mp4decoder.cpp

基于SAA7113的MPEG-4程序

#include "stdafx.h"
#include "Mp4Decoder.h"
#include "xvid.h"


CMp4Decoder::CMp4Decoder()
{
	
	CSP = XVID_CSP_BGR;
	BPP = 3;
	dec_handle = NULL;
	g_first = 1;
	use_assembler = 1;
	m_iXdim = 176;
	m_iYdim = 144;
	m_iBmpHeaderSize = 54;
	m_iDecBufLen = m_iXdim*m_iYdim*3 + m_iBmpHeaderSize;
}

CMp4Decoder::~CMp4Decoder()
{
	if (dec_handle)
	  	DecStop();
}



int CMp4Decoder::Decode(unsigned char *in_buffer,unsigned char *out_buffer,int input_len)
{
		
	unsigned char *mp4_ptr;
	int used_bytes = 0;
	
    if(g_first)
	{
		DecInit(use_assembler);
		g_first = 0;
	}

	mp4_ptr = in_buffer;

	/* This loop is needed to handle VOL/NVOP reading */
	do {
		used_bytes = DecMain(mp4_ptr, out_buffer, input_len, &xvid_dec_stats);

		/* Update buffer pointers */
		if(used_bytes > 0) {
			mp4_ptr += used_bytes;
			input_len -= used_bytes;
		}

	}while(xvid_dec_stats.type <= 0 && input_len > 0);

	return 0;
}



/*****************************************************************************
 * Routines for decoding: init decoder, use, and stop decoder
 ****************************************************************************/

/* init decoder before first run */
int CMp4Decoder::DecInit(int use_assembler)
{
	int ret;

	xvid_gbl_init_t   xvid_gbl_init;
	xvid_dec_create_t xvid_dec_create;

	/* Reset the structure with zeros */
	memset(&xvid_gbl_init, 0, sizeof(xvid_gbl_init_t));
	memset(&xvid_dec_create, 0, sizeof(xvid_dec_create_t));

	/*------------------------------------------------------------------------
	 * XviD core initialization
	 *----------------------------------------------------------------------*/

	/* Version */
	xvid_gbl_init.version = XVID_VERSION;

	/* Assembly setting */
	if(use_assembler)
#ifdef ARCH_IS_IA64
		xvid_gbl_init.cpu_flags = XVID_CPU_FORCE | XVID_CPU_IA64;
#else
	xvid_gbl_init.cpu_flags = 0;
#endif
	else
		xvid_gbl_init.cpu_flags = XVID_CPU_FORCE;

	xvid_global(NULL, 0, &xvid_gbl_init, NULL);

	/*------------------------------------------------------------------------
	 * XviD encoder initialization
	 *----------------------------------------------------------------------*/

	/* Version */
	xvid_dec_create.version = XVID_VERSION;

	/*
	 * Image dimensions -- set to 0, xvidcore will resize when ever it is
	 * needed
	 */
	xvid_dec_create.width = 0;
	xvid_dec_create.height = 0;

	ret = xvid_decore(NULL, XVID_DEC_CREATE, &xvid_dec_create, NULL);

	dec_handle = xvid_dec_create.handle;

	return(ret);
}

/* decode one frame  */
int CMp4Decoder::DecMain(unsigned char *istream,
		 unsigned char *ostream,
		 int istream_size,
		 xvid_dec_stats_t *xvid_dec_stats)
{

	int ret;

	xvid_dec_frame_t xvid_dec_frame;
	memset(&xvid_dec_frame, 0, sizeof(xvid_dec_frame_t));

	/* Set version */
	xvid_dec_frame.version = XVID_VERSION;
	xvid_dec_stats->version = XVID_VERSION;

	/* No general flags to set */
	xvid_dec_frame.general          = 0;

	/* Input stream */
	xvid_dec_frame.bitstream        = istream;
	xvid_dec_frame.length           = istream_size;

	/* Output frame structure */
	xvid_dec_frame.output.plane[0]  = ostream;
	xvid_dec_frame.output.stride[0] = m_iXdim*BPP;
	xvid_dec_frame.output.csp = CSP;

	ret = xvid_decore(dec_handle, XVID_DEC_DECODE, &xvid_dec_frame, xvid_dec_stats);

	return(ret);
}

/* close decoder to release resources */
int CMp4Decoder::DecStop()
{
	int ret;

	ret = xvid_decore(dec_handle, XVID_DEC_DESTROY, NULL, NULL);

	return(ret);
}