FFmpeg
h261enc.c
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1 /*
2  * H.261 encoder
3  * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
4  * Copyright (c) 2004 Maarten Daniels
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  * H.261 encoder.
26  */
27 
28 #include "libavutil/attributes.h"
29 #include "libavutil/avassert.h"
30 #include "avcodec.h"
31 #include "mpegutils.h"
32 #include "mpegvideo.h"
33 #include "h263.h"
34 #include "h261.h"
35 #include "mpegvideodata.h"
36 
37 static uint8_t uni_h261_rl_len [64*64*2*2];
38 #define UNI_ENC_INDEX(last,run,level) ((last)*128*64 + (run)*128 + (level))
39 
41 {
42  // QCIF
43  if (width == 176 && height == 144)
44  return 0;
45  // CIF
46  else if (width == 352 && height == 288)
47  return 1;
48  // ERROR
49  else
50  return AVERROR(EINVAL);
51 }
52 
54 {
55  H261Context *h = (H261Context *)s;
56  int format, temp_ref;
57 
59 
60  /* Update the pointer to last GOB */
61  s->ptr_lastgob = put_bits_ptr(&s->pb);
62 
63  put_bits(&s->pb, 20, 0x10); /* PSC */
64 
65  temp_ref = s->picture_number * 30000LL * s->avctx->time_base.num /
66  (1001LL * s->avctx->time_base.den); // FIXME maybe this should use a timestamp
67  put_sbits(&s->pb, 5, temp_ref); /* TemporalReference */
68 
69  put_bits(&s->pb, 1, 0); /* split screen off */
70  put_bits(&s->pb, 1, 0); /* camera off */
71  put_bits(&s->pb, 1, s->pict_type == AV_PICTURE_TYPE_I); /* freeze picture release on/off */
72 
73  format = ff_h261_get_picture_format(s->width, s->height);
74 
75  put_bits(&s->pb, 1, format); /* 0 == QCIF, 1 == CIF */
76 
77  put_bits(&s->pb, 1, 1); /* still image mode */
78  put_bits(&s->pb, 1, 1); /* reserved */
79 
80  put_bits(&s->pb, 1, 0); /* no PEI */
81  if (format == 0)
82  h->gob_number = -1;
83  else
84  h->gob_number = 0;
85  s->mb_skip_run = 0;
86 }
87 
88 /**
89  * Encode a group of blocks header.
90  */
91 static void h261_encode_gob_header(MpegEncContext *s, int mb_line)
92 {
93  H261Context *h = (H261Context *)s;
94  if (ff_h261_get_picture_format(s->width, s->height) == 0) {
95  h->gob_number += 2; // QCIF
96  } else {
97  h->gob_number++; // CIF
98  }
99  put_bits(&s->pb, 16, 1); /* GBSC */
100  put_bits(&s->pb, 4, h->gob_number); /* GN */
101  put_bits(&s->pb, 5, s->qscale); /* GQUANT */
102  put_bits(&s->pb, 1, 0); /* no GEI */
103  s->mb_skip_run = 0;
104  s->last_mv[0][0][0] = 0;
105  s->last_mv[0][0][1] = 0;
106 }
107 
109 {
110  int index = s->mb_x + s->mb_y * s->mb_width;
111 
112  if (index % 11 == 0) {
113  if (index % 33 == 0)
115  s->last_mv[0][0][0] = 0;
116  s->last_mv[0][0][1] = 0;
117  }
118 
119  /* for CIF the GOB's are fragmented in the middle of a scanline
120  * that's why we need to adjust the x and y index of the macroblocks */
121  if (ff_h261_get_picture_format(s->width, s->height) == 1) { // CIF
122  s->mb_x = index % 11;
123  index /= 11;
124  s->mb_y = index % 3;
125  index /= 3;
126  s->mb_x += 11 * (index % 2);
127  index /= 2;
128  s->mb_y += 3 * index;
129 
132  }
133 }
134 
136 {
137  MpegEncContext *const s = &h->s;
138  int sign, code;
139  if (val == 0) {
140  code = 0;
141  put_bits(&s->pb, ff_h261_mv_tab[code][1], ff_h261_mv_tab[code][0]);
142  } else {
143  if (val > 15)
144  val -= 32;
145  if (val < -16)
146  val += 32;
147  sign = val < 0;
148  code = sign ? -val : val;
149  put_bits(&s->pb, ff_h261_mv_tab[code][1], ff_h261_mv_tab[code][0]);
150  put_bits(&s->pb, 1, sign);
151  }
152 }
153 
154 static inline int get_cbp(MpegEncContext *s, int16_t block[6][64])
155 {
156  int i, cbp;
157  cbp = 0;
158  for (i = 0; i < 6; i++)
159  if (s->block_last_index[i] >= 0)
160  cbp |= 1 << (5 - i);
161  return cbp;
162 }
163 
164 /**
165  * Encode an 8x8 block.
166  * @param block the 8x8 block
167  * @param n block index (0-3 are luma, 4-5 are chroma)
168  */
169 static void h261_encode_block(H261Context *h, int16_t *block, int n)
170 {
171  MpegEncContext *const s = &h->s;
172  int level, run, i, j, last_index, last_non_zero, sign, slevel, code;
173  RLTable *rl;
174 
175  rl = &ff_h261_rl_tcoeff;
176  if (s->mb_intra) {
177  /* DC coef */
178  level = block[0];
179  /* 255 cannot be represented, so we clamp */
180  if (level > 254) {
181  level = 254;
182  block[0] = 254;
183  }
184  /* 0 cannot be represented also */
185  else if (level < 1) {
186  level = 1;
187  block[0] = 1;
188  }
189  if (level == 128)
190  put_bits(&s->pb, 8, 0xff);
191  else
192  put_bits(&s->pb, 8, level);
193  i = 1;
194  } else if ((block[0] == 1 || block[0] == -1) &&
195  (s->block_last_index[n] > -1)) {
196  // special case
197  put_bits(&s->pb, 2, block[0] > 0 ? 2 : 3);
198  i = 1;
199  } else {
200  i = 0;
201  }
202 
203  /* AC coefs */
204  last_index = s->block_last_index[n];
205  last_non_zero = i - 1;
206  for (; i <= last_index; i++) {
207  j = s->intra_scantable.permutated[i];
208  level = block[j];
209  if (level) {
210  run = i - last_non_zero - 1;
211  sign = 0;
212  slevel = level;
213  if (level < 0) {
214  sign = 1;
215  level = -level;
216  }
217  code = get_rl_index(rl, 0 /*no last in H.261, EOB is used*/,
218  run, level);
219  if (run == 0 && level < 16)
220  code += 1;
221  put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);
222  if (code == rl->n) {
223  put_bits(&s->pb, 6, run);
224  av_assert1(slevel != 0);
225  av_assert1(level <= 127);
226  put_sbits(&s->pb, 8, slevel);
227  } else {
228  put_bits(&s->pb, 1, sign);
229  }
230  last_non_zero = i;
231  }
232  }
233  if (last_index > -1)
234  put_bits(&s->pb, rl->table_vlc[0][1], rl->table_vlc[0][0]); // EOB
235 }
236 
237 void ff_h261_encode_mb(MpegEncContext *s, int16_t block[6][64],
238  int motion_x, int motion_y)
239 {
240  H261Context *h = (H261Context *)s;
241  int mvd, mv_diff_x, mv_diff_y, i, cbp;
242  cbp = 63; // avoid warning
243  mvd = 0;
244 
245  h->mtype = 0;
246 
247  if (!s->mb_intra) {
248  /* compute cbp */
249  cbp = get_cbp(s, block);
250 
251  /* mvd indicates if this block is motion compensated */
252  mvd = motion_x | motion_y;
253 
254  if ((cbp | mvd) == 0) {
255  /* skip macroblock */
256  s->skip_count++;
257  s->mb_skip_run++;
258  s->last_mv[0][0][0] = 0;
259  s->last_mv[0][0][1] = 0;
260  s->qscale -= s->dquant;
261  return;
262  }
263  }
264 
265  /* MB is not skipped, encode MBA */
266  put_bits(&s->pb,
269  s->mb_skip_run = 0;
270 
271  /* calculate MTYPE */
272  if (!s->mb_intra) {
273  h->mtype++;
274 
275  if (mvd || s->loop_filter)
276  h->mtype += 3;
277  if (s->loop_filter)
278  h->mtype += 3;
279  if (cbp)
280  h->mtype++;
281  av_assert1(h->mtype > 1);
282  }
283 
284  if (s->dquant && cbp) {
285  h->mtype++;
286  } else
287  s->qscale -= s->dquant;
288 
289  put_bits(&s->pb,
292 
293  h->mtype = ff_h261_mtype_map[h->mtype];
294 
295  if (IS_QUANT(h->mtype)) {
296  ff_set_qscale(s, s->qscale + s->dquant);
297  put_bits(&s->pb, 5, s->qscale);
298  }
299 
300  if (IS_16X16(h->mtype)) {
301  mv_diff_x = (motion_x >> 1) - s->last_mv[0][0][0];
302  mv_diff_y = (motion_y >> 1) - s->last_mv[0][0][1];
303  s->last_mv[0][0][0] = (motion_x >> 1);
304  s->last_mv[0][0][1] = (motion_y >> 1);
305  h261_encode_motion(h, mv_diff_x);
306  h261_encode_motion(h, mv_diff_y);
307  }
308 
309  if (HAS_CBP(h->mtype)) {
310  av_assert1(cbp > 0);
311  put_bits(&s->pb,
312  ff_h261_cbp_tab[cbp - 1][1],
313  ff_h261_cbp_tab[cbp - 1][0]);
314  }
315  for (i = 0; i < 6; i++)
316  /* encode each block */
317  h261_encode_block(h, block[i], i);
318 
319  if (!IS_16X16(h->mtype)) {
320  s->last_mv[0][0][0] = 0;
321  s->last_mv[0][0][1] = 0;
322  }
323 }
324 
325 static av_cold void init_uni_h261_rl_tab(RLTable *rl, uint32_t *bits_tab,
326  uint8_t *len_tab)
327 {
328  int slevel, run, last;
329 
330  av_assert0(MAX_LEVEL >= 64);
331  av_assert0(MAX_RUN >= 63);
332 
333  for(slevel=-64; slevel<64; slevel++){
334  if(slevel==0) continue;
335  for(run=0; run<64; run++){
336  for(last=0; last<=1; last++){
337  const int index= UNI_ENC_INDEX(last, run, slevel+64);
338  int level= slevel < 0 ? -slevel : slevel;
339  int len, code;
340 
341  len_tab[index]= 100;
342 
343  /* ESC0 */
344  code= get_rl_index(rl, 0, run, level);
345  len= rl->table_vlc[code][1] + 1;
346  if(last)
347  len += 2;
348 
349  if(code!=rl->n && len < len_tab[index]){
350  len_tab [index]= len;
351  }
352  /* ESC */
353  len = rl->table_vlc[rl->n][1];
354  if(last)
355  len += 2;
356 
357  if(len < len_tab[index]){
358  len_tab [index]= len;
359  }
360  }
361  }
362  }
363 }
364 
366 {
368 
369  s->min_qcoeff = -127;
370  s->max_qcoeff = 127;
371  s->y_dc_scale_table =
373  s->ac_esc_length = 6+6+8;
374 
376 
379 }
380 
381 static const AVClass h261_class = {
382  .class_name = "h261 encoder",
383  .item_name = av_default_item_name,
384  .option = ff_mpv_generic_options,
385  .version = LIBAVUTIL_VERSION_INT,
386 };
387 
389  .name = "h261",
390  .long_name = NULL_IF_CONFIG_SMALL("H.261"),
391  .type = AVMEDIA_TYPE_VIDEO,
392  .id = AV_CODEC_ID_H261,
393  .priv_data_size = sizeof(H261Context),
395  .encode2 = ff_mpv_encode_picture,
396  .close = ff_mpv_encode_end,
397  .pix_fmts = (const enum AVPixelFormat[]) { AV_PIX_FMT_YUV420P,
398  AV_PIX_FMT_NONE },
399  .priv_class = &h261_class,
400 };
#define NULL
Definition: coverity.c:32
const char const char void * val
Definition: avisynth_c.h:863
void ff_init_block_index(MpegEncContext *s)
Definition: mpegvideo.c:2274
#define UNI_ENC_INDEX(last, run, level)
Definition: h261enc.c:38
int picture_number
Definition: mpegvideo.h:127
const uint8_t * y_dc_scale_table
qscale -> y_dc_scale table
Definition: mpegvideo.h:188
int last_mv[2][2][2]
last MV, used for MV prediction in MPEG-1 & B-frame MPEG-4
Definition: mpegvideo.h:278
static void put_sbits(PutBitContext *pb, int n, int32_t value)
Definition: put_bits.h:240
void ff_h261_encode_mb(MpegEncContext *s, int16_t block[6][64], int motion_x, int motion_y)
Definition: h261enc.c:237
static void put_bits(Jpeg2000EncoderContext *s, int val, int n)
put n times val bit
Definition: j2kenc.c:208
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
MpegEncContext s
Definition: h261.h:38
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:35
const uint8_t ff_h261_mba_bits[35]
Definition: h261data.c:48
int num
Numerator.
Definition: rational.h:59
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:191
void avpriv_align_put_bits(PutBitContext *s)
Pad the bitstream with zeros up to the next byte boundary.
Definition: bitstream.c:48
H261Context.
Definition: h261.h:37
int min_qcoeff
minimum encodable coefficient
Definition: mpegvideo.h:308
int gob_number
Definition: h261.h:45
mpegvideo header.
#define HAS_CBP(a)
Definition: mpegutils.h:101
uint8_t permutated[64]
Definition: idctdsp.h:33
void ff_h261_encode_picture_header(MpegEncContext *s, int picture_number)
Definition: h261enc.c:53
uint8_t run
Definition: svq3.c:206
uint8_t * intra_ac_vlc_length
Definition: mpegvideo.h:311
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample format(the sample packing is implied by the sample format) and sample rate.The lists are not just lists
AVCodec.
Definition: avcodec.h:3481
const uint8_t ff_h261_mba_code[35]
Definition: h261data.c:34
RLTable.
Definition: rl.h:39
int qscale
QP.
Definition: mpegvideo.h:204
Macro definitions for various function/variable attributes.
const uint8_t ff_h261_cbp_tab[63][2]
Definition: h261data.c:95
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented...
Definition: avcodec.h:1688
AVCodec ff_h261_encoder
Definition: h261enc.c:388
const char * class_name
The name of the class; usually it is the same name as the context structure type to which the AVClass...
Definition: log.h:72
#define av_assert0(cond)
assert() equivalent, that is always enabled.
Definition: avassert.h:37
uint8_t * ptr_lastgob
Definition: mpegvideo.h:503
const AVOption ff_mpv_generic_options[]
Definition: mpegvideo_enc.c:85
const uint8_t ff_mpeg1_dc_scale_table[128]
Definition: mpegvideodata.c:34
The exact code depends on how similar the blocks are and how related they are to the block
uint8_t
#define av_cold
Definition: attributes.h:82
#define height
static void h261_encode_gob_header(MpegEncContext *s, int mb_line)
Encode a group of blocks header.
Definition: h261enc.c:91
int max_qcoeff
maximum encodable coefficient
Definition: mpegvideo.h:309
#define MAX_LEVEL
Definition: rl.h:36
int dquant
qscale difference to prev qscale
Definition: mpegvideo.h:210
static void ff_update_block_index(MpegEncContext *s)
Definition: mpegvideo.h:737
void ff_set_qscale(MpegEncContext *s, int qscale)
set qscale and update qscale dependent variables.
Definition: mpegvideo.c:2338
static void h261_encode_block(H261Context *h, int16_t *block, int n)
Encode an 8x8 block.
Definition: h261enc.c:169
av_cold void ff_h261_common_init(void)
Definition: h261.c:83
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:259
static uint8_t * put_bits_ptr(PutBitContext *s)
Return the pointer to the byte where the bitstream writer will put the next bit.
Definition: put_bits.h:324
static const AVClass h261_class
Definition: h261enc.c:381
uint8_t * inter_ac_vlc_last_length
Definition: mpegvideo.h:316
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
simple assert() macros that are a bit more flexible than ISO C assert().
int mtype
Definition: h261.h:42
const char * name
Name of the codec implementation.
Definition: avcodec.h:3488
uint8_t * intra_ac_vlc_last_length
Definition: mpegvideo.h:312
int n
number of entries of table_vlc minus 1
Definition: rl.h:40
#define av_assert1(cond)
assert() equivalent, that does not lie in speed critical code.
Definition: avassert.h:53
const uint16_t(* table_vlc)[2]
Definition: rl.h:42
#define width
#define s(width, name)
Definition: cbs_vp9.c:257
int block_last_index[12]
last non zero coefficient in block
Definition: mpegvideo.h:86
int n
Definition: avisynth_c.h:760
const uint8_t ff_h261_mtype_code[10]
Definition: h261data.c:63
const uint8_t ff_h261_mtype_bits[10]
Definition: h261data.c:69
int ac_esc_length
num of bits needed to encode the longest esc
Definition: mpegvideo.h:310
const uint8_t ff_h261_mv_tab[17][2]
Definition: h261data.c:89
const int ff_h261_mtype_map[10]
Definition: h261data.c:75
Libavcodec external API header.
void ff_h261_reorder_mb_index(MpegEncContext *s)
Definition: h261enc.c:108
ScanTable intra_scantable
Definition: mpegvideo.h:91
int height
picture size. must be a multiple of 16
Definition: mpegvideo.h:100
#define IS_QUANT(a)
Definition: mpegutils.h:95
int ff_h261_get_picture_format(int width, int height)
Definition: h261enc.c:40
int ff_mpv_encode_init(AVCodecContext *avctx)
uint8_t * inter_ac_vlc_length
Definition: mpegvideo.h:315
H.261 codec.
Describe the class of an AVClass context structure.
Definition: log.h:67
#define IS_16X16(a)
Definition: mpegutils.h:86
static int get_cbp(MpegEncContext *s, int16_t block[6][64])
Definition: h261enc.c:154
int index
Definition: gxfenc.c:89
static void h261_encode_motion(H261Context *h, int val)
Definition: h261enc.c:135
RLTable ff_h261_rl_tcoeff
Definition: h261data.c:150
int pict_type
AV_PICTURE_TYPE_I, AV_PICTURE_TYPE_P, AV_PICTURE_TYPE_B, ...
Definition: mpegvideo.h:212
static enum AVPixelFormat pix_fmts[]
Definition: libkvazaar.c:275
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
const uint8_t * c_dc_scale_table
qscale -> c_dc_scale table
Definition: mpegvideo.h:189
uint8_t level
Definition: svq3.c:207
MpegEncContext.
Definition: mpegvideo.h:81
#define MAX_RUN
Definition: rl.h:35
struct AVCodecContext * avctx
Definition: mpegvideo.h:98
PutBitContext pb
bit output
Definition: mpegvideo.h:151
planar YUV 4:2:0, 12bpp, (1 Cr & Cb sample per 2x2 Y samples)
Definition: pixfmt.h:66
int den
Denominator.
Definition: rational.h:60
int ff_mpv_encode_end(AVCodecContext *avctx)
static int get_rl_index(const RLTable *rl, int last, int run, int level)
Definition: rl.h:76
static uint8_t uni_h261_rl_len[64 *64 *2 *2]
Definition: h261enc.c:37
int len
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Frame references ownership and permissions
int ff_mpv_encode_picture(AVCodecContext *avctx, AVPacket *pkt, const AVFrame *frame, int *got_packet)
static av_cold void init_uni_h261_rl_tab(RLTable *rl, uint32_t *bits_tab, uint8_t *len_tab)
Definition: h261enc.c:325
av_cold void ff_h261_encode_init(MpegEncContext *s)
Definition: h261enc.c:365
AVPixelFormat
Pixel format.
Definition: pixfmt.h:64