libavformat/avc.c

   1 /*
   2  * AVC helper functions for muxers
   3  * Copyright (c) 2006 Baptiste Coudurier <baptiste.coudurier@smartjog.com>
   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
  20  */
  21 #include "avformat.h"
  22 #include "avio.h"
  23
  24 const uint8_t *ff_avc_find_startcode(const uint8_t *p, const uint8_t *end)
  25 {
  26     const uint8_t *a = p + 4 - ((long)p & 3);
  27
  28     for( end -= 3; p < a && p < end; p++ ) {
  29         if( p[0] == 0 && p[1] == 0 && p[2] == 1 )
  30             return p;
  31     }
  32
  33     for( end -= 3; p < end; p += 4 ) {
  34         uint32_t x = *(const uint32_t*)p;
  35 //      if( (x - 0x01000100) & (~x) & 0x80008000 ) // little endian
  36 //      if( (x - 0x00010001) & (~x) & 0x00800080 ) // big endian
  37         if( (x - 0x01010101) & (~x) & 0x80808080 ) { // generic
  38             if( p[1] == 0 ) {
  39                 if( p[0] == 0 && p[2] == 1 )
  40                     return p-1;
  41                 if( p[2] == 0 && p[3] == 1 )
  42                     return p;
  43             }
  44             if( p[3] == 0 ) {
  45                 if( p[2] == 0 && p[4] == 1 )
  46                     return p+1;
  47                 if( p[4] == 0 && p[5] == 1 )
  48                     return p+2;
  49             }
  50         }
  51     }
  52
  53     for( end += 3; p < end; p++ ) {
  54         if( p[0] == 0 && p[1] == 0 && p[2] == 1 )
  55             return p;
  56     }
  57
  58     return end + 3;
  59 }
  60
  61 int ff_avc_parse_nal_units(const uint8_t *buf_in, uint8_t **buf, int *size)
  62 {
  63     ByteIOContext *pb;
  64     const uint8_t *p = buf_in;
  65     const uint8_t *end = p + *size;
  66     const uint8_t *nal_start, *nal_end;
  67     int ret = url_open_dyn_buf(&pb);
  68     if(ret < 0)
  69         return ret;
  70
  71     nal_start = ff_avc_find_startcode(p, end);
  72     while (nal_start < end) {
  73         while(!*(nal_start++));
  74         nal_end = ff_avc_find_startcode(nal_start, end);
  75         put_be32(pb, nal_end - nal_start);
  76         put_buffer(pb, nal_start, nal_end - nal_start);
  77         nal_start = nal_end;
  78     }
  79     av_freep(buf);
  80     *size = url_close_dyn_buf(pb, buf);
  81     return 0;
  82 }
  83
  84 int ff_isom_write_avcc(ByteIOContext *pb, const uint8_t *data, int len)
  85 {
  86     if (len > 6) {
  87         /* check for h264 start code */
  88         if (AV_RB32(data) == 0x00000001) {
  89             uint8_t *buf=NULL, *end, *start;
  90             uint32_t sps_size=0, pps_size=0;
  91             uint8_t *sps=0, *pps=0;
  92
  93             int ret = ff_avc_parse_nal_units(data, &buf, &len);
  94             if (ret < 0)
  95                 return ret;
  96             start = buf;
  97             end = buf + len;
  98
  99             /* look for sps and pps */
 100             while (buf < end) {
 101                 unsigned int size;
 102                 uint8_t nal_type;
 103                 size = AV_RB32(buf);
 104                 nal_type = buf[4] & 0x1f;
 105                 if (nal_type == 7) { /* SPS */
 106                     sps = buf + 4;
 107                     sps_size = size;
 108                 } else if (nal_type == 8) { /* PPS */
 109                     pps = buf + 4;
 110                     pps_size = size;
 111                 }
 112                 buf += size + 4;
 113             }
 114             assert(sps);
 115             assert(pps);
 116
 117             put_byte(pb, 1); /* version */
 118             put_byte(pb, sps[1]); /* profile */
 119             put_byte(pb, sps[2]); /* profile compat */
 120             put_byte(pb, sps[3]); /* level */
 121             put_byte(pb, 0xff); /* 6 bits reserved (111111) + 2 bits nal size length - 1 (11) */
 122             put_byte(pb, 0xe1); /* 3 bits reserved (111) + 5 bits number of sps (00001) */
 123
 124             put_be16(pb, sps_size);
 125             put_buffer(pb, sps, sps_size);
 126             put_byte(pb, 1); /* number of pps */
 127             put_be16(pb, pps_size);
 128             put_buffer(pb, pps, pps_size);
 129             av_free(start);
 130         } else {
 131             put_buffer(pb, data, len);
 132         }
 133     }
 134     return 0;
 135 }