bitstream.c

基于Linux的ffmepg decoder

			READ_MARKER();

			if (BitstreamGetBit(bs))	/* fixed_vop_rate */
			{
				BitstreamSkip(bs, dec->time_inc_bits);	/* fixed_vop_time_increment */
			}

			if (dec->shape != VIDOBJLAY_SHAPE_BINARY_ONLY) {

				if (dec->shape == VIDOBJLAY_SHAPE_RECTANGULAR) {
					uint32_t width, height;

					READ_MARKER();
					width = BitstreamGetBits(bs, 13);	/* video_object_layer_width */
					READ_MARKER();
					height = BitstreamGetBits(bs, 13);	/* video_object_layer_height */
					READ_MARKER();
#if 0				//ben modify
					dec->width = width;
					dec->height = height;
#else
					/* for auto set width & height */
					if (dec->width == 0)	
						dec->width = width;
					if (dec->height == 0)
						dec->height = height;
					if (width != dec->width || height != dec->height)
						return -1;
#endif
				}

				dec->interlacing = BitstreamGetBit(bs);
				if (dec->interlacing != 0)
					return -1; 		// not support interlacing now

				if (!BitstreamGetBit(bs))	/* obmc_disable */
				{
					/* TODO */
					/* fucking divx4.02 has this enabled */
				}

				if (BitstreamGetBits(bs, (vol_ver_id == 1 ? 1 : 2)))	/* sprite_enable */
				{
					return -1;
				}

				if (vol_ver_id != 1 &&
					dec->shape != VIDOBJLAY_SHAPE_RECTANGULAR) {
					BitstreamSkip(bs, 1);	/* sadct_disable */
				}

				if (BitstreamGetBit(bs))	/* not_8_bit */
				{
					dec->quant_bits = BitstreamGetBits(bs, 4);	/* quant_precision */
					BitstreamSkip(bs, 4);	/* bits_per_pixel */
				} else {
					dec->quant_bits = 5;
				}

				if (dec->shape == VIDOBJLAY_SHAPE_GRAYSCALE) {
					BitstreamSkip(bs, 1);	/* no_gray_quant_update */
					BitstreamSkip(bs, 1);	/* composition_method */
					BitstreamSkip(bs, 1);	/* linear_composition */
				}

				dec->quant_type = BitstreamGetBit(bs);	/* quant_type */

				if (dec->quant_type) {
					if (BitstreamGetBit(bs))	/* load_intra_quant_mat */
					{
						uint8_t matrix[64];

						bs_get_matrix(bs, matrix);
						set_intra_matrix_dec((uint32_t *)((uint32_t)dec->pu32BaseAddr + CUSTOM_INTRA_MATRIX_OFF), matrix);
					} else {
						set_intra_matrix_dec((uint32_t *)((uint32_t)dec->pu32BaseAddr + CUSTOM_INTRA_MATRIX_OFF),
											get_default_intra_matrix_dec());
					}

					if (BitstreamGetBit(bs))	/* load_inter_quant_mat */
					{
						uint8_t matrix[64];
						
						bs_get_matrix(bs, matrix);
						set_inter_matrix_dec((uint32_t *)((uint32_t)dec->pu32BaseAddr + CUSTOM_INTER_MATRIX_OFF), matrix);
					} else
						set_inter_matrix_dec((uint32_t *)((uint32_t)dec->pu32BaseAddr + CUSTOM_INTER_MATRIX_OFF),
											get_default_inter_matrix_dec());

					if (dec->shape == VIDOBJLAY_SHAPE_GRAYSCALE) {
						return -1;
					}

				}


				if (vol_ver_id != 1) {
					dec->quarterpel = BitstreamGetBit(bs);	/* quarter_sample */
				}
				else {
					dec->quarterpel = 0;
				}
				if (!BitstreamGetBit(bs))	/* complexity_estimation_disable */
				{
					return -1;
				}
				dec->resync_marker_disable = BitstreamGetBits(bs,1);
				/* resync_marker_disable */
				dec->data_partitioned = BitstreamGetBits(bs,1);

				if (dec->data_partitioned)	/* data_partitioned */
				{
					dec->reversible_vlc = BitstreamGetBits(bs,1);
				}

				if (vol_ver_id != 1) {
					if (BitstreamGetBit(bs))	/* newpred_enable */
					{
						BitstreamSkip(bs, 2);	/* requested_upstream_message_type */
						BitstreamSkip(bs, 1);	/* newpred_segment_type */
					}
					if (BitstreamGetBit(bs))	/* reduced_resolution_vop_enable */
					{
						return -1;
					}
				}

				if ((dec->scalability = (int8_t)BitstreamGetBit(bs)) != 0)	/* scalability */
				{
					return -1;
				}
			} else				/* dec->shape == BINARY_ONLY */
			{
				if (vol_ver_id != 1) {
					if (BitstreamGetBit(bs))	/* scalability */
					{
						return -1;
					}
				}
				BitstreamSkip(bs, 1);	/* resync_marker_disable */
			}
		}
		else if (start_code == GRPOFVOP_START_CODE) {

			BitstreamSkip(bs, 32);
			{
				int hours, minutes, seconds;

				hours = BitstreamGetBits(bs, 5);
				minutes = BitstreamGetBits(bs, 6);
				READ_MARKER();
				seconds = BitstreamGetBits(bs, 6);
				
			}
			BitstreamSkip(bs, 1);	/* closed_gov */
			BitstreamSkip(bs, 1);	/* broken_link */

		} else if (start_code == VOP_START_CODE) {

			BitstreamSkip(bs, 32);	/* vop_start_code */
			coding_type = BitstreamGetBits(bs, 2);	/* vop_coding_type */
			dec->picture_coding_type = coding_type;
//**********************NOTE*****************************************
			coding_type = coding_type & 0x1;

/* *************************** for decode B-frame time *********************** */
			while (BitstreamGetBit(bs) != 0)	/* time_base */
				time_incr++;

			READ_MARKER();

			if (dec->time_inc_bits) {
				time_increment = (BitstreamGetBits(bs, dec->time_inc_bits));	/* vop_time_increment */
			} 

			if (coding_type != B_VOP) {
				dec->last_time_base = dec->time_base;
				dec->time_base += time_incr;
				dec->time = time_increment;

/*					dec->time_base * time_increment_resolution +
					time_increment;
*/
				if (time_increment_resolution!= 0)
					dec->time_pp = (uint32_t) 
						(time_increment_resolution + dec->time - dec->last_non_b_time)%time_increment_resolution;
				dec->last_non_b_time = dec->time;
			} else {
				dec->time = time_increment; 
/*
					(dec->last_time_base +
					 time_incr) * time_increment_resolution + time_increment; 
*/
				dec->time_bp = (uint32_t) 
					(time_increment_resolution + dec->last_non_b_time - dec->time)%time_increment_resolution;
			}

			READ_MARKER();

			if (!BitstreamGetBit(bs))	/* vop_coded */
			{
				return N_VOP;
			}

			/* fix a little bug by MinChen <[e-mail]> */
			if ((dec->shape != VIDOBJLAY_SHAPE_BINARY_ONLY) &&
				(coding_type == P_VOP)) {
				*rounding = BitstreamGetBit(bs);	/* rounding_type */
			}

			if (dec->shape != VIDOBJLAY_SHAPE_RECTANGULAR) {
				uint32_t width, height;
				uint32_t horiz_mc_ref, vert_mc_ref;

				width = BitstreamGetBits(bs, 13);
				READ_MARKER();
				height = BitstreamGetBits(bs, 13);
				READ_MARKER();
				horiz_mc_ref = BitstreamGetBits(bs, 13);
				READ_MARKER();
				vert_mc_ref = BitstreamGetBits(bs, 13);
				READ_MARKER();

				BitstreamSkip(bs, 1);	/* change_conv_ratio_disable */
				if (BitstreamGetBit(bs))	/* vop_constant_alpha */
				{
					BitstreamSkip(bs, 8);	/* vop_constant_alpha_value */
				}
			}


			if (dec->shape != VIDOBJLAY_SHAPE_BINARY_ONLY) {
				/* intra_dc_vlc_threshold */
				* intra_dc_threshold_bit= BitstreamGetBits(bs, 3);
//				* intra_dc_threshold_bit= BitstreamShowBits(bs, 3);
//				*intra_dc_threshold = intra_dc_threshold_table[BitstreamGetBits(bs, 3)];

				if (dec->interlacing) {
					dec->top_field_first = BitstreamGetBit(bs);
					dec->alternate_vertical_scan = BitstreamGetBit(bs);
				}
			}

			if ((*quant = BitstreamGetBits(bs, dec->quant_bits)) < 1)	/* vop_quant */
				*quant = 1;

			if (coding_type != I_VOP) {
				*fcode_forward = BitstreamGetBits(bs, 3);	/* fcode_forward */

//**********************NOTE*****************************************
				if (*fcode_forward < 1) *fcode_forward = 1;
			}

			if (coding_type == B_VOP) {
				*fcode_backward = BitstreamGetBits(bs, 3);	/* fcode_backward */
			}

			if (!dec->scalability) {
				if ((dec->shape != VIDOBJLAY_SHAPE_RECTANGULAR) &&
					(coding_type != I_VOP)) {
					BitstreamSkip(bs, 1);	/* vop_shape_coding_type */
				}
			}
			return coding_type;

		} else if (start_code == USERDATA_START_CODE) {
			BitstreamSkip(bs, 32);	/* user_data_start_code */
		} else					/* start_code == ? */
		{
			if (BitstreamShowBits(bs, 24) == 0x000001) {
			}
			BitstreamSkip(bs, 8);
		}
	}
	while ((BitstreamPos(bs) >> 3) < bs->length);

	return -1;					/* ignore it */
}