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 "libavutil/thread.h"
31 #include "avcodec.h"
32 #include "mpegutils.h"
33 #include "mpegvideo.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 
58  align_put_bits(&s->pb);
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;
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;
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,
267  ff_h261_mba_bits[s->mb_skip_run],
268  ff_h261_mba_code[s->mb_skip_run]);
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,
290  ff_h261_mtype_bits[h->mtype],
291  ff_h261_mtype_code[h->mtype]);
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 */
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(const RLTable *rl, uint8_t *len_tab)
326 {
327  int slevel, run, last;
328 
329  av_assert0(MAX_LEVEL >= 64);
330  av_assert0(MAX_RUN >= 63);
331 
332  for(slevel=-64; slevel<64; slevel++){
333  if(slevel==0) continue;
334  for(run=0; run<64; run++){
335  for(last=0; last<=1; last++){
336  const int index= UNI_ENC_INDEX(last, run, slevel+64);
337  int level= slevel < 0 ? -slevel : slevel;
338  int len, code;
339 
340  len_tab[index]= 100;
341 
342  /* ESC0 */
343  code= get_rl_index(rl, 0, run, level);
344  len= rl->table_vlc[code][1] + 1;
345  if(last)
346  len += 2;
347 
348  if(code!=rl->n && len < len_tab[index]){
349  len_tab [index]= len;
350  }
351  /* ESC */
352  len = rl->table_vlc[rl->n][1];
353  if(last)
354  len += 2;
355 
356  if(len < len_tab[index]){
357  len_tab [index]= len;
358  }
359  }
360  }
361  }
362 }
363 
365 {
366  static uint8_t h261_rl_table_store[2][2 * MAX_RUN + MAX_LEVEL + 3];
367 
368  ff_rl_init(&ff_h261_rl_tcoeff, h261_rl_table_store);
370 }
371 
373 {
374  static AVOnce init_static_once = AV_ONCE_INIT;
375 
376  s->min_qcoeff = -127;
377  s->max_qcoeff = 127;
378  s->y_dc_scale_table =
379  s->c_dc_scale_table = ff_mpeg1_dc_scale_table;
380  s->ac_esc_length = 6+6+8;
381 
382  s->intra_ac_vlc_length = s->inter_ac_vlc_length = uni_h261_rl_len;
383  s->intra_ac_vlc_last_length = s->inter_ac_vlc_last_length = uni_h261_rl_len + 128*64;
384  ff_thread_once(&init_static_once, h261_encode_init_static);
385 }
386 
388  .name = "h261",
389  .long_name = NULL_IF_CONFIG_SMALL("H.261"),
390  .type = AVMEDIA_TYPE_VIDEO,
391  .id = AV_CODEC_ID_H261,
392  .priv_class = &ff_mpv_enc_class,
393  .priv_data_size = sizeof(H261Context),
395  .encode2 = ff_mpv_encode_picture,
396  .close = ff_mpv_encode_end,
398  .pix_fmts = (const enum AVPixelFormat[]) { AV_PIX_FMT_YUV420P,
399  AV_PIX_FMT_NONE },
400 };
AVCodec
AVCodec.
Definition: codec.h:202
FF_CODEC_CAP_INIT_THREADSAFE
#define FF_CODEC_CAP_INIT_THREADSAFE
The codec does not modify any global variables in the init function, allowing to call the init functi...
Definition: internal.h:42
AVPixelFormat
AVPixelFormat
Pixel format.
Definition: pixfmt.h:64
level
uint8_t level
Definition: svq3.c:202
AVERROR
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
align_put_bits
static void align_put_bits(PutBitContext *s)
Pad the bitstream with zeros up to the next byte boundary.
Definition: put_bits.h:412
thread.h
ff_mpeg1_dc_scale_table
const uint8_t ff_mpeg1_dc_scale_table[128]
Definition: mpegvideodata.c:33
put_sbits
static void put_sbits(PutBitContext *pb, int n, int32_t value)
Definition: put_bits.h:280
MAX_RUN
#define MAX_RUN
Definition: rl.h:35
put_bits
static void put_bits(Jpeg2000EncoderContext *s, int val, int n)
put n times val bit
Definition: j2kenc.c:220
index
fg index
Definition: ffmpeg_filter.c:167
ff_h261_encode_mb
void ff_h261_encode_mb(MpegEncContext *s, int16_t block[6][64], int motion_x, int motion_y)
Definition: h261enc.c:237
ff_init_block_index
void ff_init_block_index(MpegEncContext *s)
Definition: mpegvideo.c:1749
mpegvideo.h
mpegutils.h
AV_CODEC_ID_H261
@ AV_CODEC_ID_H261
Definition: codec_id.h:53
ff_h261_encode_picture_header
void ff_h261_encode_picture_header(MpegEncContext *s, int picture_number)
Definition: h261enc.c:53
init
static int init
Definition: av_tx.c:47
ff_h261_mtype_map
const int ff_h261_mtype_map[10]
Definition: h261data.c:75
h261.h
RLTable
RLTable.
Definition: rl.h:39
val
static double val(void *priv, double ch)
Definition: aeval.c:76
HAS_CBP
#define HAS_CBP(a)
Definition: mpegutils.h:100
avassert.h
RLTable::n
int n
number of entries of table_vlc minus 1
Definition: rl.h:40
ff_thread_once
static int ff_thread_once(char *control, void(*routine)(void))
Definition: thread.h:175
av_cold
#define av_cold
Definition: attributes.h:90
width
#define width
s
#define s(width, name)
Definition: cbs_vp9.c:257
ff_mpv_encode_init
int ff_mpv_encode_init(AVCodecContext *avctx)
Definition: mpegvideo_enc.c:312
get_rl_index
static int get_rl_index(const RLTable *rl, int last, int run, int level)
Definition: rl.h:91
h261_encode_gob_header
static void h261_encode_gob_header(MpegEncContext *s, int mb_line)
Encode a group of blocks header.
Definition: h261enc.c:91
ff_h261_mba_code
const uint8_t ff_h261_mba_code[35]
Definition: h261data.c:34
av_assert0
#define av_assert0(cond)
assert() equivalent, that is always enabled.
Definition: avassert.h:37
ff_mpv_encode_picture
int ff_mpv_encode_picture(AVCodecContext *avctx, AVPacket *pkt, const AVFrame *frame, int *got_packet)
Definition: mpegvideo_enc.c:1681
pix_fmts
static enum AVPixelFormat pix_fmts[]
Definition: libkvazaar.c:296
ff_h261_mv_tab
const uint8_t ff_h261_mv_tab[17][2]
Definition: h261data.c:89
h261_encode_block
static void h261_encode_block(H261Context *h, int16_t *block, int n)
Encode an 8x8 block.
Definition: h261enc.c:169
AV_PIX_FMT_YUV420P
@ AV_PIX_FMT_YUV420P
planar YUV 4:2:0, 12bpp, (1 Cr & Cb sample per 2x2 Y samples)
Definition: pixfmt.h:66
ff_rl_init
av_cold void ff_rl_init(RLTable *rl, uint8_t static_store[2][2 *MAX_RUN+MAX_LEVEL+3])
Initialize index_run, max_level and max_run from n, last, table_vlc, table_run and table_level.
Definition: rl.c:27
AV_ONCE_INIT
#define AV_ONCE_INIT
Definition: thread.h:173
run
uint8_t run
Definition: svq3.c:201
RLTable::table_vlc
const uint16_t(* table_vlc)[2]
Definition: rl.h:42
AV_PICTURE_TYPE_I
@ AV_PICTURE_TYPE_I
Intra.
Definition: avutil.h:274
ff_set_qscale
void ff_set_qscale(MpegEncContext *s, int qscale)
set qscale and update qscale dependent variables.
Definition: mpegvideo.c:1785
AVOnce
#define AVOnce
Definition: thread.h:172
MAX_LEVEL
#define MAX_LEVEL
Definition: rl.h:36
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:117
format
ofilter format
Definition: ffmpeg_filter.c:172
height
#define height
mpegvideodata.h
attributes.h
IS_16X16
#define IS_16X16(a)
Definition: mpegutils.h:85
H261Context
H261Context.
Definition: h261.h:37
ff_update_block_index
static void ff_update_block_index(MpegEncContext *s)
Definition: mpegvideo.h:752
h261_encode_init_static
static av_cold void h261_encode_init_static(void)
Definition: h261enc.c:364
ff_h261_cbp_tab
const uint8_t ff_h261_cbp_tab[63][2]
Definition: h261data.c:95
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:271
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
h261_encode_motion
static void h261_encode_motion(H261Context *h, int val)
Definition: h261enc.c:135
FF_CODEC_CAP_INIT_CLEANUP
#define FF_CODEC_CAP_INIT_CLEANUP
The codec allows calling the close function for deallocation even if the init function returned a fai...
Definition: internal.h:50
av_assert1
#define av_assert1(cond)
assert() equivalent, that does not lie in speed critical code.
Definition: avassert.h:53
IS_QUANT
#define IS_QUANT(a)
Definition: mpegutils.h:94
ff_mpv_encode_end
int ff_mpv_encode_end(AVCodecContext *avctx)
Definition: mpegvideo_enc.c:937
ff_h261_reorder_mb_index
void ff_h261_reorder_mb_index(MpegEncContext *s)
Definition: h261enc.c:108
ff_h261_mtype_code
const uint8_t ff_h261_mtype_code[10]
Definition: h261data.c:63
ff_h261_get_picture_format
int ff_h261_get_picture_format(int width, int height)
Definition: h261enc.c:40
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:209
len
int len
Definition: vorbis_enc_data.h:426
get_cbp
static int get_cbp(MpegEncContext *s, int16_t block[6][64])
Definition: h261enc.c:154
avcodec.h
init_uni_h261_rl_tab
static av_cold void init_uni_h261_rl_tab(const RLTable *rl, uint8_t *len_tab)
Definition: h261enc.c:325
ff_h261_encoder
const AVCodec ff_h261_encoder
Definition: h261enc.c:387
ff_h261_rl_tcoeff
RLTable ff_h261_rl_tcoeff
Definition: h261data.c:150
put_bits_ptr
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:369
AV_PIX_FMT_NONE
@ AV_PIX_FMT_NONE
Definition: pixfmt.h:65
ff_h261_mtype_bits
const uint8_t ff_h261_mtype_bits[10]
Definition: h261data.c:69
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
ff_h261_encode_init
av_cold void ff_h261_encode_init(MpegEncContext *s)
Definition: h261enc.c:372
block
The exact code depends on how similar the blocks are and how related they are to the block
Definition: filter_design.txt:207
ff_mpv_enc_class
const AVClass ff_mpv_enc_class
Definition: mpegvideo_enc.c:101
uni_h261_rl_len
static uint8_t uni_h261_rl_len[64 *64 *2 *2]
Definition: h261enc.c:37
h
h
Definition: vp9dsp_template.c:2038
ff_h261_mba_bits
const uint8_t ff_h261_mba_bits[35]
Definition: h261data.c:48
MpegEncContext
MpegEncContext.
Definition: mpegvideo.h:69
UNI_ENC_INDEX
#define UNI_ENC_INDEX(last, run, level)
Definition: h261enc.c:38