git.sesse.net Git - ffmpeg/blob - libavcodec/hevc_parse.c

   1 /*
   2  * HEVC common 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/intreadwrite.h"
  26 #include "libavutil/mem.h"
  27
  28 #include "hevc.h"
  29
  30 /* FIXME: This is adapted from ff_h264_decode_nal, avoiding duplication
  31  * between these functions would be nice. */
  32 int ff_hevc_extract_rbsp(HEVCContext *s, const uint8_t *src, int length,
  33                          HEVCNAL *nal)
  34 {
  35     int i, si, di;
  36     uint8_t *dst;
  37
  38     if (s)
  39         s->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) {                                      \
  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) { // no escaped 0
  86         nal->data     =
  87         nal->raw_data = src;
  88         nal->size     =
  89         nal->raw_size = length;
  90         return length;
  91     }
  92
  93     av_fast_malloc(&nal->rbsp_buffer, &nal->rbsp_buffer_size,
  94                    length + FF_INPUT_BUFFER_PADDING_SIZE);
  95     if (!nal->rbsp_buffer)
  96         return AVERROR(ENOMEM);
  97
  98     dst = nal->rbsp_buffer;
  99
 100     memcpy(dst, src, i);
 101     si = di = i;
 102     while (si + 2 < length) {
 103         // remove escapes (very rare 1:2^22)
 104         if (src[si + 2] > 3) {
 105             dst[di++] = src[si++];
 106             dst[di++] = src[si++];
 107         } else if (src[si] == 0 && src[si + 1] == 0) {
 108             if (src[si + 2] == 3) { // escape
 109                 dst[di++] = 0;
 110                 dst[di++] = 0;
 111                 si       += 3;
 112
 113                 if (s) {
 114                         s->skipped_bytes++;
 115                         if (s->skipped_bytes_pos_size < s->skipped_bytes) {
 116                         s->skipped_bytes_pos_size *= 2;
 117                         av_reallocp_array(&s->skipped_bytes_pos,
 118                                 s->skipped_bytes_pos_size,
 119                                 sizeof(*s->skipped_bytes_pos));
 120                         if (!s->skipped_bytes_pos)
 121                                 return AVERROR(ENOMEM);
 122                         }
 123                         if (s->skipped_bytes_pos)
 124                         s->skipped_bytes_pos[s->skipped_bytes-1] = di - 1;
 125                 }
 126                 continue;
 127             } else // next start code
 128                 goto nsc;
 129         }
 130
 131         dst[di++] = src[si++];
 132     }
 133     while (si < length)
 134         dst[di++] = src[si++];
 135
 136 nsc:
 137     memset(dst + di, 0, FF_INPUT_BUFFER_PADDING_SIZE);
 138
 139     nal->data = dst;
 140     nal->size = di;
 141     nal->raw_data = src;
 142     nal->raw_size = si;
 143     return si;
 144 }
 145