tmndec.c

视频的h263解码

/************************************************************************
*
*  tmndec.c, main(), initialization, options for tmndecode (H.263 decoder)
*  Copyright (C) 1996  Telenor R&D, Norway
*        Karl Olav Lillevold <[e-mail]>
*设定初始化选项
*  This program is free software; you can redistribute it and/or modify
*  it under the terms of the GNU General Public License as published by
*  the Free Software Foundation; either version 2 of the License, or
*  (at your option) any later version.
*
*  This program is distributed in the hope that it will be useful,
*  but WITHOUT ANY WARRANTY; without even the implied warranty of
*  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
*  GNU General Public License for more details.
*
*  You should have received a copy of the GNU General Public License
*  along with this program; if not, write to the Free Software
*  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*  Karl Olav Lillevold               <[e-mail]>
*  Telenor Research and Development
*  P.O.Box 83                        tel.:   [phone]
*  N-2007 Kjeller, Norway            fax.:   [phone]
*
*  Robert Danielsen                  e-mail: [e-mail]
*  Telenor Research and Development  www:    http://www.nta.no/brukere/DVC/
*  P.O.Box 83                        tel.:   [phone]
*  N-2007 Kjeller, Norway            fax.:   [phone]
************************************************************************/

/*
* based on mpeg2decode, (C) 1994, MPEG Software Simulation Group
* and mpeg2play, (C) 1994 Stefan Eckart
*                         <[e-mail]>
*
*/

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <fcntl.h>
#define GLOBAL
#include "config.h"
#include "tmndec.h"
#include "global.h"

#ifdef USE_TIME
#ifndef WIN32
#include <sys/time.h>
#else
#include <windows.h>
#endif
#endif
#ifdef WIN32
#include <io.h>
#endif

#ifndef STRING_H
#include <string.h>
#endif


#ifdef WINDOWS
int initDisplay (int pels, int lines);
int closeDisplay ();
#endif

/* private prototypes */
static void initdecoder _ANSI_ARGS_((void));
static void options _ANSI_ARGS_((int *argcp, char **argvp[]));
static int getval _ANSI_ARGS_((char *argv[]));

/* private data */
static int loopflag;
int g_frame;
int able_yuv_num=0;
char yuvfile[10][30];
//定义用于存贮所得yuv文件的文件名的结构，用来传递unitestream（）的参数

void unitestream(char yuvfile[10][30],int able_yuv_num,int m_nWidth,int m_nHeight,int picsize)
 //added by cjx 20070927
 //把所有yuv文件按照顺序写到同一个文件中
{
	FILE *writestream;
	FILE *readstream[10];
	char buf[210000];
	unsigned int size;
	int num;
	int flag=0;
	for(num = 0;num < able_yuv_num;num++)
	{
		if((readstream[num]=fopen(yuvfile[num],"rb"))==NULL) 
		{
			printf("can't open the %s file!\n",yuvfile[num]);
			return;
		}
	}
	if((writestream=fopen(".\\mother_daughter_cif.yuv","wb+"))==NULL) 
	{
		printf("can't open the mother_daughter_cif.yuv file!\n");
		return;
	}
	size=picsize*3/2;
	while (1)//循环的写入
	{
		for(num = 0;num < able_yuv_num,g_frame%able_yuv_num == num;num++)
		{
			if(size==fread(buf, 1 , 3*picsize/2, readstream[num]))
				fwrite(buf,1 , 3*picsize/2, writestream);
			else
			{
				flag = 1;
				break;
			}
			g_frame++;
		}
		if(flag == 1)//若读入的一帧大小为零则完成任务
			break;
	}
	for(num = 0;num < able_yuv_num;num++)
	{
		fclose(readstream[num]);
	}
	fclose(writestream);//关闭所有文件
	return;
}

#define FILEnum 10//最多解析的文件数目
int i263,iyuv,j;
int main(argc,argv)
int argc;
char *argv[];
{
	int first, framenum;
	int yuvnum;
	char H263stream[50],YUVstream[50];//存储输入文件输出文件的名字
#ifdef USE_TIME
	int runtime;
#ifndef WIN32
	struct timeval tstart,tstop;
#else
	unsigned int startTime, stopTime;
#endif
#endif
	
#ifdef USE_TIME
	/* default is read frame rate from bitstream */
	framerate=99;//在编码过程中对频率进行过变换，怎样变？
#endif
	
	options(&argc,&argv);//分析读入的命令
	
	/* pointer to name of output files */
#if (defined DISPLAY || defined WINDOWS)
	if (outtype==T_X11 || outtype == T_WIN)
		outputname = "";//初始化为空字符串
	else
#endif//没有执行？
		 	
	ld = &base;    //???
	/* open MPEG input file(s) */
	//	if ((base.infile=open(argv[1],O_RDONLY|O_BINARY))<0)
    strcpy(H263stream,argv[1]);//读入命令行中263格式的文件名
	strcpy(YUVstream,argv[2]);//读入命令行中yuv格式的文件名
	//	added by cjx 20070921
	for(i263 = 0; i263 < 50; i263++)
	{
		if(H263stream[i263]=='.')
		{
			for(j=5;j >= 0;j--)
			{
				H263stream[j+i263]=H263stream[j+i263-1];
			}
			break;
		}
	}//变换文件名263
	for(iyuv = 0; iyuv < 50; iyuv++)
	{
		if(YUVstream[iyuv]=='.')
		{
			for(j=5;j >= 0;j--)
			{
				YUVstream[j+iyuv]=YUVstream[j+iyuv-1];
			}
			break;
		}
	}//变换文件名yuv

//	char *strncat(char *s1, const char *s2, size_t n)
	for(yuvnum = 1; yuvnum < FILEnum; yuvnum++)
	{
		H263stream[i263]= '0' + yuvnum;
		YUVstream[iyuv]= '0' + yuvnum;
		outputname = YUVstream;
		if ((base.infile=open(H263stream,O_RDONLY|O_BINARY))<0)	//识别文件
		//以二进制打开文件
		{   
			continue;
			//sprintf(errortext,"Input file %s not found\n",argv[1]);
			//error(errortext);
		}	
		first = 1;
		
		do {
			if (base.infile!=0)
				lseek(base.infile,0l,0);   //对文件的读写位置操作，SEEK_SET=0文件偏移量被设置为 01
			initbits();
			framenum = 0;
			temp_ref = 0;
			prev_temp_ref= -1; 
			
			while (getheader())     /*  开始解一帧，保存为YUV*/
				//条件函数返回怎样的值？为何以他作为条件？这个函数获得一帧的有效载荷头
			{
				if (first) //只有最外层循环的一次开始时才会执行
				{
					initdecoder();//获取263文件的解析度信息
#ifdef USE_TIME
#ifndef WIN32
//防止头文件重用
					gettimeofday(&tstart,(struct timezone *)NULL);
					//取的时间，返回类型数组
					//"sec" - 秒 ;"usec" - 百万分之一秒 ;"minuteswest" - 格林威治时间的分 ;"dsttime" - 目的的时区 
					if (framerate > 0)
						gettimeofday(&tftarget,(struct timezone *)NULL);
#else
					startTime = timeGetTime();//时间差？调节频率
					if (framerate > 0)
						targetTime = timeGetTime();
#endif
#endif
					first = 0;
				}
				getpicture(&framenum);   //run这个函数是解码的执行函数
				
				framenum++;            //run
			}                     /*  开始解一帧结束，保存为YUV*/
			
		} while (loopflag);   //what is loopflag？loopflag为一时
		
		close(base.infile);//关闭打开的263文件
		for(j = 0;j < 30;j++)
			yuvfile[able_yuv_num][j]=YUVstream[j];
		able_yuv_num++;
	}//263文件转换成yuv文件结束
	
	
#ifdef USE_TIME
#ifndef WIN32//当命令不正确即输出文件的格式选择不对时才会执行这段程序
	gettimeofday(&tstop,(struct timezone *)NULL);
	runtime = 100*(tstop.tv_sec-tstart.tv_sec)
		+ (tstop.tv_usec-tstart.tv_usec)/10000;
#else
	stopTime = timeGetTime();//????
	runtime = (stopTime - startTime) / 10;
#endif
	if (!quiet && runtime!=0)
		printf("%d.%02d seconds, %d frames, %d.%02d fps\n",
		runtime/100, runtime%100,
		framenum, ((10000*framenum+runtime/2)/runtime)/100,
		((10000*framenum+runtime/2)/runtime)%100);
#endif
	
#ifdef DISPLAY
	if (outtype==T_X11)
		exit_display();
#endif
#ifdef WINDOWS
	if (outtype == T_WIN)
		closeDisplay();
#endif
	
	unitestream(yuvfile,able_yuv_num,352, 288, 352*288);      //added by cjx 20070921
	
	return 0;    //run
}

static void initdecoder()
{
	int i, cc, size;
	FILE *cleared;
	
	/* clip table */
	if (!(clp=(unsigned char *)malloc(1024)))
		error("malloc failed\n");
	
	clp += 384;
	
	for (i=-384; i<640; i++)
		clp[i] = (i<0) ? 0 : ((i>255) ? 255 : i);
	
	/* MPEG-1 = TMN parameters */
	matrix_coefficients = 5;
	
	
	switch (source_format) {//H.263支持的五种解析度
		//每帧图象都被分为许多块组。一个块组(GOB)由k*16行组成，k由解析度决定
    case (SF_SQCIF):
		horizontal_size = 128;
		vertical_size = 96;
		break;
    case (SF_QCIF)://本程序选取的是这一种，每幅图像有9个GOB.......QCIF格式中，一个GOB包含一个宏块
		horizontal_size = 176;//亮度取样的象素个数
		vertical_size = 144;
		break;
		//QCIF的全称Quarter common intermediate format
		//每个宏块包含16行每行16个象素的Y信息，和8行每行8个象素的CB和CR信息
    case (SF_CIF):
		horizontal_size = 352;
		vertical_size = 288;
		break;
    case (SF_4CIF):
		horizontal_size = 704;
		vertical_size = 576;
		break;
    case (SF_16CIF):
		horizontal_size = 1408;
		vertical_size = 1152;
		break;
    default:
		printf("ERROR: Illegal input format\n");
		exit(-1);