video_cap.cpp

嵌入式linux系统的网络编程(C++) 在ARM上实现视频会议源码

///////////////////////////////////////////////////////
// FileName:	video_cap.cpp
// Author:		b1gm0use
// Project:		myvideo

#include <iostream>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <qsemaphore.h>

#include "video_cap.h"
#include "video_player.h"
#include "v4l.h"
#include "video.h"
#include "avi.h"

using namespace std;

///////////////////////////////////////////////////////
// Functions Declaration
///////////////////////////////////////////////////////

extern int jpeg_compress( char *dst, char *src, int width, int height, int dstsize );

///////////////////////////////////////////////////////
// Public Functions
///////////////////////////////////////////////////////

// 构造函数
video_cap::video_cap ( avi * avi_ptr_in ) // {{{
{
	verbose_output( 2, "create video_cap." );

	vid_cap = new video_capability ();

	jpeg_image = NULL;

	dev_id = 0;

	img_buff = NULL;

	frame = 0;

	avi_ptr = avi_ptr_in;

} // }}}


// 析构函数
video_cap::~video_cap ( void ) // {{{
{
	verbose_output( 2, "delete video_cap." );

	delete vid_cap;
	delete [] jpeg_image;
	delete [] img_buff;

} // }}}


// 初始化函数
// img 是图像的参数，video_dev 是设备名称
int video_cap::init ( void ) // {{{
{

	verbose_output( 2, "init video_cap." );

	if ( NULL == avi_ptr->video_dev )
	{
		cerr << "video_dev Can't be NULL" << endl;
		exit( 1 );
	}

	// 打开设备
	dev_id = open ( avi_ptr->video_dev, O_RDWR);

	if ( -1 == dev_id )
	{
		cerr << "Can't open video_dev:\t" << avi_ptr->video_dev << endl;
		exit( 1 );

	}

	if ( ioctl( dev_id, VIDIOCGCAP, vid_cap ) == -1 )
	{
		cerr << "Can't get video video_dev capability!" << endl;
		exit( 1 );
	}

	jpeg_image = new BUFF [ 
		avi_ptr->video_opt.min_width * avi_ptr->video_opt.factor * 
		avi_ptr->video_opt.min_height * avi_ptr->video_opt.factor * 3 ];

	img_buff = new BUFF [ 
		avi_ptr->video_opt.min_width * avi_ptr->video_opt.factor * 
		avi_ptr->video_opt.min_height * avi_ptr->video_opt.factor * 3 ];
	
	return 0;


} // }}}


// 取得一帧图像
// image 为传出参数，指向取得的图像
// size 为传出参数，表示图像数据大小
int video_cap::get_image ( BUFF * &image, int *size) // {{{
{
	struct video_mbuf vid_buf;
	struct video_mmap vid_mmap;

	verbose_output( 3, "get new capture image" );

	if (ioctl (dev_id, VIDIOCGMBUF, &vid_buf) == -1) 
	{
		cerr << "ioctl(VIDIOCGMBUF)" << endl;
		image = NULL;
		return -1;
	}

	verbose_output( 3, "map video_dev to memory." );

	// 开辟设备映射
	image = static_cast<BUFF *> ( mmap ( 0, vid_buf.size, PROT_READ|PROT_WRITE,MAP_PRIVATE, dev_id, 0 ) );

	if ((unsigned char *)-1 == (unsigned char *)image) 
	{
		cerr << "Error in mmap()!" << endl;
		image = NULL;
		exit( 1 );
	}

	vid_mmap.format = avi_ptr->video_opt.palette;
	vid_mmap.frame = 0;
	vid_mmap.width = avi_ptr->video_opt.min_width * avi_ptr->video_opt.factor;
	vid_mmap.height = avi_ptr->video_opt.min_height * avi_ptr->video_opt.factor;

	verbose_output( 4, "get new frame." );
	// 取得一帧
	if ( ioctl (dev_id, VIDIOCMCAPTURE, &vid_mmap ) == -1 ) 
	{
		cerr <<  "Error in VIDIOCMCAPTURE!" 
			<< " args: width=" << vid_mmap.width << " height=" << vid_mmap.height
		   	<< " palette=" << vid_mmap.format << endl;

		munmap (image, vid_buf.size);
		image = NULL;
		return -1;
	}

	verbose_output( 4, "get frame sync." );
	// 帧同步
	if (ioctl (dev_id, VIDIOCSYNC, &vid_mmap.frame) == -1) 
	{
		cerr << "Error in VIDIOCSYNC!" << endl;
		munmap (image, vid_buf.size);
		image = NULL;
		return -1;
	}

	*size = vid_buf.size;
	
	verbose_output( 4, "copy frame to buffer" );

	if ( avi_ptr->video_opt.palette == VIDEO_PALETTE_RGB24 )
	{
		memcpy( img_buff, image, avi_ptr->video_opt.min_width * avi_ptr->video_opt.factor * avi_ptr->video_opt.min_height * avi_ptr->video_opt.factor * 3 );
	}
	else
	{
		if ( avi_ptr->video_opt.palette == VIDEO_PALETTE_YUV420) 
		{
			verbose_output( 4, "converting from YUV to RGB");
			v4l_yuv420p2rgb ( ( unsigned char * ) img_buff, ( unsigned char * ) image, avi_ptr->video_opt.min_width * avi_ptr->video_opt.factor, avi_ptr->video_opt.min_height * avi_ptr->video_opt.factor, 24 );
		}
	}
	
	// 删除设备映射
	munmap (image, vid_buf.size);

	// 压缩为JPEG
	*size  = jpeg_compress((char*)jpeg_image, (char*)img_buff, 
			avi_ptr->video_opt.min_width * avi_ptr->video_opt.factor, 
			avi_ptr->video_opt.min_height * avi_ptr->video_opt.factor, 
			avi_ptr->video_opt.min_width * avi_ptr->video_opt.factor * 
			avi_ptr->video_opt.min_height * avi_ptr->video_opt.factor * 3 );

	if ( *size == -1 )
	{
		cerr << "Warning! Compress too few data" << endl;
		return -1;
	}

	image = jpeg_image;

	return 0;

} // }}}