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
  22 #include "libavutil/intreadwrite.h"
  23 #include "avformat.h"
  24 #include "avio.h"
  25
  26 const uint8_t *ff_avc_find_startcode(const uint8_t *p, const uint8_t *end)
  27 {
  28     const uint8_t *a = p + 4 - ((intptr_t)p & 3);
  29
  30     for (end -= 3; p < a && p < end; p++) {
  31         if (p[0] == 0 && p[1] == 0 && p[2] == 1)
  32             return p;
  33     }
  34
  35     for (end -= 3; p < end; p += 4) {
  36         uint32_t x = *(const uint32_t*)p;
  37 //      if ((x - 0x01000100) & (~x) & 0x80008000) // little endian
  38 //      if ((x - 0x00010001) & (~x) & 0x00800080) // big endian
  39         if ((x - 0x01010101) & (~x) & 0x80808080) { // generic
  40             if (p[1] == 0) {
  41                 if (p[0] == 0 && p[2] == 1)
  42                     return p-1;
  43                 if (p[2] == 0 && p[3] == 1)
  44                     return p;
  45             }
  46             if (p[3] == 0) {
  47                 if (p[2] == 0 && p[4] == 1)
  48                     return p+1;
  49                 if (p[4] == 0 && p[5] == 1)
  50                     return p+2;
  51             }
  52         }
  53     }
  54
  55     for (end += 3; p < end; p++) {
  56         if (p[0] == 0 && p[1] == 0 && p[2] == 1)
  57             return p;
  58     }
  59
  60     return end + 3;
  61 }
  62
  63 int ff_avc_parse_nal_units(ByteIOContext *pb, const uint8_t *buf_in, int size)
  64 {
  65     const uint8_t *p = buf_in;
  66     const uint8_t *end = p + size;
  67     const uint8_t *nal_start, *nal_end;
  68
  69     size = 0;
  70     nal_start = ff_avc_find_startcode(p, end);
  71     while (nal_start < end) {
  72         while(!*(nal_start++));
  73         nal_end = ff_avc_find_startcode(nal_start, end);
  74         put_be32(pb, nal_end - nal_start);
  75         put_buffer(pb, nal_start, nal_end - nal_start);
  76         size += 4 + nal_end - nal_start;
  77         nal_start = nal_end;
  78     }
  79     return size;
  80 }
  81
  82 int ff_avc_parse_nal_units_buf(const uint8_t *buf_in, uint8_t **buf, int *size)
  83 {
  84     ByteIOContext *pb;
  85     int ret = url_open_dyn_buf(&pb);
  86     if(ret < 0)
  87         return ret;
  88
  89     ff_avc_parse_nal_units(pb, buf_in, *size);
  90
  91     av_freep(buf);
  92     *size = url_close_dyn_buf(pb, buf);
  93     return 0;
  94 }
  95
  96 int ff_isom_write_avcc(ByteIOContext *pb, const uint8_t *data, int len)
  97 {
  98     if (len > 6) {
  99         /* check for h264 start code */
 100         if (AV_RB32(data) == 0x00000001 ||
 101             AV_RB24(data) == 0x000001) {
 102             uint8_t *buf=NULL, *end, *start;
 103             uint32_t sps_size=0, pps_size=0;
 104             uint8_t *sps=0, *pps=0;
 105
 106             int ret = ff_avc_parse_nal_units_buf(data, &buf, &len);
 107             if (ret < 0)
 108                 return ret;
 109             start = buf;
 110             end = buf + len;
 111
 112             /* look for sps and pps */
 113             while (buf < end) {
 114                 unsigned int size;
 115                 uint8_t nal_type;
 116                 size = AV_RB32(buf);
 117                 nal_type = buf[4] & 0x1f;
 118                 if (nal_type == 7) { /* SPS */
 119                     sps = buf + 4;
 120                     sps_size = size;
 121                 } else if (nal_type == 8) { /* PPS */
 122                     pps = buf + 4;
 123                     pps_size = size;
 124                 }
 125                 buf += size + 4;
 126             }
 127             assert(sps);
 128             assert(pps);
 129
 130             put_byte(pb, 1); /* version */
 131             put_byte(pb, sps[1]); /* profile */
 132             put_byte(pb, sps[2]); /* profile compat */
 133             put_byte(pb, sps[3]); /* level */
 134             put_byte(pb, 0xff); /* 6 bits reserved (111111) + 2 bits nal size length - 1 (11) */
 135             put_byte(pb, 0xe1); /* 3 bits reserved (111) + 5 bits number of sps (00001) */
 136
 137             put_be16(pb, sps_size);
 138             put_buffer(pb, sps, sps_size);
 139             put_byte(pb, 1); /* number of pps */
 140             put_be16(pb, pps_size);
 141             put_buffer(pb, pps, pps_size);
 142             av_free(start);
 143         } else {
 144             put_buffer(pb, data, len);
 145         }
 146     }
 147     return 0;
 148 }