2018-01-03 gstreamer编程入门

最近要在嵌入式板子上显示视频+字幕，摄像头移动时，qcamera显示卡顿。无奈转回gstreamer。
之前直接调用的命令行参数，但为了动态改变字幕内容，只能编程实现。

1. gstreamer安装

环境：intel-x64/ubuntu16.04

$ sudo apt-cache search gstreamer* | more
$  sudo apt-get install libgstreamer*
......
gstreamer1.0-alsa - GStreamer plugin for ALSA
gstreamer1.0-clutter-3.0 - Clutter PLugin for GStreamer 1.0
gstreamer1.0-doc - GStreamer core documentation and manuals
gstreamer1.0-plugins-base - GStreamer plugins from the "base" set
gstreamer1.0-plugins-base-appus - GStreamer helper programs from the "base" set
gstreamer1.0-plugins-base-dbg - GStreamer plugins from the "base" set
gstreamer1.0-plugins-base-doc - GStreamer documentation for plugins from the "base" set
gstreamer1.0-plugins-good - GStreamer plugins from the "good" set
gstreamer1.0-plugins-good-dbg - GStreamer plugins from the "good" set
gstreamer1.0-plugins-good-doc - GStreamer documentation for plugins from the "good" set
gstreamer1.0-pulseaudio - GStreamer plugin for PulseAudio
gstreamer1.0-tools - Tools for use with GStreamer
gstreamer1.0-x - GStreamer plugins for X11 and Pango
......
libgstreamer-plugins-base1.0-0 - GStreamer libraries from the "base" set
libgstreamer-plugins-base1.0-dev - GStreamer development files for libraries from the "base" set
libgstreamer-plugins-good1.0-0 - GStreamer development files for libraries from the "good" set
libgstreamer-plugins-good1.0-dev - GStreamer development files for libraries from the "good" set
libgstreamer1.0-0 - Core GStreamer libraries and elements
libgstreamer1.0-0-dbg - Core GStreamer libraries and elements
libgstreamer1.0-dev - GStreamer core development files

2. gstreamer helloworld

来自手册，不过还是看中文教程方便。
GStreamer基础教程01——Hello World
不过有一处变更，因为在 gstreamer 1.0中, playbin2 被重命名为 playbin。
unable to build pipeline: no element “playbin2”

  1 #include <gst/gst.h>
  2 
  3 int main(int argc, char *argv[]) {
  4       GstElement *pipeline;
  5       GstBus *bus;
  6       GstMessage *msg;
  7 
  8       /* Initialize GStreamer */
  9       gst_init (&argc, &argv);
 10 
 11       // Build the pipeline   
 12 //      pipeline = gst_parse_launch ("playbin uri=https://gstreamer.freedesktop.org/media/gst-integration-testsuite.save/defaults/webm/vorbis_vp8.0.webm", NULL);  
 13         pipeline = gst_parse_launch ("playbin uri=file:///home/sunshia/Documents/videodrv/gstreamer/vorbis_vp8.0.webm", NULL);
 14       // Start playing   
 15       gst_element_set_state (pipeline, GST_STATE_PLAYING);
 16 
 17       // Wait until error or EOS   
 18       bus = gst_element_get_bus (pipeline);
 19       msg = gst_bus_timed_pop_filtered (bus, GST_CLOCK_TIME_NONE, GST_MESSAGE_ERROR | GST_MESSAGE_EOS);
 20 
 21       // Free resources   
 22       if (msg != NULL)
 23         gst_message_unref (msg);
 24       gst_object_unref (bus);
 25       gst_element_set_state (pipeline, GST_STATE_NULL);
 26       gst_object_unref (pipeline);
 27         //
 28       return 0;
 29 }

3. 编写Makefile

  1 
  2 TARGET=gst-helloworld
  3 CC=gcc
  4 SRC=$(wildcard *.c)
  5 OBJ=$(SRC:.c=.o)
  6 
  7 PKG_CONFIG_PATH += -I/usr/include/gstreamer-1.0 -I/usr/lib/x86_64-linux-gnu/gstreamer-1.0/include
  8 
  9 CFLAGS=-g
 10 
 11 CFLAGS  += `pkg-config --cflags gstreamer-1.0 glib-2.0`
 12 LDFLAGS += `pkg-config --libs gstreamer-1.0 glib-2.0`
 13 
 14 all:depend $(TARGET)
 15 depend:
 16         $(CC) -MM $(SRC) > .depend
 17 -include .depend
 18 
 19 $(TARGET):$(OBJ)
 20         $(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)
 21 
 22 clean:
 23         rm $(TARGET) $(OBJ) .depend -f

一个简单的makefile示例及其注释
 一个简单的通用Makefile实现
 pkg-config的一些用法

4. gdb调试

$ gdb gst-helloworld -tui
用GDB调试程序（一）
gdb基本命令(非常详细)

最后，记不住markdown语法。
献给写作者的 Markdown 新手指南

最后编辑于：2018.01.03 12:12:19