Deepstream4.0的demo程序运行和注释
deepstream-test1程序注释
一、首先是运行这个程序：
拷贝sample_720p.h264到deepstream-test1
cd deepstream-test1/
make
./deepstream-test1-app sample_720p.h264
二、理解代码需要Gstreamer的知识，还需要C语言的基础
代码如下：
/*
* Copyright (c) 2018-2019, NVIDIA CORPORATION. All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
#include \n" , argv[0]);
return -1;
}
/* Standard GStreamer initialization */
gst_init (&argc, &argv); //首先我们调用了gstreamer的初始化函数
loop = g_main_loop_new (NULL, FALSE);//创建一个循环体
/* Create gstreamer elements */
/* Create Pipeline element that will form a connection of other elements */
pipeline = gst_pipeline_new ("dstest1-pipeline");
//Pipeline通过gst_pipeline_new创建，参数为pipeline的名字。
/* Source element for reading from the file */
source = gst_element_factory_make ("filesrc", "file-source");
//创建一个element 类型是filesrc，名字是file-source。
//该element用于读取文件
/* Since the data format in the input file is elementary h264 stream,
* we need a h264parser */
h264parser = gst_element_factory_make ("h264parse", "h264-parser");
//创建一个element 类型是h264parse，名字是h264-parser。
//该element用于解析h264文件
/* Use nvdec_h264 for hardware accelerated decode on GPU */
decoder = gst_element_factory_make ("nvv4l2decoder", "nvv4l2-decoder");
//该element用于调用GPU硬件加速解码h264文件
/* Create nvstreammux instance to form batches from one or more sources. */
streammux = gst_element_factory_make ("nvstreammux", "stream-muxer");
//该element用于把输入按照参数处理成一系列的视频帧
if (!pipeline || !streammux) {
g_printerr ("One element could not be created. Exiting.\n");
return -1;
}
/* Use nvinfer to run inferencing on decoder's output,
* behaviour of inferencing is set through config file */
pgie = gst_element_factory_make ("nvinfer", "primary-nvinference-engine");
//对输入图像进行推理，通过推理的配置文件
/* Use convertor to convert from NV12 to RGBA as required by nvosd */
nvvidconv = gst_element_factory_make ("nvvideoconvert", "nvvideo-converter");
//视频颜色格式转换
/* Create OSD to draw on the converted RGBA buffer */
nvosd = gst_element_factory_make ("nvdsosd", "nv-onscreendisplay");
//处理RGBA buffer 绘制ROI等 识别对象的Bounding Box，边框
//识别对象的文字标签（字体、颜色、标示框）
/* Finally render the osd output */
#ifdef PLATFORM_TEGRA //makefile里已经定义
transform = gst_element_factory_make ("nvegltransform", "nvegl-transform");
// 转换成 EGLImage instance 给nveglglessink使用
#endif
sink = gst_element_factory_make ("nveglglessink", "nvvideo-renderer");
if (!source || !h264parser || !decoder || !pgie
|| !nvvidconv || !nvosd || !sink) {
g_printerr ("One element could not be created. Exiting.\n");
return -1;
}
#ifdef PLATFORM_TEGRA
if(!transform) {
g_printerr ("One tegra element could not be created. Exiting.\n");
return -1;
}
#endif
/* we set the input filename to the source element */
g_object_set (G_OBJECT (source), "location", argv[1], NULL);
//设置source的位置，source是视频文件
g_object_set (G_OBJECT (streammux), "width", MUXER_OUTPUT_WIDTH, "height",
MUXER_OUTPUT_HEIGHT, "batch-size", 1,
"batched-push-timeout", MUXER_BATCH_TIMEOUT_USEC, NULL);
//设置视频格式，如分辨率等
/* Set all the necessary properties of the nvinfer element,
* the necessary ones are : */
g_object_set (G_OBJECT (pgie),
"config-file-path", "dstest1_pgie_config.txt", NULL);
//设置配置文件的路径。该配置文件指示tensorRT转换后的文件等。
/* we add a message handler */
bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));//
bus_watch_id = gst_bus_add_watch (bus, bus_call, loop);//指定消息处理函数
gst_object_unref (bus);
/* Set up the pipeline */
/* we add all elements into the pipeline */
#ifdef PLATFORM_TEGRA
gst_bin_add_many (GST_BIN (pipeline),
source, h264parser, decoder, streammux, pgie,
nvvidconv, nvosd, transform, sink, NULL);//element加入到pipeline
#else
gst_bin_add_many (GST_BIN (pipeline),
source, h264parser, decoder, streammux, pgie,
nvvidconv, nvosd, sink, NULL);
#endif
GstPad *sinkpad, *srcpad;
gchar pad_name_sink[16] = "sink_0";
gchar pad_name_src[16] = "src";
sinkpad = gst_element_get_request_pad (streammux, pad_name_sink);
if (!sinkpad) {
g_printerr ("Streammux request sink pad failed. Exiting.\n");
return -1;
}
//获取指定element中的指定pad 该element为 streammux
srcpad = gst_element_get_static_pad (decoder, pad_name_src);
if (!srcpad) {
g_printerr ("Decoder request src pad failed. Exiting.\n");
return -1;
}
if (gst_pad_link (srcpad, sinkpad) != GST_PAD_LINK_OK) {
g_printerr ("Failed to link decoder to stream muxer. Exiting.\n");
return -1;
}
//gst_pad_link
gst_object_unref (sinkpad);
gst_object_unref (srcpad);
/* we link the elements together */
/* file-source -> h264-parser -> nvh264-decoder ->
* nvinfer -> nvvidconv -> nvosd -> video-renderer */
if (!gst_element_link_many (source, h264parser, decoder, NULL)) {
g_printerr ("Elements could not be linked: 1. Exiting.\n");
return -1;
}
#ifdef PLATFORM_TEGRA
if (!gst_element_link_many (streammux, pgie,
nvvidconv, nvosd, transform, sink, NULL)) {
g_printerr ("Elements could not be linked: 2. Exiting.\n");
return -1;
}
#else
if (!gst_element_link_many (streammux, pgie,
nvvidconv, nvosd, sink, NULL)) {
g_printerr ("Elements could not be linked: 2. Exiting.\n");
return -1;
}
#endif
/* Lets add probe to get informed of the meta data generated, we add probe to
* the sink pad of the osd element, since by that time, the buffer would have
* had got all the metadata. */
osd_sink_pad = gst_element_get_static_pad (nvosd, "sink");
if (!osd_sink_pad)
g_print ("Unable to get sink pad\n");
else
gst_pad_add_probe (osd_sink_pad, GST_PAD_PROBE_TYPE_BUFFER,
osd_sink_pad_buffer_probe, NULL, NULL);
//osd_sink_pad_buffer_probe 创建探针
//以上都是设置属性，连接Elements，设置消息等操作，先把整个的视频处理流程勾勒出来。
/* Set the pipeline to "playing" state */
g_print ("Now playing: %s\n", argv[1]);
gst_element_set_state (pipeline, GST_STATE_PLAYING);//运行
/* Wait till pipeline encounters an error or EOS */
g_print ("Running...\n");
g_main_loop_run (loop);//bus_call 消息处理函数可以结束loop
/* Out of the main loop, clean up nicely */
g_print ("Returned, stopping playback\n");
gst_element_set_state (pipeline, GST_STATE_NULL);//释放为pipeline分配的所有资源
g_print ("Deleting pipeline\n");
gst_object_unref (GST_OBJECT (pipeline));
g_source_remove (bus_watch_id);
g_main_loop_unref (loop);//销毁loop对象
return 0;
}
参考文献
[1].https://docs.nvidia.com/metropolis/deepstream/plugin-manual/index.html
[2].https://docs.nvidia.com/metropolis/deepstream/dev-guide/DeepStream_Development_Guide/baggage/index.html