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path: root/libavcodec/h2645_parse.c (plain)
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1/*
2 * H.264/HEVC common parsing code
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21#include <string.h>
22
23#include "config.h"
24
25#include "libavutil/intmath.h"
26#include "libavutil/intreadwrite.h"
27#include "libavutil/mem.h"
28
29#include "hevc.h"
30#include "h2645_parse.h"
31
32int ff_h2645_extract_rbsp(const uint8_t *src, int length,
33 H2645NAL *nal, int small_padding)
34{
35 int i, si, di;
36 uint8_t *dst;
37 int64_t padding = small_padding ? 0 : MAX_MBPAIR_SIZE;
38
39 nal->skipped_bytes = 0;
40#define STARTCODE_TEST \
41 if (i + 2 < length && src[i + 1] == 0 && src[i + 2] <= 3) { \
42 if (src[i + 2] != 3 && src[i + 2] != 0) { \
43 /* startcode, so we must be past the end */ \
44 length = i; \
45 } \
46 break; \
47 }
48#if HAVE_FAST_UNALIGNED
49#define FIND_FIRST_ZERO \
50 if (i > 0 && !src[i]) \
51 i--; \
52 while (src[i]) \
53 i++
54#if HAVE_FAST_64BIT
55 for (i = 0; i + 1 < length; i += 9) {
56 if (!((~AV_RN64A(src + i) &
57 (AV_RN64A(src + i) - 0x0100010001000101ULL)) &
58 0x8000800080008080ULL))
59 continue;
60 FIND_FIRST_ZERO;
61 STARTCODE_TEST;
62 i -= 7;
63 }
64#else
65 for (i = 0; i + 1 < length; i += 5) {
66 if (!((~AV_RN32A(src + i) &
67 (AV_RN32A(src + i) - 0x01000101U)) &
68 0x80008080U))
69 continue;
70 FIND_FIRST_ZERO;
71 STARTCODE_TEST;
72 i -= 3;
73 }
74#endif /* HAVE_FAST_64BIT */
75#else
76 for (i = 0; i + 1 < length; i += 2) {
77 if (src[i])
78 continue;
79 if (i > 0 && src[i - 1] == 0)
80 i--;
81 STARTCODE_TEST;
82 }
83#endif /* HAVE_FAST_UNALIGNED */
84
85 if (i >= length - 1 && small_padding) { // no escaped 0
86 nal->data =
87 nal->raw_data = src;
88 nal->size =
89 nal->raw_size = length;
90 return length;
91 } else if (i > length)
92 i = length;
93
94 av_fast_padded_malloc(&nal->rbsp_buffer, &nal->rbsp_buffer_size,
95 length + padding);
96 if (!nal->rbsp_buffer)
97 return AVERROR(ENOMEM);
98
99 dst = nal->rbsp_buffer;
100
101 memcpy(dst, src, i);
102 si = di = i;
103 while (si + 2 < length) {
104 // remove escapes (very rare 1:2^22)
105 if (src[si + 2] > 3) {
106 dst[di++] = src[si++];
107 dst[di++] = src[si++];
108 } else if (src[si] == 0 && src[si + 1] == 0 && src[si + 2] != 0) {
109 if (src[si + 2] == 3) { // escape
110 dst[di++] = 0;
111 dst[di++] = 0;
112 si += 3;
113
114 if (nal->skipped_bytes_pos) {
115 nal->skipped_bytes++;
116 if (nal->skipped_bytes_pos_size < nal->skipped_bytes) {
117 nal->skipped_bytes_pos_size *= 2;
118 av_assert0(nal->skipped_bytes_pos_size >= nal->skipped_bytes);
119 av_reallocp_array(&nal->skipped_bytes_pos,
120 nal->skipped_bytes_pos_size,
121 sizeof(*nal->skipped_bytes_pos));
122 if (!nal->skipped_bytes_pos) {
123 nal->skipped_bytes_pos_size = 0;
124 return AVERROR(ENOMEM);
125 }
126 }
127 if (nal->skipped_bytes_pos)
128 nal->skipped_bytes_pos[nal->skipped_bytes-1] = di - 1;
129 }
130 continue;
131 } else // next start code
132 goto nsc;
133 }
134
135 dst[di++] = src[si++];
136 }
137 while (si < length)
138 dst[di++] = src[si++];
139
140nsc:
141 memset(dst + di, 0, AV_INPUT_BUFFER_PADDING_SIZE);
142
143 nal->data = dst;
144 nal->size = di;
145 nal->raw_data = src;
146 nal->raw_size = si;
147 return si;
148}
149
150static const char *nal_unit_name(int nal_type)
151{
152 switch(nal_type) {
153 case HEVC_NAL_TRAIL_N : return "TRAIL_N";
154 case HEVC_NAL_TRAIL_R : return "TRAIL_R";
155 case HEVC_NAL_TSA_N : return "TSA_N";
156 case HEVC_NAL_TSA_R : return "TSA_R";
157 case HEVC_NAL_STSA_N : return "STSA_N";
158 case HEVC_NAL_STSA_R : return "STSA_R";
159 case HEVC_NAL_RADL_N : return "RADL_N";
160 case HEVC_NAL_RADL_R : return "RADL_R";
161 case HEVC_NAL_RASL_N : return "RASL_N";
162 case HEVC_NAL_RASL_R : return "RASL_R";
163 case HEVC_NAL_BLA_W_LP : return "BLA_W_LP";
164 case HEVC_NAL_BLA_W_RADL : return "BLA_W_RADL";
165 case HEVC_NAL_BLA_N_LP : return "BLA_N_LP";
166 case HEVC_NAL_IDR_W_RADL : return "IDR_W_RADL";
167 case HEVC_NAL_IDR_N_LP : return "IDR_N_LP";
168 case HEVC_NAL_CRA_NUT : return "CRA_NUT";
169 case HEVC_NAL_VPS : return "VPS";
170 case HEVC_NAL_SPS : return "SPS";
171 case HEVC_NAL_PPS : return "PPS";
172 case HEVC_NAL_AUD : return "AUD";
173 case HEVC_NAL_EOS_NUT : return "EOS_NUT";
174 case HEVC_NAL_EOB_NUT : return "EOB_NUT";
175 case HEVC_NAL_FD_NUT : return "FD_NUT";
176 case HEVC_NAL_SEI_PREFIX : return "SEI_PREFIX";
177 case HEVC_NAL_SEI_SUFFIX : return "SEI_SUFFIX";
178 default : return "?";
179 }
180}
181
182static int get_bit_length(H2645NAL *nal, int skip_trailing_zeros)
183{
184 int size = nal->size;
185 int v;
186
187 while (skip_trailing_zeros && size > 0 && nal->data[size - 1] == 0)
188 size--;
189
190 if (!size)
191 return 0;
192
193 v = nal->data[size - 1];
194
195 if (size > INT_MAX / 8)
196 return AVERROR(ERANGE);
197 size *= 8;
198
199 /* remove the stop bit and following trailing zeros,
200 * or nothing for damaged bitstreams */
201 if (v)
202 size -= ff_ctz(v) + 1;
203
204 return size;
205}
206
207/**
208 * @return AVERROR_INVALIDDATA if the packet is not a valid NAL unit,
209 * 0 if the unit should be skipped, 1 otherwise
210 */
211static int hevc_parse_nal_header(H2645NAL *nal, void *logctx)
212{
213 GetBitContext *gb = &nal->gb;
214 int nuh_layer_id;
215
216 if (get_bits1(gb) != 0)
217 return AVERROR_INVALIDDATA;
218
219 nal->type = get_bits(gb, 6);
220
221 nuh_layer_id = get_bits(gb, 6);
222 nal->temporal_id = get_bits(gb, 3) - 1;
223 if (nal->temporal_id < 0)
224 return AVERROR_INVALIDDATA;
225
226 av_log(logctx, AV_LOG_DEBUG,
227 "nal_unit_type: %d(%s), nuh_layer_id: %d, temporal_id: %d\n",
228 nal->type, nal_unit_name(nal->type), nuh_layer_id, nal->temporal_id);
229
230 return nuh_layer_id == 0;
231}
232
233static int h264_parse_nal_header(H2645NAL *nal, void *logctx)
234{
235 GetBitContext *gb = &nal->gb;
236
237 if (get_bits1(gb) != 0)
238 return AVERROR_INVALIDDATA;
239
240 nal->ref_idc = get_bits(gb, 2);
241 nal->type = get_bits(gb, 5);
242
243 av_log(logctx, AV_LOG_DEBUG,
244 "nal_unit_type: %d, nal_ref_idc: %d\n",
245 nal->type, nal->ref_idc);
246
247 return 1;
248}
249
250int ff_h2645_packet_split(H2645Packet *pkt, const uint8_t *buf, int length,
251 void *logctx, int is_nalff, int nal_length_size,
252 enum AVCodecID codec_id, int small_padding)
253{
254 int consumed, ret = 0;
255 const uint8_t *next_avc = is_nalff ? buf : buf + length;
256
257 pkt->nb_nals = 0;
258 while (length >= 4) {
259 H2645NAL *nal;
260 int extract_length = 0;
261 int skip_trailing_zeros = 1;
262
263 if (buf == next_avc) {
264 int i = 0;
265 extract_length = get_nalsize(nal_length_size,
266 buf, length, &i, logctx);
267 if (extract_length < 0)
268 return extract_length;
269
270 buf += nal_length_size;
271 length -= nal_length_size;
272
273 next_avc = buf + extract_length;
274 } else {
275 if (buf > next_avc)
276 av_log(logctx, AV_LOG_WARNING, "Exceeded next NALFF position, re-syncing.\n");
277
278 /* search start code */
279 while (buf[0] != 0 || buf[1] != 0 || buf[2] != 1) {
280 ++buf;
281 --length;
282 if (length < 4) {
283 if (pkt->nb_nals > 0) {
284 // No more start codes: we discarded some irrelevant
285 // bytes at the end of the packet.
286 return 0;
287 } else {
288 av_log(logctx, AV_LOG_ERROR, "No start code is found.\n");
289 return AVERROR_INVALIDDATA;
290 }
291 } else if (buf >= (next_avc - 3))
292 break;
293 }
294
295 buf += 3;
296 length -= 3;
297 extract_length = FFMIN(length, next_avc - buf);
298
299 if (buf >= next_avc) {
300 /* skip to the start of the next NAL */
301 int offset = next_avc - buf;
302 buf += offset;
303 length -= offset;
304 continue;
305 }
306 }
307
308 if (pkt->nals_allocated < pkt->nb_nals + 1) {
309 int new_size = pkt->nals_allocated + 1;
310 void *tmp = av_realloc_array(pkt->nals, new_size, sizeof(*pkt->nals));
311
312 if (!tmp)
313 return AVERROR(ENOMEM);
314
315 pkt->nals = tmp;
316 memset(pkt->nals + pkt->nals_allocated, 0,
317 (new_size - pkt->nals_allocated) * sizeof(*pkt->nals));
318
319 nal = &pkt->nals[pkt->nb_nals];
320 nal->skipped_bytes_pos_size = 1024; // initial buffer size
321 nal->skipped_bytes_pos = av_malloc_array(nal->skipped_bytes_pos_size, sizeof(*nal->skipped_bytes_pos));
322 if (!nal->skipped_bytes_pos)
323 return AVERROR(ENOMEM);
324
325 pkt->nals_allocated = new_size;
326 }
327 nal = &pkt->nals[pkt->nb_nals];
328
329 consumed = ff_h2645_extract_rbsp(buf, extract_length, nal, small_padding);
330 if (consumed < 0)
331 return consumed;
332
333 if (is_nalff && (extract_length != consumed) && extract_length)
334 av_log(logctx, AV_LOG_DEBUG,
335 "NALFF: Consumed only %d bytes instead of %d\n",
336 consumed, extract_length);
337
338 pkt->nb_nals++;
339
340 /* see commit 3566042a0 */
341 if (consumed < length - 3 &&
342 buf[consumed] == 0x00 && buf[consumed + 1] == 0x00 &&
343 buf[consumed + 2] == 0x01 && buf[consumed + 3] == 0xE0)
344 skip_trailing_zeros = 0;
345
346 nal->size_bits = get_bit_length(nal, skip_trailing_zeros);
347
348 ret = init_get_bits(&nal->gb, nal->data, nal->size_bits);
349 if (ret < 0)
350 return ret;
351
352 if (codec_id == AV_CODEC_ID_HEVC)
353 ret = hevc_parse_nal_header(nal, logctx);
354 else
355 ret = h264_parse_nal_header(nal, logctx);
356 if (ret <= 0 || nal->size <= 0) {
357 if (ret < 0) {
358 av_log(logctx, AV_LOG_ERROR, "Invalid NAL unit %d, skipping.\n",
359 nal->type);
360 }
361 pkt->nb_nals--;
362 }
363
364 buf += consumed;
365 length -= consumed;
366 }
367
368 return 0;
369}
370
371void ff_h2645_packet_uninit(H2645Packet *pkt)
372{
373 int i;
374 for (i = 0; i < pkt->nals_allocated; i++) {
375 av_freep(&pkt->nals[i].rbsp_buffer);
376 av_freep(&pkt->nals[i].skipped_bytes_pos);
377 }
378 av_freep(&pkt->nals);
379 pkt->nals_allocated = 0;
380}
381
generated by cgit at 2024-05-17 05:13:03 (GMT)