modules/packetizer/hxxx_nal.c

   1 /*****************************************************************************
   2  * Copyright © 2015 VideoLAN Authors
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU Lesser General Public License as published by
   6  * the Free Software Foundation; either version 2.1 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  12  * GNU Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public License
  15  * along with this program; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  17  *****************************************************************************/
  18 #ifdef HAVE_CONFIG_H
  19 # include "config.h"
  20 #endif
  21
  22 #include "hxxx_nal.h"
  23
  24 #include <vlc_block.h>
  25
  26 static bool block_WillRealloc( block_t *p_block, ssize_t i_prebody, size_t i_body )
  27 {
  28     if( i_prebody <= 0 && i_body <= (size_t)(-i_prebody) )
  29         return false;
  30     else
  31         return ( i_prebody + i_body <= p_block->i_size );
  32 }
  33
  34 static inline void hxxx_WritePrefix( uint8_t i_nal_length_size, uint8_t *p_dest, uint32_t i_payload )
  35 {
  36     if( i_nal_length_size == 4 )
  37         SetDWBE( p_dest, i_payload );
  38     else if( i_nal_length_size == 2 )
  39         SetWBE( p_dest, i_payload );
  40     else
  41         *p_dest = i_payload;
  42 }
  43
  44 block_t *hxxx_AnnexB_to_xVC( block_t *p_block, uint8_t i_nal_length_size )
  45 {
  46     unsigned i_nalcount = 0;
  47     unsigned i_list = 16;
  48     struct nalmoves_e
  49     {
  50         const uint8_t *p; /* start of prefixed nal */
  51         uint8_t  prefix; /* startcode length */
  52         off_t    move; /* move offset */
  53     } *p_list = NULL;
  54
  55     if(!p_block->i_buffer || p_block->p_buffer[0])
  56         goto error;
  57
  58     if(! (p_list = malloc( sizeof(*p_list) * i_list )) )
  59         goto error;
  60
  61     /* Search all startcode of size 3 */
  62     const uint8_t *p_buf = p_block->p_buffer;
  63     const uint8_t *p_end = &p_block->p_buffer[p_block->i_buffer];
  64     unsigned i_bitflow = 0;
  65     off_t i_move = 0;
  66     while( p_buf != p_end )
  67     {
  68         i_bitflow <<= 1;
  69         if( !*p_buf )
  70         {
  71             i_bitflow |= 1;
  72         }
  73         else if( *p_buf == 0x01 && (i_bitflow & 0x06) == 0x06 ) /* >= two zero prefixed 1 */
  74         {
  75             if( i_bitflow & 0x08 ) /* three zero prefixed 1 */
  76             {
  77                 p_list[i_nalcount].p = &p_buf[-3];
  78                 p_list[i_nalcount].prefix = 4;
  79             }
  80             else /* two zero prefixed 1 */
  81             {
  82                 p_list[i_nalcount].p = &p_buf[-2];
  83                 p_list[i_nalcount].prefix = 3;
  84             }
  85             i_move += (off_t) i_nal_length_size - p_list[i_nalcount].prefix;
  86             p_list[i_nalcount++].move = i_move;
  87
  88             /* Check and realloc our list */
  89             if(i_nalcount == i_list)
  90             {
  91                 i_list += 16;
  92                 struct nalmoves_e *p_new = realloc( p_list, sizeof(*p_new) * i_list );
  93                 if(unlikely(!p_new))
  94                     goto error;
  95                 p_list = p_new;
  96             }
  97         }
  98         p_buf++;
  99     }
 100
 101     if( !i_nalcount )
 102         goto error;
 103
 104     /* Optimization for 1 NAL block only case */
 105     if( i_nalcount == 1 && block_WillRealloc( p_block, p_list[0].move, p_block->i_buffer ) )
 106     {
 107         uint32_t i_payload = p_block->i_buffer - p_list[0].prefix;
 108         block_t *p_newblock = block_Realloc( p_block, p_list[0].move, p_block->i_buffer );
 109         if( unlikely(!p_newblock) )
 110             goto error;
 111         p_block = p_newblock;
 112         hxxx_WritePrefix( i_nal_length_size, p_block->p_buffer , i_payload );
 113         free( p_list );
 114         return p_block;
 115     }
 116
 117     block_t *p_release = NULL;
 118     const uint8_t *p_source = NULL;
 119     const uint8_t *p_sourceend = NULL;
 120     uint8_t *p_dest = NULL;
 121     const size_t i_dest = p_block->i_buffer + p_list[i_nalcount - 1].move;
 122
 123     if( p_list[i_nalcount - 1].move != 0 || i_nal_length_size != 4 )  /* We'll need to grow or shrink */
 124     {
 125         /* If we grow in size, try using realloc to avoid memcpy */
 126         if( p_list[i_nalcount - 1].move > 0 && block_WillRealloc( p_block, 0, i_dest ) )
 127         {
 128             uint32_t i_sizebackup = p_block->i_buffer;
 129             block_t *p_newblock = block_Realloc( p_block, 0, i_dest );
 130             if( unlikely(!p_newblock) )
 131                 goto error;
 132
 133             p_block = p_newblock;
 134             p_sourceend = &p_block->p_buffer[i_sizebackup];
 135             p_source = p_dest = p_block->p_buffer;
 136         }
 137         else
 138         {
 139             block_t *p_newblock = block_Alloc( i_dest );
 140             if( unlikely(!p_newblock) )
 141                 goto error;
 142
 143             p_release = p_block; /* Will be released after use */
 144             p_source = p_release->p_buffer;
 145             p_sourceend = &p_release->p_buffer[p_release->i_buffer];
 146
 147             p_block = p_newblock;
 148             p_dest = p_newblock->p_buffer;
 149         }
 150     }
 151     else
 152     {
 153         p_source = p_dest = p_block->p_buffer;
 154         p_sourceend = &p_block->p_buffer[p_block->i_buffer];
 155     }
 156
 157     if(!p_dest)
 158         goto error;
 159
 160     /* Do reverse order moves, so we never overlap when growing only */
 161     for( unsigned i=i_nalcount; i!=0; i-- )
 162     {
 163         const uint8_t *p_readstart = p_list[i - 1].p;
 164         uint32_t i_payload = p_sourceend - p_readstart - p_list[i - 1].prefix;
 165         off_t offset = p_list[i - 1].p - p_source + p_list[i - 1].prefix + p_list[i - 1].move;
 166 //        printf(" move offset %ld, length = %ld  prefix %ld move %ld\n", p_readstart - p_source, i_payload, p_list[i - 1].prefix, p_list[i-1].move);
 167
 168         /* move in same / copy between buffers */
 169         memmove( &p_dest[ offset ], &p_list[i - 1].p[ p_list[i - 1].prefix ], i_payload );
 170
 171         hxxx_WritePrefix( i_nal_length_size, &p_dest[ offset - i_nal_length_size ] , i_payload );
 172
 173         p_sourceend = p_readstart;
 174     }
 175
 176     if( p_release )
 177         block_Release( p_release );
 178     free( p_list );
 179     return p_block;
 180
 181 error:
 182     free( p_list );
 183     block_Release( p_block );
 184     return NULL;
 185 }