Parse NAL units in H264 parser.
[libav.git] / libavcodec / h264_parser.c
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1/*
2 * H.26L/H.264/AVC/JVT/14496-10/... parser
3 * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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20 */
21
22/**
bad5537e 23 * @file libavcodec/h264_parser.c
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24 * H.264 / AVC / MPEG4 part10 parser.
25 * @author Michael Niedermayer <michaelni@gmx.at>
26 */
27
28#include "parser.h"
29#include "h264_parser.h"
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30#include "h264data.h"
31#include "golomb.h"
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32
33#include <assert.h>
34
35
36int ff_h264_find_frame_end(H264Context *h, const uint8_t *buf, int buf_size)
37{
38 int i;
39 uint32_t state;
40 ParseContext *pc = &(h->s.parse_context);
41//printf("first %02X%02X%02X%02X\n", buf[0], buf[1],buf[2],buf[3]);
42// mb_addr= pc->mb_addr - 1;
43 state= pc->state;
44 if(state>13)
45 state= 7;
46
47 for(i=0; i<buf_size; i++){
48 if(state==7){
b250f9c6 49#if HAVE_FAST_UNALIGNED
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50 /* we check i<buf_size instead of i+3/7 because its simpler
51 * and there should be FF_INPUT_BUFFER_PADDING_SIZE bytes at the end
52 */
b250f9c6 53# if HAVE_FAST_64BIT
4d8eb2e8 54 while(i<buf_size && !((~*(const uint64_t*)(buf+i) & (*(const uint64_t*)(buf+i) - 0x0101010101010101ULL)) & 0x8080808080808080ULL))
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55 i+=8;
56# else
4d8eb2e8 57 while(i<buf_size && !((~*(const uint32_t*)(buf+i) & (*(const uint32_t*)(buf+i) - 0x01010101U)) & 0x80808080U))
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58 i+=4;
59# endif
60#endif
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61 for(; i<buf_size; i++){
62 if(!buf[i]){
63 state=2;
64 break;
65 }
66 }
67 }else if(state<=2){
68 if(buf[i]==1) state^= 5; //2->7, 1->4, 0->5
69 else if(buf[i]) state = 7;
70 else state>>=1; //2->1, 1->0, 0->0
71 }else if(state<=5){
72 int v= buf[i] & 0x1F;
73 if(v==7 || v==8 || v==9){
74 if(pc->frame_start_found){
75 i++;
9aa1cfec 76 goto found;
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77 }
78 }else if(v==1 || v==2 || v==5){
79 if(pc->frame_start_found){
80 state+=8;
81 continue;
82 }else
83 pc->frame_start_found = 1;
84 }
85 state= 7;
86 }else{
87 if(buf[i] & 0x80)
88 goto found;
89 state= 7;
90 }
91 }
92 pc->state= state;
93 return END_NOT_FOUND;
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94
95found:
96 pc->state=7;
97 pc->frame_start_found= 0;
98 return i-(state&5);
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99}
100
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101/*!
102 * Parse NAL units of found picture and decode some basic information.
103 *
104 * @param s parser context.
105 * @param avctx codec context.
106 * @param buf buffer with field/frame data.
107 * @param buf_size size of the buffer.
108 */
109static inline int parse_nal_units(AVCodecParserContext *s,
110 AVCodecContext *avctx,
111 const uint8_t *buf, int buf_size)
112{
113 H264Context *h = s->priv_data;
114 const uint8_t *buf_end = buf + buf_size;
115 unsigned int slice_type;
116 int state;
117 const uint8_t *ptr;
118
119 /* set some sane default values */
120 s->pict_type = FF_I_TYPE;
121
122 h->s.avctx= avctx;
123
124 for(;;) {
125 int src_length, dst_length, consumed;
126 buf = ff_find_start_code(buf, buf_end, &state);
127 if(buf >= buf_end)
128 break;
129 --buf;
130 src_length = buf_end - buf;
131 switch (state & 0x1f) {
132 case NAL_SLICE:
133 case NAL_IDR_SLICE:
134 // Do not walk the whole buffer just to decode slice header
135 if (src_length > 20)
136 src_length = 20;
137 break;
138 }
139 ptr= ff_h264_decode_nal(h, buf, &dst_length, &consumed, src_length);
140 if (ptr==NULL || dst_length < 0)
141 break;
142
143 init_get_bits(&h->s.gb, ptr, 8*dst_length);
144 switch(h->nal_unit_type) {
145 case NAL_SPS:
146 ff_h264_decode_seq_parameter_set(h);
147 break;
148 case NAL_PPS:
149 ff_h264_decode_picture_parameter_set(h, h->s.gb.size_in_bits);
150 break;
151 case NAL_SEI:
152 ff_h264_decode_sei(h);
153 break;
154 case NAL_IDR_SLICE:
155 case NAL_SLICE:
156 get_ue_golomb(&h->s.gb); // skip first_mb_in_slice
157 slice_type = get_ue_golomb_31(&h->s.gb);
158 s->pict_type = golomb_to_pict_type[slice_type % 5];
159 return 0; /* no need to evaluate the rest */
160 }
161 buf += consumed;
162 }
163 /* didn't find a picture! */
164 av_log(h->s.avctx, AV_LOG_ERROR, "missing picture in access unit\n");
165 return -1;
166}
167
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168static int h264_parse(AVCodecParserContext *s,
169 AVCodecContext *avctx,
170 const uint8_t **poutbuf, int *poutbuf_size,
171 const uint8_t *buf, int buf_size)
172{
173 H264Context *h = s->priv_data;
174 ParseContext *pc = &h->s.parse_context;
175 int next;
176
177 if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
178 next= buf_size;
179 }else{
180 next= ff_h264_find_frame_end(h, buf, buf_size);
181
182 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
183 *poutbuf = NULL;
184 *poutbuf_size = 0;
185 return buf_size;
186 }
187
188 if(next<0 && next != END_NOT_FOUND){
189 assert(pc->last_index + next >= 0 );
190 ff_h264_find_frame_end(h, &pc->buffer[pc->last_index + next], -next); //update state
191 }
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192
193 parse_nal_units(s, avctx, buf, buf_size);
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194 }
195
196 *poutbuf = buf;
197 *poutbuf_size = buf_size;
198 return next;
199}
200
201static int h264_split(AVCodecContext *avctx,
202 const uint8_t *buf, int buf_size)
203{
204 int i;
205 uint32_t state = -1;
206 int has_sps= 0;
207
208 for(i=0; i<=buf_size; i++){
209 if((state&0xFFFFFF1F) == 0x107)
210 has_sps=1;
211/* if((state&0xFFFFFF1F) == 0x101 || (state&0xFFFFFF1F) == 0x102 || (state&0xFFFFFF1F) == 0x105){
212 }*/
213 if((state&0xFFFFFF00) == 0x100 && (state&0xFFFFFF1F) != 0x107 && (state&0xFFFFFF1F) != 0x108 && (state&0xFFFFFF1F) != 0x109){
214 if(has_sps){
215 while(i>4 && buf[i-5]==0) i--;
216 return i-4;
217 }
218 }
219 if (i<buf_size)
220 state= (state<<8) | buf[i];
221 }
222 return 0;
223}
224
dd990075 225static void close(AVCodecParserContext *s)
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226{
227 H264Context *h = s->priv_data;
228 ParseContext *pc = &h->s.parse_context;
229
230 av_free(pc->buffer);
231}
232
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233
234AVCodecParser h264_parser = {
0d3d172f 235 { CODEC_ID_H264 },
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236 sizeof(H264Context),
237 NULL,
238 h264_parse,
3ee4f5e4 239 close,
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240 h264_split,
241};