FFmpeg
mpeg12.c
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1 /*
2  * MPEG-1/2 decoder
3  * Copyright (c) 2000, 2001 Fabrice Bellard
4  * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 /**
24  * @file
25  * MPEG-1/2 decoder
26  */
27 
28 #define UNCHECKED_BITSTREAM_READER 1
29 
30 #include "libavutil/attributes.h"
31 #include "libavutil/avassert.h"
32 #include "libavutil/thread.h"
33 
34 #include "avcodec.h"
35 #include "mpegvideo.h"
36 #include "mpeg12.h"
37 #include "mpeg12codecs.h"
38 #include "mpeg12data.h"
39 #include "mpeg12dec.h"
40 #include "rl.h"
41 #include "startcode.h"
42 
43 static const uint8_t table_mb_ptype[7][2] = {
44  { 3, 5 }, // 0x01 MB_INTRA
45  { 1, 2 }, // 0x02 MB_PAT
46  { 1, 3 }, // 0x08 MB_FOR
47  { 1, 1 }, // 0x0A MB_FOR|MB_PAT
48  { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
49  { 1, 5 }, // 0x12 MB_QUANT|MB_PAT
50  { 2, 5 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
51 };
52 
53 static const uint8_t table_mb_btype[11][2] = {
54  { 3, 5 }, // 0x01 MB_INTRA
55  { 2, 3 }, // 0x04 MB_BACK
56  { 3, 3 }, // 0x06 MB_BACK|MB_PAT
57  { 2, 4 }, // 0x08 MB_FOR
58  { 3, 4 }, // 0x0A MB_FOR|MB_PAT
59  { 2, 2 }, // 0x0C MB_FOR|MB_BACK
60  { 3, 2 }, // 0x0E MB_FOR|MB_BACK|MB_PAT
61  { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA
62  { 2, 6 }, // 0x16 MB_QUANT|MB_BACK|MB_PAT
63  { 3, 6 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT
64  { 2, 5 }, // 0x1E MB_QUANT|MB_FOR|MB_BACK|MB_PAT
65 };
66 
67 av_cold void ff_init_2d_vlc_rl(const uint16_t table_vlc[][2], RL_VLC_ELEM rl_vlc[],
68  const int8_t table_run[], const uint8_t table_level[],
69  int n, unsigned static_size, int flags)
70 {
71  int i;
72  VLCElem table[680] = { 0 };
73  VLC vlc = { .table = table, .table_allocated = static_size };
74  av_assert0(static_size <= FF_ARRAY_ELEMS(table));
75  vlc_init(&vlc, TEX_VLC_BITS, n + 2, &table_vlc[0][1], 4, 2, &table_vlc[0][0], 4, 2, VLC_INIT_USE_STATIC | flags);
76 
77  for (i = 0; i < vlc.table_size; i++) {
78  int code = vlc.table[i].sym;
79  int len = vlc.table[i].len;
80  int level, run;
81 
82  if (len == 0) { // illegal code
83  run = 65;
84  level = MAX_LEVEL;
85  } else if (len<0) { //more bits needed
86  run = 0;
87  level = code;
88  } else {
89  if (code == n) { //esc
90  run = 65;
91  level = 0;
92  } else if (code == n + 1) { //eob
93  run = 0;
94  level = 127;
95  } else {
96  run = table_run [code] + 1;
97  level = table_level[code];
98  }
99  }
100  rl_vlc[i].len = len;
101  rl_vlc[i].level = level;
102  rl_vlc[i].run = run;
103  }
104 }
105 
107 {
108  s->last_dc[0] = 1 << (7 + s->intra_dc_precision);
109  s->last_dc[1] = s->last_dc[0];
110  s->last_dc[2] = s->last_dc[0];
111  memset(s->last_mv, 0, sizeof(s->last_mv));
112 }
113 
114 
115 /******************************************/
116 /* decoding */
117 
119 
122 
127 
130 
131 static av_cold void mpeg12_init_vlcs(void)
132 {
135  ff_mpeg12_vlc_dc_lum_code, 2, 2, 0);
140  &ff_mpeg12_mbMotionVectorTable[0][1], 2, 1,
141  &ff_mpeg12_mbMotionVectorTable[0][0], 2, 1, 0);
143  &ff_mpeg12_mbAddrIncrTable[0][1], 2, 1,
144  &ff_mpeg12_mbAddrIncrTable[0][0], 2, 1, 0);
146  &ff_mpeg12_mbPatTable[0][1], 2, 1,
147  &ff_mpeg12_mbPatTable[0][0], 2, 1, 0);
148 
150  &table_mb_ptype[0][1], 2, 1,
151  &table_mb_ptype[0][0], 2, 1, 0);
153  &table_mb_btype[0][1], 2, 1,
154  &table_mb_btype[0][0], 2, 1, 0);
155 
162 }
163 
165 {
166  static AVOnce init_static_once = AV_ONCE_INIT;
167  ff_thread_once(&init_static_once, mpeg12_init_vlcs);
168 }
169 
170 #define MAX_INDEX (64 - 1)
171 
173  const uint16_t *quant_matrix,
174  const uint8_t *scantable, int last_dc[3],
175  int16_t *block, int index, int qscale)
176 {
177  int dc, diff, i = 0, component;
178 
179  /* DC coefficient */
180  component = index <= 3 ? 0 : index - 4 + 1;
181 
182  diff = decode_dc(gb, component);
183 
184  dc = last_dc[component];
185  dc += diff;
186  last_dc[component] = dc;
187 
188  block[0] = dc * quant_matrix[0];
189 
190  {
191  OPEN_READER(re, gb);
192  UPDATE_CACHE(re, gb);
193  if (((int32_t)GET_CACHE(re, gb)) <= (int32_t)0xBFFFFFFF)
194  goto end;
195 
196  /* now quantify & encode AC coefficients */
197  while (1) {
198  int level, run, j;
199 
201  TEX_VLC_BITS, 2, 0);
202 
203  if (level != 0) {
204  i += run;
205  if (i > MAX_INDEX)
206  break;
207 
208  j = scantable[i];
209  level = (level * qscale * quant_matrix[j]) >> 4;
210  level = (level - 1) | 1;
211  level = (level ^ SHOW_SBITS(re, gb, 1)) -
212  SHOW_SBITS(re, gb, 1);
213  SKIP_BITS(re, gb, 1);
214  } else {
215  /* escape */
216  run = SHOW_UBITS(re, gb, 6) + 1;
217  LAST_SKIP_BITS(re, gb, 6);
218  UPDATE_CACHE(re, gb);
219  level = SHOW_SBITS(re, gb, 8);
220  SKIP_BITS(re, gb, 8);
221 
222  if (level == -128) {
223  level = SHOW_UBITS(re, gb, 8) - 256;
224  SKIP_BITS(re, gb, 8);
225  } else if (level == 0) {
226  level = SHOW_UBITS(re, gb, 8);
227  SKIP_BITS(re, gb, 8);
228  }
229 
230  i += run;
231  if (i > MAX_INDEX)
232  break;
233 
234  j = scantable[i];
235  if (level < 0) {
236  level = -level;
237  level = (level * qscale * quant_matrix[j]) >> 4;
238  level = (level - 1) | 1;
239  level = -level;
240  } else {
241  level = (level * qscale * quant_matrix[j]) >> 4;
242  level = (level - 1) | 1;
243  }
244  }
245 
246  block[j] = level;
247  if (((int32_t)GET_CACHE(re, gb)) <= (int32_t)0xBFFFFFFF)
248  break;
249 
250  UPDATE_CACHE(re, gb);
251  }
252 end:
253  LAST_SKIP_BITS(re, gb, 2);
254  CLOSE_READER(re, gb);
255  }
256 
257  if (i > MAX_INDEX)
259 
260  return i;
261 }
ff_mb_pat_vlc
VLCElem ff_mb_pat_vlc[512]
Definition: mpeg12.c:126
level
uint8_t level
Definition: svq3.c:205
thread.h
MPEG12_RL_NB_ELEMS
#define MPEG12_RL_NB_ELEMS
Definition: mpeg12vlc.h:52
table_mb_btype
static const uint8_t table_mb_btype[11][2]
Definition: mpeg12.c:53
table
static const uint16_t table[]
Definition: prosumer.c:203
VLCElem::len
VLCBaseType len
Definition: vlc.h:33
mpegvideo.h
UPDATE_CACHE
#define UPDATE_CACHE(name, gb)
Definition: get_bits.h:225
MAX_INDEX
#define MAX_INDEX
Definition: mpeg12.c:170
ff_mpeg12_vlc_dc_chroma_bits
const unsigned char ff_mpeg12_vlc_dc_chroma_bits[12]
Definition: mpeg12data.c:63
ff_mpeg12_vlc_dc_lum_bits
const unsigned char ff_mpeg12_vlc_dc_lum_bits[12]
Definition: mpeg12data.c:56
GET_CACHE
#define GET_CACHE(name, gb)
Definition: get_bits.h:263
ff_mpeg2_rl_vlc
RL_VLC_ELEM ff_mpeg2_rl_vlc[674]
Definition: mpeg12.c:129
ff_mpeg12_mbAddrIncrTable
const uint8_t ff_mpeg12_mbAddrIncrTable[36][2]
Definition: mpeg12data.c:167
ff_mbincr_vlc
VLCElem ff_mbincr_vlc[538]
Definition: mpeg12.c:123
GetBitContext
Definition: get_bits.h:108
ff_mpeg12_mbMotionVectorTable
const uint8_t ff_mpeg12_mbMotionVectorTable[17][2]
Definition: mpeg12data.c:273
VLCElem::sym
VLCBaseType sym
Definition: vlc.h:33
avassert.h
mpeg12.h
ff_thread_once
static int ff_thread_once(char *control, void(*routine)(void))
Definition: thread.h:205
FF_ARRAY_ELEMS
#define FF_ARRAY_ELEMS(a)
Definition: sinewin_tablegen.c:29
av_cold
#define av_cold
Definition: attributes.h:90
mpeg12_init_vlcs
static av_cold void mpeg12_init_vlcs(void)
Definition: mpeg12.c:131
CLOSE_READER
#define CLOSE_READER(name, gb)
Definition: get_bits.h:188
s
#define s(width, name)
Definition: cbs_vp9.c:198
ff_mv_vlc
VLCElem ff_mv_vlc[266]
Definition: mpeg12.c:118
ff_dc_lum_vlc
VLCElem ff_dc_lum_vlc[512]
Definition: mpeg12.c:120
SHOW_SBITS
#define SHOW_SBITS(name, gb, num)
Definition: get_bits.h:260
av_assert0
#define av_assert0(cond)
assert() equivalent, that is always enabled.
Definition: avassert.h:40
vlc_init
#define vlc_init(vlc, nb_bits, nb_codes, bits, bits_wrap, bits_size, codes, codes_wrap, codes_size, flags)
Definition: vlc.h:62
SKIP_BITS
#define SKIP_BITS(name, gb, num)
Definition: get_bits.h:241
rl_vlc
static const VLCElem * rl_vlc[2]
Definition: mobiclip.c:278
MB_PTYPE_VLC_BITS
#define MB_PTYPE_VLC_BITS
Definition: mpeg12vlc.h:39
AV_ONCE_INIT
#define AV_ONCE_INIT
Definition: thread.h:203
run
uint8_t run
Definition: svq3.c:204
LAST_SKIP_BITS
#define LAST_SKIP_BITS(name, gb, num)
Definition: get_bits.h:247
ff_mpeg1_rl_vlc
RL_VLC_ELEM ff_mpeg1_rl_vlc[680]
Definition: mpeg12.c:128
MB_BTYPE_VLC_BITS
#define MB_BTYPE_VLC_BITS
Definition: mpeg12vlc.h:40
mpeg12codecs.h
AVOnce
#define AVOnce
Definition: thread.h:202
index
int index
Definition: gxfenc.c:90
ff_mpeg12_run
const int8_t ff_mpeg12_run[MPEG12_RL_NB_ELEMS]
Definition: mpeg12data.c:150
ff_init_2d_vlc_rl
av_cold void ff_init_2d_vlc_rl(const uint16_t table_vlc[][2], RL_VLC_ELEM rl_vlc[], const int8_t table_run[], const uint8_t table_level[], int n, unsigned static_size, int flags)
Definition: mpeg12.c:67
MAX_LEVEL
#define MAX_LEVEL
Definition: rl.h:36
startcode.h
dc
Tag MUST be and< 10hcoeff half pel interpolation filter coefficients, hcoeff[0] are the 2 middle coefficients[1] are the next outer ones and so on, resulting in a filter like:...eff[2], hcoeff[1], hcoeff[0], hcoeff[0], hcoeff[1], hcoeff[2] ... the sign of the coefficients is not explicitly stored but alternates after each coeff and coeff[0] is positive, so ...,+,-,+,-,+,+,-,+,-,+,... hcoeff[0] is not explicitly stored but found by subtracting the sum of all stored coefficients with signs from 32 hcoeff[0]=32 - hcoeff[1] - hcoeff[2] - ... a good choice for hcoeff and htaps is htaps=6 hcoeff={40,-10, 2} an alternative which requires more computations at both encoder and decoder side and may or may not be better is htaps=8 hcoeff={42,-14, 6,-2}ref_frames minimum of the number of available reference frames and max_ref_frames for example the first frame after a key frame always has ref_frames=1spatial_decomposition_type wavelet type 0 is a 9/7 symmetric compact integer wavelet 1 is a 5/3 symmetric compact integer wavelet others are reserved stored as delta from last, last is reset to 0 if always_reset||keyframeqlog quality(logarithmic quantizer scale) stored as delta from last, last is reset to 0 if always_reset||keyframemv_scale stored as delta from last, last is reset to 0 if always_reset||keyframe FIXME check that everything works fine if this changes between framesqbias dequantization bias stored as delta from last, last is reset to 0 if always_reset||keyframeblock_max_depth maximum depth of the block tree stored as delta from last, last is reset to 0 if always_reset||keyframequant_table quantization tableHighlevel bitstream structure:==============================--------------------------------------------|Header|--------------------------------------------|------------------------------------|||Block0||||split?||||yes no||||......... intra?||||:Block01 :yes no||||:Block02 :....... ..........||||:Block03 ::y DC ::ref index:||||:Block04 ::cb DC ::motion x :||||......... :cr DC ::motion y :||||....... ..........|||------------------------------------||------------------------------------|||Block1|||...|--------------------------------------------|------------ ------------ ------------|||Y subbands||Cb subbands||Cr subbands||||--- ---||--- ---||--- ---|||||LL0||HL0||||LL0||HL0||||LL0||HL0|||||--- ---||--- ---||--- ---||||--- ---||--- ---||--- ---|||||LH0||HH0||||LH0||HH0||||LH0||HH0|||||--- ---||--- ---||--- ---||||--- ---||--- ---||--- ---|||||HL1||LH1||||HL1||LH1||||HL1||LH1|||||--- ---||--- ---||--- ---||||--- ---||--- ---||--- ---|||||HH1||HL2||||HH1||HL2||||HH1||HL2|||||...||...||...|||------------ ------------ ------------|--------------------------------------------Decoding process:=================------------|||Subbands|------------||||------------|Intra DC||||LL0 subband prediction ------------|\ Dequantization ------------------- \||Reference frames|\ IDWT|------- -------|Motion \|||Frame 0||Frame 1||Compensation . OBMC v -------|------- -------|--------------. \------> Frame n output Frame Frame<----------------------------------/|...|------------------- Range Coder:============Binary Range Coder:------------------- The implemented range coder is an adapted version based upon "Range encoding: an algorithm for removing redundancy from a digitised message." by G. N. N. Martin. The symbols encoded by the Snow range coder are bits(0|1). The associated probabilities are not fix but change depending on the symbol mix seen so far. bit seen|new state ---------+----------------------------------------------- 0|256 - state_transition_table[256 - old_state];1|state_transition_table[old_state];state_transition_table={ 0, 0, 0, 0, 0, 0, 0, 0, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 190, 191, 192, 194, 194, 195, 196, 197, 198, 199, 200, 201, 202, 202, 204, 205, 206, 207, 208, 209, 209, 210, 211, 212, 213, 215, 215, 216, 217, 218, 219, 220, 220, 222, 223, 224, 225, 226, 227, 227, 229, 229, 230, 231, 232, 234, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 248, 0, 0, 0, 0, 0, 0, 0};FIXME Range Coding of integers:------------------------- FIXME Neighboring Blocks:===================left and top are set to the respective blocks unless they are outside of the image in which case they are set to the Null block top-left is set to the top left block unless it is outside of the image in which case it is set to the left block if this block has no larger parent block or it is at the left side of its parent block and the top right block is not outside of the image then the top right block is used for top-right else the top-left block is used Null block y, cb, cr are 128 level, ref, mx and my are 0 Motion Vector Prediction:=========================1. the motion vectors of all the neighboring blocks are scaled to compensate for the difference of reference frames scaled_mv=(mv *(256 *(current_reference+1)/(mv.reference+1))+128)> the median of the scaled top and top right vectors is used as motion vector prediction the used motion vector is the sum of the predictor and(mvx_diff, mvy_diff) *mv_scale Intra DC Prediction block[y][x] dc[1]
Definition: snow.txt:400
RL_VLC_ELEM
Definition: vlc.h:56
ff_mpeg12_level
const int8_t ff_mpeg12_level[MPEG12_RL_NB_ELEMS]
Definition: mpeg12data.c:133
ff_mpeg1_clean_buffers
void ff_mpeg1_clean_buffers(MpegEncContext *s)
Definition: mpeg12.c:106
VLCElem
Definition: vlc.h:32
diff
static av_always_inline int diff(const struct color_info *a, const struct color_info *b, const int trans_thresh)
Definition: vf_paletteuse.c:165
OPEN_READER
#define OPEN_READER(name, gb)
Definition: get_bits.h:177
attributes.h
ff_mpeg1_decode_block_intra
int ff_mpeg1_decode_block_intra(GetBitContext *gb, const uint16_t *quant_matrix, const uint8_t *scantable, int last_dc[3], int16_t *block, int index, int qscale)
Definition: mpeg12.c:172
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:256
code
and forward the test the status of outputs and forward it to the corresponding return FFERROR_NOT_READY If the filters stores internally one or a few frame for some it can consider them to be part of the FIFO and delay acknowledging a status change accordingly Example code
Definition: filter_design.txt:178
ff_mpeg12_init_vlcs
av_cold void ff_mpeg12_init_vlcs(void)
Definition: mpeg12.c:164
MB_PAT_VLC_BITS
#define MB_PAT_VLC_BITS
Definition: mpeg12vlc.h:38
len
int len
Definition: vorbis_enc_data.h:426
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static const uint8_t table_mb_ptype[7][2]
Definition: mpeg12.c:43
ff_mpeg12_mbPatTable
const uint8_t ff_mpeg12_mbPatTable[64][2]
Definition: mpeg12data.c:206
avcodec.h
GET_RL_VLC
#define GET_RL_VLC(level, run, name, gb, table, bits, max_depth, need_update)
Definition: get_bits.h:606
ff_mpeg12_vlc_dc_chroma_code
const uint16_t ff_mpeg12_vlc_dc_chroma_code[12]
Definition: mpeg12data.c:60
TEX_VLC_BITS
#define TEX_VLC_BITS
Definition: dvdec.c:147
ff_mpeg1_vlc_table
const uint16_t ff_mpeg1_vlc_table[MPEG12_RL_NB_ELEMS+2][2]
Definition: mpeg12data.c:67
mpeg12data.h
SHOW_UBITS
#define SHOW_UBITS(name, gb, num)
Definition: get_bits.h:259
mpeg12dec.h
VLC_INIT_STATIC_TABLE
#define VLC_INIT_STATIC_TABLE(vlc_table, nb_bits, nb_codes, bits, bits_wrap, bits_size, codes, codes_wrap, codes_size, flags)
Definition: vlc.h:270
VLC
Definition: vlc.h:36
ff_mpeg2_vlc_table
const uint16_t ff_mpeg2_vlc_table[MPEG12_RL_NB_ELEMS+2][2]
Definition: mpeg12data.c:100
VLC::table
VLCElem * table
Definition: vlc.h:38
ff_mb_ptype_vlc
VLCElem ff_mb_ptype_vlc[64]
Definition: mpeg12.c:124
VLC::table_size
int table_size
Definition: vlc.h:39
ff_dc_chroma_vlc
VLCElem ff_dc_chroma_vlc[514]
Definition: mpeg12.c:121
rl.h
int32_t
int32_t
Definition: audioconvert.c:56
flags
#define flags(name, subs,...)
Definition: cbs_av1.c:474
ff_mpeg12_vlc_dc_lum_code
const uint16_t ff_mpeg12_vlc_dc_lum_code[12]
Definition: mpeg12data.c:53
block
The exact code depends on how similar the blocks are and how related they are to the block
Definition: filter_design.txt:207
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:61
VLC_INIT_USE_STATIC
#define VLC_INIT_USE_STATIC
Definition: vlc.h:182
ff_mb_btype_vlc
VLCElem ff_mb_btype_vlc[64]
Definition: mpeg12.c:125
DC_VLC_BITS
#define DC_VLC_BITS
Definition: intrax8.c:41
MV_VLC_BITS
#define MV_VLC_BITS
Definition: mpeg12vlc.h:34
MpegEncContext
MpegEncContext.
Definition: mpegvideo.h:73
decode_dc
static int decode_dc(GetBitContext *gb, int component)
Definition: mpeg12dec.h:28
MBINCR_VLC_BITS
#define MBINCR_VLC_BITS
Definition: mpeg12vlc.h:37