header.c

Mobile IP VCEG的信道模拟程序

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

#include "global.h"
#include "elements.h"
#include "header.h"




#if TRACE
#define SYMTRACESTRING(s) strcpy(sym.tracestring,s)
#else
#define SYMTRACESTRING(s)	/* to nothing */
#endif


/************************************************************************
*
*  Routine      PictureHeader
*
*  Description: read the whole Picture header without the Startcode UVLC
* Returns the number of bits used by the header exclusing start code
*
************************************************************************/
int PictureHeader(struct img_par *img, struct inp_par *inp) 
{

	int dP_nr = assignSE2partition[inp->partition_mode][SE_HEADER];
    Slice *currSlice = img->currentSlice;
	Bitstream *currStream = (currSlice->partArr[dP_nr]).bitstream;
	DataPartition *partition = &(currSlice->partArr[dP_nr]);
	SyntaxElement sym;
	int UsedBits=31;


    sym.type = SE_HEADER;
    sym.mapping = linfo;

    // 1. TRType = 0
	SYMTRACESTRING("PH TemporalReferenceType");
	readSyntaxElement_UVLC (&sym,img,inp,partition);
    //currSlice-> ?????????
	// Currently, only the value 0 is supported, hence a simple assert to
	// catch evenntual  encoder problems
	if (sym.value1 != 0) {
		printf ("Unsupported value %d in Picture Header TemporalReferenceType, len %d info %d\n", sym.value1, sym.len, sym.inf);
		exit (-1);
	}
	UsedBits += sym.len;
// printf ("PH Tenporal Reference Type len %d info %d val %d\n", sym.len, sym.inf, sym.value1);
// printf ("UsedBits %d\n", UsedBits);

    // 2. TR, variable length
	SYMTRACESTRING("PH TemporalReference");
	readSyntaxElement_UVLC (&sym,img,inp,partition);
    currSlice->picture_id = img->tr = sym.value1;					
// printf ("PH TR len %d info %d val %d\n", sym.len, sym.inf, sym.value1);
	UsedBits += sym.len;
// printf ("UsedBits %d\n", UsedBits);

	// 3. Size Type
	SYMTRACESTRING ("PH WhichSize...");
	readSyntaxElement_UVLC (&sym,img,inp,partition);
// printf ("PH: SizeType %d\n", sym.value1);
	UsedBits += sym.len;
// printf ("UsedBits %d\n", UsedBits);
	if (sym.value1 == 0)
		SYMTRACESTRING("PH:    Size Information Unchanged");
	else {
		        // width * 16
        SYMTRACESTRING("PH FullSize-X");
		readSyntaxElement_UVLC (&sym,img,inp,partition);
        img->width = sym.value1 * MB_BLOCK_SIZE;
        img->width_cr = img->width/2;
		UsedBits+=sym.len;
// printf ("UsedBits %d\n", UsedBits);
        // height * 16
		SYMTRACESTRING("PH FullSize-Y");
		readSyntaxElement_UVLC (&sym,img,inp,partition);
        img->height = sym.value1 * MB_BLOCK_SIZE;
        img->height_cr = img->height/2;
// printf ("PH: Size %d x %d\n", img->width, img->height);
		UsedBits+= sym.len;
// printf ("UsedBits %d\n", UsedBits);
	}

    // 4. Picture Type indication (I, P, Mult_P, B , Mult_B)
	SYMTRACESTRING("PHPictureType");
	readSyntaxElement_UVLC (&sym,img,inp,partition);
    currSlice->picture_type = img->type = sym.value1;			
// printf ("PH: Type len %d, info %d, val %d\n", sym.len, sym.inf, img->type);
    UsedBits += sym.len;
// printf ("UsedBits %d\n", UsedBits);

	// Finally, read Reference Picture ID (same as TR here).  Note that this is an
	// optional field that is not present if the input parameters do not indicate
	// multiframe prediction ??

	// Ok, the above comment is nonsense.  There is no way how a decoder could
	// know that we use multiple reference frames (except probably through a 
	// sequence header).  Hence, it's now an if (1) -- PHRefPicID is always present

    // Of course, the decoder can know. It is indicated by the previously decoded
    // parameter "PHPictureType". So, I changed the if-statement again to be
    // compatible with the encoder.

    if (1)
    //  if ((img->type == INTER_IMG_MULT) || (img->type == B_IMG_MULT))
    {	// more than one reference frames
        // TR, variable length
		SYMTRACESTRING("PHRefPicID");
		readSyntaxElement_UVLC (&sym,img,inp,partition);
		UsedBits += sym.len;
// printf ("PH: Read PHRefPicID len %d info %d (and throw it away)\n", sym.len, sym.inf);
	}

	// Now get the first Slice Header without a start code

	UsedBits += SliceHeader (img, inp);
	//	printf ("UsedBits %d\n", UsedBits);
	
	return UsedBits;
}

/************************************************************************
*
*  Routine      SliceHeader
*
*  Description: read the whole Slice header without the Startcode UVLC
*
************************************************************************/
int SliceHeader(struct img_par *img, struct inp_par *inp) 
{
	int dP_nr = assignSE2partition[inp->partition_mode][SE_HEADER];	
    Slice *currSlice = img->currentSlice;
    Bitstream *currStream = (currSlice->partArr[dP_nr]).bitstream;
	DataPartition *partition = &(currSlice->partArr[dP_nr]);
	SyntaxElement sym;
	int UsedBits=0;

    sym.type = SE_HEADER;
    sym.mapping = linfo;

	if (img->current_mb_nr)
		UsedBits=31;

	// 1. Get MB-Adresse
	SYMTRACESTRING("SH FirstMBInSlice");
    readSyntaxElement_UVLC (&sym,img,inp,partition);
    currSlice->start_mb_nr = sym.value1;
// printf ("SliceHeader: got MB Adresse %d, len %d info %d\n", sym.value1, sym.len, sym.inf);
	UsedBits += sym.len;

	// 2. Get Quant. 
	SYMTRACESTRING("SH SliceQuant");
	readSyntaxElement_UVLC (&sym,img,inp,partition);
    currSlice->qp = img->qp = 31 - sym.value1;
// printf ("SliceHeader: got QP %d, len %d info %d\n", sym.value1, sym.len, sym.inf);
	UsedBits += sym.len;
// printf ("SliceHeader: got Mb Adress %d, Quant %d\n", currSlice->start_mb_nr, currSlice->qp);

	// 2. Get MVResolution 
	SYMTRACESTRING("SH MVResolution");
	readSyntaxElement_UVLC (&sym,img,inp,partition);
    img->mv_res = sym.value1;
// printf ("SliceHeader: got MVRse %d, len %d info %d\n", sym.value1, sym.len, sym.inf);
	UsedBits += sym.len;
// printf ("SliceHeader: got Mb Adress %d, MVRes %d\n", currSlice->start_mb_nr, img->mv_res);
	
	img->max_mb_nr = (img->width * img->height) / (MB_BLOCK_SIZE * MB_BLOCK_SIZE);
	if (inp->symbol_mode ==CABAC)
	{
		// 3. Get number of MBs in this slice
		SYMTRACESTRING("SH Last MB in Slice");
		readSyntaxElement_UVLC (&sym,img,inp,partition);
		currSlice->last_mb_nr = currSlice->start_mb_nr+sym.value1;
		//Note: if one slice == one frame the number of MBs in this slice is coded as 0
		if (currSlice->last_mb_nr == currSlice->start_mb_nr)
			currSlice->last_mb_nr = img->max_mb_nr; 
		UsedBits += sym.len;
	}
	return UsedBits;
}