summaryrefslogtreecommitdiff
path: root/libavcodec/h264_parser.c
blob: 26281958445d849b5e6472df24f793b8a3664120 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
/*
 * H.26L/H.264/AVC/JVT/14496-10/... parser
 * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * H.264 / AVC / MPEG4 part10 parser.
 * @author Michael Niedermayer <michaelni@gmx.at>
 */

#define UNCHECKED_BITSTREAM_READER 1

#include "parser.h"
#include "h264data.h"
#include "golomb.h"


static int ff_h264_find_frame_end(H264Context *h, const uint8_t *buf, int buf_size)
{
    int i, j;
    uint32_t state;
    ParseContext *pc = &(h->s.parse_context);
    int next_avc= h->is_avc ? 0 : buf_size;

//    mb_addr= pc->mb_addr - 1;
    state= pc->state;
    if(state>13)
        state= 7;

    if(h->is_avc && !h->nal_length_size)
        av_log(h->s.avctx, AV_LOG_ERROR, "AVC-parser: nal length size invalid\n");

    for(i=0; i<buf_size; i++){
        if(i >= next_avc) {
            int nalsize = 0;
            i = next_avc;
            for(j = 0; j < h->nal_length_size; j++)
                nalsize = (nalsize << 8) | buf[i++];
            if(nalsize <= 0 || nalsize > buf_size - i){
                av_log(h->s.avctx, AV_LOG_ERROR, "AVC-parser: nal size %d remaining %d\n", nalsize, buf_size - i);
                return buf_size;
            }
            next_avc= i + nalsize;
            state= 5;
        }

        if(state==7){
#if HAVE_FAST_UNALIGNED
        /* we check i<buf_size instead of i+3/7 because its simpler
         * and there should be FF_INPUT_BUFFER_PADDING_SIZE bytes at the end
         */
#    if HAVE_FAST_64BIT
            while(i<next_avc && !((~*(const uint64_t*)(buf+i) & (*(const uint64_t*)(buf+i) - 0x0101010101010101ULL)) & 0x8080808080808080ULL))
                i+=8;
#    else
            while(i<next_avc && !((~*(const uint32_t*)(buf+i) & (*(const uint32_t*)(buf+i) - 0x01010101U)) & 0x80808080U))
                i+=4;
#    endif
#endif
            for(; i<next_avc; i++){
                if(!buf[i]){
                    state=2;
                    break;
                }
            }
        }else if(state<=2){
            if(buf[i]==1)   state^= 5; //2->7, 1->4, 0->5
            else if(buf[i]) state = 7;
            else            state>>=1; //2->1, 1->0, 0->0
        }else if(state<=5){
            int v= buf[i] & 0x1F;
            if(v==6 || v==7 || v==8 || v==9){
                if(pc->frame_start_found){
                    i++;
                    goto found;
                }
            }else if(v==1 || v==2 || v==5){
                state+=8;
                continue;
            }
            state= 7;
        }else{
            h->parse_history[h->parse_history_count++]= buf[i];
            if(h->parse_history_count>3){
                unsigned int mb, last_mb= h->parse_last_mb;
                GetBitContext gb;

                init_get_bits(&gb, h->parse_history, 8*h->parse_history_count);
                h->parse_history_count=0;
                mb= get_ue_golomb_long(&gb);
                last_mb= h->parse_last_mb;
                h->parse_last_mb= mb;
                if(pc->frame_start_found){
                    if(mb <= last_mb)
                        goto found;
                }else
                    pc->frame_start_found = 1;
                state= 7;
            }
        }
    }
    pc->state= state;
    if(h->is_avc)
        return next_avc;
    return END_NOT_FOUND;

found:
    pc->state=7;
    pc->frame_start_found= 0;
    if(h->is_avc)
        return next_avc;
    return i-(state&5) - 3*(state>7);
}

/**
 * Parse NAL units of found picture and decode some basic information.
 *
 * @param s parser context.
 * @param avctx codec context.
 * @param buf buffer with field/frame data.
 * @param buf_size size of the buffer.
 */
static inline int parse_nal_units(AVCodecParserContext *s,
                                  AVCodecContext *avctx,
                                  const uint8_t *buf, int buf_size)
{
    H264Context *h = s->priv_data;
    const uint8_t *buf_end = buf + buf_size;
    unsigned int pps_id;
    unsigned int slice_type;
    int state = -1;
    const uint8_t *ptr;
    int q264 = buf_size >=4 && !memcmp("Q264", buf, 4);

    /* set some sane default values */
    s->pict_type = AV_PICTURE_TYPE_I;
    s->key_frame = 0;

    h->s.avctx= avctx;
    h->sei_recovery_frame_cnt = -1;
    h->sei_dpb_output_delay         =  0;
    h->sei_cpb_removal_delay        = -1;
    h->sei_buffering_period_present =  0;

    if (!buf_size)
        return 0;

    for(;;) {
        int src_length, dst_length, consumed, nalsize = 0;
        if (h->is_avc) {
            int i;
            if (h->nal_length_size >= buf_end - buf) break;
            nalsize = 0;
            for (i = 0; i < h->nal_length_size; i++)
                nalsize = (nalsize << 8) | *buf++;
            if (nalsize <= 0 || nalsize > buf_end - buf) {
                av_log(h->s.avctx, AV_LOG_ERROR, "AVC: nal size %d\n", nalsize);
                break;
            }
            src_length = nalsize;
        } else {
        buf = avpriv_mpv_find_start_code(buf, buf_end, &state);
        if(buf >= buf_end)
            break;
        --buf;
        src_length = buf_end - buf;
        }
        switch (state & 0x1f) {
        case NAL_SLICE:
        case NAL_IDR_SLICE:
            // Do not walk the whole buffer just to decode slice header
            if (src_length > 20)
                src_length = 20;
            break;
        }
        ptr= ff_h264_decode_nal(h, buf, &dst_length, &consumed, src_length);
        if (ptr==NULL || dst_length < 0)
            break;

        init_get_bits(&h->s.gb, ptr, 8*dst_length);
        switch(h->nal_unit_type) {
        case NAL_SPS:
            ff_h264_decode_seq_parameter_set(h);
            break;
        case NAL_PPS:
            ff_h264_decode_picture_parameter_set(h, h->s.gb.size_in_bits);
            break;
        case NAL_SEI:
            ff_h264_decode_sei(h);
            break;
        case NAL_IDR_SLICE:
            s->key_frame = 1;
            /* fall through */
        case NAL_SLICE:
            get_ue_golomb_long(&h->s.gb);  // skip first_mb_in_slice
            slice_type = get_ue_golomb_31(&h->s.gb);
            s->pict_type = golomb_to_pict_type[slice_type % 5];
            if (h->sei_recovery_frame_cnt >= 0) {
                /* key frame, since recovery_frame_cnt is set */
                s->key_frame = 1;
            }
            pps_id= get_ue_golomb(&h->s.gb);
            if(pps_id>=MAX_PPS_COUNT) {
                av_log(h->s.avctx, AV_LOG_ERROR, "pps_id out of range\n");
                return -1;
            }
            if(!h->pps_buffers[pps_id]) {
                av_log(h->s.avctx, AV_LOG_ERROR, "non-existing PPS referenced\n");
                return -1;
            }
            h->pps= *h->pps_buffers[pps_id];
            if(!h->sps_buffers[h->pps.sps_id]) {
                av_log(h->s.avctx, AV_LOG_ERROR, "non-existing SPS referenced\n");
                return -1;
            }
            h->sps = *h->sps_buffers[h->pps.sps_id];
            h->frame_num = get_bits(&h->s.gb, h->sps.log2_max_frame_num);

            avctx->profile = ff_h264_get_profile(&h->sps);
            avctx->level   = h->sps.level_idc;

            if(h->sps.frame_mbs_only_flag){
                h->s.picture_structure= PICT_FRAME;
            }else{
                if(get_bits1(&h->s.gb)) { //field_pic_flag
                    h->s.picture_structure= PICT_TOP_FIELD + get_bits1(&h->s.gb); //bottom_field_flag
                } else {
                    h->s.picture_structure= PICT_FRAME;
                }
            }

            if(h->sps.pic_struct_present_flag) {
                switch (h->sei_pic_struct) {
                    case SEI_PIC_STRUCT_TOP_FIELD:
                    case SEI_PIC_STRUCT_BOTTOM_FIELD:
                        s->repeat_pict = 0;
                        break;
                    case SEI_PIC_STRUCT_FRAME:
                    case SEI_PIC_STRUCT_TOP_BOTTOM:
                    case SEI_PIC_STRUCT_BOTTOM_TOP:
                        s->repeat_pict = 1;
                        break;
                    case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
                    case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
                        s->repeat_pict = 2;
                        break;
                    case SEI_PIC_STRUCT_FRAME_DOUBLING:
                        s->repeat_pict = 3;
                        break;
                    case SEI_PIC_STRUCT_FRAME_TRIPLING:
                        s->repeat_pict = 5;
                        break;
                    default:
                        s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
                        break;
                }
            } else {
                s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;
            }

            return 0; /* no need to evaluate the rest */
        }
        buf += h->is_avc ? nalsize : consumed;
    }
    if (q264)
        return 0;
    /* didn't find a picture! */
    av_log(h->s.avctx, AV_LOG_ERROR, "missing picture in access unit with size %d\n", buf_size);
    return -1;
}

static int h264_parse(AVCodecParserContext *s,
                      AVCodecContext *avctx,
                      const uint8_t **poutbuf, int *poutbuf_size,
                      const uint8_t *buf, int buf_size)
{
    H264Context *h = s->priv_data;
    ParseContext *pc = &h->s.parse_context;
    int next;

    if (!h->got_first) {
        h->got_first = 1;
        if (avctx->extradata_size) {
            h->s.avctx = avctx;
            // must be done like in decoder, otherwise opening the parser,
            // letting it create extradata and then closing and opening again
            // will cause has_b_frames to be always set.
            // Note that estimate_timings_from_pts does exactly this.
            if (!avctx->has_b_frames)
                h->s.low_delay = 1;
            ff_h264_decode_extradata(h, avctx->extradata, avctx->extradata_size);
        }
    }

    if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
        next= buf_size;
    }else{
        next= ff_h264_find_frame_end(h, buf, buf_size);

        if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
            *poutbuf = NULL;
            *poutbuf_size = 0;
            return buf_size;
        }

        if(next<0 && next != END_NOT_FOUND){
            av_assert1(pc->last_index + next >= 0 );
            ff_h264_find_frame_end(h, &pc->buffer[pc->last_index + next], -next); //update state
        }
    }

    parse_nal_units(s, avctx, buf, buf_size);

    if (h->sei_cpb_removal_delay >= 0) {
        s->dts_sync_point    = h->sei_buffering_period_present;
        s->dts_ref_dts_delta = h->sei_cpb_removal_delay;
        s->pts_dts_delta     = h->sei_dpb_output_delay;
    } else {
        s->dts_sync_point    = INT_MIN;
        s->dts_ref_dts_delta = INT_MIN;
        s->pts_dts_delta     = INT_MIN;
    }

    if (s->flags & PARSER_FLAG_ONCE) {
        s->flags &= PARSER_FLAG_COMPLETE_FRAMES;
    }

    *poutbuf = buf;
    *poutbuf_size = buf_size;
    return next;
}

static int h264_split(AVCodecContext *avctx,
                      const uint8_t *buf, int buf_size)
{
    int i;
    uint32_t state = -1;
    int has_sps= 0;

    for(i=0; i<=buf_size; i++){
        if((state&0xFFFFFF1F) == 0x107)
            has_sps=1;
/*        if((state&0xFFFFFF1F) == 0x101 || (state&0xFFFFFF1F) == 0x102 || (state&0xFFFFFF1F) == 0x105){
        }*/
        if((state&0xFFFFFF00) == 0x100 && (state&0xFFFFFF1F) != 0x107 && (state&0xFFFFFF1F) != 0x108 && (state&0xFFFFFF1F) != 0x109){
            if(has_sps){
                while(i>4 && buf[i-5]==0) i--;
                return i-4;
            }
        }
        if (i<buf_size)
            state= (state<<8) | buf[i];
    }
    return 0;
}

static void close(AVCodecParserContext *s)
{
    H264Context *h = s->priv_data;
    ParseContext *pc = &h->s.parse_context;

    av_free(pc->buffer);
    ff_h264_free_context(h);
}

static int init(AVCodecParserContext *s)
{
    H264Context *h = s->priv_data;
    h->thread_context[0] = h;
    h->s.slice_context_count = 1;
    return 0;
}

AVCodecParser ff_h264_parser = {
    .codec_ids      = { AV_CODEC_ID_H264 },
    .priv_data_size = sizeof(H264Context),
    .parser_init    = init,
    .parser_parse   = h264_parse,
    .parser_close   = close,
    .split          = h264_split,
};