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path: root/libavcodec/h261enc.c (plain)
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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
37static 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
40int ff_h261_get_picture_format(int width, int height)
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
53void ff_h261_encode_picture_header(MpegEncContext *s, int picture_number)
54{
55 H261Context *h = (H261Context *)s;
56 int format, temp_ref;
57
58 avpriv_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 */
91static 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
108void ff_h261_reorder_mb_index(MpegEncContext *s)
109{
110 int index = s->mb_x + s->mb_y * s->mb_width;
111
112 if (index % 11 == 0) {
113 if (index % 33 == 0)
114 h261_encode_gob_header(s, 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
130 ff_init_block_index(s);
131 ff_update_block_index(s);
132 }
133}
134
135static void h261_encode_motion(H261Context *h, int val)
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
154static 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 */
169static 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
237void 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 */
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
325static 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
365av_cold void ff_h261_encode_init(MpegEncContext *s)
366{
367 ff_h261_common_init();
368
369 s->min_qcoeff = -127;
370 s->max_qcoeff = 127;
371 s->y_dc_scale_table =
372 s->c_dc_scale_table = ff_mpeg1_dc_scale_table;
373 s->ac_esc_length = 6+6+8;
374
375 init_uni_h261_rl_tab(&ff_h261_rl_tcoeff, NULL, uni_h261_rl_len);
376
377 s->intra_ac_vlc_length = s->inter_ac_vlc_length = uni_h261_rl_len;
378 s->intra_ac_vlc_last_length = s->inter_ac_vlc_last_length = uni_h261_rl_len + 128*64;
379}
380
381static 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
388AVCodec ff_h261_encoder = {
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),
394 .init = ff_mpv_encode_init,
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};
401
generated by cgit at 2024-05-17 02:26:48 (GMT)