WebSVN - shark - Blame - Rev 1182 - /demos/trunk/fsf/mpeg2/getpic.c

Rev	Author	Line No.	Line
1182	giacomo	1	/* getpic.c, picture decoding */
		2
		3	/* Copyright (C) 1996, MPEG Software Simulation Group. All Rights Reserved. */
		4
		5	/*
		6	* Disclaimer of Warranty
		7	*
		8	* These software programs are available to the user without any license fee or
		9	* royalty on an "as is" basis. The MPEG Software Simulation Group disclaims
		10	* any and all warranties, whether express, implied, or statuary, including any
		11	* implied warranties or merchantability or of fitness for a particular
		12	* purpose. In no event shall the copyright-holder be liable for any
		13	* incidental, punitive, or consequential damages of any kind whatsoever
		14	* arising from the use of these programs.
		15	*
		16	* This disclaimer of warranty extends to the user of these programs and user's
		17	* customers, employees, agents, transferees, successors, and assigns.
		18	*
		19	* The MPEG Software Simulation Group does not represent or warrant that the
		20	* programs furnished hereunder are free of infringement of any third-party
		21	* patents.
		22	*
		23	* Commercial implementations of MPEG-1 and MPEG-2 video, including shareware,
		24	* are subject to royalty fees to patent holders. Many of these patents are
		25	* general enough such that they are unavoidable regardless of implementation
		26	* design.
		27	*
		28	*/
		29
		30	#include "config.h"
		31	#include "global.h"
		32
		33	/* private prototypes*/
		34	static void picture_data _ANSI_ARGS_((int framenum));
		35	static void macroblock_modes _ANSI_ARGS_((int pmacroblock_type, int pstwtype,
		36	int pstwclass, int pmotion_type, int pmotion_vector_count, int pmv_format, int *pdmv,
		37	int pmvscale, int pdct_type));
		38	static void Clear_Block _ANSI_ARGS_((int comp));
		39	static void Sum_Block _ANSI_ARGS_((int comp));
		40	static void Saturate _ANSI_ARGS_((short *bp));
		41	static void Add_Block _ANSI_ARGS_((int comp, int bx, int by,
		42	int dct_type, int addflag));
		43	static void Update_Picture_Buffers _ANSI_ARGS_((void));
		44	static void frame_reorder _ANSI_ARGS_((int bitstream_framenum,
		45	int sequence_framenum));
		46	static void Decode_SNR_Macroblock _ANSI_ARGS_((int SNRMBA, int SNRMBAinc,
		47	int MBA, int MBAmax, int *dct_type));
		48
		49	static void motion_compensation _ANSI_ARGS_((int MBA, int macroblock_type,
		50	int motion_type, int PMV[2][2][2], int motion_vertical_field_select[2][2],
		51	int dmvector[2], int stwtype, int dct_type));
		52
		53	static void skipped_macroblock _ANSI_ARGS_((int dc_dct_pred[3],
		54	int PMV[2][2][2], int *motion_type, int motion_vertical_field_select[2][2],
		55	int stwtype, int macroblock_type));
		56
		57	static int slice _ANSI_ARGS_((int framenum, int MBAmax));
		58
		59	static int start_of_slice _ANSI_ARGS_ ((int MBAmax, int *MBA,
		60	int *MBAinc, int dc_dct_pred[3], int PMV[2][2][2]));
		61
		62	static int decode_macroblock _ANSI_ARGS_((int *macroblock_type,
		63	int stwtype, int stwclass, int motion_type, int dct_type,
		64	int PMV[2][2][2], int dc_dct_pred[3],
		65	int motion_vertical_field_select[2][2], int dmvector[2]));
		66
		67
		68	/* decode one frame or field picture */
		69	void Decode_Picture(bitstream_framenum, sequence_framenum)
		70	int bitstream_framenum, sequence_framenum;
		71	{
		72
		73	if (picture_structure==FRAME_PICTURE && Second_Field)
		74	{
		75	/* recover from illegal number of field pictures */
		76	cprintf("odd number of field pictures\n");
		77	Second_Field = 0;
		78	}
		79
		80	/* IMPLEMENTATION: update picture buffer pointers */
		81	Update_Picture_Buffers();
		82
		83	#ifdef VERIFY
		84	Check_Headers(bitstream_framenum, sequence_framenum);
		85	#endif /* VERIFY */
		86
		87	/* ISO/IEC 13818-4 section 2.4.5.4 "frame buffer intercept method" */
		88	/* (section number based on November 1995 (Dallas) draft of the
		89	conformance document) */
		90	if(Ersatz_Flag)
		91	Substitute_Frame_Buffer(bitstream_framenum, sequence_framenum);
		92
		93	/* form spatial scalable picture */
		94
		95	/* form spatial scalable picture */
		96	/* ISO/IEC 13818-2 section 7.7: Spatial scalability */
		97	if (base.pict_scal && !Second_Field)
		98	{
		99	Spatial_Prediction();
		100	}
		101
		102	/* decode picture data ISO/IEC 13818-2 section 6.2.3.7 */
		103	picture_data(bitstream_framenum);
		104
		105	/* write or display current or previously decoded reference frame */
		106	/* ISO/IEC 13818-2 section 6.1.1.11: Frame reordering */
		107	frame_reorder(bitstream_framenum, sequence_framenum);
		108
		109	if (picture_structure!=FRAME_PICTURE)
		110	Second_Field = !Second_Field;
		111	}
		112
		113
		114	/* decode all macroblocks of the current picture */
		115	/* stages described in ISO/IEC 13818-2 section 7 */
		116	static void picture_data(framenum)
		117	int framenum;
		118	{
		119	int MBAmax;
		120	int ret;
		121
		122	/* number of macroblocks per picture */
		123	MBAmax = mb_width*mb_height;
		124
		125	if (picture_structure!=FRAME_PICTURE)
		126	MBAmax>>=1; /* field picture has half as mnay macroblocks as frame */
		127
		128	for(;;)
		129	{
		130	if((ret=slice(framenum, MBAmax))<0)
		131	return;
		132	}
		133
		134	}
		135
		136
		137
		138	/* decode all macroblocks of the current picture */
		139	/* ISO/IEC 13818-2 section 6.3.16 */
		140	static int slice(framenum, MBAmax)
		141	int framenum, MBAmax;
		142	{
		143	int MBA;
		144	int MBAinc, macroblock_type, motion_type, dct_type;
		145	int dc_dct_pred[3];
		146	int PMV[2][2][2], motion_vertical_field_select[2][2];
		147	int dmvector[2];
		148	int stwtype, stwclass;
		149	int SNRMBA, SNRMBAinc;
		150	int ret;
		151
		152	MBA = 0; /* macroblock address */
		153	MBAinc = 0;
		154
		155	if((ret=start_of_slice(MBAmax, &MBA, &MBAinc, dc_dct_pred, PMV))!=1)
		156	return(ret);
		157
		158	if (Two_Streams && enhan.scalable_mode==SC_SNR)
		159	{
		160	SNRMBA=0;
		161	SNRMBAinc=0;
		162	}
		163
		164	Fault_Flag=0;
		165
		166	for (;;)
		167	{
		168
		169	/* this is how we properly exit out of picture */
		170	if (MBA>=MBAmax)
		171	return(-1); /* all macroblocks decoded */
		172
		173	#ifdef TRACE
		174	if (Trace_Flag)
		175	cprintf("frame %d, MB %d\n",framenum,MBA);
		176	#endif /* TRACE */
		177
		178	#ifdef DISPLAY
		179	if (!progressive_frame && picture_structure==FRAME_PICTURE
		180	&& MBA==(MBAmax>>1) && framenum!=0 && Output_Type==T_X11
		181	&& !Display_Progressive_Flag)
		182	{
		183	Display_Second_Field();
		184	}
		185	#endif
		186
		187	ld = &base;
		188
		189	if (MBAinc==0)
		190	{
		191	if (base.scalable_mode==SC_DP && base.priority_breakpoint==1)
		192	ld = &enhan;
		193
		194	if (!Show_Bits(23) \|\| Fault_Flag) /* next_start_code or fault */
		195	{
		196	resync: /* if Fault_Flag: resynchronize to next next_start_code */
		197	Fault_Flag = 0;
		198	return(0); /* trigger: go to next slice */
		199	}
		200	else /* neither next_start_code nor Fault_Flag */
		201	{
		202	if (base.scalable_mode==SC_DP && base.priority_breakpoint==1)
		203	ld = &enhan;
		204
		205	/* decode macroblock address increment */
		206	MBAinc = Get_macroblock_address_increment();
		207
		208	if (Fault_Flag) goto resync;
		209	}
		210	}
		211
		212	if (MBA>=MBAmax)
		213	{
		214	/* MBAinc points beyond picture dimensions */
		215	if (!Quiet_Flag)
		216	cprintf("Too many macroblocks in picture\n");
		217	return(-1);
		218	}
		219
		220	if (MBAinc==1) /* not skipped */
		221	{
		222	ret = decode_macroblock(&macroblock_type, &stwtype, &stwclass,
		223	&motion_type, &dct_type, PMV, dc_dct_pred,
		224	motion_vertical_field_select, dmvector);
		225
		226	if(ret==-1)
		227	return(-1);
		228
		229	if(ret==0)
		230	goto resync;
		231
		232	}
		233	else /* MBAinc!=1: skipped macroblock */
		234	{
		235	/* ISO/IEC 13818-2 section 7.6.6 */
		236	skipped_macroblock(dc_dct_pred, PMV, &motion_type,
		237	motion_vertical_field_select, &stwtype, &macroblock_type);
		238	}
		239
		240	/* SCALABILITY: SNR */
		241	/* ISO/IEC 13818-2 section 7.8 */
		242	/* NOTE: we currently ignore faults encountered in this routine */
		243	if (Two_Streams && enhan.scalable_mode==SC_SNR)
		244	Decode_SNR_Macroblock(&SNRMBA, &SNRMBAinc, MBA, MBAmax, &dct_type);
		245
		246	/* ISO/IEC 13818-2 section 7.6 */
		247	motion_compensation(MBA, macroblock_type, motion_type, PMV,
		248	motion_vertical_field_select, dmvector, stwtype, dct_type);
		249
		250
		251	/* advance to next macroblock */
		252	MBA++;
		253	MBAinc--;
		254
		255	/* SCALABILITY: SNR */
		256	if (Two_Streams && enhan.scalable_mode==SC_SNR)
		257	{
		258	SNRMBA++;
		259	SNRMBAinc--;
		260	}
		261
		262	if (MBA>=MBAmax)
		263	return(-1); /* all macroblocks decoded */
		264	}
		265	}
		266
		267
		268	/* ISO/IEC 13818-2 section 6.3.17.1: Macroblock modes */
		269	static void macroblock_modes(pmacroblock_type,pstwtype,pstwclass,
		270	pmotion_type,pmotion_vector_count,pmv_format,pdmv,pmvscale,pdct_type)
		271	int pmacroblock_type, pstwtype, *pstwclass;
		272	int pmotion_type, pmotion_vector_count, pmv_format, pdmv, *pmvscale;
		273	int *pdct_type;
		274	{
		275	int macroblock_type;
		276	int stwtype, stwcode, stwclass;
		277	int motion_type = 0;
		278	int motion_vector_count, mv_format, dmv, mvscale;
		279	int dct_type;
		280	static unsigned char stwc_table[3][4]
		281	= { {6,3,7,4}, {2,1,5,4}, {2,5,7,4} };
		282	static unsigned char stwclass_table[9]
		283	= {0, 1, 2, 1, 1, 2, 3, 3, 4};
		284
		285	/* get macroblock_type */
		286	macroblock_type = Get_macroblock_type();
		287
		288	if (Fault_Flag) return;
		289
		290	/* get spatial_temporal_weight_code */
		291	if (macroblock_type & MB_WEIGHT)
		292	{
		293	if (spatial_temporal_weight_code_table_index==0)
		294	stwtype = 4;
		295	else
		296	{
		297	stwcode = Get_Bits(2);
		298	#ifdef TRACE
		299	if (Trace_Flag)
		300	{
		301	cprintf("spatial_temporal_weight_code (");
		302	Print_Bits(stwcode,2,2);
		303	cprintf("): %d\n",stwcode);
		304	}
		305	#endif /* TRACE */
		306	stwtype = stwc_table[spatial_temporal_weight_code_table_index-1][stwcode];
		307	}
		308	}
		309	else
		310	stwtype = (macroblock_type & MB_CLASS4) ? 8 : 0;
		311
		312	/* SCALABILITY: derive spatial_temporal_weight_class (Table 7-18) */
		313	stwclass = stwclass_table[stwtype];
		314
		315	/* get frame/field motion type */
		316	if (macroblock_type & (MACROBLOCK_MOTION_FORWARD\|MACROBLOCK_MOTION_BACKWARD))
		317	{
		318	if (picture_structure==FRAME_PICTURE) /* frame_motion_type */
		319	{
		320	motion_type = frame_pred_frame_dct ? MC_FRAME : Get_Bits(2);
		321	#ifdef TRACE
		322	if (!frame_pred_frame_dct && Trace_Flag)
		323	{
		324	cprintf("frame_motion_type (");
		325	Print_Bits(motion_type,2,2);
		326	cprintf("): %s\n",motion_type==MC_FIELD?"Field":
		327	motion_type==MC_FRAME?"Frame":
		328	motion_type==MC_DMV?"Dual_Prime":"Invalid");
		329	}
		330	#endif /* TRACE */
		331	}
		332	else /* field_motion_type */
		333	{
		334	motion_type = Get_Bits(2);
		335	#ifdef TRACE
		336	if (Trace_Flag)
		337	{
		338	cprintf("field_motion_type (");
		339	Print_Bits(motion_type,2,2);
		340	cprintf("): %s\n",motion_type==MC_FIELD?"Field":
		341	motion_type==MC_16X8?"16x8 MC":
		342	motion_type==MC_DMV?"Dual_Prime":"Invalid");
		343	}
		344	#endif /* TRACE */
		345	}
		346	}
		347	else if ((macroblock_type & MACROBLOCK_INTRA) && concealment_motion_vectors)
		348	{
		349	/* concealment motion vectors */
		350	motion_type = (picture_structure==FRAME_PICTURE) ? MC_FRAME : MC_FIELD;
		351	}
		352	#if 0
		353	else
		354	{
		355	printf("maroblock_modes(): unknown macroblock type\n");
		356	motion_type = -1;
		357	}
		358	#endif
		359
		360	/* derive motion_vector_count, mv_format and dmv, (table 6-17, 6-18) */
		361	if (picture_structure==FRAME_PICTURE)
		362	{
		363	motion_vector_count = (motion_type==MC_FIELD && stwclass<2) ? 2 : 1;
		364	mv_format = (motion_type==MC_FRAME) ? MV_FRAME : MV_FIELD;
		365	}
		366	else
		367	{
		368	motion_vector_count = (motion_type==MC_16X8) ? 2 : 1;
		369	mv_format = MV_FIELD;
		370	}
		371
		372	dmv = (motion_type==MC_DMV); /* dual prime */
		373
		374	/* field mv predictions in frame pictures have to be scaled
		375	* ISO/IEC 13818-2 section 7.6.3.1 Decoding the motion vectors
		376	* IMPLEMENTATION: mvscale is derived for later use in motion_vectors()
		377	* it displaces the stage:
		378	*
		379	* if((mv_format=="field")&&(t==1)&&(picture_structure=="Frame picture"))
		380	* prediction = PMV[r][s][t] DIV 2;
		381	*/
		382
		383	mvscale = ((mv_format==MV_FIELD) && (picture_structure==FRAME_PICTURE));
		384
		385	/* get dct_type (frame DCT / field DCT) */
		386	dct_type = (picture_structure==FRAME_PICTURE)
		387	&& (!frame_pred_frame_dct)
		388	&& (macroblock_type & (MACROBLOCK_PATTERN\|MACROBLOCK_INTRA))
		389	? Get_Bits(1)
		390	: 0;
		391
		392	#ifdef TRACE
		393	if (Trace_Flag && (picture_structure==FRAME_PICTURE)
		394	&& (!frame_pred_frame_dct)
		395	&& (macroblock_type & (MACROBLOCK_PATTERN\|MACROBLOCK_INTRA)))
		396	cprintf("dct_type (%d): %s\n",dct_type,dct_type?"Field":"Frame");
		397	#endif /* TRACE */
		398
		399	/* return values */
		400	*pmacroblock_type = macroblock_type;
		401	*pstwtype = stwtype;
		402	*pstwclass = stwclass;
		403	*pmotion_type = motion_type;
		404	*pmotion_vector_count = motion_vector_count;
		405	*pmv_format = mv_format;
		406	*pdmv = dmv;
		407	*pmvscale = mvscale;
		408	*pdct_type = dct_type;
		409	}
		410
		411
		412	/* move/add 8x8-Block from block[comp] to backward_reference_frame */
		413	/* copy reconstructed 8x8 block from block[comp] to current_frame[]
		414	* ISO/IEC 13818-2 section 7.6.8: Adding prediction and coefficient data
		415	* This stage also embodies some of the operations implied by:
		416	* - ISO/IEC 13818-2 section 7.6.7: Combining predictions
		417	* - ISO/IEC 13818-2 section 6.1.3: Macroblock
		418	*/
		419	static void Add_Block(comp,bx,by,dct_type,addflag)
		420	int comp,bx,by,dct_type,addflag;
		421	{
		422	int cc,i, j, iincr;
		423	unsigned char *rfp;
		424	short *bp;
		425
		426
		427	/* derive color component index */
		428	/* equivalent to ISO/IEC 13818-2 Table 7-1 */
		429	cc = (comp<4) ? 0 : (comp&1)+1; /* color component index */
		430
		431	if (cc==0)
		432	{
		433	/* luminance */
		434
		435	if (picture_structure==FRAME_PICTURE)
		436	if (dct_type)
		437	{
		438	/* field DCT coding */
		439	rfp = current_frame[0]
		440	+ Coded_Picture_Width*(by+((comp&2)>>1)) + bx + ((comp&1)<<3);
		441	iincr = (Coded_Picture_Width<<1) - 8;
		442	}
		443	else
		444	{
		445	/* frame DCT coding */
		446	rfp = current_frame[0]
		447	+ Coded_Picture_Width*(by+((comp&2)<<2)) + bx + ((comp&1)<<3);
		448	iincr = Coded_Picture_Width - 8;
		449	}
		450	else
		451	{
		452	/* field picture */
		453	rfp = current_frame[0]
		454	+ (Coded_Picture_Width<<1)*(by+((comp&2)<<2)) + bx + ((comp&1)<<3);
		455	iincr = (Coded_Picture_Width<<1) - 8;
		456	}
		457	}
		458	else
		459	{
		460	/* chrominance */
		461
		462	/* scale coordinates */
		463	if (chroma_format!=CHROMA444)
		464	bx >>= 1;
		465	if (chroma_format==CHROMA420)
		466	by >>= 1;
		467	if (picture_structure==FRAME_PICTURE)
		468	{
		469	if (dct_type && (chroma_format!=CHROMA420))
		470	{
		471	/* field DCT coding */
		472	rfp = current_frame[cc]
		473	+ Chroma_Width*(by+((comp&2)>>1)) + bx + (comp&8);
		474	iincr = (Chroma_Width<<1) - 8;
		475	}
		476	else
		477	{
		478	/* frame DCT coding */
		479	rfp = current_frame[cc]
		480	+ Chroma_Width*(by+((comp&2)<<2)) + bx + (comp&8);
		481	iincr = Chroma_Width - 8;
		482	}
		483	}
		484	else
		485	{
		486	/* field picture */
		487	rfp = current_frame[cc]
		488	+ (Chroma_Width<<1)*(by+((comp&2)<<2)) + bx + (comp&8);
		489	iincr = (Chroma_Width<<1) - 8;
		490	}
		491	}
		492
		493	bp = ld->block[comp];
		494
		495	if (addflag)
		496	{
		497	for (i=0; i<8; i++)
		498	{
		499	for (j=0; j<8; j++)
		500	{
		501	rfp = Clip[bp++ + *rfp];
		502	rfp++;
		503	}
		504
		505	rfp+= iincr;
		506	}
		507	}
		508	else
		509	{
		510	for (i=0; i<8; i++)
		511	{
		512	for (j=0; j<8; j++)
		513	rfp++ = Clip[bp++ + 128];
		514
		515	rfp+= iincr;
		516	}
		517	}
		518	}
		519
		520
		521	/* ISO/IEC 13818-2 section 7.8 */
		522	static void Decode_SNR_Macroblock(SNRMBA, SNRMBAinc, MBA, MBAmax, dct_type)
		523	int SNRMBA, SNRMBAinc;
		524	int MBA, MBAmax;
		525	int *dct_type;
		526	{
		527	int SNRmacroblock_type, SNRcoded_block_pattern, SNRdct_type, dummy;
		528	int slice_vert_pos_ext, quantizer_scale_code, comp, code;
		529
		530	ld = &enhan;
		531
		532	if (*SNRMBAinc==0)
		533	{
		534	if (!Show_Bits(23)) /* next_start_code */
		535	{
		536	next_start_code();
		537	code = Show_Bits(32);
		538
		539	if (code<SLICE_START_CODE_MIN \|\| code>SLICE_START_CODE_MAX)
		540	{
		541	/* only slice headers are allowed in picture_data */
		542	if (!Quiet_Flag)
		543	cprintf("SNR: Premature end of picture\n");
		544	return;
		545	}
		546
		547	Flush_Buffer32();
		548
		549	/* decode slice header (may change quantizer_scale) */
		550	slice_vert_pos_ext = slice_header();
		551
		552	/* decode macroblock address increment */
		553	*SNRMBAinc = Get_macroblock_address_increment();
		554
		555	/* set current location */
		556	*SNRMBA =
		557	((slice_vert_pos_ext<<7) + (code&255) - 1)mb_width + SNRMBAinc - 1;
		558
		559	SNRMBAinc = 1; / first macroblock in slice: not skipped */
		560	}
		561	else /* not next_start_code */
		562	{
		563	if (*SNRMBA>=MBAmax)
		564	{
		565	if (!Quiet_Flag)
		566	cprintf("Too many macroblocks in picture\n");
		567	return;
		568	}
		569
		570	/* decode macroblock address increment */
		571	*SNRMBAinc = Get_macroblock_address_increment();
		572	}
		573	}
		574
		575	if (*SNRMBA!=MBA)
		576	{
		577	/* streams out of sync */
		578	if (!Quiet_Flag)
		579	cprintf("Cant't synchronize streams\n");
		580	return;
		581	}
		582
		583	if (SNRMBAinc==1) / not skipped */
		584	{
		585	macroblock_modes(&SNRmacroblock_type, &dummy, &dummy,
		586	&dummy, &dummy, &dummy, &dummy, &dummy,
		587	&SNRdct_type);
		588
		589	if (SNRmacroblock_type & MACROBLOCK_PATTERN)
		590	*dct_type = SNRdct_type;
		591
		592	if (SNRmacroblock_type & MACROBLOCK_QUANT)
		593	{
		594	quantizer_scale_code = Get_Bits(5);
		595	ld->quantizer_scale =
		596	ld->q_scale_type ? Non_Linear_quantizer_scale[quantizer_scale_code] : quantizer_scale_code<<1;
		597	}
		598
		599	/* macroblock_pattern */
		600	if (SNRmacroblock_type & MACROBLOCK_PATTERN)
		601	{
		602	SNRcoded_block_pattern = Get_coded_block_pattern();
		603
		604	if (chroma_format==CHROMA422)
		605	SNRcoded_block_pattern = (SNRcoded_block_pattern<<2) \| Get_Bits(2); /* coded_block_pattern_1 */
		606	else if (chroma_format==CHROMA444)
		607	SNRcoded_block_pattern = (SNRcoded_block_pattern<<6) \| Get_Bits(6); /* coded_block_pattern_2 */
		608	}
		609	else
		610	SNRcoded_block_pattern = 0;
		611
		612	/* decode blocks */
		613	for (comp=0; comp<block_count; comp++)
		614	{
		615	Clear_Block(comp);
		616
		617	if (SNRcoded_block_pattern & (1<<(block_count-1-comp)))
		618	Decode_MPEG2_Non_Intra_Block(comp);
		619	}
		620	}
		621	else /* SNRMBAinc!=1: skipped macroblock */
		622	{
		623	for (comp=0; comp<block_count; comp++)
		624	Clear_Block(comp);
		625	}
		626
		627	ld = &base;
		628	}
		629
		630
		631
		632	/* IMPLEMENTATION: set scratch pad macroblock to zero */
		633	static void Clear_Block(comp)
		634	int comp;
		635	{
		636	short *Block_Ptr;
		637	int i;
		638
		639	Block_Ptr = ld->block[comp];
		640
		641	for (i=0; i<64; i++)
		642	*Block_Ptr++ = 0;
		643	}
		644
		645
		646	/* SCALABILITY: add SNR enhancement layer block data to base layer */
		647	/* ISO/IEC 13818-2 section 7.8.3.4: Addition of coefficients from the two layes */
		648	static void Sum_Block(comp)
		649	int comp;
		650	{
		651	short Block_Ptr1, Block_Ptr2;
		652	int i;
		653
		654	Block_Ptr1 = base.block[comp];
		655	Block_Ptr2 = enhan.block[comp];
		656
		657	for (i=0; i<64; i++)
		658	Block_Ptr1++ += Block_Ptr2++;
		659	}
		660
		661
		662	/* limit coefficients to -2048..2047 */
		663	/* ISO/IEC 13818-2 section 7.4.3 and 7.4.4: Saturation and Mismatch control */
		664	static void Saturate(Block_Ptr)
		665	short *Block_Ptr;
		666	{
		667	int i, sum, val;
		668
		669	sum = 0;
		670
		671	/* ISO/IEC 13818-2 section 7.4.3: Saturation */
		672	for (i=0; i<64; i++)
		673	{
		674	val = Block_Ptr[i];
		675
		676	if (val>2047)
		677	val = 2047;
		678	else if (val<-2048)
		679	val = -2048;
		680
		681	Block_Ptr[i] = val;
		682	sum+= val;
		683	}
		684
		685	/* ISO/IEC 13818-2 section 7.4.4: Mismatch control */
		686	if ((sum&1)==0)
		687	Block_Ptr[63]^= 1;
		688
		689	}
		690
		691
		692	/* reuse old picture buffers as soon as they are no longer needed
		693	based on life-time axioms of MPEG */
		694	static void Update_Picture_Buffers()
		695	{
		696	int cc; /* color component index */
		697	unsigned char tmp; / temporary swap pointer */
		698
		699	for (cc=0; cc<3; cc++)
		700	{
		701	/* B pictures do not need to be save for future reference */
		702	if (picture_coding_type==B_TYPE)
		703	{
		704	current_frame[cc] = auxframe[cc];
		705	}
		706	else
		707	{
		708	/* only update at the beginning of the coded frame */
		709	if (!Second_Field)
		710	{
		711	tmp = forward_reference_frame[cc];
		712
		713	/* the previously decoded reference frame is stored
		714	coincident with the location where the backward
		715	reference frame is stored (backwards prediction is not
		716	needed in P pictures) */
		717	forward_reference_frame[cc] = backward_reference_frame[cc];
		718
		719	/* update pointer for potential future B pictures */
		720	backward_reference_frame[cc] = tmp;
		721	}
		722
		723	/* can erase over old backward reference frame since it is not used
		724	in a P picture, and since any subsequent B pictures will use the
		725	previously decoded I or P frame as the backward_reference_frame */
		726	current_frame[cc] = backward_reference_frame[cc];
		727	}
		728
		729	/* IMPLEMENTATION:
		730	one-time folding of a line offset into the pointer which stores the
		731	memory address of the current frame saves offsets and conditional
		732	branches throughout the remainder of the picture processing loop */
		733	if (picture_structure==BOTTOM_FIELD)
		734	current_frame[cc]+= (cc==0) ? Coded_Picture_Width : Chroma_Width;
		735	}
		736	}
		737
		738
		739	/* store last frame */
		740
		741	void Output_Last_Frame_of_Sequence(Framenum)
		742	int Framenum;
		743	{
		744	if (Second_Field)
		745	cprintf("last frame incomplete, not stored\n");
		746	else
		747	Write_Frame(backward_reference_frame,Framenum-1);
		748	}
		749
		750
		751
		752	static void frame_reorder(Bitstream_Framenum, Sequence_Framenum)
		753	int Bitstream_Framenum, Sequence_Framenum;
		754	{
		755	/* tracking variables to insure proper output in spatial scalability */
		756	static int Oldref_progressive_frame, Newref_progressive_frame;
		757
		758	if (Sequence_Framenum!=0)
		759	{
		760	if (picture_structure==FRAME_PICTURE \|\| Second_Field)
		761	{
		762	if (picture_coding_type==B_TYPE)
		763	Write_Frame(auxframe,Bitstream_Framenum-1);
		764	else
		765	{
		766	Newref_progressive_frame = progressive_frame;
		767	progressive_frame = Oldref_progressive_frame;
		768
		769	Write_Frame(forward_reference_frame,Bitstream_Framenum-1);
		770
		771	Oldref_progressive_frame = progressive_frame = Newref_progressive_frame;
		772	}
		773	}
		774	#ifdef DISPLAY
		775	else if (Output_Type==T_X11)
		776	{
		777	if(!Display_Progressive_Flag)
		778	Display_Second_Field();
		779	}
		780	#endif
		781	}
		782	else
		783	Oldref_progressive_frame = progressive_frame;
		784
		785	}
		786
		787
		788	/* ISO/IEC 13818-2 section 7.6 */
		789	static void motion_compensation(MBA, macroblock_type, motion_type, PMV,
		790	motion_vertical_field_select, dmvector, stwtype, dct_type)
		791	int MBA;
		792	int macroblock_type;
		793	int motion_type;
		794	int PMV[2][2][2];
		795	int motion_vertical_field_select[2][2];
		796	int dmvector[2];
		797	int stwtype;
		798	int dct_type;
		799	{
		800	int bx, by;
		801	int comp;
		802
		803	/* derive current macroblock position within picture */
		804	/* ISO/IEC 13818-2 section 6.3.1.6 and 6.3.1.7 */
		805	bx = 16*(MBA%mb_width);
		806	by = 16*(MBA/mb_width);
		807
		808	/* motion compensation */
		809	if (!(macroblock_type & MACROBLOCK_INTRA))
		810	form_predictions(bx,by,macroblock_type,motion_type,PMV,
		811	motion_vertical_field_select,dmvector,stwtype);
		812
		813	/* SCALABILITY: Data Partitioning */
		814	if (base.scalable_mode==SC_DP)
		815	ld = &base;
		816
		817	/* copy or add block data into picture */
		818	for (comp=0; comp<block_count; comp++)
		819	{
		820	/* SCALABILITY: SNR */
		821	/* ISO/IEC 13818-2 section 7.8.3.4: Addition of coefficients from
		822	the two a layers */
		823	if (Two_Streams && enhan.scalable_mode==SC_SNR)
		824	Sum_Block(comp); /* add SNR enhancement layer data to base layer */
		825
		826	/* MPEG-2 saturation and mismatch control */
		827	/* base layer could be MPEG-1 stream, enhancement MPEG-2 SNR */
		828	/* ISO/IEC 13818-2 section 7.4.3 and 7.4.4: Saturation and Mismatch control */
		829	if ((Two_Streams && enhan.scalable_mode==SC_SNR) \|\| ld->MPEG2_Flag)
		830	Saturate(ld->block[comp]);
		831
		832	/* ISO/IEC 13818-2 section Annex A: inverse DCT */
		833	if (Reference_IDCT_Flag)
		834	Reference_IDCT(ld->block[comp]);
		835	else
		836	Fast_IDCT(ld->block[comp]);
		837
		838	/* ISO/IEC 13818-2 section 7.6.8: Adding prediction and coefficient data */
		839	Add_Block(comp,bx,by,dct_type,(macroblock_type & MACROBLOCK_INTRA)==0);
		840	}
		841
		842	}
		843
		844
		845
		846	/* ISO/IEC 13818-2 section 7.6.6 */
		847	static void skipped_macroblock(dc_dct_pred, PMV, motion_type,
		848	motion_vertical_field_select, stwtype, macroblock_type)
		849	int dc_dct_pred[3];
		850	int PMV[2][2][2];
		851	int *motion_type;
		852	int motion_vertical_field_select[2][2];
		853	int *stwtype;
		854	int *macroblock_type;
		855	{
		856	int comp;
		857
		858	/* SCALABILITY: Data Paritioning */
		859	if (base.scalable_mode==SC_DP)
		860	ld = &base;
		861
		862	for (comp=0; comp<block_count; comp++)
		863	Clear_Block(comp);
		864
		865	/* reset intra_dc predictors */
		866	/* ISO/IEC 13818-2 section 7.2.1: DC coefficients in intra blocks */
		867	dc_dct_pred[0]=dc_dct_pred[1]=dc_dct_pred[2]=0;
		868
		869	/* reset motion vector predictors */
		870	/* ISO/IEC 13818-2 section 7.6.3.4: Resetting motion vector predictors */
		871	if (picture_coding_type==P_TYPE)
		872	PMV[0][0][0]=PMV[0][0][1]=PMV[1][0][0]=PMV[1][0][1]=0;
		873
		874	/* derive motion_type */
		875	if (picture_structure==FRAME_PICTURE)
		876	*motion_type = MC_FRAME;
		877	else
		878	{
		879	*motion_type = MC_FIELD;
		880
		881	/* predict from field of same parity */
		882	/* ISO/IEC 13818-2 section 7.6.6.1 and 7.6.6.3: P field picture and B field
		883	picture */
		884	motion_vertical_field_select[0][0]=motion_vertical_field_select[0][1] =
		885	(picture_structure==BOTTOM_FIELD);
		886	}
		887
		888	/* skipped I are spatial-only predicted, */
		889	/* skipped P and B are temporal-only predicted */
		890	/* ISO/IEC 13818-2 section 7.7.6: Skipped macroblocks */
		891	*stwtype = (picture_coding_type==I_TYPE) ? 8 : 0;
		892
		893	/* IMPLEMENTATION: clear MACROBLOCK_INTRA */
		894	*macroblock_type&= ~MACROBLOCK_INTRA;
		895
		896	}
		897
		898
		899	/* return==-1 means go to next picture */
		900	/* the expression "start of slice" is used throughout the normative
		901	body of the MPEG specification */
		902	static int start_of_slice(MBAmax, MBA, MBAinc,
		903	dc_dct_pred, PMV)
		904	int MBAmax;
		905	int *MBA;
		906	int *MBAinc;
		907	int dc_dct_pred[3];
		908	int PMV[2][2][2];
		909	{
		910	unsigned int code;
		911	int slice_vert_pos_ext;
		912
		913	ld = &base;
		914
		915	Fault_Flag = 0;
		916
		917	next_start_code();
		918	code = Show_Bits(32);
		919
		920	if (code<SLICE_START_CODE_MIN \|\| code>SLICE_START_CODE_MAX)
		921	{
		922	/* only slice headers are allowed in picture_data */
		923	if (!Quiet_Flag)
		924	cprintf("start_of_slice(): Premature end of picture\n");
		925
		926	return(-1); /* trigger: go to next picture */
		927	}
		928
		929	Flush_Buffer32();
		930
		931	/* decode slice header (may change quantizer_scale) */
		932	slice_vert_pos_ext = slice_header();
		933
		934
		935	/* SCALABILITY: Data Partitioning */
		936	if (base.scalable_mode==SC_DP)
		937	{
		938	ld = &enhan;
		939	next_start_code();
		940	code = Show_Bits(32);
		941
		942	if (code<SLICE_START_CODE_MIN \|\| code>SLICE_START_CODE_MAX)
		943	{
		944	/* only slice headers are allowed in picture_data */
		945	if (!Quiet_Flag)
		946	cprintf("DP: Premature end of picture\n");
		947	return(-1); /* trigger: go to next picture */
		948	}
		949
		950	Flush_Buffer32();
		951
		952	/* decode slice header (may change quantizer_scale) */
		953	slice_vert_pos_ext = slice_header();
		954
		955	if (base.priority_breakpoint!=1)
		956	ld = &base;
		957	}
		958
		959	/* decode macroblock address increment */
		960	*MBAinc = Get_macroblock_address_increment();
		961
		962	if (Fault_Flag)
		963	{
		964	cprintf("start_of_slice(): MBAinc unsuccessful\n");
		965	return(0); /* trigger: go to next slice */
		966	}
		967
		968	/* set current location */
		969	/* NOTE: the arithmetic used to derive macroblock_address below is
		970	* equivalent to ISO/IEC 13818-2 section 6.3.17: Macroblock
		971	*/
		972	MBA = ((slice_vert_pos_ext<<7) + (code&255) - 1)mb_width + *MBAinc - 1;
		973	MBAinc = 1; / first macroblock in slice: not skipped */
		974
		975	/* reset all DC coefficient and motion vector predictors */
		976	/* reset all DC coefficient and motion vector predictors */
		977	/* ISO/IEC 13818-2 section 7.2.1: DC coefficients in intra blocks */
		978	dc_dct_pred[0]=dc_dct_pred[1]=dc_dct_pred[2]=0;
		979
		980	/* ISO/IEC 13818-2 section 7.6.3.4: Resetting motion vector predictors */
		981	PMV[0][0][0]=PMV[0][0][1]=PMV[1][0][0]=PMV[1][0][1]=0;
		982	PMV[0][1][0]=PMV[0][1][1]=PMV[1][1][0]=PMV[1][1][1]=0;
		983
		984	/* successfull: trigger decode macroblocks in slice */
		985	return(1);
		986	}
		987
		988
		989	/* ISO/IEC 13818-2 sections 7.2 through 7.5 */
		990	static int decode_macroblock(macroblock_type, stwtype, stwclass,
		991	motion_type, dct_type, PMV, dc_dct_pred,
		992	motion_vertical_field_select, dmvector)
		993	int *macroblock_type;
		994	int *stwtype;
		995	int *stwclass;
		996	int *motion_type;
		997	int *dct_type;
		998	int PMV[2][2][2];
		999	int dc_dct_pred[3];
		1000	int motion_vertical_field_select[2][2];
		1001	int dmvector[2];
		1002	{
		1003	/* locals */
		1004	int quantizer_scale_code;
		1005	int comp;
		1006
		1007	int motion_vector_count;
		1008	int mv_format;
		1009	int dmv;
		1010	int mvscale;
		1011	int coded_block_pattern;
		1012
		1013	/* SCALABILITY: Data Patitioning */
		1014	if (base.scalable_mode==SC_DP)
		1015	{
		1016	if (base.priority_breakpoint<=2)
		1017	ld = &enhan;
		1018	else
		1019	ld = &base;
		1020	}
		1021
		1022	/* ISO/IEC 13818-2 section 6.3.17.1: Macroblock modes */
		1023	macroblock_modes(macroblock_type, stwtype, stwclass,
		1024	motion_type, &motion_vector_count, &mv_format, &dmv, &mvscale,
		1025	dct_type);
		1026
		1027	if (Fault_Flag) return(0); /* trigger: go to next slice */
		1028
		1029	if (*macroblock_type & MACROBLOCK_QUANT)
		1030	{
		1031	quantizer_scale_code = Get_Bits(5);
		1032
		1033	#ifdef TRACE
		1034	if (Trace_Flag)
		1035	{
		1036	cprintf("quantiser_scale_code (");
		1037	Print_Bits(quantizer_scale_code,5,5);
		1038	cprintf("): %d\n",quantizer_scale_code);
		1039	}
		1040	#endif /* TRACE */
		1041
		1042	/* ISO/IEC 13818-2 section 7.4.2.2: Quantizer scale factor */
		1043	if (ld->MPEG2_Flag)
		1044	ld->quantizer_scale =
		1045	ld->q_scale_type ? Non_Linear_quantizer_scale[quantizer_scale_code]
		1046	: (quantizer_scale_code << 1);
		1047	else
		1048	ld->quantizer_scale = quantizer_scale_code;
		1049
		1050	/* SCALABILITY: Data Partitioning */
		1051	if (base.scalable_mode==SC_DP)
		1052	/* make sure base.quantizer_scale is valid */
		1053	base.quantizer_scale = ld->quantizer_scale;
		1054	}
		1055
		1056	/* motion vectors */
		1057
		1058
		1059	/* ISO/IEC 13818-2 section 6.3.17.2: Motion vectors */
		1060
		1061	/* decode forward motion vectors */
		1062	if ((*macroblock_type & MACROBLOCK_MOTION_FORWARD)
		1063	\|\| ((*macroblock_type & MACROBLOCK_INTRA)
		1064	&& concealment_motion_vectors))
		1065	{
		1066	if (ld->MPEG2_Flag)
		1067	motion_vectors(PMV,dmvector,motion_vertical_field_select,
		1068	0,motion_vector_count,mv_format,f_code[0][0]-1,f_code[0][1]-1,
		1069	dmv,mvscale);
		1070	else
		1071	motion_vector(PMV[0][0],dmvector,
		1072	forward_f_code-1,forward_f_code-1,0,0,full_pel_forward_vector);
		1073	}
		1074
		1075	if (Fault_Flag) return(0); /* trigger: go to next slice */
		1076
		1077	/* decode backward motion vectors */
		1078	if (*macroblock_type & MACROBLOCK_MOTION_BACKWARD)
		1079	{
		1080	if (ld->MPEG2_Flag)
		1081	motion_vectors(PMV,dmvector,motion_vertical_field_select,
		1082	1,motion_vector_count,mv_format,f_code[1][0]-1,f_code[1][1]-1,0,
		1083	mvscale);
		1084	else
		1085	motion_vector(PMV[0][1],dmvector,
		1086	backward_f_code-1,backward_f_code-1,0,0,full_pel_backward_vector);
		1087	}
		1088
		1089	if (Fault_Flag) return(0); /* trigger: go to next slice */
		1090
		1091	if ((*macroblock_type & MACROBLOCK_INTRA) && concealment_motion_vectors)
		1092	Flush_Buffer(1); /* remove marker_bit */
		1093
		1094	if (base.scalable_mode==SC_DP && base.priority_breakpoint==3)
		1095	ld = &enhan;
		1096
		1097	/* macroblock_pattern */
		1098	/* ISO/IEC 13818-2 section 6.3.17.4: Coded block pattern */
		1099	if (*macroblock_type & MACROBLOCK_PATTERN)
		1100	{
		1101	coded_block_pattern = Get_coded_block_pattern();
		1102
		1103	if (chroma_format==CHROMA422)
		1104	{
		1105	/* coded_block_pattern_1 */
		1106	coded_block_pattern = (coded_block_pattern<<2) \| Get_Bits(2);
		1107
		1108	#ifdef TRACE
		1109	if (Trace_Flag)
		1110	{
		1111	cprintf("coded_block_pattern_1: ");
		1112	Print_Bits(coded_block_pattern,2,2);
		1113	cprintf(" (%d)\n",coded_block_pattern&3);
		1114	}
		1115	#endif /* TRACE */
		1116	}
		1117	else if (chroma_format==CHROMA444)
		1118	{
		1119	/* coded_block_pattern_2 */
		1120	coded_block_pattern = (coded_block_pattern<<6) \| Get_Bits(6);
		1121
		1122	#ifdef TRACE
		1123	if (Trace_Flag)
		1124	{
		1125	cprintf("coded_block_pattern_2: ");
		1126	Print_Bits(coded_block_pattern,6,6);
		1127	cprintf(" (%d)\n",coded_block_pattern&63);
		1128	}
		1129	#endif /* TRACE */
		1130	}
		1131	}
		1132	else
		1133	coded_block_pattern = (*macroblock_type & MACROBLOCK_INTRA) ?
		1134	(1<<block_count)-1 : 0;
		1135
		1136	if (Fault_Flag) return(0); /* trigger: go to next slice */
		1137
		1138	/* decode blocks */
		1139	for (comp=0; comp<block_count; comp++)
		1140	{
		1141	/* SCALABILITY: Data Partitioning */
		1142	if (base.scalable_mode==SC_DP)
		1143	ld = &base;
		1144
		1145	Clear_Block(comp);
		1146
		1147	if (coded_block_pattern & (1<<(block_count-1-comp)))
		1148	{
		1149	if (*macroblock_type & MACROBLOCK_INTRA)
		1150	{
		1151	if (ld->MPEG2_Flag)
		1152	Decode_MPEG2_Intra_Block(comp,dc_dct_pred);
		1153	else
		1154	Decode_MPEG1_Intra_Block(comp,dc_dct_pred);
		1155	}
		1156	else
		1157	{
		1158	if (ld->MPEG2_Flag)
		1159	Decode_MPEG2_Non_Intra_Block(comp);
		1160	else
		1161	Decode_MPEG1_Non_Intra_Block(comp);
		1162	}
		1163
		1164	if (Fault_Flag) return(0); /* trigger: go to next slice */
		1165	}
		1166	}
		1167
		1168	if(picture_coding_type==D_TYPE)
		1169	{
		1170	/* remove end_of_macroblock (always 1, prevents startcode emulation) */
		1171	/* ISO/IEC 11172-2 section 2.4.2.7 and 2.4.3.6 */
		1172	marker_bit("D picture end_of_macroblock bit");
		1173	}
		1174
		1175	/* reset intra_dc predictors */
		1176	/* ISO/IEC 13818-2 section 7.2.1: DC coefficients in intra blocks */
		1177	if (!(*macroblock_type & MACROBLOCK_INTRA))
		1178	dc_dct_pred[0]=dc_dct_pred[1]=dc_dct_pred[2]=0;
		1179
		1180	/* reset motion vector predictors */
		1181	if ((*macroblock_type & MACROBLOCK_INTRA) && !concealment_motion_vectors)
		1182	{
		1183	/* intra mb without concealment motion vectors */
		1184	/* ISO/IEC 13818-2 section 7.6.3.4: Resetting motion vector predictors */
		1185	PMV[0][0][0]=PMV[0][0][1]=PMV[1][0][0]=PMV[1][0][1]=0;
		1186	PMV[0][1][0]=PMV[0][1][1]=PMV[1][1][0]=PMV[1][1][1]=0;
		1187	}
		1188
		1189	/* special "No_MC" macroblock_type case */
		1190	/* ISO/IEC 13818-2 section 7.6.3.5: Prediction in P pictures */
		1191	if ((picture_coding_type==P_TYPE)
		1192	&& !(*macroblock_type & (MACROBLOCK_MOTION_FORWARD\|MACROBLOCK_INTRA)))
		1193	{
		1194	/* non-intra mb without forward mv in a P picture */
		1195	/* ISO/IEC 13818-2 section 7.6.3.4: Resetting motion vector predictors */
		1196	PMV[0][0][0]=PMV[0][0][1]=PMV[1][0][0]=PMV[1][0][1]=0;
		1197
		1198	/* derive motion_type */
		1199	/* ISO/IEC 13818-2 section 6.3.17.1: Macroblock modes, frame_motion_type */
		1200	if (picture_structure==FRAME_PICTURE)
		1201	*motion_type = MC_FRAME;
		1202	else
		1203	{
		1204	*motion_type = MC_FIELD;
		1205	/* predict from field of same parity */
		1206	motion_vertical_field_select[0][0] = (picture_structure==BOTTOM_FIELD);
		1207	}
		1208	}
		1209
		1210	if (*stwclass==4)
		1211	{
		1212	/* purely spatially predicted macroblock */
		1213	/* ISO/IEC 13818-2 section 7.7.5.1: Resetting motion vector predictions */
		1214	PMV[0][0][0]=PMV[0][0][1]=PMV[1][0][0]=PMV[1][0][1]=0;
		1215	PMV[0][1][0]=PMV[0][1][1]=PMV[1][1][0]=PMV[1][1][1]=0;
		1216	}
		1217
		1218	/* successfully decoded macroblock */
		1219	return(1);
		1220
		1221	} /* decode_macroblock */
		1222
		1223

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