modules/demux/av1_unpack.h

   1 /*****************************************************************************
   2  * av1_unpack.h: AV1 samples expander
   3  *****************************************************************************
   4  * Copyright (C) 2018 VideoLabs, VLC authors and VideoLAN
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU Lesser General Public License as published by
   8  * the Free Software Foundation; either version 2.1 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program 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
  14  * GNU Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public License
  17  * along with this program; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  19  *****************************************************************************/
  20 #ifndef VLC_AV1_UNPACK_H
  21 #define VLC_AV1_UNPACK_H
  22
  23 #include "../packetizer/av1_obu.h"
  24 #include <vlc_common.h>
  25 #include <vlc_block.h>
  26
  27 static inline uint8_t leb128_expected(uint32_t v)
  28 {
  29     if     (v < (1U << 7))  return 1;
  30     else if(v < (1U << 14)) return 2;
  31     else if(v < (1U << 21)) return 3;
  32     else if(v < (1U << 28)) return 4;
  33     else                    return 5;
  34 }
  35
  36 static inline void leb128_write(uint32_t v, uint8_t *p)
  37 {
  38     for(;;)
  39     {
  40         *p = v & 0x7F;
  41         v >>= 7;
  42         if(v == 0)
  43             break;
  44         *p++ |= 0x80;
  45     }
  46 }
  47
  48 static inline block_t * AV1_Unpack_Sample_ExpandSize(block_t *p_block)
  49 {
  50     AV1_OBU_iterator_ctx_t ctx;
  51     AV1_OBU_iterator_init(&ctx, p_block->p_buffer, p_block->i_buffer);
  52     const uint8_t *p_obu = NULL; size_t i_obu;
  53     while(AV1_OBU_iterate_next(&ctx, &p_obu, &i_obu))
  54     {
  55         if(AV1_OBUHasSizeField(p_obu))
  56             continue;
  57         const uint8_t i_header = 1 + AV1_OBUHasExtensionField(p_obu);
  58         const uint8_t i_sizelen = leb128_expected(i_obu - i_header);
  59         const size_t i_obu_offset = p_obu - p_block->p_buffer;
  60
  61         /* Make room for i_sizelen after header */
  62         if(2 * (i_obu_offset + i_header) + i_sizelen < p_block->i_buffer)
  63         {
  64             /* move data to the left */
  65             p_block = block_Realloc(p_block, i_sizelen, p_block->i_buffer);
  66             if(p_block)
  67                 memmove(p_block->p_buffer, &p_block->p_buffer[i_sizelen],
  68                         i_obu_offset + i_header);
  69         }
  70         else
  71         {
  72             /* move data to the right */
  73             p_block = block_Realloc(p_block, 0, p_block->i_buffer + i_sizelen);
  74             if(p_block)
  75             {
  76                 const size_t i_off = i_obu_offset + i_header;
  77                 memmove(&p_block->p_buffer[i_off + i_sizelen], &p_block->p_buffer[i_off],
  78                         p_block->i_buffer - i_off - i_sizelen);
  79             }
  80         }
  81
  82         if(likely(p_block))
  83         {
  84             leb128_write(i_obu - i_header, &p_block->p_buffer[i_obu_offset + i_header]);
  85             p_block->p_buffer[i_obu_offset] |= 0x02;
  86         }
  87
  88         break;
  89     }
  90     return p_block;
  91 }
  92
  93 /*
  94     Restores TD OBU and last size field from MP4/MKV sample format
  95     to full AV1 low overhead format.
  96
  97     AV1 ISOBMFF Mapping 2.4
  98     https://aomediacodec.github.io/av1-isobmff/#sampleformat
  99     Matroska/WebM
 100     https://github.com/Matroska-Org/matroska-specification/blob/master/codec/av1.md
 101 */
 102 static inline block_t * AV1_Unpack_Sample(block_t *p_block)
 103 {
 104     /* Restore last size field if missing */
 105     p_block = AV1_Unpack_Sample_ExpandSize(p_block);
 106     /* Reinsert removed TU: See av1-isobmff 2.4 */
 107     if(p_block &&
 108        (p_block->p_buffer[0] & 0x81) == 0 && /* reserved flags */
 109        (p_block->p_buffer[0] & 0x7A) != 0x12) /* no TEMPORAL_DELIMITER */
 110     {
 111         p_block = block_Realloc(p_block, 2, p_block->i_buffer);
 112         if(p_block)
 113         {
 114             p_block->p_buffer[0] = 0x12;
 115             p_block->p_buffer[1] = 0x00;
 116         }
 117     }
 118     return p_block;
 119 }
 120
 121 #endif