headers.c

jpeg and mpeg 编解码技术源代码

	}

/*printf("mpeg3video_picture_coding_extension %d\n", video->repeat_count); */
	composite_display_flag = mpeg3bits_getbit_noptr(video->vstream);

	if(composite_display_flag)
	{
    	v_axis = mpeg3bits_getbit_noptr(video->vstream);
    	field_sequence = mpeg3bits_getbits(video->vstream, 3);
    	sub_carrier = mpeg3bits_getbit_noptr(video->vstream);
    	burst_amplitude = mpeg3bits_getbits(video->vstream, 7);
    	sub_carrier_phase = mpeg3bits_getbyte_noptr(video->vstream);
	}
	return 0;
}


/* decode picture spatial scalable extension */

int mpeg3video_picture_spatial_scalable_extension(mpeg3video_t *video)
{
	video->pict_scal = 1; /* use spatial scalability in this picture */

	video->lltempref = mpeg3bits_getbits(video->vstream, 10);
	mpeg3bits_getbit_noptr(video->vstream);
	video->llx0 = mpeg3bits_getbits(video->vstream, 15);
	if(video->llx0 >= 16384) video->llx0 -= 32768;
	mpeg3bits_getbit_noptr(video->vstream);
	video->lly0 = mpeg3bits_getbits(video->vstream, 15);
	if(video->lly0 >= 16384) video->lly0 -= 32768;
	video->stwc_table_index = mpeg3bits_getbits(video->vstream, 2);
	video->llprog_frame = mpeg3bits_getbit_noptr(video->vstream);
	video->llfieldsel = mpeg3bits_getbit_noptr(video->vstream);
	return 0;
}


/* decode picture temporal scalable extension
 *
 * not implemented
 *
 */

int mpeg3video_picture_temporal_scalable_extension(mpeg3video_t *video)
{
  	fprintf(stderr, "mpeg3video_picture_temporal_scalable_extension: temporal scalability not supported\n");
	return 0;
}


/* decode extension and user data */

int mpeg3video_ext_user_data(mpeg3video_t *video)
{
  	int code = mpeg3bits_next_startcode(video->vstream);


  	while((code == MPEG3_EXT_START_CODE || code == MPEG3_USER_START_CODE) &&
		!mpeg3bits_eof(video->vstream))
	{
    	mpeg3bits_refill(video->vstream);
		
    	if(code == MPEG3_EXT_START_CODE)
		{
      		int ext_id = mpeg3bits_getbits(video->vstream, 4);
      		switch(ext_id)
			{
    			case SEQ_ID:
					mpeg3video_sequence_extension(video);
					break;
    			case DISP_ID:
					mpeg3video_sequence_display_extension(video);
					break;
    			case QUANT_ID:
					mpeg3video_quant_matrix_extension(video);
					break;
    			case SEQSCAL_ID:
					mpeg3video_sequence_scalable_extension(video);
					break;
    			case PANSCAN_ID:
					mpeg3video_picture_display_extension(video);
					break;
    			case CODING_ID:
					mpeg3video_picture_coding_extension(video);
					break;
    			case SPATSCAL_ID:
					mpeg3video_picture_spatial_scalable_extension(video);
					break;
    			case TEMPSCAL_ID:
					mpeg3video_picture_temporal_scalable_extension(video);
					break;
    			default:
					fprintf(stderr,"mpeg3video_ext_user_data: reserved extension start code ID %d\n", ext_id);
					break;
      		}
   		}
   		code = mpeg3bits_next_startcode(video->vstream);
  	}
	return 0;
}


/* decode group of pictures header */

int mpeg3video_getgophdr(mpeg3video_t *video)
{
	int drop_flag, closed_gop, broken_link;

//printf("%x\n", mpeg3bits_tell(video->vstream));
	video->has_gops = 1;
	drop_flag = mpeg3bits_getbit_noptr(video->vstream);
	video->gop_timecode.hour = mpeg3bits_getbits(video->vstream, 5);
	video->gop_timecode.minute = mpeg3bits_getbits(video->vstream, 6);
	mpeg3bits_getbit_noptr(video->vstream);
	video->gop_timecode.second = mpeg3bits_getbits(video->vstream, 6);
	video->gop_timecode.frame = mpeg3bits_getbits(video->vstream, 6);
	closed_gop = mpeg3bits_getbit_noptr(video->vstream);
	broken_link = mpeg3bits_getbit_noptr(video->vstream);

/*
 * printf("%d:%d:%d:%d %d %d %d\n", video->gop_timecode.hour, video->gop_timecode.minute, video->gop_timecode.second, video->gop_timecode.frame, 
 *  	drop_flag, closed_gop, broken_link);
 */
	return mpeg3bits_error(video->vstream);
}

/* decode picture header */

int mpeg3video_getpicturehdr(mpeg3video_t *video)
{
	int temp_ref, vbv_delay;

	video->pict_scal = 0; /* unless overwritten by pict. spat. scal. ext. */

	temp_ref = mpeg3bits_getbits(video->vstream, 10);
	video->pict_type = mpeg3bits_getbits(video->vstream, 3);
	vbv_delay = mpeg3bits_getbits(video->vstream, 16);

	if(video->pict_type == P_TYPE || video->pict_type == B_TYPE)
	{
    	video->full_forw = mpeg3bits_getbit_noptr(video->vstream);
    	video->forw_r_size = mpeg3bits_getbits(video->vstream, 3) - 1;
	}

	if(video->pict_type == B_TYPE)
	{
    	video->full_back = mpeg3bits_getbit_noptr(video->vstream);
    	video->back_r_size = mpeg3bits_getbits(video->vstream, 3) - 1;
	}

/* get extra bit picture */
	while(mpeg3bits_getbit_noptr(video->vstream) &&
		!mpeg3bits_eof(video->vstream)) 
		mpeg3bits_getbyte_noptr(video->vstream);
	return 0;
}


int mpeg3video_get_header(mpeg3video_t *video, int dont_repeat)
{
	unsigned int code;

/* a sequence header should be found before returning from `getheader' the */
/* first time (this is to set horizontal/vertical size properly) */

/* Repeat the frame until it's less than 1 count from repeat_count */
	if(video->repeat_count - video->current_repeat >= 100 && !dont_repeat)
	{
		return 0;
	}

	if(dont_repeat)
	{
		video->repeat_count = 0;
		video->current_repeat = 0;
	}
	else
		video->repeat_count -= video->current_repeat;

//printf("mpeg3video_get_header 1 %d %d\n", 
//	video->vstream->demuxer->titles[0]->fs->current_byte, 
//	video->vstream->demuxer->titles[0]->fs->total_bytes);

	while(1)
	{
//printf("mpeg3video_get_header 1 %llx\n", mpeg3bits_tell(video->vstream));
/* look for startcode */
    	code = mpeg3bits_next_startcode(video->vstream);


//printf("mpeg3video_get_header 2 %x %x %08x\n", 
//	video->vstream->demuxer->titles[0]->fs->current_byte, 
//	video->vstream->demuxer->titles[0]->fs->total_bytes,
//	code);
//printf("mpeg3video_get_header 2 %d\n", mpeg3bits_eof(video->vstream));
		if(mpeg3bits_eof(video->vstream)) return 1;
		if(code != MPEG3_SEQUENCE_END_CODE) mpeg3bits_refill(video->vstream);
 
    	switch(code)
		{
    		case MPEG3_SEQUENCE_START_CODE:
    			video->found_seqhdr = 1;
    			mpeg3video_getseqhdr(video);  
    			mpeg3video_ext_user_data(video);
    			break;

    		case MPEG3_GOP_START_CODE:
    			mpeg3video_getgophdr(video);
    			mpeg3video_ext_user_data(video);
    			break;

    		case MPEG3_PICTURE_START_CODE:
//printf("%x\n", mpeg3bits_tell(video->vstream));
    			mpeg3video_getpicturehdr(video);
    			mpeg3video_ext_user_data(video);
    			if(video->found_seqhdr) return 0;       /* Exit here */
    			break;

    		case MPEG3_SEQUENCE_END_CODE:
// Continue until the end
				mpeg3bits_refill(video->vstream);
				break;

    		default:
    			break;
    	}
  	}
 	return 1;      /* Shouldn't be reached. */
}

int mpeg3video_ext_bit_info(mpeg3_slice_buffer_t *slice_buffer)
{
	while(mpeg3slice_getbit(slice_buffer)) mpeg3slice_getbyte(slice_buffer);
	return 0;
}

/* decode slice header */
int mpeg3video_getslicehdr(mpeg3_slice_t *slice, mpeg3video_t *video)
{
	int slice_vertical_position_extension, intra_slice;
	int qs;

  	slice_vertical_position_extension = (video->mpeg2 && video->vertical_size > 2800) ? 
		mpeg3slice_getbits(slice->slice_buffer, 3) : 0;

  	if(video->scalable_mode == SC_DP) slice->pri_brk = mpeg3slice_getbits(slice->slice_buffer, 7);

  	qs = mpeg3slice_getbits(slice->slice_buffer, 5);
  	slice->quant_scale = video->mpeg2 ? (video->qscale_type ? mpeg3_non_linear_mquant_table[qs] : (qs << 1)) : qs;

  	if(mpeg3slice_getbit(slice->slice_buffer))
	{
    	intra_slice = mpeg3slice_getbit(slice->slice_buffer);
    	mpeg3slice_getbits(slice->slice_buffer, 7);
    	mpeg3video_ext_bit_info(slice->slice_buffer);
  	}
  	else 
		intra_slice = 0;

	return slice_vertical_position_extension;
}