);
/* Listen to the bus */
bus = gst_element_get_bus (data.pipeline);
do {
msg = gst_bus_timed_pop_filtered (bus, GST_CLOCK_TIME_NONE,
GST_MESSAGE_STATE_CHANGED | GST_MESSAGE_ERROR | GST_MESSAGE_EOS);
/* Parse message */
if (msg != NULL) {
GError *err;
gchar *debug_info;
switch (GST_MESSAGE_TYPE (msg)) {
case GST_MESSAGE_ERROR:
gst_message_parse_error (msg, &err, &debug_info);
g_printerr ("Error received from element %s: %s\n", GST_OBJECT_NAME (msg->src), err->message);
g_printerr ("Debugging information: %s\n", debug_info ? debug_info : "none");
g_clear_error (&err);
g_free (debug_info);
terminate = TRUE;
break;
case GST_MESSAGE_EOS:
g_print ("End-Of-Stream reached.\n");
terminate = TRUE;
break;
case GST_MESSAGE_STATE_CHANGED:
/* We are only interested in state-changed messages from the pipeline */
if (GST_MESSAGE_SRC (msg) == GST_OBJECT (data.pipeline)) {
GstState old_state, new_state, pending_state;
gst_message_parse_state_changed (msg, &old_state, &new_state, &pending_state);
g_print ("Pipeline state changed from %s to %s:\n",
gst_element_state_get_name (old_state), gst_element_state_get_name (new_state));
}
break;
default:
/* We should not reach here */
g_printerr ("Unexpected message received.\n");
break;
}
gst_message_unref (msg);
}
} while (!terminate);
/* Free resources */
gst_object_unref (bus);
gst_element_set_state(data.pipeline, GST_STATE_NULL);
gst_object_unref(data.pipeline);
return 0;
}
#包括
//更容易将它们作为回调传递
类型定义结构\u自定义数据{
GstElement*管道；
GstElement*来源；
GstElement*转换；
GstElement*水槽；
}海关数据；
//回调函数
//这里src是v4l2src，newpad是刚刚添加到src元素的gstpad。这通常是我们想要的键盘
//数据是我们在附加到信号时提供的指针。
添加了静态无效填充处理程序（GstElement*src、GstPad*新填充、CustomData*数据）
{
GstPad*sink\u pad=gst\u element\u get\u static\u pad（数据->转换，“sink”）；
gstpadlinkret；
GstCaps*新焊盘焊帽=NULL；
GST结构*new_pad_struct=NULL；
常量gchar*新焊盘类型=空；
如果（gst_焊盘_连接（水槽_焊盘））
{
g_print（“我们是链接的。igonring\n”）；
}
//检查新的焊盘类型
//我们之前已经创建了一条处理与xvimagesink链接的videoconvert的管道，我们将能够将其链接到制作视频的pad。
//gst-pad\u get\u current\u caps（）-检索pad的当前功能
新焊盘盖=gst焊盘盖获取当前焊盘盖（新焊盘）；
new_pad_struct=gst_caps_get_structure（new_pad_caps，0）；
新建垫块类型=gst垫块结构名称（新建垫块结构）；
如果（！g_str_具有_前缀（新的_pad_类型，“视频/x-raw”））
{
g_print（“它有新的衬垫类型”）；
}
//gst_pad_link尝试链接两个焊盘。必须指定从源到接收器的链接，并且两个焊盘必须由驻留在同一管道中的元素所有
ret=gst_焊盘_链路（新_焊盘、水槽_焊盘）；
如果（GST_焊盘_连接_失败（ret））
{
g_打印（“类型是新的_pad_类型”）；
}
如果（新焊盘焊帽！=NULL）
{
gst_caps_unref（新的_pad_caps）；
}
gst_对象_unref（水槽_垫）；
}
int main（int argc，char*argv[]）
{
GMainLoop*循环；
客户数据；
GstBus*总线；
GstMessage*msg；
gboolean终止=FALSE；
gst_init（&argc，&argv）；
//loop=g_main_loop_new（NULL，FALSE）；
//创建元素
data.source=gst元素工厂制造（“v4l2src”，“source”）；
data.convert=gst元素工厂制造（“视频转换”、“转换”）；
data.sink=gst元素工厂制造（“xImage sink”、“sink”）；
data.pipeline=gst_pipeline_new（“新管道”）；
如果（！data.pipeline | | |！data.source | |！data.convert | |！data.sink）
{
g_printerr（“不是所有元素都可以创建\n”）；
返回-1；
}
//目前我们还没有链接源代码，我们将稍后再做
gst_bin_add_many（gst_bin（data.pipeline）、data.source、data.convert、data.sink、NULL）；
//我们将convert元素链接到sink，而不是将它们链接到source。我们这里没有source Pad。所以我们只有videoconvert->sink unlinked
//gst_元素_链接（data.source，data.convert）；
if（！gst_元素_链接（data.convert，data.sink））
{
g_printerr（“无法链接元素”）；
gst_object_unref（数据管道）；
返回-1；
}
//我们设置了设备源
//g_对象_集（源，“设备”，“/dev/video0”，空）；
//连接到pad附加信号。
//我们希望将pad添加的信号附加到源元素。为此，我们使用g_signal_connect并提供回调函数和数据指针。
//当源元素有足够的信息开始生成数据时，它将创建源pad并触发pad added信号
g_信号连接（g_对象（data.source），“添加了焊盘”，g_回调（添加了焊盘处理程序），&data）；
//g_信号连接（g_对象（data.source），“添加了pad”，g_回调（handler），&data）；
GSTStateChangeRet；
ret=gst\u元素\u集合\u状态（data.pipeline，gst\u状态\u PLAYING）；
如果（ret==GST\u状态\u变化\u失败）{
g_printerr（“无法将管道设置为播放状态。\n”）；
gst_object_unref（数据管道）；
返回-1；
}
//g_主循环运行（循环）；
/*听公共汽车*/
总线=gst\u元素\u获取\u总线（数据管道）；
做{
msg=gst\总线\定时\弹出\过滤（总线、gst\时钟\时间\无、，
GST_消息_状态_变更| GST_消息_错误| GST_消息_EOS）；
/*解析消息*/
如果（msg！=NULL）{
GError*err；
gchar*调试信息；
开关（GST\信息\类型（msg））{
案例GST\u消息\u错误：
gst\消息\解析\错误（消息、错误和调试\信息）；
g_printerr（“从元素%s接收到错误：%s\n”，GST_对象名称（msg->src），err->message）；
g_printerr（“调试信息：%s\n”，调试信息？调试信息：“无”）；
g_清除_错误（&err）；
g_免费（调试信息）；
终止=真；
打破
案例GST\信息\ EOS：
g_print（“到达流结束。\n”）；
终止=真；
打破
案例GST\消息\状态\更改：
/*我们只对来自管道的状态更改消息感兴趣*/
if（GST_MESSAGE_SRC（msg）=GST_对象（data.pipeline））{
GST状态旧状态、新状态、待定状态；
gst\消息\解析\状态\已更改（消息、旧状态、新状态和挂起状态）；
g_print（“管道状态从%s更改为%s:\n”，
gst_元素_状态_获取名称（旧状态），gst_元素_状态_获取名称（新状态））；
}
打破
违约：
/*我们不应该到达这里*/
g_printerr（“收到意外消息。\n”）；
打破
}
gst_消息_unref（msg）；
}
}而（！终止）；
/*免费资源*/
商品及服务税（巴士）；
gst_元素_集合_状态（data.pipeline，gst_状态_NULL）；
gst_object_unref（数据管道）；
返回0；
}