gstreamer - 垫创建和 gst_parse_launch 上的一些错误
问题描述
我是 gstreamer 的新手,我想知道我们是否必须为流水线中的视频转换等转换创建源垫和接收垫。我有这样的管道
gst-launch-1.0 v4l2src ! video/x-raw,format=YUY2 ! videoconvert ! xvimagesink
我正在尝试创建一个简单的 c 应用程序来了解垫的创建,并想知道视频转换是否也有源垫和接收垫。我正在为过滤器创建一个源和接收器垫。
编辑:是的,你看,我尝试按照动态管道示例并编写下面的代码
#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)
{
g_print("In pad handler\n");
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);
g_print ("It has type '%s' which is not raw audio. Ignoring.\n", new_pad_type);
if(!g_str_has_prefix(new_pad_type, "video/x-raw,format=(string)YUY2"))
{
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_print("before signal connect\n");
gint id= g_signal_connect(G_OBJECT(data.source), "pad-added", G_CALLBACK(pad_added_handler), &data );
g_print("after signal connect with id = %d\n", id);
//g_signal_connect(G_OBJECT(data.source), "pad-added", G_CALLBACK(handler), &data);
// gst_element_link(data.source, data.convert);
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;
}
它给了我一个错误
before signal connect
after signal connect with id = 1
Pipeline state changed from NULL to READY:
Pipeline state changed from READY to PAUSED:
Error received from element source: Internal data stream error.
Debugging information: gstbasesrc.c(3055): gst_base_src_loop (): /GstPipeline:new-pipeline/GstV4l2Src:source:
streaming stopped, reason not-linked (-1)
(如果我在用于转换和接收的元素链接语句之后编写 gst_elements_link(data.source, data.convert),则上述代码有效)
所以我尝试了正常的方式,将所有元素添加并链接在一起,它开始在不使用垫的情况下工作。
#include <gst/gst.h>
int main(int argc, char *argv[])
{
GstElement *pipeline, *source, *convert, *sink;
GstBus *bus;
GstMessage *msg;
gst_init(&argc, &argv);
source = gst_element_factory_make("v4l2src", "source");
convert = gst_element_factory_make("nvvidconv", "convert");
sink = gst_element_factory_make("xvimagesink", "sink");
pipeline = gst_pipeline_new("pipe");
gst_bin_add_many(GST_BIN(pipeline), source,convert,sink, NULL);
gst_element_link_many(source,convert,sink,NULL);
gst_element_set_state(pipeline,GST_STATE_PLAYING);
bus = gst_element_get_bus (pipeline);
msg = gst_bus_timed_pop_filtered (bus, GST_CLOCK_TIME_NONE, 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);
break;
case GST_MESSAGE_EOS:
g_print ("End-Of-Stream reached.\n");
break;
default:
/* We should not reach here because we only asked for ERRORs and EOS */
g_printerr ("Unexpected message received.\n");
break;
}
gst_message_unref (msg);
}
/* Free resources */
gst_object_unref(bus);
gst_element_set_state(pipeline,GST_STATE_NULL);
gst_object_unref(pipeline);
}
但是,为了完全掌握 pad 的知识,我想用 pad 执行更简单的管道。我只是不完全了解垫子的用法并将它们和所有东西联系起来。
编辑2:
最终我想为这样的管道编写应用程序,它在命令行上运行得非常好,
gst-launch-1.0 v4l2src device='/dev/video0' ! 'video/x-raw,format=(string)YUY2,width=(int)640,height=(int)480' ! nvvidconv ! 'video/x-raw(memory:NVMM),format=(string)NV12,width=(int)640,height=(int)480' ! nvvidconv ! 'video/x-raw,format=(string)NV12,width=(int)640,height=(int)480' ! nvvideoconvert ! 'video/x-raw(memory:NVMM),format=(string)NV12,width=(int)640,height=(int)480' ! mux.sink_0 nvstreammux live-source=1 name=mux batch-size=1 width=640 height=480 ! nvinfer config-file-path=/opt/nvidia/deepstream/deepstream-4.0/sources/apps/sample_apps/deepstream-test1/dstest1_pgie_config.txt batch-size=1 ! nvmultistreamtiler rows=1 columns=1 width=640 height=480 ! nvvideoconvert ! nvdsosd ! nvegltransform ! nveglglessink sync=false -v
但由于我不了解 pad 和 bin 的用法,我无法在上面的管道中实现它们。但是,我试过这个,
#include <gst/gst.h>
#include <glib.h>
#include <stdio.h>
#include "gstnvdsmeta.h"
#define MAX_DISPLAY_LEN 64
#define PGIE_CLASS_ID_VEHICLE 0
#define PGIE_CLASS_ID_PERSON 2
gint frame_number = 0;
gchar pgie_classes_str[4][32] = { "Vehicle", "TwoWheeler", "Person",
"Roadsign"
};
static GstPadProbeReturn osd_sink_pad_buffer_probe(GstPad *pad, GstPadProbeInfo *info, gpointer u_data)
{
GstBuffer *buf=(GstBuffer *)info->data;
guint num_rects =0;
NvDsObjectMeta *obj_meta = NULL;
guint vehicle_count = 0;
guint person_count = 0;
NvDsMetaList * l_frame = NULL;
NvDsMetaList * l_obj = NULL;
NvDsDisplayMeta *display_meta = NULL;
NvDsBatchMeta *batch_meta = gst_buffer_get_nvds_batch_meta (buf);
for (l_frame = batch_meta->frame_meta_list; l_frame != NULL;
l_frame = l_frame->next) {
NvDsFrameMeta *frame_meta = (NvDsFrameMeta *) (l_frame->data);
int offset = 0;
for (l_obj = frame_meta->obj_meta_list; l_obj != NULL;
l_obj = l_obj->next) {
obj_meta = (NvDsObjectMeta *) (l_obj->data);
if (obj_meta->class_id == PGIE_CLASS_ID_VEHICLE) {
vehicle_count++;
num_rects++;
}
if (obj_meta->class_id == PGIE_CLASS_ID_PERSON) {
person_count++;
num_rects++;
}
}
display_meta = nvds_acquire_display_meta_from_pool(batch_meta);
NvOSD_TextParams *txt_params = &display_meta->text_params[0];
display_meta->num_labels = 1;
txt_params->display_text = g_malloc0 (MAX_DISPLAY_LEN);
offset = snprintf(txt_params->display_text, MAX_DISPLAY_LEN, "Person = %d ", person_count);
offset = snprintf(txt_params->display_text + offset , MAX_DISPLAY_LEN, "Vehicle = %d ", vehicle_count);
/* Now set the offsets where the string should appear */
txt_params->x_offset = 10;
txt_params->y_offset = 12;
/* Font , font-color and font-size */
txt_params->font_params.font_name = "Serif";
txt_params->font_params.font_size = 10;
txt_params->font_params.font_color.red = 1.0;
txt_params->font_params.font_color.green = 1.0;
txt_params->font_params.font_color.blue = 1.0;
txt_params->font_params.font_color.alpha = 1.0;
/* Text background color */
txt_params->set_bg_clr = 1;
txt_params->text_bg_clr.red = 0.0;
txt_params->text_bg_clr.green = 0.0;
txt_params->text_bg_clr.blue = 0.0;
txt_params->text_bg_clr.alpha = 1.0;
nvds_add_display_meta_to_frame(frame_meta, display_meta);
}
g_print ("Frame Number = %d Number of objects = %d "
"Vehicle Count = %d Person Count = %d\n",
frame_number, num_rects, vehicle_count, person_count);
frame_number++;
return GST_PAD_PROBE_OK;
}
int main(int argc, char *argv[])
{
GstElement *pipeline, *source, *filter1, *convert,*filter2, *filter3, *vidconv, *filter4, *mux, *infer, *tiler, *osd, *transform , *sink, *bin, *convert2 , *vidconv2;
GMainLoop *loop;
GstCaps *caps1, *caps2, *caps3, *caps4;
GstPad *osd_sink_pad =NULL, *srcpad, *sinkpad;
loop = g_main_loop_new(NULL,FALSE);
gst_init(&argc, &argv);
pipeline = gst_pipeline_new("nv_pipeline");
gchar *string1 = "video/x-raw(memory:NVMM),format=(string)NV12";
source = gst_element_factory_make("v4l2src", "source");
filter1 = gst_element_factory_make("capsfilter", "filter1");
convert = gst_element_factory_make("nvvidconv", "convert");
filter2 = gst_element_factory_make("capsfilter", "filter2");
filter3 = gst_element_factory_make("capsfilter", "filter3");
filter4 = gst_element_factory_make("capsfilter", "filter4");
vidconv = gst_element_factory_make("nvvideoconvert", "vidconv");
mux = gst_element_factory_make("nvstreammux", "mux");
infer = gst_element_factory_make("nvinfer", "infer");
tiler = gst_element_factory_make("nvmultistreamtiler", "tiler");
osd = gst_element_factory_make("nvosd", "osd");
transform = gst_element_factory_make("nvegltransform", "transform");
sink = gst_element_factory_make("nveglglessink", "sink");
convert2 = gst_element_factory_make("nvvidconv", "convert2");
vidconv2 = gst_element_factory_make("nvvideoconvert", "vidconv2");
gst_bin_add_many(GST_BIN(pipeline), source,filter1,convert,filter2, convert2,filter3,vidconv, filter4,mux,infer, tiler,vidconv2, osd,transform,sink,NULL);
gst_element_link_many(source,filter1,convert,filter2, convert2,filter3, vidconv, filter4,mux,infer, tiler,vidconv2, osd,transform,sink,NULL);
osd_sink_pad = gst_element_get_static_pad(osd, "sink");
gst_pad_add_probe(osd_sink_pad, GST_PAD_PROBE_TYPE_BUFFER, osd_sink_pad_buffer_probe, NULL, NULL);
caps1 = gst_caps_new_simple("video/x-raw", "format",G_TYPE_STRING,"YUY2",NULL);
caps2 = gst_caps_from_string(string1);
caps3 = gst_caps_new_simple("video/x-raw", "format", G_TYPE_STRING,"NV12", NULL);
caps4 = gst_caps_from_string(string1);
g_object_set(G_OBJECT(filter1), "caps", caps1, NULL);
g_object_set(G_OBJECT(filter2), "caps", caps2, NULL);
g_object_set(G_OBJECT(filter3), "caps", caps3, NULL);
g_object_set(G_OBJECT(filter4), "caps", caps4, NULL);
g_object_set(G_OBJECT(mux), "live-source", 1, "name", "mux", "batch-size", 1, "width", 1280, "height", 720, NULL);
g_object_set(G_OBJECT(infer), "config-file-path","/opt/nvidia/deepstream/deepstream-4.0/sources/apps/sample_apps/deepstream-test1/dstest1_pgie_config.txt",NULL);
g_object_set(G_OBJECT(infer), "batch-size", 1, NULL);
g_object_set(G_OBJECT(tiler), "rows", 1, "columns", 1, "width", 1280, "height", 720, NULL);
gst_caps_unref(caps1);
gst_caps_unref(caps2);
gst_caps_unref(caps3);
gst_caps_unref(caps4);
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_print("Running ...\n");
g_main_loop_run(loop);
gst_element_set_state(pipeline,GST_STATE_NULL);
gst_object_unref(pipeline);
return 0;
}
它给出了与命令行 gst-launch-1.0 完全相同的输出,例如,
(deep_pads:15648): GLib-GObject-WARNING **: 11:29:18.761: cannot register existing type 'GstInterpolationMethod'
(deep_pads:15648): GLib-GObject-CRITICAL **: 11:29:18.761: g_param_spec_enum: assertion 'G_TYPE_IS_ENUM (enum_type)' failed
(deep_pads:15648): GLib-GObject-CRITICAL **: 11:29:18.761: validate_pspec_to_install: assertion 'G_IS_PARAM_SPEC (pspec)' failed
(deep_pads:15648): GStreamer-CRITICAL **: 11:29:18.814: gst_element_get_static_pad: assertion 'GST_IS_ELEMENT (element)' failed
(deep_pads:15648): GStreamer-CRITICAL **: 11:29:18.814: gst_pad_add_probe: assertion 'GST_IS_PAD (pad)' failed
0:00:00.843318172 15648 0x5591be52c0 INFO nvinfer gstnvinfer.cpp:519:gst_nvinfer_logger:<infer> NvDsInferContext[UID 1]:initialize(): Trying to create engine from model files
0:00:20.693301580 15648 0x5591be52c0 INFO nvinfer gstnvinfer.cpp:519:gst_nvinfer_logger:<infer> NvDsInferContext[UID 1]:generateTRTModel(): Storing the serialized cuda engine to file at /opt/nvidia/deepstream/deepstream-4.0/samples/models/Primary_Detector/resnet10.caffemodel_b1_int8.engine
除了它不显示来自上述 c 应用程序的输出窗口,也不显示其余部分。
解决方案
您的第一个示例失败,因为data.source
元素实际上从未链接到data.convert
元素。由于这两个元素都有静态焊盘,因此您需要“手动”创建它们并将它们链接起来,然后再将管道设置为GST_STATE_PLAYING
:
GstPad *source_pad = gst_element_get_static_pad(data.source, "src");
GstPad *sink_pad = gst_element_get_static_pad(data.convert, "sink");
ret = gst_pad_link(source_pad, sink_pad);
您可能期望您的data.source
元素的静态源垫会以某种方式自动创建,因此您注册了
g_signal_connect(G_OBJECT(data.source), "pad-added", G_CALLBACK(pad_added_handler), &data );
但是,正如您从调试中看到的那样,pad_added_handler
从未调用过,因为g_signal_connect
可以注册并将为具有动态 pads的元素调用。例如,解复用器tsdemux
将在发现基本流期间动态创建其源填充,因此在这种情况下,pad-added
回调注册将是必要的。
学习曲线的第一步是了解“静态”(强制,始终存在,“手动”创建)、动态(有时存在,由元素自动创建)和请求(可选,在需要时“手动”创建)之间的根本区别) gstreamer垫。在那之后,一切对你来说都会容易得多。
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