dlib C++ Library - ffmpeg_video_demuxing2_ex.cpp

// The contents of this file are in the public domain. See LICENSE_FOR_EXAMPLE_PROGRAMS.txt
/*
 This is an example illustrating the use of the ffmpeg wrappers, 
 in this case the demuxer API.
 In this example, we show how to read both images and audio.
*/
#include <cstdio>
#include <dlib/media.h>
#include <dlib/gui_widgets.h>
#include <dlib/cmd_line_parser.h>
using namespace std;
using namespace dlib;
using namespace dlib::ffmpeg;
int main(const int argc, const char** argv)
try
{
 command_line_parser parser;
 parser.add_option("i", "input video", 1);
 parser.add_option("verbose", "enable all internal ffmpeg logging");
 parser.set_group_name("Help Options");
 parser.add_option("h", "alias of --help");
 parser.add_option("help", "display this message and exit");
 parser.parse(argc, argv);
 const char* one_time_opts[] = {"i"};
 parser.check_one_time_options(one_time_opts);
 if (parser.option("h") || parser.option("help"))
 {
 parser.print_options();
 return 0;
 }
 const std::string filepath = parser.option("i").argument();
 // We use the most simple constructor, the one that takes in filepath.
 // By default, both images and audio are read.
 demuxer cap(filepath);
 if (!cap.is_open())
 {
 printf("%s is not a valid video file\n", filepath.c_str());
 return EXIT_FAILURE;
 }
 // Read images and audio.
 // Images are plotted, audio samples are counted.
 frame f;
 array2d<rgb_pixel> img;
 image_window win;
 int nsamples{0};
 // When reading frames, we get exactly what's in the codec by default.
 // To resize, change pixel format, resample or change sample format, 
 // you have to pass extra arguments to read() which either resize or resample
 // the frame. Since we want rgb_pixel, we need to set the pixel format appropriately.
 const resizing_args args_image {0, 0, pix_traits<rgb_pixel>::fmt};
 while (cap.read(f, args_image))
 {
 if (f.is_image())
 {
 convert(f, img);
 win.set_image(img);
 }
 else if (f.is_audio())
 {
 nsamples += f.nsamples();
 }
 }
 
 printf("Read %i audio samples\n", nsamples);
 return EXIT_SUCCESS;
}
catch (const std::exception& e)
{
 printf("%s\n", e.what());
 return EXIT_FAILURE;
}